Vitamin D benefit and side effects, risks, dangers, harm of excess dosage, foods that contain it, cancer protection, and discussion of deficiency - Are too many doctors recommending unnecessary blood testing? Is there a risk or danger of taking too much? by Ray Sahelian, M.D.
November 20 2016

There has been a lot of attention given lately to this vitamin and many people are starting to take high dosages and doctors are recommending routine testing for blood levels. Are these justified or are some people putting their health in danger by taking very high amounts and wasting money on blood testing? Is there a risk that high dosages will lead to calcification of various tissues in the body, including brain tissue? This article provides you with my honest and balanced opinion. Make sure you read at least half way down the page where I review the potential dangers of excessive dosage that many doctors may not be aware of.

Vitamin D plays an important role in calcium balance and for skeletal growth and bone strength. The major role is to improve calcium absorption from the small intestine. Research shows low levels lead to a higher incidence of breast cancer, colon cancer, prostate cancer, ovarian cancer, as well as multiple myeloma. Patients with Crohn's disease are known to have low levels. Vitamin D supplementation may even decrease symptoms of depression during the winter months. Many other benefits are constantly being discovered. Vitamin D plays several roles in the body, influencing bone health as well as serum calcium and phosphate levels. Furthermore, it may modify immune function, cell proliferation, differentiation and apoptosis.
   Delivering vitamin D supplements to homebound seniors might help lower their risk of falls. Previous research has found vitamin D plays an important role in maintaining muscle strength, and some studies have suggested vitamin D may help prevent falls, Wake Forest Baptist Medical Center, news release, Aug. 18, 2015.

The routine recommended daily intake of vitamin D by various medical organizations is 400 iu to 800 units for adults younger than 50 years and 600 iu to 1000 units for those older than 70 years. IU means international units. Vitamin D supplementation is especially important in the elderly because skin synthesis and absorption may be impaired. As time goes on, the scientific community is recognizing that perhaps higher amounts may be appropriate, perhaps up to 1,000 or 2,000 iu a day, but more time is needed to determine whether higher intake through supplementation is safe.

Are you taking too much?
Few people now question the importance of this vitamin, and with the benefits being touted in the media (without mention of potential problems), many consumers, and doctors, now think that the more they take the healthier they will be. I want to caution you of the risk regarding excessive intake. Vitamin D taken in high amounts can cause excessive calcification of bone, calcification of soft tissues, kidney stones, headaches, weakness, nausea, and vomiting. Are there currently unknown long term effects of daily high dose use? Does the production of this vitamin through sun exposure influence the body differently than through pill intake?

My current recommendations (I may change my mind as more research is published):
Some people may not need to supplement since their diet includes plenty of the vitamin and they get a lot of sun exposure. In a study with Asian subjects, 45 min sunlight exposure at noon of a casually clothed individuals exposing about 30 percent of their body to sun, 3 times a week for 6 weeks, led to an average increase in the blood level of about 8 ng/ml. Am J Clin Nutr. June 2013. Efficacy of a dose range of simulated sunlight exposures in raising vitamin D status in South Asian adults.Most people may benefit from taking 400 units to 1000 iu a day either as a separate pill or as part of their multivitamin product (in addition to their diet and some sun exposure which could be several hundred units a day).
A few people -- those who do not consume much of this vitamin in their diet, live in Northern latitudes, or some elderly who get little sun -- may benefit from taking 600 to 2000 units daily. More is needed in the winter season and less in the summer season.
Those who have hardly any sun exposure, or have certain chronic medical conditions, may need 2000 to 3000 units a day for a few weeks or months and then down to 1000 to 2000 units daily.
The vast majority of people do not need to be monitored by blood tests. Just take 1000 units a day if you are not sure if you are getting enough and don't waste time and money on regular blood tests.There is no need for the vast majority of Americans to take more than 2,000 units a day for the long run.
There could be a detriment to taking 5,000 or 10,000 units a day. Many people are taking an unnecessary gamble taking these very high amounts.
I do not think that the average person with a good diet and some regular sun exposure needs to take more than 1000 iu a day as a supplement. I have received emails from some doctors who claim I am being too cautious. I would rather err on the side of taking less until long term studies are published regarding the safety of supplementing with 5000 units or more taken daily for a decade or several decades. If such studies do get published in the next few years that show the safety of high dose supplementation, I will change my recommendations. At this time I certainly do not think the 5000 iu pills being promoted are appropriate for the vast majority of the population, and certainly not the 10,000 iu pills. Could people taking these high dosages end up dying sooner due to excessive calcification of their blood vessels and soft tissues? There is some early indication that high dosages of vitamin D could cause calcification of vessels in the brain leading to mental decline. Could excess intake lead to calcification of various tissues in the body including the sinus node and atrial node responsible for heart rhythm maintenance? What about interactions with other medications and supplements? Could taking high doses of calcium along with these excessive doses of vitamin D make matters even worse?As with many natural vitamins and supplements, too low a dosage can be detrimental to health and too high an intake can have adverse effects.

2011 studies, danger to heart
People with excessive blood levels from overdosing with supplements had an increased incidence of atrial fibrillation and levels of CRP, C-reactive-protein, a marker for inflammation.

2010 study. Potential risk and harm to health: Researchers measured vitamin D levels and assessed frailty in thousands of women aged 69 and older. Women were considered to be frail if they had symptoms such as a slow walking speed, weak hand grip or exhaustion. The risk of frailty was lowest among women with vitamin D levels between 20 nanograms and 30 nanograms per milliliter and highest among women with levels less than 20 ng/ml and more than 30 ng/ml. Dr. Kristine Ensrud, a professor of medicine and epidemiology at Minneapolis VA Medical Center and the University of Minnesota, reports, "The industry-sponsored Vitamin D Council recommends a "minimal acceptable" blood level of 50 ng/ml. Dr. Kristine Ensrud questions this. She says, "Our study did not find that higher vitamin D status [more than 30 ng/ml] was associated with lower subsequent risks of frailty or death. In fact, higher levels of vitamin D were associated with increased likelihood of frailty.

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This MultiVit Rx supplement product has 400 units.




Side effects, caution, safety, danger, toxicity, harm of taking too much
High dosages of vitamin D may cause short term or long term side effects. Excess intake makes the intestines absorb too much calcium. Headache, nausea, vomiting, loss of appetite, dry mouth, abdominal or bone pain, muscle pain, fatigue and dizziness are some of the symptoms of vitamin D toxicity. Itching, impaired kidney function, calcification of organs and blood vessels, osteoporosis, and seizures are other signs that develop at the later stages.
   The vitamin D receptor is now known to be present in dozens of tissues. It is possible that taking high dosages can reduce cancer incidence, but it could increase the incidence of other medical conditions. Until more research is published regarding the influence of high dose intake over a decade or more, I prefer keeping dosages to below 2000 units a day unless a person has a severe deficiency. High dosages could cause atrial fibrillation or cause other types of cardiovascular problems.

Side effect testimonials
I was reading your info regarding Vit D and the side effects of taking too much. A year ago my dr prescribed me to take a round of Vit D 50,000. After that she did another blood test and advised me to take 5000 daily. Over the past year I have been gradually developing, joint pain. Starting first in my right hand... almost felt like I was getting arthritis. It's gotten to the point where I get pain either in my hand, my elbow, my bicep, shoulder and/or collar bone on a daily basis. It's disrupted my sleeping on a nightly basis. I cannot reach behind me as I use to and even putting my hand on my hip causes pain. I mentioned this to my dr...without even examining my arm she felt that it was a rotator cuff sprain and gave me a prescription for an anti-inflammatory which hasn't been helpful. She said that if that didn't work then I would need an MRI. I have been trying to tough it out but as I said, it's been a gradual progression and it's gotten to the point where I'm at my wits end with the pain and lack of sleep. Last nite it dawned on me the correlation between me starting Vit D and having all these symptoms. Between your article and another website, I noticed where it can cause joint and muscle pain as well muscle weakness all of which I am experiencing. So this morning I decided to stop taking Vit D with the exception of the 500 mg that is already in my daily vitamin.

Thank you once again for your fair and unbiased reporting of the good and bad effects of different supplements. I seem to be having the vitamin D side effects and am going to stop supplementing it immediately, I just hope it goes back to normal. Almost immediately after taking 2000IU once or twice a day I started having very bad joint and muscle pain, especially in the knees. I generally eat healthy and get great exercise. I didn't put two and two together as most sites said you would need way more than that to have toxicity.

I had been taking 8000 iu's of vitamin d3 for neuropathy for several months. And, separately I was taking a calcium supplement with d which probably put me over 10000 iu's altogether. Unfortunately a few weeks ago I woke up with numbness in my hands and feet as well as a burning sensation down my calves and ankles. Although I did not attribute these side effects immediately to the d3 I eventually stopped the supplement altogether. Currently my numbness is slightly better but the burning sensation comes and goes. From your extensive research can you tell me whether these symptoms are in fact a side effect of the d3 and will these symptoms go away on their own or will I have to seek medical attention to help me deal with this problem.
   A. Although I have not come across numbness and burning sensation as specific vitamin D side effects, not enough is known about the long term adverse reactions to high dose use and I would not rule out the supplement as a cause.

Brain lesions, cognitive impairment, dementia risk:
Duke University researchers connect high vitamin D with brain lesions. See

Vitamin D and vascular calcification.
Vascular calcification is frequently found in patients with osteoporosis, atherosclerosis and chronic kidney disease, leading to high morbidity and mortality rates. The effects of vitamin D excess and deficiency on vascular calcification are reviewed in this article. There is evidence from experimental studies that mediacalcinosis induced by vitamin D excess is an active and reversible process. Vitamin D excess, however, is rarely seen in the general human population. Experimental data also demonstrate that physiologic vitamin D actions include the inhibition of processes that are important for intimal and medial artery calcification such as pro-inflammatory cytokine release, adhesion molecule release, and proliferation and migration of vascular smooth muscle cells. Available data indicate that vitamin D exerts a biphasic 'dose response' curve on vascular calcification with deleterious consequences not only of vitamin D excess but also of vitamin D deficiency. Curr Opin Lipidol. 2007. Department of Cardiothoracic Surgery, Northrhine Westfalia Heart Center, Ruhr University Bochum, Bad Oeynhausen, Germany.

