Selenium benefits for health include support for the immune system, thyroid function, circulation, brain health and more.
Selenium is an essential component of glutathione, the body’s most important antioxidant enzyme that protect normal cell function by scavenging free radicals.
Like iodine, selenium is also known to be important for proper thyroid hormone activity. It plays a role in helping to resist infection and sickness, has anti-inflammatory properties and is required for the production of prostaglandins that support normal blood flow.
Various health conditions are associated with low levels of selenium in the blood. However, researchers are not sure if using a supplement with this essential mineral can improve these conditions.
Preliminary research suggests there may be a benefit from consuming selenium-rich foods and reducing cancer risk. However, the FDA has determined that initial evidence is limited and not conclusive.



- Cofactor for antioxidant enzymes
- Supports thyroid function & metabolism
- Promotes immune function & fertility
Selenium Health Benefits
According to Life Extension, “Studies show that selenium, a trace mineral, is an important common denominator among some of the world’s longest-living people.”
Selenium is a trace element (Se) that is required by the human body to function normally. It is not prevalent in nature but exists in small amounts in soil and water.
The adult human body only requires 55 mcg (micrograms) per day for people over the age of 14. Pregnant and breast-feeding mothers require slightly more to meet their needs.
Selenium deficiencies are rare, especially in the US and Canada. However, there may be instances in which getting more of this mineral in your diet could have added health benefits.
Low selenium levels are associated with decreases immunity, cognitive decline and greater risk for cardiovascular disease and mortality in general. Studies also suggest that people with low levels may have higher rates of certain forms of cancer.
Having normal levels of selenium is correlated with a lower risk of thyroid disease, normal fertility in both sexes and antiviral protection.
However, getting too much of this mineral in the diet could lead to health problems. Some evidence suggests that chronically high levels may increase the risk of Type II Diabetes Mellitus.
Antioxidant Benefits
One of the most important roles for selenium in the body is as a cofactor in certain antioxidant enzymes that combat free radical damage in your cells.
Free radicals are molecules with unpaired electrons that can initiate disruptive chain reactions that lead to impaired cell function or premature cell death. These molecules cause oxidative damage which can accumulate over time and lead to deleterious effects on health.
Free radicals are generated naturally in the body through normal metabolism. We are also exposed to them through the environment and foods that we eat.
Radical agents from industrial pollutants, food toxins, smoking, excessive sun exposure and more can damage our cells. When cell membranes and DNA get damaged by oxidizing agents, risks of cardiovascular disease, cancer and numerous other conditions may increase.
Antioxidants quench free radical molecules and inhibit their molecular chain reactions, protecting cells from oxidative damage. Selenium is a potent antioxidant and is required to make glutathione, one of the most important antioxidant systems in the body.
Selenium is also believed to support the antioxidant effects of other compounds in the body. It is commonly taken orally in combination with vitamin E because it helps to recycle its antioxidant capacity.
Some health professionals believe that using antioxidant supplements can improve well-being on multiple levels. More research is needed to understand how use of oral antioxidants contributes to various health goals.
Benefits for Cancer
Selenium is purported to have anti-cancer effects and is commonly taken to boost defenses to this condition. However, it has not been approved by the FDA as a drug for the prevention or treatment of cancer.
Multiple epidemiological studies have shown that too little selenium is associated with an elevated risk of death from cancer.
In geographic areas where selenium is found in highest concentrations in the soil, cancer rates are significantly lower than in areas where it is rare. Also, people who have cancer – regardless of the type of cancer – usually have low selenium levels.
This population data is suggestive of a correlation but does not necessarily mean that increasing your selenium intake will cause you to have lower risk for cancer.
In order to evaluate the causative effect, double-blind placebo-controlled studies are used as opposed to population-based studies. The preliminary evidence from these studies is mixed.
Some studies show that daily intake of 200 mcg of selenium in oral supplement form protects against certain types of cancer. Other studies show no apparent benefits for cancer protection or progression.
According to the University of Maryland Medical Center, “For most types of cancer, selenium does not appear to have much effect.” There is some evidence that it may protect against colorectal cancer, but does not appear to reduce risk factors for esophageal or skin cancer.
Long-term daily ingestion of selenized yeast has been shown to reduce the risk of colon cancer. In one study of more than 1300 subjects over more than 4 years, selenized yeast equivalent to 200 mcg/day of selenium seemed to reduce the risk for prostate cancer by about two-thirds.
In this study, those that benefited the most had low baseline selenium levels to begin with. It may be the case that supplementation only improves risk profiles for people who are deficient or who have low levels of this mineral in their diet.
Not all results are positive. There is some evidence that suggests increasing selenium intake can slightly increase the risk for non-melanoma skin cancer and squamous cell carcinoma.
If you are interested in using selenium for its purported anti-cancer benefits, consult with a doctor before you start taking it. More human research trials are needed to determine the effects of selenium supplementation for cancer.
Selenium for Heart Health
The effects of selenium on cardiovascular health are not yet fully understood, but some research suggests that this micromineral is important for circulatory function and to protect the heart from oxidative damage.
Research shows that selenium deficiency can exacerbate atherosclerosis (clogged arteries). In severe cases, low levels may contribute to heart failure.
Increasing your intake of this mineral along with beta-carotene and Vitamin E Can support normal cholesterol levels and reduce the oxidation of blood lipids. Research suggests that this combination can lower LDL-C (low density lipoprotein cholesterol) levels.
