January 23, 2017

The Amazing Power of Selenium

A single nutrient that holds great power for the prevention of disease and disability

by Dr. Scott Saunders, M.D.

A remarkable study on Selenium was published in The Journal of the American Medical Association in 1996. It reported a group of 1312 people in Arizona who were not deficient in selenium. Half were given 200 micrograms of selenium per day. After only five years, compared to those not given the supplement, there were:

  • 17% fewer deaths overall
  • 52% less cancer deaths
  • 37% less cancer, especially lung, prostate and colon – each of which was cut by about 50%[1]

This is dramatic and impressive, considering that no other nutrient or treatment can boast such numbers. Not even chemotherapy!

Selenium to stay young
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Selenium is a micronutrient that gets little attention. Since the Recommended Daily Allowance is only 55 micrograms per day, it is thought that Americans get enough in the diet. Indeed, The National Health and Nutrition Examination Survey (NHANES III) reported that over 99% of US participants had sufficient blood concentrations. It suggests selenium supplementation is not needed.[2] Thus, nutrition professionals and physicians may not recognize any need for selenium supplementation.

Low levels of selenium are present in meat and seafood. Selenium is not found in plants unless it is in the soil. Plants will include selenium in their proteins only if they are grown in areas where the mineral is abundant. But, soils depleted of selenium are not replenished because selenium isn’t necessary for the plant to grow, or bear fruit. Thus, the intake of selenium from food is highly dependent on the place it is grown, and not on the type of food.

What Does Selenium Do?

Selenium is part of a group of proteins that regulate three known actions:

Though it is needed in tiny amounts, each of these actions has a very large effect on your body.

Selenium to Stay Young All Your Life

Many of the diseases we face in the modern world are due to inflammation, including cancer, heart disease, arthritis, and diabetes. Selenium can improve function and prevent degeneration, or aging by lowering inflammation. We are told that it is normal to “get old” and have memory loss, diabetes, arthritis, or even heart disease. Actually, we don’t have to decline in function; we can continue to improve if we care for our bodies well.

By removing inflammation inside the cells, they function better, and are more able to regenerate, preventing aging. Selenium even prevents the peroxides in hair cells that cause us to get gray hair.

Getting adequate selenium is an important part of any anti-aging program.

Selenium for the “Big C”

Selenium has a very big effect on cancer.  Not only can selenium help prevent cancer, as noted above, but it can also treat an already existing cancer. Cancerous cells reproduce indefinitely.  But selenium programs them to die. This is called apoptosis, essentially triggering a suicide gene in the cancer cell. Control is taken away from the cancer cell by blocking the protein that protects the cancer cell.[3]

Selenium supplementation should be included in any cancer regimen.

Selenium for brain health
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Selenium for BRAIN health

As we age, we believe it is normal for the brain to degenerate. We accept memory loss and an inability to think clearly as a natural result of aging.  This, however, does not have to be the case.  We can continue to function all our lives if we know how to take care of the brain.

One of the most important ways to prevent degeneration of the brain is GLUTATHIONE. This powerful anti-oxidant is found everywhere in the body.  As cells use energy, oxygen free-radicals are produced. A large supply of anti-oxidants needs to be available to prevent damage to DNA and tissues.

This is especially true of the brain, since it uses 20% of the energy of our body.  Glutathione is the most important anti-oxidant in the brain, preventing or reversing diseases such as:

Selenium is part of an enzyme used to regenerate glutathione, or glutathione peroxidase.  As selenium levels drop, so do the levels of glutathione peroxidase. As a result, inflammation causes degeneration of the brain.  Keeping selenium up is important to protect brain cells from damage over time.

Take selenium to prevent loss of brain function as you age.

Selenium for Thyroid Blues

A very important part of the function of selenium is to help us convert the inactive T4 thyroid hormone to the active T3 thyroid hormone. The thyroid gland makes T4, but tissues use T3 for metabolism.

Interestingly, T4 is the only component of most prescription thyroid medications.  In cases of selenium deficiency, conversion of T4 to T3 is impaired and leads to hypothyroid symptoms.

Increasing the medication won’t help either, because we still can’t use it.  Adding selenium will improve the function of thyroid medications, and may even allow you to discontinue them entirely.

Moreover, because of the antioxidant properties of selenium, it prevents and treats Hashimoto’s thyroiditis. This is an autoimmune thyroid disease where people make antibodies against an enzyme in the thyroid gland.[4] One study concluded that three out of four trials with selenium supplementation for Hashimoto’s thyroiditis showed a decrease in auto-antibody levels.[5]

Selenium needs to be a part of treatment for any thyroid problem.

Selenium for Arthritis

A disease in China called Kashin-Beck is caused by low selenium, and includes breakdown of the joint cartilage. Studies done on children in Tibet and parts of China that contain low levels of selenium in the soil have shown improvement in the condition with supplementation.[6] Osteoarthritis is a major problem in the United States, as well as other developed countries.

There are no specific studies, but it would be a good idea to be sure you have enough selenium to repair the joints, or prevent inflammation that can further damage them.