Readers send us their feedback and experiences
We had an email from someone who claims high dosages caused excitation and excess energy and here are other emails we have received:

My personal effort to raise blood level of Vit D 25 OH with higher doses of Vit D3 (upwards of 7000 IU) led to a strange elevation in blood pressure, from 115/70 to 180/90. I double checked. Now I take only 2000 IU without elevation of blood pressure. This may only be a personal reaction, but worth consideration by your readers.

My physician prescribed 50000 iu vitamin d to be taken once per week. I took my first dose on a Friday, felt wonderful over the weekend but by Monday I had dizziness, felt exhausted, toxic, had a headache, my head felt constricted. I felt so tired I could not stay awake.

I am a medical student at UIC (University of Illinois) and I am studying for my board exam. These taking large doses of this vitamin who experience jitteryness and whole body anxiety are likely suffering from hypervitaminosis D. Although typically this takes months to develop, its symptoms include irritability. By inducing hypercalcemia they may also be at risk for hypertension.

Once again Dr. Sahelian brings calm, sound advice. Because of him, awhile back I decreased my level of DHEA with great results. I recently got on the band wagon regarding supplementing, ie 1000 iu every couple days and then 10,000 iu for three days trying to avoid the flu, hardly a massive amount compared to many people. My symptoms on third day were massive headache and over the last couple weeks, excessive thirst, lung sensitivity (different than ever had before), itchy feeling in chest (never before had), almost feeling asthmatic (not one). Took me awhile to even suspect the vitamin D and when I did, kept finding out overdose would almost be impossible at this dose and length of time. I'm glad doctors are starting to use supplements occasionally instead of going straight to pharmaceuticals. But constraint is still needed on their part as well as people like me. Next time I will always go to Dr. Sahelian's site as I know he is wise enough to not get carried away with the newest fad. Thank you so much to Dr. Sahelian and this staff.

In your e-newsletter you printed an email from someone who had reacted to high dose vitamin D with anxiety. I believe she was taking 3,000 units daily. You asked if anyone else had these reactions. I am currently on 4,000 units daily, 5 days per week, plus a prescription dose of 50,000 units, 2 days per week. This is due to deficiency since I almost never go outside for any length of time due to allergy to stinging insects (I'd been stung 6 times in 3 years). Also, my doctor wants me to be at an optimal level, since I have 2 precancerous growths (stomach and right eye). There is a strong history of stomach cancer in my family. I started with a vitamin D level of 31. It is now up to 51, and the goal is 65. It has definitely increased my anxiety. I was already on Xanax for muscle spasms that kept me from walking, and have now had to increase the dosage for only the second time in 24 years of taking it. I already take a high dose of L-tryptophan. Nothing seems to help. Luckily, I am now at a high enough level of vit. D that I should be cutting back soon. I had no trouble at all on 4,000 units daily.

I started to take 5000 IU of vitamin d-3 daily, because I almost get no sunshine for a few years. After a few weeks of using it, I had numbness in my hands while I was asleep. Sometimes it woke me up, sometimes I couldn't feel my hand when I wake up in the morning. I had to shake my hand for a few seconds, so I could feel it again. I even had numbness in sacrum part if I sit for long hours. After stopping vitamin d, these problems disappeared. I'm getting 1000 IU now which is included in my multi, there is no problem with 1000 IU either. Do you have any idea about his? Why would vitamin d-3 cause such problems?
    It's possible that high dosages in your case may cause nerve damage or numbness in nerves. I don't have a good understanding of the full biochemical effects of this hormone.

Sun exposure a few minutes a day
A few minutes a day of midday summer sun can raise most fair-skinned people's vitamin D levels to sufficient, but not optimal, levels. Those with darker skin need longer time of exposure. The skin's production of vitamin D upon exposure to ultraviolet B radiation in sunlight is the body's predominant source for the hornone. Dr. Lesley E. Rhodes of Salford Royal NHS Foundation Hospital in Manchester  exposed 109 fair-skinned men and women to light equivalent to 13 minutes of midday summer sun three times a week for six weeks. Study participants wore shorts and T-shirts during their brief sun baths. The study was done during the winter months, when people would be getting very little vitamin D from sunlight, to focus on the effects of the sun baths. All of the study participants had low vitamin D intakes, and none were taking vitamin D supplements. Participants' average blood level of vitamin D rose from around 18 nanograms per milliliter to 28 nanograms per milliliter. Some doctors think 20 nanograms per milliliter and above is sufficient, and 32 nanograms per milliliter and above is optimal whereas other doctors think people should have a minimum of 40ng/ml. Based on the results, Dr. Lesley E. Rhodes predicted that with this amount of sun exposure, 90 percent of white adults in Manchester under the age of 65 would have sufficient vitamin D levels, while 26 percent would have optimal levels. Depending on latitude, the average amount of sun exposure required for similar effects in North America would range from nine to 16 minutes. Journal of Investigative Dermatology, online January 14, 2010.
How it is made
When humans are exposed to sunlight, 7-dehydrocholesterol in the skin absorbs UVB (290–315 nm) radiation resulting in the production of vitamin D3, also known as cholecalciferol. Vitamin D3 is found naturally in cod liver oil and oily fish such as salmon. Vitamin D3 is also made by irradiating 7-dehydrocholesterol obtained from lanolin from sheep’s wool with UVB radiation. Vitamin D2, known as ergocalciferol, which comes from the UV irradiation of ergosterol obtained from yeast, has been the mainstay for the prevention and treatment of vitamin D deficiency in children and adults.
   Both vitamin D2 and vitamin D3 when ingested undergo metabolism in the liver to form 25-hydroxyvitamin D [25(OH)D; D represents either D2 or D3] and in the kidneys to 1,25-dihydroxyvitamin D. Both vitamin D2 and vitamin D3 are available in supplements, but only vitamin D2 is available as a pharmaceutical preparation because its use predated the Food and Drug Administration and, thus, was grandfathered as a pharmaceutical drug. Vitamin D3 was commercially developed in the 1950s and has not been approved as a pharmaceutical agent in the United States but is used in food supplementation and vitamin supplements.

During sun exposure, the solar ultraviolet B photons (290-315 nm) penetrate the skin where they cause the photolysis of 7-dehydrocholesterol to precholecalciferol. Once formed, precholecalciferol undergoes a rearrangement of its double bonds to form cholecalciferol. Those who are dark skinned and older make less. Application of sunscreen reduces production.

Through windows and glass
Because windowpane glass absorbs ultraviolet B radiation, exposure of sunlight through glass windows will result in little or production of cholecalciferol.

The best known vitamin D benefit is in keeping bones and teeth strong and healthy. Vitamin D helps regulate the growth and activity of cells and it reduces inflammation. There are dozens of receptors in the body that this prohormone can have an effect on.
   People with higher levels of vitamin D are less likely to suffer autoimmune diseases, including type 1 diabetes and multiple sclerosis. They may even have less heart disease and better lung function. Vitamin D does far more than aid calcium absorption. Vitamin D has a benefit on the immune system — which explains its effect on autoimmune diseases. Biochemical studies suggest that it helps keep cells from becoming malignant — and when cells do go bad, it encourages them to self-destruct. Scientists suspect the vitamin has still other functions. Tissues throughout the body have receptors for vitamin D.
    Vitamin D has other benefits: It reduces the risk for of chronic diseases, including type 2 diabetes, heart disease, osteoporosis, and probably cancers such as breast cancer, colon cancer, and ovarian cancer.

Note: Dozens of studies have shown that people with high levels in their blood have lower rates of diseases and a lower death rate. However, that doesn't prove that people can lower their risk of illness by taking a supplement to raise their vitamin D level. Perhaps sun exposure itself, being active outside, or other factors associated with high blood levels of vitamin D in the blood, influence disease risk. Previous research had suggested that high levels of beta carotene were associated with lower rates of cancer, but when people took beta carotene supplements as part of a clinical trial, they were more likely to die from cancer. Thus far it appears that those with low levels of this hormone can improve their health by taking supplements, but more evidence is needed to prove this likely hypothesis.

Cancer prevention
Cancer researchers are urging people to take a vitamin D supplement to lower their risk of colon, pancreatic, prostate, breast and ovarian cancer, saying studies showed a clear link.

Breast cancer prevention or treatment
Supplementation appears to reduce the risk for breast cancer.

Breast cells have receptors for vitamin D, raising the possibility that the nutrient could help regulate the division and proliferation of these cells; there's also growing evidence that vitamin D could help protect against other types of cancer. Laura N. Anderson, a doctoral student at Cancer Care Ontario in Toronto, sought to separate out the effects of vitamin D and calcium on breast cancer risk by surveying 3,101 breast cancer patients and 3,471 healthy controls about their intake of food and supplements. No relationship between overall vitamin D intake and breast cancer risk was found; nor was there any association between overall calcium intake and risk of the disease. However, women who reported taking at least 400 international units of vitamin D every day were at 24 percent lower risk of developing breast cancer. American Journal of Clinical Nutrition, online April 14, 2010.