However, several studies indicate that selenium supplementation does not affect heart disease progression or protect against heart attacks. While it may have a protective effect in people with a deficiency, it is not clear whether there is any added benefit to using oral supplements.
More human research is required to understand if and how selenium may help to improve heart health or prevent cardiovascular disease.
Selenium may also interact negatively with cholesterol-lowering drugs. If you are concerned about your cardiovascular health, speak with a doctor about using selenium before you take it.
If you have already been diagnosed with a heart condition or high cholesterol levels, do not use selenium supplements without first consulting with a doctor.
Health Benefits for Men
Selenium is purported to have benefits for male sexual health and fertility. Low levels of this mineral can contribute to poor sperm quality and motility.
Having adequate levels can improve the ability of sperm to swim and to fertilize the egg. However, getting too much can negatively influence sperm quality and lead to worsening fertility metrics.
Another purported benefit of selenium for men is supporting prostate health. Prostate cancer affects millions of men worldwide. Some research suggests a protective effect against the development of this condition, but results have been mixed.
Some bodybuilders supplement with selenium as part of a multi-vitamin regimen. Not having adequate selenium can result in muscle weakness and fatigue.
General Health Benefits
Many of the health benefits of selenium affect both men and women an equally. For men and women, the health benefits of selenium include:
- Helping to detoxify heavy metals from cells;
- Protecting cells from oxidative damage;
- Facilitating thyroid function:
- Preventing the accumulation of peroxidised fatty acids;
- Strengthening immunity;
The US Recommended Dietary Allowance (RDA) is 55 mcg for adult males and females.
Women who are pregnant or nursing need more selenium than others. Pregnant mothers are recommended to take 60 mcg per day while women who are breastfeeding require 70 mcg per day.
Most people that eat a well-balanced, healthy diet will get enough selenium without the need to supplement. However, certain conditions can reduce levels of this mineral in the body.
Some factors that can deplete selenium include smoking or using tobacco products, drinking too much alcohol and/or taking birth control drugs.
Also, people with conditions like ulcerative colitis and Crohn’s disease may not be able to absorb selenium from the foods they eat.
Additional Research
According to the Natural Medicines Comprehensive Database, selenium is being investigated for its effects on asthma, HIV/AIDS, diabetes, Rheumatoid Arthritis and Hashimoto’s disease.
It is also used for the following conditions:
- Avian Flu
- Swine Flu
- Macular Degeneration
- Allergic Rhinitis
- Infertility
- Cataracts
- Gray Hair
- Abnormal Pap Smears
- Chronic Fatigue Syndrome (CFS)
- Chemotherapy Toxicity
- Post-Surgical Lymphedema
- Arsenic Poisoning
- Osgood-Schlatter Disease
- Keshan Disease
- Mood Disorders
- Preventing Miscarriage
While NMCD notes that it has been studied for these conditions, it has not been approved as a drug for the prevention or treatment of any of these conditions. More human research is required to evaluate therapeutic efficacy.
NMCD rates selenium supplements as Likely Effective for improving selenium deficiency and Possibly Effective for autoimmune thyroiditis and dyslipidemia.
Talk to your doctor to learn more about selenium benefits and to determine whether this supplement is appropriate for you. Make sure to disclose your health history, as well as all medications and herbal supplements you use.
- Rayman MP1. Selenium and human health. Lancet. 2012 Mar 31;379(9822):1256-68. doi: 10.1016/S0140-6736(11)61452-9. Epub 2012 Feb 29.
- Kieliszek M1, B?a?ejak S2. Current Knowledge on the Importance of Selenium in Food for Living Organisms: A Review. Molecules. 2016 May 10;21(5). pii: E609. doi: 10.3390/molecules 21050609.
- Duffield-Lillico AJ1, Dalkin BL, Reid ME, Turnbull BW, Slate EH, Jacobs ET, Marshall JR, Clark LC; Nutritional Prevention of Cancer Study Group. Selenium supplementation, baseline plasma selenium status and incidence of prostate cancer: an analysis of the complete treatment period of the Nutritional Prevention of Cancer Trial. BJU Int. 2003 May;91(7):608-12.
- Flores-Mateo G1, Navas-Acien A, Pastor-Barriuso R, Guallar E. Selenium and coronary heart disease: a meta-analysis. Am J Clin Nutr. 2006 Oct;84(4):762-73.
- BELLINGER, Frederick P. et al. "Regulation and Function of Selenoproteins in Human Disease." The Biochemical journal 422.1 (2009): 11–22. PMC. Web. 18 July 2016.
- Rayman MP1, Rayman MP. The argument for increasing selenium intake. Proc Nutr Soc. 2002 May;61(2):203-15.
- Schomburg L1. Selenium, selenoproteins and the thyroid gland: interactions in health and disease. Nat Rev Endocrinol. 2011 Oct 18;8(3):160-71. doi: 10.1038/nrendo.2011.174.
- Brown KM1, Arthur JR. Selenium, selenoproteins and human health: a review. Public Health Nutr. 2001 Apr;4(2B):593-9.
- Life Extension Super Selenium Complex 200 mcg and Vitamin E, 100 Vegetarian Capsules. Amazon.
Article last updated on: July 3rd, 2018 by Nootriment