Calcium supplement health benefit and side effects, risk of overdosage or excess intake
October 12 2016 by
Ray Sahelian, M.D.

A calcium supplement is derived from natural products, such as oyster shell or bone. Although it was well accepted for decades that supplementation reduces the risk for osteoporosis and bone fracture, new research is not as consistent as previous findings. There is concern that high dosages may increase the risk for hardening of the arteries leading to a higher rate of heart disease and stroke. They also increase the risk for kidney stones. To balance the benefits versus risks, perhaps one should limit daily calcium supplement dosage to no more than 400 or 600 mg a day rather than the 1,000 mg to 1,500 mg range, unless there is a serious condition of bone loss. Most women may not require any supplementation. I discuss the risks and benefits in more detail below.

Food sources, dietary intake
Calcium is found in a wide variety of foods, but some are more rich than others. The food group with the most calcium is dairy - milk, yogurt and cheese. For instance, one cup of milk has about 300 mg. One ounce of cheese has about 200 mg. Other food sources rich in calcium include beans, almonds, oysters, and dark green leafy vegetables such as spinach and kale.
The NIH recommends milk and other dairy products as a primary source. By eating a wide variety of foods, you can help make sure to get the amount you need each day. The body's absorption drops the more calcium you get via foods and supplements.

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If your diet does not include an adequate amount of calcium, a high quality calcium supplement could provide you with health benefits. It's the easy way to keep your bones healthy and strong.

Calcium reduces the risk of osteoporosis. Osteoporosis affects middle-aged and older persons. A lifetime of regular exercise and a healthy diet that includes calcium builds and maintain good bone health and may reduce the risk of osteoporosis late in life. Daily intakes above 600 mg are not proven to provide any additional benefits to bone health.

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Supplement Facts
Serving Size: 2 Capsules
Servings Per Container: 125
  Amount Per Serving % Daily Value
Total Carbohydrate 1 g <1%†
Calcium (as calcium citrate/calcium carbonate/calcium malate) 500 mg 50%

Suggested use: Take one to three calcium supplement tablets a day or as recommended by your health care professional. This mineral is best taken with meals.

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Other products online
Supplement Facts, amount per 2 tablets:
Vitamin D (as cholecalciferol) 133 IU - 30% daily value
Calcium from tricalcium phosphate 160 mg, carbonate 160 mg, and gluconate 13 mg

Additional products available online
Nature's Way, Alive! Calcium, Bone Formula, 120 Tablets

Latest studies, conflicting results
Osteoporosis International. 2015. Calcium plus vitamin D supplementation and risk of fractures: an updated meta-analysis from the National Osteoporosis Foundation. The aim was to meta-analyze randomized controlled trials of calcium plus vitamin D supplementation and fracture prevention. Meta-analysis showed a significant 15 % reduced risk of total fractures and a 30 % reduced risk of hip fractures.

British Medical Journal. 2015. Calcium intake and bone mineral density: systematic review and meta-analysis. Increasing calcium intake from dietary sources or by taking calcium supplements produces small non-progressive increases in bone mineral density, which are unlikely to lead to a clinically significant reduction in risk of fracture.

Calcium supplement side effects, safety, risk, danger
The most common adverse effects of calcium supplements are constipation, intestinal bloating and excess gas. Adverse effects occur most frequently with calcium carbonate. Switching preparations or increasing fluid intake may relieve symptoms. Patients who form calcium-containing kidney stones are generally advised not to take calcium supplements. It is possible that a very, very low intake of calcium can aggravate the risk of stone formation by increasing absorption and urinary excretion of oxalate.
   A newly recognized worrisome concern on higher dosages is an increased risk for hardening of the arteries and heart attacks. See a discussion in the September 2010 issue of the supplement research and complementary medicine newsletter and read below.

A team of scientists led by Qian Xiao, of the U.S. National Cancer Institute, collected data on more than 388,000 men and women, aged 50 to 71 years old. They took part in a study on diet and health conducted by the U.S. National Institutes of Health and the AARP from 1995 to 1996. Over an average 12 years of follow-up men taking 1,000 milligrams a day of a calcium supplement had an increased risk of dying from heart disease and perhaps a slightly higher risk of stroke. Among women, however, calcium supplements were not linked to an increased risk of dying from cardiovascular disease. And, calcium from diet didn't increase the risk of dying from cardiovascular disease for either sex.  Feb. 4, 2013, JAMA Internal Medicine, online
   Comments: Until the results are replicated, it does seem prudent that men limit their calcium intake from supplements to less than 600 mg a day.