Vitamin D and prevention of breast cancer: pooled analysis.
Inadequate photosynthesis or oral intake of Vitamin D are associated with high incidence and mortality rates of breast cancer in ecological and observational studies, but the dose-response relationship in individuals has not been adequately studied. A literature search for all studies that reported risk by of breast cancer by quantiles of 25(OH)D identified two studies with 1760 individuals. Data were pooled to assess the dose-response association between serum 25(OH)D and risk of breast cancer. According to the pooled analysis, individuals with serum 25(OH)D of approximately 52 ng/ml had 50% lower risk of breast cancer than those with serum <13 ng/ml. This serum level corresponds to intake of 4000 IU/day. This exceeds the National Academy of Sciences upper limit of 2000 IU/day. A 25(OH)D level of 52 ng/ml could be maintained by intake of 2000 IU/day and, when appropriate, about 12 min/day in the sun, equivalent to oral intake of 3000 IU of Vitamin D(3). Intake of 2000 IU/day of Vitamin D(3), and, when possible, very moderate exposure to sunlight, could raise serum 25(OH)D to 52 ng/ml, a level associated with reduction by 50% in incidence of breast cancer, accorMarch; Garland CF, Gorham ED, Mohr SB, Grant WB, Giovannucci EL, Lipkin M, Newmark H, Holick MF, Garland FC. Department of Family and Preventive Medicine, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA, USA.
    Comments: Those who had higher levels of vitamin D probably were outside more often, did they exercise more? Did they sleep better due to exercise and sun exposure? Did these influence breast cancer risk also and not just the vitamin D production?

Colon cancer prevention
When epidemiologists began mapping the incidence of colon cancer in the United States back in the 1970s, they noted a curious pattern. People in the South were half as likely to die of colon cancer as those in the Northeast. Could the reason be the sunshine vitamin D?

Optimal vitamin D status for colorectal cancer prevention: a quantitative meta analysis.
Previous studies, such as the Women's Health Initiative, have shown that a low dose of vitamin D did not protect against colorectal cancer. Five studies of serum 25(OH)D in association with colorectal cancer risk were identified using PubMed. A 50% lower risk of colorectal cancer was associated with a serum 25(OH)D level > or =33 ng/mL, compared to < or =12 ng/mL. The evidence to date suggests that daily intake of 1000-2000 IU/day could reduce the incidence of colorectal with minimal risk.
Am J Prev Med. 2007. University of California San Diego, Department of Family and Preventive Medicine, School of Medicine, La Jolla, California, USA.

Dr. Mazda Jenab of the International Agency for Research on Cancer in Lyon, France, reports that among more than 1200 people who developed colorectal cancer and an equal number who did not, those with the highest levels of vitamin D in their blood had a nearly 40 percent reduced risk of developing colorectal cancer compared to those with the lowest levels. Dr. Mazda Jenab cautions that this has to be balanced regarding the potential toxic effects of too much vitamin D and the fact that very little is known about its association with either increased or reduced risk of other cancers. British Medical Journal Online First, Jan 22, 2010.

Lung cancer
Plenty of sunshine and vitamin D may help people with early stage lung cancer survive longer after surgery. Patients who have high levels of vitamin D and had lung cancer surgery in sunny months are more than twice as likely to be alive five years after surgery compared to patients with low levels who had surgery in the winter.

Osteoarthritis, arthritis
J Nutr. 2014. Vitamin d deficiency is associated with progression of knee osteoarthritis.

Pancreatic cancer
Consumption of Vitamin D tablets was found to cut the risk of pancreatic cancer by 40 percent, according to a study led by researchers at Northwestern and Harvard universities. The study, led by Halcyon Skinner, Ph.D., of Northwestern, appears in the September, 2006 issue of Cancer Epidemiology Biomarkers & Prevention. The study examined data from two large, long-term health surveys and found that taking the U.S. Recommended Daily Allowance of Vitamin D (400 IU/day) reduced the risk of pancreatic cancer by 43 percent. By comparison, those who consumed less than 150 IUs per day experienced a 22 percent reduced risk of cancer. Increased consumption of the vitamin beyond 400 IUs per day resulted in no significant increased benefit.

Prostate cancer
Vitamin D supplements may slow or prevent low-grade prostate cancer from progressing, March 22, 2015, presentation, American Chemical Society meeting, Denver.

Older men and women with lower levels of vitamin D in their blood are more prone to become depressed over time. The study does not prove that low vitamin D levels cause depression; people with low levels of the nutrient might have other characteristics that predispose them to the blues or spending time outdoors. Journal of Clinical Endocrinology and Metabolism, online May 5, 2010.

Vitamin D and depressive symptoms in women during the winter: a pilot study.
Research indicates that vitamin D supplementation may decrease depressive symptoms during the winter months. In this study, nine women with serum vitamin D levels <40 ng/ml were administered the Beck Depression Inventory (BDI)-II. After vitamin D3 supplementation, six of these women completed the BDI-II and had their serum vitamin D levels reassessed. Vitamin D supplementation was associated not only with an increase in the serum D levels by an average of 27 ng/ml but also with a decline in the BDI-II scores of an average of 10 points. This study suggests that supplemental vitamin D3 reduces depressive symptoms. Appl Nurs Res. 2009. Washington State University, Richland, WA, USA.

Fibromyalgia pain reduction
Reporting in the February 2014 issue of the journal Pain, researchers said those who took supplements for a few months reported less pain and morning fatigue over time than those who did not receive them.

Gum disease
People with higher blood levels of vitamin D may be less likely to develop gum disease. Using data from a national U.S. health survey, researchers found that teenagers and adults with the highest blood levels of vitamin D were 20 percent less likely than those with the lowest levels to show signs of gingivitis -- a milder form of gum disease in which the gums become swollen and bleed easily. The study can only show that there's an association between vitamin D status and gum health, and not that the vitamin is providing the benefit.

Heart disease, heart attack, MI, heart failure.
Vitamin D supplementation might protect against cardiac failure in older people but does not appear to protect against MI or stroke. Cardiovascular disease and vitamin D supplementation: trial analysis, systematic review, and meta-analysis. Am J Clin Nutr 2014.

Immune system benefit
T cells of the immune system rely on vitamin D to become active and remain dormant and unaware of the possibility of threat from an infection or pathogen if vitamin D is lacking in the blood. Carsten Geisler of Copenhagen University's department of international health, immunology and microbiology, proposes that when a T cell is exposed to a foreign pathogen, it extends a signaling device or 'antenna' known as a vitamin D receptor, with which it searches for vitamin D. This means the T cell must have vitamin D or activation of the cell will cease. If the T cells cannot find enough vitamin D in the blood, they won't even begin to mobilize.

In a study of Japanese schoolchildren, vitamin D supplements taken during the winter and early spring reduced seasonal flu and asthma attacks. According to Dr. Mitsuyoshi Urashima of Jikei University School of Medicine, Tokyo, the idea for the study came from an earlier one looking at whether the supplement could help prevent osteoporosis. Dr. Mitsuyoshi Urashima noticed that people taking vitamin D were much less likely to report cold and flu symptoms. American Journal of Clinical Nutrition, online March 10, 2010.

Lupus, systemic lupus erythematosus
Serum concentrations have been found to be inversely related to lupus disease activity.

Multiple sclerosis
There appears to be a higher relapse rate in those with low levels. Perhaps supplementation could reduce the risk for relapse of multiple sclerosis.

Boston researchers report a link between low serum levels of vitamin D and decreased knee function in patients with osteoarthritis of the knee. At the annual meeting of the American College of Rheumatology in San Antonio, researchers presented findings from 221 subjects recruited from the Boston VA Medical Center. All had knee arthritis and reported knee pain on most days in the month before they joined the study. The investigators measured blood levels of vitamin D at the start and again after 15 and 30 months. They compared change in vitamin D levels with changes in knee pain, physical function and muscle strength during the 30-month study period. Low levels were associated with higher levels of pain and disability and to a lesser extent muscle weakness. The researchers also found that about 50 percent of the population were deficient in vitamin D.

Vitamin D deficiency is quite common in cases of hip fractures. A look-back study of 548 patients older than 60 years of age who were admitted at South Glasgow University Hospital in Scotland in the previous 4 years, showed that 97 percent of the patients had vitamin D levels below normal. Dr. Stephen Gallacher, lead researcher and consultant endocrinologist at the hospital said: ''Although the numbers were too small to justify extensive subgroup analyses the study appears to demonstrate that vitamin D inadequacy represents a significant correctable risk factor for fragility fracture and perhaps specifically for the hip."
   Older men and women who fail to get enough vitamin D -- either from their diets or exposure to the sun -- are at heightened risk for muscle weakness and poor physical performance. This is troubling given the high numbers of older folks who are deficient in vitamin D. However, even good sun exposure does not guarantee adequate blood levels of vitamin D. In many individuals, vitamin D level can remain low despite abundant exposure to sunlight.
    Dr. Sahelian comments: Most elderly patients have a vitamin D deficiency due to lack of adequate sun exposure, particularly in cold climates with long winters. And there could be a deficiency even with many hours of sun exposure a week. Vitamin D can be supplemented by taking a multivitamin and mineral complex, or through cod liver oil. A dosage of 400 to 800 units should be adequate. Sitting by the window or taking walks outside could be helpful. Osteoporosis risk can be reduced. Low vitamin D status is defined as 25-hydroxyvitamin D concentrations below 30 ng/mL
. A good blood level of 25-hydroxyvitamin D is between 50 to 60 ng/mL.
   Levels in the body vary according to the season the blood test is done. Seasonal variation significantly affects the diagnosis of vitamin D sufficiency, which requires seasonally adjusted thresholds individualized for different locations. Doctors should consider the month of sampling and the amount of body fat when interpreting vitamin D measurements.

