What Is Selenium and Its Health Benefits?

Selenium is a vital mineral for the immune system, thyroid, and heart. Its health benefits include boosting immune and thyroid function and acting as an antioxidant.

Selenium is essential for proper body function and health, and it is classified as a trace mineral that the body requires in small amounts.

Selenium is a crucial component of selenoproteins, which are proteins that protect cells from damage and aid in the production and use of hormones by the thyroid. The body combines selenium with the amino acid methionine and stores it in the muscles.

You can obtain selenium from food or supplements, but caution must be exercised to avoid excessive intake.

Selenium Deficiency

Selenium deficiency is rare in the United States, but certain groups are more prone to lower selenium levels, such as individuals with HIV, those undergoing kidney dialysis, individuals who consume foods grown in low-selenium soil, vegetarians or vegans, and individuals with absorption issues from bowel diseases like Crohn’s disease or ulcerative colitis.

Health Benefits of Selenium

Selenium serves several vital functions in the body, although further research is necessary to fully understand its potential benefits.

Antioxidant: Selenium acts as an antioxidant, working in collaboration with other antioxidants like vitamin C and vitamin E to neutralize harmful free radicals and protect against cellular damage caused by these unstable molecules.

Immune System Support: Selenium is essential for proper immune system function and plays a role in the production of white blood cells, which are crucial for fighting off infections. It may also enhance the response to flu vaccinations.

Thyroid Function: Selenium is vital for thyroid health, being stored in higher amounts in the thyroid than any other organ or gland in the body. Low levels of selenium and iodine in the blood can lead to thyroid problems, such as low hormone levels and goiter.

Heart Health: Selenium’s role in protecting against cell damage and preventing platelet clumping makes it potentially beneficial for heart health. However, the findings on selenium supplements and their effects on heart disease risk are inconclusive.

Cancer Risk Reduction: Selenium has demonstrated anti-cancer activities in animal studies, and low selenium levels have been associated with an increased risk of certain cancers in humans. However, the effects of selenium supplements on cancer risk remain uncertain and vary depending on the type of cancer.

Male Infertility: Selenium is involved in the creation of proteins in sperm, so ensuring adequate levels of selenium might help improve sperm growth. However, excessive selenium intake can negatively affect sperm, warranting further research.

Asthma Symptoms: Studies investigating the relationship between selenium and asthma have yielded conflicting results, with some smaller studies suggesting potential benefits, while larger studies have demonstrated no significant effects.

Selenium Supplements

Selenium supplements are available in various forms, including individual selenium supplements, multivitamins, and combined antioxidant or nutritional supplements. The most common forms are selenomethionine and sodium selenate.

Dosage and Safety: Selenium supplements come in different doses, with a daily recommended amount of 55 micrograms for adults. Higher doses can be toxic and cause adverse effects, such as skin rashes, diarrhea, and nervous system problems. It is crucial to stay within the recommended limits to avoid selenium toxicity.

Side Effects: Selenium supplements can interact with certain medications, including blood thinners and chemotherapy drugs. High doses of selenium can raise cholesterol levels, contribute to diabetes, and exacerbate iodine deficiency.

Selenium Food Sources

Selenium is naturally present in numerous foods, including fortified options. Consuming a well-balanced diet with adequate selenium-rich foods is the best and safest way to meet your recommended selenium intake. Some good food sources of selenium include seafood, meat, poultry, eggs, dairy products, grains, brewer’s yeast, wheat germ, Brazil nuts, garlic, beans, and lentils.

Brazil nuts, in particular, are an excellent source of selenium, and consuming just one Brazil nut a day can fulfill your selenium requirements.

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The Bottom Line: Prioritize Food Sources

While selenium supplements can increase blood selenium levels, their effectiveness in treating diseases remains inconclusive. Unless you have been diagnosed with a selenium deficiency or are at risk for low selenium levels, it is generally unnecessary to take selenium supplements. Obtaining essential vitamins and minerals from a well-rounded diet is the optimal and safest approach. Consult your doctor before considering selenium supplementation.

Sources: Harvard T.H. Chan School of Public Health, International Journal of General Medicine, Mayo Clinic, Mount Sinai, National Institutes of Health Office of Dietary Supplements, Oregon State University Linus Pauling Institute, U.S. Department of Agriculture FoodData Central