Heart attack risk
Did you see this worrisome headline? "Older women who take calcium supplements to maintain bone strength may have an increased risk of heart attack." Researchers at the University of Auckland in New Zealand evaluated 1,471 healthy post-menopausal women, average age 74, for a period of five years. Of them, 732 were given a daily calcium supplement and 739 were given a placebo. Participants received either 1 g of elemental calcium daily as the citrate (Citracal; Mission Pharmacal, San Antonio, TX) or identical placebo. They were asked to take two tablets (each containing 200 mg) before breakfast and three in the evening. Over the next few years, heart attacks were more common in the women taking the calcium supplements.
   Comments: Many women take calcium supplements to try to prevent osteoporosis. These supplements elevate blood calcium levels possibly accelerating vascular calcification. Doctors and patients are now presented with a very difficult challenge. At what level of calcium supplement intake do the benefits of osteoporosis prevention or treatment outweigh the possible risks of kidney stones are heart attacks? Firstly, I would like to see a few more studies regarding the role of calcium supplements and heart attack rate. Perhaps the results of this study were a fluke and other studies may not find the same association. Assuming that there is such an association, recommending calcium supplements for post menopausal osteoporosis prevention becomes quite difficult. I don't have absolute answers on this issue, but, for the time being, a reasonable balance would be to reduce one's calcium intake from supplements. If you are taking 1,200 mg a day, you may wish to drop to 800 or 1,000 mg. If you are taking 800 a day, you may wish to drop to 600 mg. Discuss with your doctor the results of this study and both of you could come to a mutually satisfying decision regarding the appropriate dosage in your particular case. Different doctors and researchers are likely to have different opinions on this topic. I am not aware of any research in men taking calcium supplements and the risk for increased heart attacks. Most men don't take very high dosages. My guess it that, if it is true that high dosages increase the risk for atherosclerosis in women, then the effects would be similar in men.

Macular degeneration
Older people who take more than 800 mg of calcium a day are almost twice as likely to be diagnosed with age-related macular degeneration (AMD), a condition that causes vision loss. JAMA Ophthalmology, published online April 9, 2015.

Vascular events in healthy older women receiving calcium supplementation: randomised controlled trial.
BMJ. 2008.
1471 postmenopausal women (mean age 74): 732 were randomised to calcium supplementation and 739 to placebo. Myocardial infarction was more commonly reported in the calcium group than in the placebo group.

Osteoporosis study
The benefits of calcium supplementation as a way to reduce bone fractures is still being debated, but most studies do indicate that calcium pills do reduce the risk for bone fracture. Men's bones benefit from calcium supplementation just as much as women's do.

Effects of calcium supplementation on clinical fracture and bone structure: results of a 5-year, double-blind, placebo-controlled trial in elderly women.
Arch Intern Med. 2006. School of Medicine and Pharmacology, University of Western Australia, Australia.
Five-year, double-blind, placebo-controlled study of 1460 women recruited from the population and older than 70 years who were randomized to receive calcium carbonate 600 mg twice per day, or identical placebo. Supplementation did not significantly reduce fracture risk. However, 830 patients (56%) who took 80% or more of their tablets (calcium or placebo) per year had reduced fracture incidence in the calcium compared with the placebo groups (10% vs 15%). Calcium-treated patients had improved quantitative ultrasonography findings of the heel, femoral neck and whole-body dual x-ray absorptiometry data, and bone strength compared with placebo-treated patients. Of the 92 000 adverse events recorded, constipation was the only event increased by the treatment. Supplementation with calcium carbonate tablets supplying 1200 mg/d is ineffective as a public health intervention in preventing clinical fractures in the ambulatory elderly population owing to poor long-term compliance, but it is effective in those patients who are compliant.

Effect of calcium supplementation on fracture risk: a double-blind randomized controlled trial1,2,3
American Journal of Clinical Nutrition, 2008.
The objective of this calcium study was to determine whether 4 years of calcium supplementation would reduce the fracture risk during treatment. The participants were aged less than 80 y at study entry (mean age: 61 y), were generally healthy, and had a recent diagnosis of colorectal adenoma. A total of 930 participants (72% men; mean age: 61 y) were randomly assigned to receive 4 y of treatment with 3 g calcium carbonate (1200 mg elemental Ca) daily or placebo and were followed for a mean of 10 years. Calcium supplementation reduced the risk of all fractures and of minimal trauma fractures among healthy individuals. The benefit appeared to dissipate after treatment was stopped.