Do not use once-a-year single high dose
A single yearly oral dose of 500,000 international units of cholecalciferol does not protect generally healthy older women from falls and fractures. On the contrary, it appears to increase the risk of falls and fractures. Dr. Geoff C. Nicholson, from Barwon Health and the University of Melbourne in Geelong, recruited community-dwelling women, aged 70 and older, who were considered to be at high risk for fracture. The women were given a single oral dose of 500,000 IU of vitamin D taken in the autumn or winter for 3 to 5 years. Women in the annual high-dose vitamin D group experienced 15% more falls and had more fractures. JAMA 2010;303.

Parathyroid hormone influence
In a four month study on older individuals with vitamin D deficiency, serum 25(OH)D concentrations rose significantly (from 14 to 26 ng/mL) in patients treated with 8400 IU vitamin D3 once weekly, but not in patients treated with placebo. Adverse experiences and incidences of hypercalcemia, hypercalciuria, and elevated creatinine were similar with both treatments. In patients treated with 8400 IU vitamin D3, but not in placebo-treated patients, parathyroid hormone decreased significantly. American Journal of Clinical Nutrition, April 2010.

Older Americans need more vitamin D to help strengthen bones than what current guidelines recommend. Men and women age 50 and older should take about 600 to 1000 international units of vitamin D each day. Sunscreen, protective clothing and time spent indoors already keep most older Americans from getting enough vitamin D from exposure to sunlight's ultraviolet-B rays.

Teenage girls
Many adolescent girls have low vitamin D levels, especially non-white girls. Reduced sunshine exposure is probably more of a factor than dietary intake. Vitamin D deficiency during childhood and adolescence might impair the acquisition of peak bone mass at the end of skeletal growth and maturation, thereby increasing the risk of osteoporotic fracture later in life. A vitamin D supplement could be of benefit.

Deficiency symptoms and signs
Deficiency symptoms refer to various symptoms that a patient notices, and deficiency signs refers to physical signs that can be seen. Deficiency results in lowered absorption of calcium and phosphorous. Prolonged vitamin D deficiency has a negative impact on bone mineralization and leads to several bone diseases including: Rickets: a childhood disease characterized by failure of growth and deformity of long bones. Osteoporosis; and Osteomalacia: a bone-thinning disorder in adults that is characterized by proximal muscle weakness and bone fragility. Osteomalacia can only occur in a mature skeleton. As little as 100 IU vitamin D2 is effective in the prevention of rickets.
   Rickets appears to be the tip of the vitamin D deficiency iceberg. There is evidence that vitamin D deficiency is still common in children and adults even though certain foods have been fortified with the vitamin. In utero and during childhood, vitamin D deficiency can cause growth retardation and skeletal deformities and may increase the risk of hip fracture later in life. Vitamin D deficiency in adults can precipitate or exacerbate osteopenia and osteoporosis, cause osteomalacia and muscle weakness, and increase the risk for certain cancers.
   Children with inflammatory bowel disease have a high prevalence of vitamin D deficiency.
n all regions of the world, more than half of postmenopausal women with the crippling bone disease osteoporosis are vitamin D deficient.
   Soft drink, juice and iced tea intake are related to a greater risk of vitamin D deficiency. On the other hand, adolescents who drink milk and eat cereal are less likely to be deficient on the vitamin.
   About a quarter of Britons suffer from a winter deficiency of vitamin D, which can increase the risk of muscle weakness, autoimmune diseases, osteoporosis and certain types of cancer. Britain's northern location and lack of sunshine means that during the winter months many people do not get enough vitamin D, which the body makes when it is exposed to sunlight. Foods such as oily fish and egg yoke are rich in vitamin D and breakfast cereals and margarine are fortified with it, but it might not be enough to get Britons through the winter months when their stores of vitamin D diminish.
   Deficiency is widespread in India, Pakistan, and South Asia.
   People taking oral steroids increase their risk for deficiency, which can lead to bone disease or muscle weakness.

Adolescents and teenagers
Vitamin D deficiency may be a common but unrecognized problem among U.S. adolescents. Researchers found that among 11- to 18-year-olds living in Boston, nearly one-quarter were deficient in vitamin D, a nutrient that aids in calcium absorption and is vital for healthy bone development. The problem is preventable with an adequate diet and time outdoors. The body naturally synthesizes vitamin D when the skin is exposed to the sun, and milk and certain other foods, including many breakfast cereals, are fortified with the vitamin. But U.S. children increasingly fill up on soft drinks at the expense of milk, and spend more time in front of the TV or computer than outdoors.

Blood levels and testing
Unless a person has an unusual diet or a chronic health condition that could lead to severe vitamin D deficiency, I don't think testing is necessary before starting a supplement. Some scientists believe that optimal serum 25-hydroxyvitamin D [25(OH)D] level should be greater than 60 nmol/L. Another measurement is serum hydroxyvitamin D level of 40 to 60 ng/ml. In older adults, a serum 25-hydroxyvitamin D concentration greater than 60 nmol/L lowers the risk of fracture. However, I am still not convinced that we know the ideal dosage to supplement with based on blood test results. In January of 2010 I attended Natural Supplements: An Evidence-Based Update, a conference sponsored by Scripps clinic in La Jolla, CA. I asked several doctors who were attending the conference what dosage of vitamin D they would recommend to a patient who had a blood level of 40 ng/ml. The range of responses was from 0 units to 5000 units daily!! Since there is no medical consensus on how much to dose based on blood levels, what's the point of testing? Let's just give everyone 400 to 2000 units a day based on the patient's desire and sun exposure. Those who are overweight or obese tend to have lower blood levels.

Reasons not to test
There are hundreds of blood tests available to check levels of different vitamins, minerals, amino acids, hormones, cholesterol, various lipids, inflammation markers, liver function studies, kidney studies, etc., etc.. At some point one has to balance the costs and inconvenience of testing versus the potential benefits they provide.  There is no proof at this time that testing, and rechecking levels a few times a year, improves health or increases longevity. In the USA we already spend more than 7000 dollars a year per person for healthcare. Do we really need to add another few hundred dollars a year per person on regular vitamin D level testing and the doctor visits? I am cost conscious and practical in my approach. I think in this country we are going overboard in terms of testing, and for the amount of money we spend on diagnostic testing and health care we are not even close to being one of the healthiest nations on the planet. We do so many diagnostic tests in this country without knowing whether people are actually healthier or live longer as a result of the testing. The people who end up being better off are doctors and the those who own the labs.
    Those who still insist on testing, I have some questions for you: Would you want to check your folic acid level before taking a supplement? What about your vitamin E level before you take a vitamin E pill? What about your thiamine, riboflavin, calcium, magnesium, selenium, or vitamin C level, etc., before you take a multivitamin?

Unless a person has an unusual medical condition or diet where blood vitamin D levels are suspected to be too low or too high, blood testing does not give us much of a clue on exactly how much to supplement. I think the vast majority of people who don't have an unusual diet or serious and chronic medical condition just take 400 to 2000 units a day they should be fine and they don't have to worry about checking for vitamin D levels. Those who want to take more can try 3000 units a day just as long as they understand the potential long term side effects.

Different labs that test for levels may provide different results. For instance, the same blood sample sent to different labs may show results that could vary as much as 20 percent or more.

The same person may have a different vitamin D level at different times or seasons of the year.

There is no agreement by the medical community regarding the ideal blood level of this prohormone. Therefore, what's the point of testing since we don't know how much to give to achieve an ideal level?

I believe sir that you are about making a sincere effort to inform your readers as best as you and your staff can. That said, I have become a proponent of Vitamin D (and as you know, it is not a real vitamin at all) because of all that I have read about it, starting with Dr. John Cannell MD at his web site vitamin d council. All the up to date information and research you could ever hope to find is on this site and Dr. Sahelian I know Dr. John Cannell would love to hear from you about your concerns for taking Vitamin D3. Like you, he is very concerned with getting out factual information to as many people as possible. I ask that you and or your staff please have a thorough look at his vitamin d council site and all the information there.
   This Vitamin D Council site appears to be overly enthusiastic about the benefits of this natural hormone and appears to recommend that most everyone get blood levels checked as if there is unlimited health care money in this country to do so and without proof that such testing will help improve health and increase lifespan.

Lifeguards, certain farmers and sailors and others who work outside and who are out in the sun all day can make 10,000 of units of vitamin D a day. Doesn't this prove that this supplement is safe in 10,000 unit dosages?
    Firstly, the amount of vitamin D made by sun exposure is done gradually throughout the day as opposed to taking a 10,000 unit pill that raises blood levels excessively high right away. Second, is there any evidence that people who are exposed to such high amounts daily are healthier and live longer? Thirdly, Is it possible that a daily intake of 1000 units is just as beneficial as taking 10,000 units and probably with fewer side effects?

I read your email updates with interest. I am a Pediatric Oncologist from Minnesota with an interest in vitamin D. I screen all my patients with 25-hydroxy vitamin D levels done by Mayo Medical Laboratories (Cost 179 dollars). I recommend supplementation if they are under 32 ng/mL. I have found about 90% of my patients are <32 ng/mL especially in the winter. A study from Germany which is about the same latitude as Minnesota found that the peak 25 hydroxy vitamin D levels are in August and the nadir in February. I have enclosed a copy of 2 reviews written by Dr Greg Plotnikoff who directs the complimentary medicine center at Abbott Northwestern Hospital in Minneapolis. He makes a point that you cannot ensure vitamin D adequacy without checking levels even if you are on supplementation. Also as vitamin D is fat soluble obese children and adults need higher levels. I would not supplement with vitamin D for a level of 40 ng/mL.
    The notion of testing everyone would be partially acceptable if money was no object. But if a person were to get three tests a year to check for vitamin D levels, and add the doctor's visit cost, it would be about 1000 dollars per person. An average family makes 30 to 40 thousand dollars a year. Are we going to spend a thousand dollars a year just on vitamin D testing? Should we be testing once, twice or three times a year for the rest of a person's life? If insurance pays for it then premiums will go up for everyone. Academics in hospital settings can sometimes be out of touch with the reality of economics and limited funds for health care. Furthermore, there are no acceptable guidelines on how much of this supplement to give a person based on a particular blood level and we don't know the long term consequences of excess supplementation. I think my practical approach of giving most everyone 400 to 2000 units a day, unless they have a serious medical condition, works much better in the reality of finances and costs. And those who insist on testing should answer why we should not test for levels of vitamin C, E, selenium, zinc, and a host of other important nutrient levels. Aren't these important too, and isn't it possible that certain people could be deficient? Do we test for vitamin C and E levels before we give someone a multivitamin?

