Selenium supplement dietary source, foods Health benefit, side effects, danger and safety
September 19 2018 by
Ray Sahelian, M.D.

Selenium is a mineral required in small amounts to maintain good health. Selenium is necessary to generate antioxidant proteins that help prevent cell damage from free radicals, which are thought to contribute to the development of certain chronic diseases. Selenium also has a role in regulating thyroid gland function and the immune system. Along with vitamin C, Vitamin E, selenium is one of the more popular antioxidants. This mineral activates the antioxidant enzyme glutathione peroxidase.
   Low dietary intake of selenium leads to health problems, a moderate intake is ideal, and too much selenium in the body can potentially cause harm including the possibility of increasing toxicity and the risk for certain types of cancer.

buy Selenium supplement 100 mcg per pill

Dietary Supplement

Selenium is essential for the functioning of the biologically important enzyme glutathione peroxidase. Glutathione peroxidase neutralizes hydrogen peroxide thereby promoting healthy tissues.

Buy Selenium 100 mcg or MultiVit Rx

Supplement Facts
Serving Size: 1 Tablet
  Amount Per Serving % DV
Selenium (as L-selenomethionine) 100 mcg 143%
DV = Daily Value.

Suggested Use: One selenium tablet a few times a week with a meal, or as recommended by your health care professional.
Supplement Facts: Selenium - 100 mcg each pill

Other products sold online
Nature's Bounty, Selenium, 200 mcg, 100 Tablets

Benefit of selenium
Most Americans do not have a significant selenium deficiency unless a person has an unusual fad diet. The benefit of selenium is that it can provide antioxidant properties. It's possible that a deficiency can increase the risk for cancer. Another benefit is that it can potentially reduce the risk for cataract by increasing levels of the body's glutathione antioxidant system. Too much in the body can be counterproductive to ideal health.

MultiVit Rx - High Quality Daily Vitamins and Minerals with Vitamin E and Selenium supplement

Manufactured by a FDA-approved and GMP-certified facility.

MultiVit Rx Supplement Facts:
Vitamin A
     Beta Carotene
     Retinyl Palmitate
Vitamin C with Rose hips
Vitamin D
Vitamin E (mixed tocopherols)
Vitamin B-1 (thiamine hcl)
Vitamin B-2 (riboflavin)
Vitamin B-6
Folic acid
Vitamin B12
Biotin - 300 mcg
Pantothenic acid (d-calcium pantothenate)
Calcium (citrate)
Iodine (potassium iodine)
Magnesium (oxide)
Zinc (oxide)
Selenium (amino acid chelate) - The body incorporates selenium into proteins called selenoproteins, which act as antioxidant enzymes.
Copper (amino acid chelate)
Manganese (carbonate)
Chromium (amino acid chelate)
Molybdenum (amino acid chelate)
Potassium (carbonate)
Green Tea (leaves)
Inulin (Jerusalem artichoke plant fiber extract inuflora)
PABA (para aminobenzoic acid)
Citrus Bioflavonoid Complex
Choline (bitartrate)
Betaine (HCI)
Beta Glucan 1/3-Beta, 1/6-Glucan (insoluble form from cell walls of Saccharomyces cerevisiae)
Lycopene (from tomato)
Lutein (from marigold extract)

Selenium overdose, side effects, safety, excess, adverse events, toxicity
I personally do not think daily ingestion of selenium greater than 100 mcg is necessary. If you buy it at the 200 mcg dosage, you would not need to take it every day, but just twice a week, unless your doctor has found that you have a severe deficiency. Selenium toxicity may occur when daily doses are above 500 to 1000 mcg for prolonged periods. High dosages are not advised in those who have diabetes.

Cholesterol elevation
Taking too much selenium could increase cholesterol levels by 10 percent and, as a result, may raise the risk of heart disease. Dr. Saverio Stranges of the Warwick Medical School in Warwick, England, said the findings of this observational study are "consistent with the findings of earlier clinical work," which have suggested an association between elevated blood levels of selenium and an increased risk of type 2 diabetes and high cholesterol. Dr. Saverio Stranges says, "We believe that the widespread use of selenium supplements or of any other strategy that artificially increases selenium status above the level required is unwarranted at the present time." Journal of Nutrition 2009.

J Trace Elem Med Biol. 2016. Effects of selenium supplementation on glucose homeostasis and free androgen index in women with polycystic ovary syndrome: A randomized, double blinded, placebo controlled clinical trial. Insulin resistance (IR) is a main pathophysiologic feature in polycystic ovary syndrome (PCOS) patients which is triggered by elevated oxidative stress in these patients. Selenium, an essential micronutrient, is a major constituent of antioxidant enzymes such as glutathione peroxidase. Recently, decreased plasma selenium concentrations were reported in PCOS patients. So, the present study was carried out in order to assess whether selenium consumption can improve the metabolic response to insulin and reduce the insulin resistance in these women. A total of 53 PCOS patients (diagnosed by Rotterdam criteria), 18-42 years old, participated in this randomized, double-blind and placebo controlled trial for 12 weeks. The effects of daily administration of 200μg selenium or placebo on serum glucose, total testosterone (tT), sex hormone binding globulin (SHBG) and free androgen index (FAI) in fasting state were evaluated. This study showed that selenium supplementation in PCOS patients may worsen insulin resistance in them. Until the results of larger studies become available, indiscriminate consumption of selenium supplements in PCOS patients will warrant caution.