Calcium- and vitamin D3-fortified milk reduces bone loss at clinically relevant skeletal sites in older men: a 2-year randomized controlled trial.
J Bone Miner Res. 2006 Mar. Centre for Physical Activity and Nutrition Research, School of Exercise and Nutrition Sciences, Deakin University, Melbourne, Australia.
In this 2-year randomized controlled study of 167 men  aged 50 years of age and older, supplementation with calcium-vitamin D3-fortified milk providing an additional 1000 mg of calcium and 800 IU of vitamin D3 per day was effective for suppressing PTH and stopping or slowing bone loss at several clinically important skeletal sites at risk for fracture.

Is it okay to take a strontium supplement along with a calcium supplement to prevent osteoporosis?
   I have not seen any long term studies regarding the combination of strontium pill and calcium pills taken together and their influence on bone health and bone strength.

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Health claim allowed by FDA
Regular exercise and a healthy diet with enough calcium helps teens and young adult white and Asian women maintain good bone health and may reduce their high risk of osteoporosis later in life.

Colon cancer
Higher milk and calcium consumption is linked with reduced odds of developing colon cancer. However this relationship is still being evaluated and not all studies have confirmed this finding.

Colon polyp
Taking calcium supplements protects against the development of colon polyps, which can become cancerous, and this benefit appears to persist for up to 5 years after people stop taking the calcium supplements.

Excessive secretion of parathyroid hormone can lead to hyperparathyroidism and elevated blood calcium levels. Very high calcium levels lead to a condition known as hypercalcemia.

Dosage recommendations
A high dietary calcium intake combined with vitamin D can increase bone density and perhaps reduce fractures in older women and, probably, men. The Institute of Medicine recommends that persons 19 to 50 years of age consume 1,000 mg per day and that persons older than 50 years consume 1,200 mg per day through a combination of food and supplements. The average American consumes less than 800 mg per day. However, other studies indicate that if enough vitamin D is ingested, the daily calcium supplement dosage need not exceed 800 mg. My personal opinion is that daily doses of 300 to 600 mg are adequate for most people.
   Taking a calcium supplement with food in dosages of 500 mg or less increases absorption. Calcium preparations must be dissolved before they can be absorbed; the absorption rate for calcium is about 20 to 30 percent. The absorption of calcium supplements differs by preparation. Foods such as spinach, rhubarb and wheat bran can decrease calcium absorption. Calcium can interfere with absorption of iron, zinc, bisphosphonates and tetracycline. Absorption also requires adequate doses of vitamin D. Vitamin D supplementation is especially important in elderly persons because skin synthesis and absorption of vitamin D may be impaired.
   Calcium supplements given to healthy children to improve their bone density are unlikely to prevent broken bones. Therefore it does not appear to be necessary to give children calcium supplements.

Professor Heike Bischoff-Ferrari, of University Hospital Zurich, Switzerland combined data from randomized controlled trials involving over 5,600 mostly postmenopausal women aged 58 years and older, and found that calcium supplementation by itself without vitamin D or phosphorus may increase the risk for hip fracture. Other nutritional deficiencies, involving phosphate and vitamin D, appear to affect calcium absorption and, in turn, influence bone health. Earlier studies documented that calcium supplements (citrate and carbonate) may reduce the phosphate absorption needed to build calcium into bone. The combined effect may enhance bone loss, especially among frail older individuals. Calcium absorption is enhanced significantly with better vitamin D status. It may be that current recommendations are too low for vitamin D, and too high for calcium. American Journal of Clinical Nutrition, December 2007

Function in the body
Calcium is a mineral that is the chief supportive element in bones and teeth. Calcium salts make up about 70 percent of bone by weight and give that substance its strength and rigidity. About 99 percent of the calcium in the human body is found in the bones and teeth. The remaining 1 percent circulates in the bloodstream, where it performs a variety of important functions. This mineral helps to contract muscles and to regulate the contractions of the heart. It plays a role in the transmission of nerve impulses and in the clotting of blood. Calcium is involved in the stimulation of contractions of the uterus during childbirth and in the production of milk. It also regulates the secretion of various hormones and aids in the functioning of various enzymes within the body.