I am a naturopathic doctor and I think all patients should have vitamin D levels tested.
   Please explain how our country can afford a few hundred dollars a year more per person for testing of vitamin D levels when a third of the population does not have adequate health insurance and 20 percent of the population is either unemployed or partially employed and the government is trillions of dollars in debt. What if all doctors ordered vitamin D tests on all Medicare patients where would money come from to treat other medical conditions and emergencies?

There is an enormous amount of evidence that people living the the Northern part of the US and in Canada have low levels of vitamin D in their bloodstream. Low vitamin D levels have been associated by on-line publications with osteoporosis, higher incidence of prostate cancer, and bone fractures. The minimum amount of vitamin D listed on the lab report forms is 30 ng/ml, the upper toxic limit is 100 ng/ml. I took a vitamin mineral supplement for years, and when tested the first time in 7/2008 I had a level of 22 ng/ml. On line articles (I mean peer review journals epublication) associate low vitamin D with atherosclerosis, heart disease, diabetes, and more. Are all these journals, and all published research wrong? The accepted level of 400 IU/day is under attack from many quarters. I stated to you before I take 5000 IU vitamin D3/day. I think vitamin D testing is a good idea, it should not be done excessively, but it should definitely be done.   
    I am a proponent of supplementation but question the need for everyone in the country to get tested. In your opinion, how often should people be tested? What happens if a person does not have insurance and they make an average income of 40,000 a year, is it worth it for them to get their vitamin D level tested 3 or 4 times a year at a cost of 500 to 1000 dollars a year? How much a year would health insurance costs rise each year if each person were tested several times a year? Once testing is done for a year, is it necessary to test again the following year? Is there proof that taking 5000 units a day provides more benefits than 2000 units and still has no risks when taken for decades?

I like your newsletter and always appreciate your erring on the cautious side in your recommendations. I agree that we should be cautious about adding large doses of vitamin D or other supplements. However, I'm not sure where you got your data that vitamin D tests cost very much. If you google "vitamin D test cost" online, you'll find a number of different places that appear to be reputable, offering tests that mostly range anywhere from $25 to $68, and even references to labs that do the test for $10. According to Medscape, "Some health insurances cover vitamin D testing and some do not, and prices vary from $10 to $50..." Other examples: Virginia Hopkins: test cost: $68; Saveonlabs: $44.75; Grass roots health dot net: $60; The website Women to Women describes tests that are available for $25. I also found a statement on Wiki that Medicare pays $40 for vitamin D tests. I think what we're seeing is that as demand for Vitamin D deficiency tests goes up, labs start competing with each other for customers and the tests go down. I purchased four test kits for Vitamin D3 from Dr. John Cannell of the Vitamin Research Council. The tests are by ZRT Labs, and I paid $220 for them. Testing twice a year would cost a family of four $440, which amounts to 1 % of an annual income of $40,000 per year, which sounds affordable to me, especially when you consider that maintaining healthy blood levels of D3 could pay for the cost of the tests in saved medical bills.
    Most people go to their doctor's office to get tested which adds a doctor's visit cost and most physicians are likely to add additional blood tests since the person is getting their blood drawn, anyway, thus adding to the overall cost. There are concerns that different labs are not consistent in the levels they measure and some of the cheap ones may not provide accurate information. When health insurers or Medicare cover the cost, eventually all of us will pay for it through additional premiums or increase in tax rate. I am not sure how reliable the tests by ZRT labs are compared to other tests done in a doctor's office. There are differences in results between different labs. One percent of a family's total income is still very high for just testing a level of one of countless hormones, amino acids, vitamins, minerals, nutrients, fatty acids, etc that are in the body. Omega-3 oils are crucial for optimal health. Why not spend another 1 percent of one's income on testing this? What about vitamin C and E levels; what about testing different hormone levels? Where does one draw the line? Plus, there is no guarantee that those who test for levels will live longer than those who just spend 10 minutes a day in the sun and take 400 to 1000 or 2000 units a day.

The vitamin D receptor is now known to be present in over 35 tissues. Bone and vascular smooth muscle have vitamin D receptors, so do heart muscle cells.

Vitamin D in Food and in our diet
Vitamin D is found in milk, yogurt and cheeses, as well as in some fortified orange juice, fish, oysters, and certain fortified cereals. Good sources include fish liver oil, eggs and fatty fish such as salmon, herring and mackerel. People might want to consider a vitamin D supplement to raise their intake to 400 to 800 IUs per day, which is well within the safety guidelines established by the National Academy of Sciences. Taking more could be especially important for people living in northern areas, which receive less vitamin D from sunshine. African Americans, who don't produce as much vitamin D because of their skin pigment, could also benefit significantly from a higher intake.

Animal foodstuffs (e.g., fish, meat, offal, egg, dairy) are the main sources for naturally occurring cholecalciferol (vitamin D-3). The highest values are found in fish and especially in fish liver, but offal (organ meats, entrails) also provides considerable amounts. The content in muscle meat is generally much lower. Concentrations in egg yolks range between the values for meat and offal. If milk and dairy products are not fortified, they are normally low in vitamin D, with the exception of butter because of its high fat content.

Breastfed babies living in northern latitudes often lack healthy levels of vitamin D, and may even be severely deficient. In northern latitudes, such as that in Iowa (41 degrees North), sunshine is too diminished in the winter for the infants to generate enough vitamin D on their own. Many infants are vitamin D deficient during winter than during summer. The vitamin D deficiency is less prevalent as babies get older. Many decades ago it was standard practice to give infants a teaspoon of cod liver oil, which averages about 400 units of vitamin D per day. When the use of baby formula became popular, enough vitamin D was added to the formula to prevent deficiency. Then since the 1970s women returned to breast feeding, but they did not think of giving their babies vitamin D supplements. Breastfed infants require about 200 units of vitamin D per day. It may be a good idea for women breastfeeding their infants to give them cod liver oil supplements during the winter months. Pediatrics, August 2006.

Vitamin D and Pregnancy
The children of mothers who had low levels of vitamin D during their pregnancy have reduced bone mineral content during childhood, potentially increasing their risk of osteoporosis in later life.
     High levels of vitamin D during pregnancy may lower the risk of wheezing and asthma in offspring during early childhood. Vitamin D deficiency and asthma are both common in the northeastern part of the United States, suggesting that the two may be related. Moreover, while vitamin D has important effects on the immune system, its affect on asthma is not known. Researchers tracked 1,306 mother-child pairs for more than three years, and used a food frequency questionnaire to assess levels of maternal vitamin D during pregnancy. By age two, there was a clear association between increasing prenatal levels of vitamin D in the mother and decreasing risk of wheezing or doctor-diagnosed asthma in the child. The average total vitamin D intake during pregnancy was 550 international units (IU) per day. In a more thorough analysis, a 100-IU increase in maternal vitamin D intake was associated with an odds ratio of 0.90 for "any wheeze" in the child -- defined as mother-reported wheeze during the first two years of life. When the data were adjusted to account for dietary levels of fruit, vegetables, and fish, the results did not change. A preliminary look at the three-year data show a similar strong association between higher maternal vitamin D levels and lower risk of wheezing and asthma at age three years.

Vitamin D from Sun or supplement pill?
Should you purposely tan for vitamin D? You can get all the vitamin D with a vitamin supplement pill -- you do not have to put yourself at increased risk of skin cancer and photoaging. The public is getting a mixed message on sun and health because advocates of increased UV exposure, like the indoor tanning industry, are advocating sunbathing as a means of getting more vitamin D for everyone, including young light-skinned people who face the greatest skin cancer risk. New research has indeed shown that some groups of people who may get little sun exposure and don't drink much milk, for example frail elderly individuals at risk of bone fractures, will benefit from getting more vitamin D than is currently recommended by the US Department of Agriculture. There's also evidence that people with very dark skin and those who live in northern climes may be deficient in the vitamin. But such deficiencies can be handled with oral supplementation. If you are worried that you're not getting enough vitamin D, take a vitamin D supplement pill.

Vitamin D needed by diabetics
A majority of patients with type 2 diabetes show signs of vitamin D deficiency. Because a lack of vitamin D can negatively affect bone health and have other adverse effects routine vitamin D supplementation with about 400 units a day should be considered for people with diabetes.
   People with a low level of vitamin D in the blood have poorly functioning insulin-producing cells and show a poor response to insulin, even when their blood sugar levels are normal.