Selenium for Infections

Chronic infections are becoming epidemic.  Millions in the United States are suffering from:

  • HIV
  • Coxsackie virus
  • Lyme disease
  • Candida
  • Epstein-Barr
  • Fibromyalgia
  • Chronic fatigue syndrome

Selenium is an important part of both the immune system function. It increases the cellular immune response by increasing T-cells production. The T-cells will help remove chronic infection, as well as decrease inflammation that can result from such infections.

Selenium deficiency causes immune system dysfunction in both the T-cell immunity and antibodies. Studies on HIV show that selenium alone can prevent the progression of HIV in those who are deficient.[7] Individuals who were positive for Hepatitis B, were given selenium, and followed for eight years. Those given selenium had a 35% decrease in liver cancer.[8]

Selenium needs to be part of treatment for any infectious disease.

Selenium Toxicity

Selenium is a very important trace mineral, but it can be toxic in large amounts. It is easy to take too much selenium because it is only needed in very small amounts. Less than 1 milligram per day is enough to cause the symptoms of selenium toxicity, including:

  • Hair and nail brittleness and loss
  • Gastrointestinal disturbances
  • Skin rashes
  • Garlic breath odor
  • Fatigue
  • Irritability
  • Neurologic disorders[9]

Most supplements are 200 micrograms (mcg), or less, so there is little chance of overdosing. Also, the studies on selenium supplementation for cancer and deficiency generally use a dose of 200 mcg per day with no evidence of toxicity. Symptoms of toxicity are found in areas where there is a lot of selenium in the soils. In these cases, blood levels correspond to as little as 850 mcg per day of selenium intake. Some is good, but more is not better in the case of selenium. You can determine whether you have a selenium deficiency with a simple blood test.


Everyone who lives in areas of low levels of selenium, including United States, Europe and parts of China, should take:

  • 200 micrograms of selenium per day for at least 90 days
  • Then take 200 micrograms per week

An alternative is to use nutritional yeast, which contains selenium. Two tablespoons contains from 50 to 200 mcg of selenium, depending on the manufacturer.

The only food that has consistently shown to have sufficient selenium is Brazil Nuts. They contain anywhere from 20 mcg to 100 mcg per nut. Thus, just a couple of Brazil Nuts per day, or several per week, is sufficient that you wouldn’t need any pills.

I add selenium (pills, yeast, or Brazil nuts) to the supplement list of all of my patients for several reasons.

  1. Patients come in with a problem, usually related to inflammation, and need selenium.
  2. I test almost everyone and find deficiency of selenium is common. Unlike the NHANESIII study quoted above, only those who already have a selenium supplement are sufficient, in my experience.
  3. Selenium is more powerful for the prevention of disease and disability, as noted above, than any other supplement.
  4. And, last of all – it’s cheap! People are spending hundreds of dollars per month on questionable supplements to prevent cancer and other diseases when they could get much more “bang for the buck” with a tiny dose of selenium. Selenium plays a crucial role in cancer prevention. 

Take selenium to live a longer, healthier life. Selenium will lower inflammation, prevent degeneration, prevent cancer and prevent disease and disability. 


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Dr. Scott D. Saunders, M.D. is a practicing physician, specializing in preventative health care, who utilizes eclectic health care for the whole family, including conventional, orthomolecular and natural medicine. He is also the medical director of The Integrative Medical Center of Santa Barbara in Lompoc, CA. He went to UCLA medical school and is board certified in family medicine. View natural remedies with Dr. Saunders at: http://drsaundersmd.com





[1] Effects of Selenium Supplementation for Cancer Prevention in Patients with Carcinoma of the Skin, Larry Clark et al – JAMA, 1996
[2] Food and Nutrition Board, Institute of Medicine. Selenium. Dietary reference intakes for vitamin C, vitamin E, selenium, and carotenoids. Washington, D.C.: National Academy Press; 2000:284-324. (National Academy Press)
[3] Ma Q, Fang H, Shang W, et al. Superoxide flashes: early mitochondrial signals for oxidative stress-induced apoptosis. J Biol Chem. 2011 Aug 5;286(31):27573-81
[4] Schomburg L. Selenium, selenoproteins and the thyroid gland: interactions in health and disease. Nat Rev Endocrinol. 2012;8(3):160-171
[5] Winther KH, Watt T, Bjorner JB, et al. The chronic autoimmune thyroiditis quality of life selenium trial (CATALYST): study protocol for a randomized controlled trial. Trials. 2014;15:115
[6] Jirong Y, Huiyun P, Zhongzhe Y, et al. Sodium selenite for treatment of Kashin-Beck disease in children: a systematic review of randomised controlled trials. Osteoarthritis Cartilage. 2012;20(7):605-613
[7] http://lpi.oregonstate.edu/mic/minerals/selenium#reference92
[8] Yu SY, Zhu YJ, Li WG. Protective role of selenium against hepatitis B virus and primary liver cancer in Qidong. Biol Trace Elem Res. 1997;56(1):117-124.
[9] http://lpi.oregonstate.edu/mic/minerals/selenium





  1. Very interesting. Can I find this a health food store?

  2. Absolutely. Selenium can be found at any health store or online!

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