Additional benefits
Many calcium supplements are marketed primarily as antacids. It may be helpful in premenstrual syndrome. The rational for supplementation in women with PMS lies in several studies suggesting that PMS patients have altered calcium homeostasis and increased risk of osteoporosis.

Healthy bones require a combination of calcium, phosphorus and magnesium. They also need adequate protein to form their basic framework, vitamin K to maintain structural proteins, and two other bone strengtheners: vitamin D (for calcium absorption) and exercise (to stimulate bone-building cells). But calcium does more than build strong bones. It is crucial for transmitting nerve impulses and maintaining a regular heartbeat. It stimulates hormone secretions and activates enzymes. Only about half of Americans are getting the required amount says the National Osteoporosis Foundation. Recommended intake is 1,000 milligrams a day for adults — 1,200 for women older than 50 and 1,300 for teens.

Forms and supplements
Calcium is found in several forms including carbonate, chloride, citrate, gluconate, pyruvate, and others.
   Calcium carbonate and phosphate preparations have the highest concentration of elemental calcium, about 40 percent. Citrate contains 21 percent elemental calcium. Lactate and gluconate contain 13 and 9 percent, respectively. Absorption of calcium citrate is higher than that of carbonate. However, for practical purposes, any form, such as citrate, gluconate, or carbonate should be satisfactory for general health purposes. Although there are variations in absorption between the different calcium supplement forms, whether in the long run they make much of a physiological difference is not fully clear. I don't think we need to worry much about which form we are ingesting. Even if one form, such as citrate, may be better absorbed than another form, such as carbonate, there is a possibility that too much calcium ingestion may not be such a good thing or necessary. A high amount may actually lead to the possibility of kidney stones. You will also find many supplements that include calcium with magnesium.
   The following are the most common forms: Calcium Carbonate is available as capsules, tablets, oral suspension, and chewable tablets; Citrate is often sold as tablets; Glubionate often as syrup; Gluceptate and Gluconate as oral solution, Gluconate as tablets and chewable tablets; Lactate as tablets; Lactate-Gluconate; Dibasic Calcium Phosphate as tablets; and Tribasic Calcium Phosphate as tablets.
   Raw material suppliers often sell it in bulk in the following forms: Caseinate, Chloride, Chloride Anhydrous, Chloride Dihydrate, and Formate.

A low level of calcium in the blood  is called hypocalcemia. Calcium deficiency can make the nervous system highly irritable causing spasms of the hands and feet, muscle cramps, abdominal cramps, and overly active reflexes. Chronic calcium deficiency contributes to poor mineralization of bones, soft bones (osteomalacia) and osteoporosis. In children, calcium deficiency causes rickets and impaired growth.

Supplements or from Food?
Young girls who get extra calcium from food tend to gain more bone mass than those who get it from tablet supplements, but children who already receive adequate amounts of calcium in their diets do not benefit from any form of extra calcium. "We conducted the study to learn how to maximize the children's peak bone mass during the rapid-growth period of puberty -- in which 60 percent of the adult bone mass accumulates -- and thus prevent osteoporosis in adulthood," said Dr. Sulin Cheng from the University of Jyväskylä in Finland. For two years, Cheng and her colleagues followed a group of 195 healthy girls, ages 10 to 12, whose calcium intake was under the National Nutrition Council recommended levels (less than 900 mg a day.) They randomly assigned the children to receive 1000 mg calcium tablets, 1000 mg calcium plus 200 IU vitamin D tablets, low-fat cheese (1000 mg of calcium), or placebo tablets. The researchers measured the effects of calcium supplementation on bone mass and body composition. They found that the cheese group showed more beneficial effects in their bones than any of the other groups, but when they took into account the individual growth speed, no beneficial effect was found with any of the interventions -- calcium alone, calcium plus vitamin D, or even cheese supplementation. This means that if you exceed certain levels of your dietary calcium intake, it doesn't matter how much you take; you won't get any benefits.