D2 or D3?
It appears that both forms of the vitamin are useful

Vitamin D2 Is as Effective as Vitamin D3 in Maintaining Circulating Concentrations of 25-Hydroxyvitamin D.
J Clin Endocrinol Metab. 2008 March; Michael F. Holick, Rachael M. Biancuzzo, Tai C. Chen, Ellen K. Klein, Azzie Young, Douglass Bibuld, Richard Reitz, Wael Salameh, Allen Ameri, and Andrew D. Tannenbaum. Endocrine Section, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts 02118;
Two reports suggested that vitamin D2 is less effective than vitamin D3 in maintaining vitamin D status. Our objective was to determine whether vitamin D2 was less effective than vitamin D3 in maintaining serum 25-hydroxyvitamin D levels or increased the catabolism of 25-hydroxyvitamin D3. This was a randomized, placebo-controlled, double-blinded study of healthy adults ages 18–84 yr who received placebo, 1000 IU vitamin D3, 1000 IU vitamin D2, or 500 IU vitamin D2 plus 500 IU vitamin D3 daily for 11 wk at the end of the winter. Sixty percent of the healthy adults were vitamin D deficient at the start of the study. The circulating levels of 25-hydroxyvitamin D (mean ± sd) increased to the same extent in the groups that received 1000 IU daily as vitamin D2. Our results suggest a 1000 IU dose of vitamin D2 daily was as effective as 1000 IU vitamin D3 in maintaining serum 25-hydroxyvitamin D levels and did not negatively influence serum 25-hydroxyvitamin D3 levels. Therefore, vitamin D2 is equally as effective as vitamin D3 in maintaining 25-hydroxyvitamin D status.

I am a medical doctor and really respect your balance and wisdom, which I find very professional. However I have a different opinion about your recent discussions about Vitamin D as multiple authorities have recommended increasing the RDA dramatically. We are dealing with a hormone here, not a vitamin, and this needs to be emphasized by enlightened authors. In sunny climates women produce 8000 units a day, and men 10000. An English study gave 10000 U daily IM for 120 days with no side effects. CM Heaney and a large group of respected researchers recommended to governments that 2400 U gave even elderly women with poor absorption a modest level, and 6000 U in those working in full sun gave no-one too much. One potential issue is supplementing with magnesium to reduce renal excretion of calcium.
    Until we see studies that show giving people several thousands of units a day for 10 to 20 years or longer provides benefits that are superior to giving 400 to 2000 units a day, I will stay on the cautious side. Over the past few decades I have seen too many enthusiastic doctors prescribe high dosages of certain vitamins, herbs, supplements and hormones only to later realize that adverse effects occurred that were not initially easy to predict.

I have a question regarding the source of Vitamin D. I understand cholecalciferol or D3 has the origin from animal products such as sheep wool and hides. Also, I read somewhere that vegans usually obtain vitamin D from the action of sunlight on the skin or by taking fortified foods such as soya milk, margarine, breakfast cereals and vitamin supplements which are made from yeast or other fungi. Fortified vegan products contain D2 ( ergocalciferol ). Vegans are careful about their source as D3 ( Cholecalciferol ) which is animal-derived.
   It appears to be true that Vitamin D in the form of cholecalciferol is derived from sheep wool. Therefore, this would make it fine for a vegetarian but not for a strict vegan. The sheep are not killed. The wool is sheared, and lanolin from the sheep wool is chemically altered in the lab to produce vitamin D3 or cholecalciferol.

Vitamin D Research study
People on strict raw food vegetarian diets are thin but healthy. Although nutritionists and the food industry have warned that a diet without dairy foods can lead to the bone-thinning disease osteoporosis, a team at Washington University School of Medicine in St. Louis found the vegans they studied had many of the signs of strong bones. Raw food vegetarians believe in eating only plant-derived foods that have not been cooked, processed, or otherwise altered from their natural state. Researchers expected the vegans to have low vitamin D levels because they avoid dairy products, which are fortified with the vitamin. But in fact their vitamin D levels were "markedly higher" than average. Vitamin D is made by the skin when the body is exposed to sunlight and is key to keeping strong bones. And the vegans had low levels of C-reactive protein, an inflammatory molecule that is linked with the risk of heart disease, diabetes and other chronic disease. Furthermore, they had lower levels of IGF-1, a growth factor linked to risk of breast and prostate cancer.

People who try to stay bronze with the help of a tanning bed tend to have higher blood levels of vitamin D than those shun the salon. The study of 156 adults found those who regularly soaked up the artificial rays of a tanning bed had a 90 percent higher average vitamin D concentration in their blood. The tanners, who frequented the salon at least once a week for 6 or more months, also had greater bone density in the hips. The study, published in the American Journal of Clinical Nutrition, was partially financed by the UV Foundation, which is funded by the Indoor Tanning Association, an industry group. A precursor to vitamin D exists naturally in the skin, and exposure to the sun's ultraviolet (UV) rays touches off a chemical process that creates the usable form of the vitamin. Because vitamin D is needed for proper calcium absorption, the nutrient is vital to bone health. There is also a body of research suggesting vitamin D helps protect against certain cancers and some autoimmune diseases, such as type 1 diabetes and multiple sclerosis. But the fact that UV radiation is the major cause of skin cancer, as well as the major source of vitamin D, has made for a controversy over how much sun -- or artificial sun -- people should get.

Tanning is associated with optimal vitamin D status (serum 25-hydroxyvitamin D concentration) and higher bone mineral density
American Journal of Clinical Nutrition, Vol. 80, No. 6, 1645-1649, December 2004
Subjects who use a tanning bed that emits ultraviolet B radiation (290–315 nm) are likely to have higher 25-hydroxyvitamin D [25(OH)D] concentrations than do subjects who do not regularly use a tanning bed. Objective: The first objective of this study was to ascertain whether subjects who regularly use a tanning bed have higher 25(OH)D concentrations than do subjects who do not use a tanning bed. The second objective was to ascertain whether higher 25(OH)D concentrations correlated positively with bone mineral density. Design: This cross-sectional analysis examined 50 subjects who used a tanning bed at least once a week and 106 control subjects. Each subject gave a blood specimen for measurement of serum 25(OH)D and parathyroid hormone concentrations. Each subject underwent bone mineral density testing of the hip and spine. Results: Subjects who used a tanning bed had serum 25(OH)D concentrations 90% higher than those of control subjects. Subjects who used a tanning bed had parathyroid hormone concentrations 18% lower than those of control subjects. Tanners had significantly higher BMD and z scores at the total hip than did nontanners. The regular use of a tanning bed that emits vitamin D–producing ultraviolet radiation is associated with higher 25(OH)D concentrations and thus may have a benefit for the skeleton.

Vitamin D Council - one opinion out of many
I'm writing to you regarding the information you have presented on this topic and to let you know about the Vitamin D Council. Dr. John Cannell, MD has THE most up-to-date info on "which lab to be tested by, EXACTLY what are the levels that should be in the blood, dosage amounts (including the ridiculous hysteria about over-dosing with vitamin D) and the latest research findings on this subject." I've read his site from front to back and looked at the research. They say, "At this time, we advise even healthy people (those without the diseases of vitamin D deficiency) to seek a knowledgeable physician and have your 25(OH)D level measured. If your levels are below 50 ng/mL you need enough sun, artificial light, oral vitamin D3 supplements, or some combination of the three, to maintain your 25(OH)D levels between 50–80 ng/mL year-round. How Much Vitamin D? If you refuse to see a physician, or can't find a knowledgeable one, purchase the 1000 IU/day vitamin D3 cholecalciferol pills that are available over-the-counter in North America or a 5,000 IU capsule. Take an average of 5,000 IU a day, year-round, if you have some sun exposure."
    I am much more cautious. I have learned over my more than 3 decades of studying nutrition and medicine that some researchers and medical doctors make wide ranging recommendations to the general public without a full understanding of the long term consequences. For decades doctors recommended hormone replacement therapy to their menopausal patients only to discover that more harm than good was being done. I am not saying the vitamin D supplementation is as much of a concern as estrogen and progesterone replacement, but just to point out that it takes decades of research to learn the consequences of supplementing with medications or natural supplements. After so much time studying calcium supplementation for osteoporosis prevention or treatment, we still don't have a full understanding of the benefits, risks, and proper dosage. Therefore, for the Vitamin D council (and, by the way, who funds them and who are they?) to make such confident statements about how much the general public should supplement, in my opinion, is premature. It is up to each individual to read all the info they can on this topic and make their own decision. What if we find out years from now that taking such high amounts as recommended by the people who run the Vitamin D Council actually shortens lifespan by calcifying various tissues in the body, including the brain and blood vessels? By the way, it has links from its site to sites that sell the supplement, and they make money from such sales. They also promote blood level testing and sell vitamin D kits. Hence, in my opinion, they are not an independent source of information.

Can you comment on this article by Dr. John Cannell, M.D. "The Truth About Vitamin D Toxicity. Vitamin D Toxicity Fears Unwarranted. Is vitamin D toxic? Not if we take the same amount nature intended when we go out in the sun. Vieth R. Vitamin D supplementation, 25-hydroxyvitamin D concentration, and safety. Am J Clin Nutr. 1999;69:842–56. Vieth attempted to dispel unwarranted fears in medical community of physiological doses of vitamin D in 1999 with his exhaustive and well-written review. D-Lite, Renew, & Sun Splash UV/Tanning Systems Is toxicity a concern for you? If so, then increase your levels the way nature intended, with ultraviolet B light! His conclusions: fear of vitamin D toxicity is unwarranted, and such unwarranted fear, bordering on hysteria, is rampant in the medical profession. Vieth R, Chan PC, MacFarlane GD. Efficacy and safety of vitamin D3 intake exceeding the lowest observed adverse effect level. Am J Clin Nutr. 2001 Feb;73(2):288–94. Even Ian Monroe, the chair of the relevant IOM committee, wrote to the Journal to compliment Vieth's work and to promise his findings will be considered at the time of a future Institute of Medicine review. Munro I. Derivation of tolerable upper intake levels of nutrients. Letter, Am J Clin Nutr. 2001;74:865. That was more than two years ago. In 1999, Vieth indirectly asked the medical community to produce any evidence 10,000 units of vitamin D a day was toxic, saying "Throughout my preparation of this review, I was amazed at the lack of evidence supporting statements about the toxicity of moderate doses of vitamin D." He added: "If there is published evidence of toxicity in adults from an intake of 250 ug (10,000 IU) per day, and that is verified by the 25(OH)D concentration, I have yet to find it." Vieth R. Vitamin D supplementation, 25-hydroxyvitamin D concentration, and safety. Am J Clin Nutr. 1999;69:842–56.
   I recommend for the time being 400 to 2000 units a day for most people. There is a significant difference between short term acute and noticeable toxicity versus potential long term slow damage to tissues that occur without much obvious signs over years and decades of supplementation. Even if toxicity does not occur, this does not mean that people taking these massive amounts are going to live longer.