In 2008 the FDA warned consumers not to purchase or use "Total Body Formula" in flavors Tropical Orange and Peach Nectar and "Total Body Mega Formula" in the Orange / Tangerine flavor of these products after receiving reports of adverse reactions in users. The adverse reactions generally occurred after five to 10 days of daily ingestion of the product, and included hair loss, muscle cramps, diarrhea, joint pain, deformed fingernails, and fatigue. Selenium, a naturally occurring mineral, is needed only in very small amounts for good health. Selenium can boost the immune system. Generally, normal consumption of food and water provides adequate selenium to support good health. Excessive intake of selenium is known to cause symptoms to include significant hair loss, muscle cramps, diarrhea, joint pain, fatigue, loss of finger nails and blistering skin. Analyses of samples of the products by FDA laboratories have now found most of the samples contain extremely high levels of selenium--up to 40,800 micrograms per recommended serving, or more than 200 times the amount of selenium per serving (i.e., 200 micrograms) indicated on the labels of the products. Both product lines are distributed by Total Body Essential Nutrition of Atlanta, which is listed on the products' labels.

Selenium in food and cause of deficiency
Selenium is found in high amounts in meats and seafood. In the U.S., meats, nuts and bread are common sources. Brazil nuts have a high content. Eating two Brazil nuts daily is as effective for increasing selenium status and enhancing glutathione peroxidase activity as 100 g selenium as selenomethionine.
   Plants are the major dietary sources in most countries around the world since most of the people living in poorer counties do not have easy access to meat and fish. A major influence on the selenium content in food depends on the soil where these plants are grown. Deficiency can occur in certain areas where the soil is poor in selenium, such as certain regions of China and Russia. Selenium deficiency is quite often found in those areas because most food in those areas is grown and eaten locally and the locals do not have much access to imported foods from other regions.

Brazil nuts: an effective way to improve selenium status.
Am J Clin Nutr. 2008.
Participants consumed 2 Brazil nuts thought to provide approximately 100 mug Selenium, 100 mug Selenium as selenomethionine, or placebo daily for 12 wk. Actual intake from nuts averaged 53 mug Selenium /d (possible range: 20-84 mug Se). Plasma selenium and plasma and whole blood glutathione peroxidase activities were measured at baseline and at 2, 4, 8, and 12 wk, and effects of treatments were compared. Plasma selenium increased by 64%, 61%, and 7%; plasma glutathione peroxidase by 8%, 3%, and -1%; and whole blood glutathione peroxidase by 13%, 5%, and 1.9% in the Brazil nut, selenomethionine, and placebo groups, respectively. Consumption of 2 Brazil nuts daily is as effective for increasing selenium status and enhancing glutathione peroxidase activity as 100 mug Se as selenomethionine.

Selenium and mortality - the ideal amount
Studies show moderate levels of selenium mineral are associated with longevity. However, when levels pass a certain level, the odds of dying from any cause, or from cancer specifically, begin to go upward. Dr. Joachim Bleys of Johns Hopkins University School of Public Health in Baltimore, evaluated 14,000 U.S. adults. He and his colleagues found that higher blood levels of selenium were linked to a lower risk of death over a 12 year period, at which point the risk appears to increase. Apparently high levels of selenium are associated with an increased risk of mortality. Many Americans ingest more than the recommended amount of selenium. While the recommended dietary allowance (RDA) is only 55 micrograms per day, the typical intake in the U.S. ranges from 60 to 220 micrograms daily.
Once blood levels of selenium go over 130 ng/mL, the benefits of selenium stop. Once selenium blood levels pass 150 ng/mL, the risk of dying from any cause, or from cancer in particular, increases.
   This study raises the question as to selenium supplements are necessary to enhance health and longevity. Those who want to take selenium supplements should limit ingestion to two or three times a week rather than daily. Archives of Internal Medicine, February 25, 2008.

Selenium plays a positive role in a number of degenerative conditions including cancer, inflammatory diseases, thyroid function, heart disease, neurological diseases, aging, infertility, and infections. Most of the effects in these conditions are related to the function of selenium in antioxidant enzyme systems. Increasing the levels of selenoprotein antioxidant enzymes (glutathione peroxidase, thioredoxin reductase, etc.) appears to be only one of many ways in which selenium-based metabolites contribute to normal cellular growth and function.

Bladder cancer
Diets rich in this mineral could reduce the risk for bladder cancer according to Dr. Nuria Malats of the Spanish National Cancer Research Center in Madrid, Spain,. The study, published in Cancer Epidemiology, Biomarkers & Prevention, 2010.