Children - Supplement for a Child
Many American children do not consume enough milk or other calcium-rich foods like yogurt and cheese, or dark green leafy vegetables, that build strong bones. A calcium deficiency -- whether blamed on children's finicky diets or teenagers choosing soft drinks instead of milk -- could pose risks later on of broken bones or osteoporosis. Just one out of 10 adolescent girls consumes the recommended daily calcium intake of 1,200 milligrams per day. Between the ages of 12 and 19, children generally consume between 700 and 1,000 milligrams a day -- often under recommended levels. Calcium is particularly important during early adolescence when more of the mineral is needed during a three- to four-year period when peak bone growth occurs and 40 percent of total lifetime bone mass is accumulated. Low bone mass has also been shown to contribute to fractures in children. A calcium supplement in a child may be beneficial if it is suspected that dietary calcium intake from food is low. For a child with low calcium intake, a daily calcium supplement dose of 300 mg of calcium carbonate or calcium citrate should be helpful.

Bioavailability of calcium: comparison of calcium carbonate and milk and the effect of vitamin D, age, and sex using 24-hour urine calcium as a method.
Calcif Tissue Int. 2005. Medical Department, Roskilde University Hospital, Koge, Denmark
The aim of the present study was to compare the bioavailability of calcium from calcium carbonate and milk and to investigate if 1,200 IU of cholecalciferol ( vitamin D ) a day increased intestinal absorption of calcium carbonate. Both young women and a group of older persons of both sexes were included to study the influence of age and sex. In total, 53 healthy women and men were included: a group of 23 younger women (median age 30) and an older group of 15 women and 15 men (median age 66). The study period was 4 weeks; each participant completed four treatment regimens randomly: calcium carbonate, calcium carbonate + vitamin D, milk, and placebo. All regimens were distributed three times a day and consisted of 1,200 mg of elementary calcium carbonate. The 24-hour urine calcium excretion was used as a method. Total urinary calcium excretion rates (mmol/day) were as follows (mean +/- SD): placebo 4.41, milk 5.17, calcium carbonate 5.83, and calcium carbonate + vitamin D 6.06. All regimens compared to placebo were significant. Addition of vitamin D to the calcium carbonate regimen increased calcium excretion but insignificantly. The bioavailability of calcium carbonate and milk was demonstrated. Additional vitamin D to individuals in positive calcium balance with serum 25(OH)D levels >50 nmol/L only marginally increased calcium absorption from calcium carbonate in a short-term intervention.

Children who drink more milk do not necessarily develop healthier bones. The U.S. government has gradually increased recommendations for daily calcium intake, largely from dairy products, to between 600 and 1,200 milligrams to promote healthy bones and prevent osteoporosis. But the report, published in the journal Pediatrics, said boosting consumption of milk or other dairy products was not necessarily the best way to provide the minimal calcium intake of at least 400 milligrams per day. Other ways to obtain the absorbable calcium found in one cup of cow's milk include a cup of fortified orange juice, a cup of cooked kale or turnip greens, two packages of instant oats, two-thirds cup of tofu, or 1-2/3 cups of broccoli.

Stone forming risk of calcium citrate supplementation in healthy postmenopausal women.
J Urol. 2004 Sep.
We evaluated the effect of calcium citrate supplementation alone or in combination with potassium citrate on the stone forming propensity in healthy postmenopausal women. A total of 18 postmenopausal women without stones underwent a randomized trial of 4 phases comprised of 2 weeks of treatment with placebo, calcium citrate (400 mg calcium twice daily), potassium citrate (20 mEq twice daily), and calcium citrate and potassium citrate (at same doses). During the last 2 days of each phase urine was collected in 24-hour pools for complete stone risk analysis. RESULTS: Compared to placebo, calcium citrate increased urinary calcium and citrate but decreased urinary oxalate and phosphate. Urinary saturation of calcium oxalate, brushite and undissociated uric acid did not change. Potassium citrate decreased urinary calcium, and increased urinary citrate and pH. It decreased urinary saturation of calcium oxalate and undissociated uric acid, and did not change the saturation of brushite. When calcium citrate was combined with potassium citrate, urinary calcium remained high, urinary citrate increased even further and urinary oxalate remained reduced from the calcium citrate alone, thereby marginally decreasing the urinary saturation of calcium oxalate. Urinary pH increased, decreasing urinary undissociated uric acid. The increase in pH increased the saturation of brushite despite the decrease in urinary phosphorus.  Calcium citrate supplementation does not increase the risk of stone formation in healthy postmenopausal women. The co-administered potassium citrate may provide additional protection against formation of uric acid and calcium oxalate stones.

Calcium deposit
People use the term calcium deposit to indicate the accumulation of calcium in a tissue, for instance a tendon. A deposit in a tendon could cause no problems or it could lead to calcific tendonitis. In severe cases, surgical removal is possible. Recently, shock waves have been used with some success in breaking up the calcium deposit.