Vitamin D supplement use emails
Q. I live in the UK and due to the lack of sunshine, would like to buy a Vitamin D supplement. However, i am now completely confused ! I have just read the new study from Australia ( Science Daily Jan. 27, 2008 ) that suggests taking a Vitamin D supplement ORALLY is BAD for you. Its actually a pretty damning study regarding ORAL Vitamin D. It says: "ingested vitamin D is immunosuppressive and that low blood levels of vitamin D may be actually a result of the disease process. Supplementation may make the disease worse. Vitamin D deficiency, long interpreted as a cause of disease, is more likely the result of the disease process, and increasing intake often makes the disease worse. We have found that vitamin D supplementation, even at levels many consider desirable, interferes with recovery in these patients. Vitamin D is a secosteroid hormone, and the body regulates the production of all it needs. In fact, the use of supplements can be harmful, because they suppress the immune system so that the body cannot fight disease and infection effectively. The Science Daily article, dated 28 Jan 08. What is your opinion on this new study?
   A. Different scientists have different opinions regarding nutrition and supplement use. The reason is that this field is extremely complicated and it is difficult to do well-controlled long term studies. Furthermore, different results could be obtained depending on the dosage used for the vitamin or supplement or in different populations or groups of patients. For instance, it is possible that opposite results could be obtained by providing vitamin D at 200 units a day versus 1,000 units a day, even though it is the same vitamin. For the time being, I think taking a vitamin D supplement at 400 units probably provides more benefits than harm to those who live in climates where there is little sun exposure or little vitamin D in the foods people ingest.
   There is a four year long vitamin D study that has interesting results.

Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial.
Am J Clin Nutr. 2007 June.Lappe JM, Travers-Gustafson D, Davies KM, Recker RR, Heaney RP. Osteoporosis Research Center, Creighton University, Omaha, NE 68131, USA.
The purpose of this analysis was to determine the efficacy of calcium alone and calcium plus vitamin D in reducing incident cancer risk of all types. This was a 4-y, population-based, double-blind, randomized placebo-controlled trial. The primary outcome was fracture incidence, and the principal secondary outcome was cancer incidence. The subjects were 1179 community-dwelling women randomly selected from the population of healthy postmenopausal women aged >55 y in a 9-county rural area of Nebraska centered at latitude 41.4 degrees N. Subjects were randomly assigned to receive 1400-1500 mg supplemental calcium/d alone (Ca-only), supplemental calcium plus 1100 IU vitamin D3 / d (Ca + D), or placebo. Cancer incidence was lower in the Ca + vitamin D women than in the placebo control subjects. In conclusion, Improving calcium and vitamin D nutritional status substantially reduces all-cancer risk in postmenopausal women.

Q. I, myself, have been diagnosed with very low bone density and, at the time of diagnosis, my Vitamin D (25-OH) was 10 nanograms per ml. I have subsequently -- and under monitoring -- taken 4,000 I.U. of D3 and still only managed to raise my levels to 39. I am now taking 5,000 I.U. and due to be tested soon. I know of several people who are taking Vitamin D3 doses in the 4-6,000 I.U. range and still maintaining what are considered to be barely adequate levels of D (around 50). One is having her parathyroid levels measured at the same time and, at 6,000 I.U., has noticed no problems. In a study in Hawaii of subjects who reported 22.4 hours average sun exposure without sunscreen, 51% were reported to be Vitamin D deficient. My question is: if even "heroic" doses of Vitamin D3 are merely maintaining what are considered desirable levels, can these doses still pose potential health problems?
   A. It's difficult to say. Blood levels of vitamin D may not necessarily reflect what is actually going on in bone tissue, brain tissue, or other parts of the body. Many doctors overly rely on blood levels to determine the proper dosage of vitamins, drugs, and hormones, but blood tests do not always reflect accurately the levels or effects of these medications in various tissues of the body or what is actually going on within each cell. There could be a normal level of the vitamin or medication in the blood stream yet untoward effects could be going on in some part of the body. For instance, if a person takes DHEA and their blood test shows the level to be within the normal range, it is possible that the levels in hair tissue could be high causing hair loss. Same with vitamin D. It is possible that blood levels could be low or normal, yet untoward reactions could be occurring in other tissues, such as brain tissue.

Q. This note is just to let you know that there is another side-effect of high vitamin D supplementation, that you may not be aware of: whole-body anxiety. I acquired hypothyroidism due to destruction of my thyroid by Hashimoto's autoimmune thyroiditis; the Hashimoto was perhaps caused by gluten. I also acquired multiple nutritional deficiencies as the result of gluten enteropathy. After getting off gluten in 2003, the process of finding and fixing the many nutritional deficiencies the enteropathy caused, has been lengthy. Early in 2008 I discovered that taking vitamin D3 caused me to go into diagnosed hyperthyroidism (TSH < 0.015). I had to lower my T4 dose from its high of 118mcg. After taking up to 3000 IU D3 daily for 5 months and finally achieving D sufficiency at 50ng/ml, I dropped back to about 600 IU D3 daily. Reducing the level of D supplementation, improved the way I feel. Apparently high blood levels of vitamin D are excitatory for some people, because the 3000 IU vitamin D supplementation had created a whole-body anxiety situation. It had also interfered with my thyroid treatment; taking T4 while I also had a high blood level of D3, would cause intense anxiety, so I had throttled back my T4 dose to a low level (usually 12mcg per day) that wasn't sufficient to keep my TSH reasonably low and my FT3 and FT4 both within the normal ranges. Based on what you said in your column, I've taken your advice and also reduced my calcium supplementation. I have a friend whose son was put on high vitamin D supplementation after he was found to have gluten sensitivity, and have multiple deficiencies. The doc put him on a dose of 8000 IU D3 as drops, once per week. When I talked to his mom about my experience with high-dose vitamin D supplementation, she found it interesting. She told me that when she gives her son his 8000 IU D3 on Sunday, he acts "crazy" on Monday.

I recently went to see a new Internist that practices Integrative Medicine (combines Eastern and Western Medicine). He has his own line of nutraceuticals. His name is Dr. Michael Hirt out of Tarzana, Ca. At my first visit Dr. Michael Hirt drew my blood and said that I am deficient in Vitamin D. He recommends that I take 3,000 i.u. per day. Is this way too much? I am 48 y.o. and suffer from Type 2 diabetes, chronic fatigue syndrome, obstructive sleep apnea, obesity and a whole host of other health problems. I have no energy.
   Research regarding the ideal dosage of vitamin D supplementation is still in its early stages and different doctors have different opinions regarding the right dosage to prescribe to their patients. It also depends on the blood studies as to how deficient a person is, and how long treatment needs to continue. Personally I prefer to use lower dosages of prescription medications and supplements than other doctors but this is my approach.

I am an older male with a prostate enlargement and I use saw palmetto herb daily along with a pygeum africanum extract. Just wondering whether 400 units of vitamin D has any interactions with other supplements. I also occasionally use a potent aphrodisiac called tongkat ali herb.
   This low amount should not interfere with other herbal products.

Researchers like Michael Holick and Reinhold Veith are now suggesting that up to 10,000 I.U. is a safe daily dose.
   Throughout medical and nutritional research history there are countless examples of medications or supplements that researchers have been excited about and began recommending large dosages only later to find out that there were unknown long term side effects that did not appear initially. I suggest, as a general guideline, a supplement dosage of 400 to 2000 units a day for most people with exception regarding sun exposure and dietary intake.

I would like point out that UVB light (which promotes vitamin D production) is not available above 38 degrees N latitude (as in the Bay Area and northward) during the dark months (November through February). Also, dark-skinned folk living at these latitudes above 30 degrees may need more exposure to the sun than their paler colleagues. Finally, if one measures 25 hydroxy vitamin D3 as a reference point for adequate vitamin D levels in the body, and regularly finds them pitifully low, would not that suggest that 400 IU is rather low for daily intake? There is some consideration now being given that 1000 IU should be the new RDA (not that RDAs represent optimal levels). Drs. John Cannell, Michael Holick, Reinhold Vieth, and William Grant have done extensive research on vitamin D, which I hope you have had the opportunity to review.
    It is possible that 1,000 units should be the new RDA but I prefer waiting a few more years for additional research before making widespread recommendations.

I'm a health talk radio host in New York City and I've been carefully charting my D3 levels. I thought you might have an interest in my experiment:
2,400 IU of D3 got me to 46 ng/ml
5,400 IU = 57 ng/ml
10,400 IU = 61 ng/ml
The Grassroots Health Vitamin D organization recommends 2,000 IU to get us to the 40-60 ng/ml range. The 60 level offers the most overall health protection as displayed on the chart posted on their website. Additionally, many integrative physician's think the optimal level is over 70 or 80 ng/ml, so I'm now taking 15,400 IU. The 400-800 IU you're recommending wouldn't bring me to even 40 ng/ml.
     Let us know over the next few weeks, months, or years what kind of benefits or harm you encounter, we would be quite interested. I am not sure where and how The Grassroots health Vitamin D organization came up with 60 plus as the ideal blood level since no such long term human studies have been published.