Eur J Cancer. 2016. Phase III randomised chemoprevention study with selenium on the recurrence of non-invasive urothelial carcinoma. The SELEnium and BLAdder cancer Trial. Patients were randomly assigned to oral selenium yeast 200 μg once a day or placebo for three years, in addition to standard care. Selenium supplementation did not lower the probability of recurrence in bladder cancer patients.

Prostate cancer
J Natl Cancer Inst. 2013. Advanced prostate cancer risk in relation to toenail selenium levels. Toenail selenium level was associated with a substantial decrease in risk of advanced PCa.
However, other studies point to an increased rate of prostate cancer in those who take high amounts of this mineral supplement.

Cataract eye disease
Selenium has been linked with a reduced risk of cataract and activates the antioxidant enzyme glutathione peroxidase, protecting cell membranes from oxidative damage.

Cognitive decline
Selenium levels decrease with age, which may contribute to a loss of neurological abilities in the elderly. Dr. N. Tasnime Akbaraly, of Universite Montpellier, and colleagues recruited 1,389 French subjects between 1991 and 1993 for a 9-year study with 6 follow-up periods. At study entry, the average selenium levels in the blood were 1.09 micromoles per liter -- and the average levels decreased by the end of the study. However, cognitive declines were not seen in all subjects. The investigators report that cognitive decline was associated with decreases of selenium over time, after accounting for other risk factors. Subjects with the highest levels of selenium loss had a higher probability of cognitive decline. These findings, along with information on the relationship between brain functions and selenoproteins, proteins containing selenium, support a relationship between selenium levels and cognitive function in the elderly. The ability of selenium supplements to protect against the loss of cognitive function in the elderly needs to be evaluated in a large clinical trial. Epidemiology, January 2007.

In the largest and longest clinical trial to date comparing the effects of selenium supplements versus placebo or dummy pills, daily doses of the mineral failed to reduce the occurrence of type 2 diabetes and may have increased it. In the study, people who took a 200 microgram selenium supplement each day for almost eight years had an increased risk of developing type 2 diabetes relative to people who took a placebo. Annals of Internal Medicine, 2007.

Thyroid function, what is the influence?
Thyroid function depends on the essential trace mineral selenium, which is at the active center of the iodothyronine deiodinase enzymes that catalyze the conversion of the prohormone thyroxine (T4) to the active form of thyroid hormone, triiodothyronine (T3). A British study did not find selenium supplements to benefit T4 to T3 conversion in the elderly. American Journal of Clinical Nutrition, 2008.

Selenium Research study
Selenium forms part of a very important enzyme normally present in our bodies called glutathione peroxidase. The richest sources of selenium are organ meats and seafood, followed by meat, cereal products, and dairy. The average intake of selenium in the American diet is 70 to 100 micrograms a day. Occasional supplementation with 20 to 100 micrograms of this mineral appears to be safe. Selenium in much higher amounts can act as an oxidant and thus is counterproductive.

Q. On your website page on selenium, the page mentions two things that seem to conflict. Regarding dietary sources of selenium, this quote "Plants are the major dietary sources of selenium" seems to contradict this later quote on the same page "The richest sources of selenium are organ meats and seafood, followed by meat, cereal products, and dairy." What plants are good sources of selenium? Or, could you otherwise help me understand how plants are the major source, but the richest sources are meats, dairy, and what sounds like a very narrow type of plant-based food (cereals)?
   A. We clarified our statement to say plants are the major dietary source of selenium in poorer countries since poor people do not have access to meat and fish as much as those living in Western countries.

Q. I think consumers should know that may be its prudent to wait for the results of the SELECT trial (2013) to see any possible diabetes risk with prolonged high selenium intake before taking in higher than 100 mcg of selenium. Regards, Hasan Saleem Head: New Product Development Flex Pharma 20 FCC, Maratab Ali Road Gulberg IV, Lahore Pakistan.
   A. We agree that at this point there is no need to take more than 100 mcg a day, and not just for the risk of diabetes, but just over toxicity if minerals are taken in too high a dose. I think selenium 200 mcg 2 or 3 times a week is sufficient.

Thank you for your very informative website. I look at it very often. I see from your website you recommend a smaller therapeutic dose of selenium (i.e. 100 mcg) I was taking 200 mcg at first for hypothyroidism, then I was getting an upset stomach so I started to take 100 mcg. It really seemed to help me at first, now it seems to have made me worse even at the smaller dose (50 mcg x 2 a day) so I am going to discontinue it. (i.e., I am getting fatigue, depression, etc) I recently became concerned with information that too much selenium can cause type II diabetes. If this is the case, how does too much selenium cause that? Does selenium affect blood sugar or cortisol? Is is better to take a whole food supplement of selenium?
   I am not sure I fully understand how excess selenium influences the pancreas, perhaps excess selenium is harmful to pancreatic cells. I see no reason that a whole food supplement of selenium would be better than other forms of selenium as long as the dosage of selenium ingested is the same.