Calcium deposit in the brain, or microcalcification, is seen in a number of disease conditions, such as vascular dementia, Alzheimer's disease, Parkinson's disease, astrogliomas, and posttraumatic epilepsy.

Is there any supplement that can help to retard or even reverse the uptake of calcium into soft tissue such as heart valves and blood vessels?
   A. I am not aware of any specific such studies.

Q. I purchased a calcium supplement. However, I have long been confused about the best form. I am a 40 yr old female, and mother of 2. I have heard of the buzz about coral calcium. Is it less effective than calcium carbonate or calcium citrate? And, what advice / recommendations can you offer about coral calcium, best calcium supplement, and which to choose. I've also heard that chelated calcium is the 'best.' Is calcium citrate the only chelated calcium? I've spoken to pharmacists to try and unravel the calcium mystery and make the best calcium supplement hoice for me.
   A. There is a lot of controversy regarding which form of calcium - carbonate, citrate, etc - is the best. Different experts have different opinions. In my judgment, and for practical purposes, I don't think we need to worry about the form. Overall it probably does not make too much difference. One good option is to purchase a different form of calcium each time you buy a calcium supplement, and this way you could expose your body to the different variations.
   As to coral calcium, the jury is still out whether if offers benefits to any significant extent than calcium and magnesium supplements. However it is difficult to say since we have not seen any human trials comparing calcium versus coral calcium. Therefore, the best calcium supplement may be any form of calcium, and might as well choose the cheapest calcium supplement.

Q. Does calcium influence iron absorption and vice versa?
   A. In short-term studies, dietary calcium and supplemental doses of calcium chloride or calcium carbonate inhibit iron absorption. In contrast, long-term studies regarding the effect of calcium supplementation on iron status in populations at high risk for compromised iron status failed to show any problems with iron status. Long-term consumption of calcium supplements does not seem to affect overall iron status.

Q. Why do doctors check a blood calcium level?
   A. A test for blood calcium is used by doctors to diagnose and monitor a range of medical conditions relating to the bones, heart, nerves, and kidneys. It is difficult to know levels of calcium in your tissues based on blood calcium level. Blood calcium levels do not directly tell how much calcium is in the bones, but rather, how much total calcium or ionized calcium is circulating in the blood. The blood calcium level could be high while the amount of calcium in the bones could be low. A high blood calcium level is  called hypercalcemia, and low blood calcium is called hypocalcemia.

Q. I'm a post-menopausal woman who needs to take in calcium. But...I have chronic gastritis and can't tolerate any type of Calcium supplement on the market...I've tried chelated, liquid chalcium, chewable calcium ... health food store products ... over the counter pharmacy products, etc. I do take an enteric coated multi vitamin but there is not very much calcium in it. I need more....but I'm allergic to milk products. Can you direct me to an enteric coated calcium supplement?
   A. It should be easy to find by doing a google search for calcium enteric coated.

Q. I was under the impression that calcium loss is due to consuming too much animal protein. I have been a vegetarian all my life and also never drink milk. My last bone density test was fine, it showed only a very slight decline ... but after all, I am 77 now ... and feeling great! I take1500 to 2000mg calcium every night ... and add Dandelion to help against gallstones and kidney stones ... this comes from my European training . Dandelion has always been strong in Austria and Germany ... not like here, where it is considered an unsightly weed!
   A. Although calcium loss could be partially due to consuming too much animal protein, there are quite a number of factors that are involved in maintaining healthy calcium levels in the body. Some people may tolerate high calcium supplement intake of the amount you mention, but others could increase their risk for kidney stones. I have not seen research on dandelion and kidney stones, but then again there is not that much research on herbal medicine.

Q. You often recommend taking a break from supplements. Does taking a break from supplements include calcium, especially for women? Also, it's often said that taking calcium close to whole grains, beans and some other foods, makes it harder to absorb. Is it better to take it between meals for that reason?
   A. Each person is different, but as a rule and for practical reasons one need not worry about the timing of calcium. It should be taken whenever convenient, sometimes with meals, sometimes on an empty stomach. As for breaks with a calcium supplement, this probably does not apply to women who are prone to moderate to severe osteoporosis, it is probably better they take the calcium quite regularly.