I am a chiropractor who thinks higher dosages of vitamin D supplements should be taken. Reinhold Vieth and other researchers have recommendations about D3. Certainly a few hundred I.U. D3 is better than none, it leaves most people in North America with low serum levels, which becomes obvious with testing. Perhaps you could recommend people have their serum levels checked, and act accordingly with a willing, up-to-date provider. Here in the Northwest supplementation needs are higher, and my doctor follows me with 25(OH)D serum levels. While everyone agrees that <20 nmol/L is a deficiency, it is only becoming accepted that optimal levels reduce many other risk factors. Optimum being >85 nmol/L. My original serum level was below 30 nml/L. After several months of 6000 I.U. a day, the recheck was only in the lower 40s. During the winter I am taking 10,000 IU to try and keep levels up -- hopefully to 60 or higher. Cost? 15 cents a day. In 1999, Reinhold Vieth indirectly asked the medical community to produce any evidence 10,000 units of vitamin D a day was toxic, saying "Throughout my preparation of this review, I was amazed at the lack of evidence supporting statements about the toxicity of moderate doses of vitamin D." He added: "If there is published evidence of toxicity in adults from an intake of 250 ug (10,000 IU) per day, and that is verified by the 25(OH)D concentration, I have yet to find it."
    There is a difference between short term toxicity and long term health damage. Until there is proof that taking 10000 units of vitamin D increases lifespan, it is premature to make recommendations to patients to take excessively high dosages. There is no proof that testing for vitamin D levels, or levels of many other vitamins, necessarily tells us the ideal dosage of the vitamin to supplement with or whether overall health is improved by such testing. Too many tests are being done in this country with no proof that such testing increases longevity.

A research letter published in the October 26, 2009 issue of the American Medical Association Journal Archives of Internal Medicine revealed that treatment with 50,000 international units (IU) of vitamin D2 per week was safe and effective over an 8 week period, and could also be safe to use every other week as maintenance. The authors, from Boston University School of Medicine, note that "To prevent recurrent vitamin D deficiency and also to maintain adequate levels in patients who are vitamin D sufficient, we treat with 50,000 IU ergocalciferol every other week indefinitely, a regimen that, to our knowledge, has not been published to date." The researchers, including well-known authority Michael F. Holick, PhD, MD, reviewed medical records of 86 patients aged 18 to 91 who had received two or more blood tests for 25-hydroxyvitamin D levels and were treated for vitamin D deficiency or insufficiency. Pretreatment 25-hydroxyvitamin D levels of 92 percent of the patients were below 30 nanograms per milliliter (ng/mL). Forty-one subjects received 50,000 IU vitamin D2 (ergocalciferol) weekly for 8 weeks followed by a maintenance dose of 50,000 IU every other week for up to 6 years. The remainder of the patients received every other week maintenance therapy without the initial weekly treatment. For the 41 patients who received the weekly 50,000 IU starting therapy, average 25-hydroxyvitamin D levels rose from 19 ng/mL to 37 ng/mL after 8 weeks. For the patients who received only maintenance therapy, 25-hydroxyvitamin D levels increased from an average of 26 ng/mL to 47 ng/mL. Serum calcium levels, which could be an area of concern when high amounts of vitamin D are ingested, did not change over the course of treatment. No kidney stones or other signs of vitamin D toxicity were observed.
    Several questions still remain: Is longevity enhanced by such dosages or are there certain potential medical problems that have not been noticed, for instance increased calcification in arteries? Would lower dosages have similar benefits with fewer side effects? Just because one does not notice an obvious toxicity does not mean no harm is occurring in certain parts of the body. It took the medical community several decades to realize that hormone replacement therapy was actually increasing the risk for heart disease, blood clots and cancer. High dosage vitamin D use is just beginning now in the US by many people and it may take a long time before we find out the full consequences, good and bad.

Several female friends of mine, my mother and myself have all been found to have low vitamin D levels. While I like your cautious approach in discouraging people from randomly taking high doses for an extended period of time, I do feel it is vitally important for women, especially menopausal women who are prone to osteoporosis, or have it, to automatically be tested. I have been being treated for osteoporosis with no sign of improvement for years. We then found out how low my D levels were. I am hoping that bringing them up will help the absorption of calcium and the Boniva for the treatment of the osteoporosis.
    Each person is free, if they can afford it or have insurance, to get tested for vitamin D levels. However, there is no evidence that testing tells a medical doctor with the appropriate dosage that should be used for supplementation. For instance, if the blood levels comes back as 25 ng/ml, one doctor may feel a person needs no additional supplementation, whereas another doctor may think it would be a good idea to take 1000 units and a third doctor may think 2000 units is best while another opinion may be to take 5000 units. When should a person be tested again and how often? Adding the doctors visits and the testing can result in several hundred dollars or a thousand dollars more a year to health care costs. Plus, how do we know in the long run whether taking such additional amounts will be helpful or harmful? What if we find out years from now that taking these high amounts leads to calcification of arteries in the brain that accelerates dementia? Many people think that the more testing they do and the more results they have about the various levels in their blood of certain vitamins, hormones, liver function, kidney functions, Chest X-rays, mammograms, bone density tests, etc., the healthier they will be. There is no evidence that excessive testing improves health or longevity. In fact, excessive testing can be counterproductive. There is too much testing done in this country as if there is no limit on money we have to spend on health care.  The amount of money that we spend on unnecessary testing raises insurance costs for everyone and everyone's taxes if such testing is done for those on Medicare. As Americans we have to start changing our viewpoints that all testing is good. It's not, unnecessary testing has drawbacks, both for health reasons and finances.

My Kaiser doctor is biased against supplements recommending only drugs and surgery for my last five medical conditions - from osteoarthritis in the knee to tachycardia and even a small brain tumor (acoustic neuroma). I manage all five conditions quite nicely thank you, using diet, exercise, and supplements - somewhere around 20, but larger in dose than you seem to recommend. For example I consume almost 20 grams of soluble oat fiber per day plus supplements that claim to stimulate bile flow. On this protocol my lipid profile changed so dramatically that I now find my HDL (at 95) greater than my LDL (at 70). With regard to vitamin D. I rely on the work of Dr John Cannell at the Vitamin D Council. He has written several papers. All the patients in his ward in a mental hospital were replete with vitamin D because of a experiment he was conducting to see if there was any affect on schizophrenia. A flu ravaged the hospital but none of his patients got it. He talks about lifeguards producing 10,000 IU of vitamin D per day. He recommends a protocol of 50,000 per day for three days at the first sign of the flu. My daughter, a 32 year old waitress in NYC, followed this and felt well enough to go out partying 36 hours after onset of fever, chills etc. Because of my Melanoma (and widespread cancer in the family) I avoid the sun. I have dosed at 5000 IU daily for a year and my vitamin D only rose from 40 to 50 ng/dL. Over at Grass roots health website you can see a chart of levels and read about levels above 60 for cancer protection. I am swinging on the information in books like yours and these pages and wanted your rebuttal to the orthomolecular logic that just as a 150 lb goat will produce 10,000 units of vitamin C in response to a pathogen and humans produce 10,000 IU of vit D in summer, then it is safe to dose at these levels for extended periods?
    There are several points to keep in mind. Firstly, the amount of vitamin D made by sun exposure is done so gradually throughout the day as opposed to taking a 10,000 unit pill that raises blood levels excessively high right away. Second, is there any evidence that people who are exposed to such high amounts daily are healthier and live longer? Thirdly, Is it possible that a daily intake of 1000 units is just as beneficial as taking 10,000 units and probably with fewer side effects?

Having worked with antiopiates in treating autoimmune diseases while working on my PhD, I am sure that the opiate modulating effects of sun exposure play a significant factor in the observed clinical benefits attributed to vitamin D. In fact, I would personally bet that vitamin D is likely a biomarker for opiate modulation through ultraviolet exposure, and thus simply taking vitamin D may only be emulating one measurable biological change associated with this exposure. I don't deny that vitamin D has beneficial effects on health, but not to the extent that is currently attributed to this vitamin. Keep up the good work! While we are in the honeymoon stage in the medical profession’s embrace of Vitamin D supplementation for a whole host of conditions, and prevention of even more conditions, this love affair should perhaps be tempered, especially for those that advocate chronic administration of high dosages. Many, if not most, of the heath benefits currently attributed to Vitamin D are immunological in nature, or rely on changes in immunological functioning. It is likely best to temper sweeping medical claims currently attributed to this vitamin, at least those made simply by measuring Vitamin D and correlating these levels with positive health benefits. Studies have shown increased calcification of soft tissues associated with increased Vitamin D intake, which should not be overlooked, especially with long term use at high dosages. Many chronic tanning booth users show classical opiate withdrawal symptoms when given an opiate antagonist such as naltrexone, clearly demonstrating that opioids role in maintaining health should not be a factor to be dismissed so readily.

On several occasions I have tried vitamin D3 in different forms - gel capsules and sublingual tablets - and different dosages. After each dose, with as little as 200 IU, within approximately 1 hour, I experience spasms under my right rib cage in the area of my liver. I've never experienced this effect before with anything else. I am in my 40s, have no known health problems or complaints, and am in excellent physical condition.

I read the letter from Nyles Bauer regarding Vitamin D, tanning booth users, etc, and a thought came to mind. Are there any benefits to tanning booth use, in great moderation, of course? I ask this because several years ago in January (I live in Delaware), I was suffering from a sinus infection and a general feeling of malaise. Having read extensively about "light" therapy, I decided to try a stand-up tanning booth. (I refused to use those beds reminds me of a coffin, not to mention the bacteria that may be lingering there.) I tried only 4 minutes and the effect was fairly intense. The sinus infection cleared up the next day (without antibiotic use or other medication), and the feeling of euphoria I experienced helped markedly with the malaise. I used the booth two more times that winter, each time at four minutes, with good results. What is your opinion regarding tanning booths in moderation?
    As long as you stay in them for a short period of time and infrequently I think they are safe, and it appears in your case the experience has been beneficial.

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