Q. I have been advised to take calcium caltrate. Do you have any information on it. How does it differ from other forms. I have osteoporosis, not too bad and have been taking Actonel which I prefer not to.
   A. Calcium Caltrate is the brand name product for calcium carbonate and vitamin D. Calcium Caltrate contains the following: Calcium Carbonate, Cholecalciferol (Vitamin D), Starch. Contains Less than 2% of the Following: Croscarmellose Sodium, Dl-Alpha Tocopherol, FD&C Yellow No. 6 Aluminum Lake, Gelatin, Hydroxypropyl Methylcellulose, Magnesium Stearate, Partially Hydrogenated Soybean Oil, Sucrose (Adds a Negligible Amount of Sugar), Titanium Dioxide. May Contain Less than 2% of the Following: Glycerin, Polydextrose.

Are there any negative side effects to taking the full amount of calcium at one time? I have been taking a multivitamin with 450mg of calcium along with another 500mg calcium supplement in the evenings due to a medication I have to take in the mornings which shouldn’t be combined with a either of those supplements.
   It is difficult to say for sure, but perhaps the risk for kidney stone could be higher if a very high amount of calcium is taken at one time? We are not sure, it is just an educated guess.

What do you know about calcium aspartate anhydrous for osteoporosis? My OBGYN has never heard of it, but I saw their web site (Made by Elixer Co.) and they make strong claims about calcium aspartate anhydrous for osteoporosis. I can't find any information on about calcium aspartate anhydrous, any thoughts?
   We have not seen any significant human research with calcium aspartate anhydrous for osteoporosis, therefore any claims that this form of calcium is superior to other forms of calcium, such as calcium citrate or calcium carbonate, is premature.

I am a medical doctor from Mumbai, India, and had an opportunity to visit your website and was impressed with the knowledge base it offers from a clinician of stature of Dr. Sahelian. I am a physician using conventional calcium formulations in clinical practice in various indications including pregnancy, lactation and in osteoporosis. Recently, claims are made for better absorbable calcium are made for various new formulations e.g., calcium aspartate anhydrous (CAA). Unfortunately, the scientific information on calcium aspartate anhydrous is limited. I am informed that calcium aspartate anhydrous is perhaps one of the few formulations which provides highest "absorbable" calcium. Now, this could probably change the rules of the game, as the conventional calcium formulations always talked about "elemental" calcium, while calcium aspartate anhydrous is talking about higher "absorbable" calcium. We have been taught through textbooks, & all guidelines (RDAs/ RDIs/ RNIs) also tell us to calculate the calcium intake based on "elemental" calcium per tablet, which however as we know, does not translate into "absorbable" calcium, which finally is bioavailable. My question simply put is, Whether we can have any guidelines on daily requirement of "absorbable" calcium? I understand that calcium supplementation needs to be individualized, but due to new formulations and new concepts coming up, we need to have this basic information, so as to use it appropriately. I will very much appreciate if you could kindly send me the response & related information, which would be a great learning for an academically oriented clinician like me.
   Even after several decades of research with well known types, such as calcium carbonate and calcium citrate, the ideal dosage and frequency of use has not been fully determined for the treatment of osteoporosis. Many newer forms are being promoted, such as aspartate anhydrous. Since long term human studies with calcium aspartate anhydrous are lacking, it is difficult to make any recommendations. For the time being, one should rely mostly on carbonate or citrate, although alternating these with calcium aspartate anhydrous seems to be practical and reasonable. If calcium aspartate anhydrous is claimed to be better absorbed, could it also lead to a higher risk of side effects, such as kidney stones?

For about half a year I used Alchas Calcareas form New Chapter. It has calcium and magnesium from whole foods from alchas calcareas, and it has cultured vitamin D3 and vitamin K2 added to it. Do you think this calcium is better absorbed than chelated from a chelated multi mineral supplement? That has all the minerals in chelated form and a 1000mg of calcium and 500mg of magnesium in chelated forms as well in two capsules, (I would probably only take one). I can get vitamin D in cod liver oil and I can take vitamin K2 from natto separately, because I do believe it helps with putting the calcium in the bones. The natural calcium supplement is just very expensive and again I'm not sure if it is really so much better.
   Although calcium absorption is important in deciding on what kind of calcium supplement to take, I don't think practically speaking it makes much difference in the long run. Plus, studies are controversial regarding the benefits of high dosage calcium supplement use and maybe taking less or not absorbing all the calcium is better. There are no easy answers and therefore using the cheapest one for the time being seems practical.