When it comes to essential nutrients, selenium often doesn’t get the spotlight—but it should. This underrated trace mineral may be required in small amounts daily, but it plays a monumental role in your health. From thyroid balance to brain health, immune defense to fertility, selenium works quietly behind the scenes to keep your body running smoothly.
What Is Selenium and Why Is It Important?
Selenium is a natural trace mineral found in soil, water, and some foods. Although only small amounts are needed, selenium is crucial for producing selenoproteins – specialized proteins involved in thyroid hormone metabolism, antioxidant production (which protects cells from damage), cellular DNA synthesis, and improved immune function (1).
Selenium supports many physiological functions, including:
- Regulating metabolism (the mechanism responsible for converting food into energy)
- Protecting against oxidative stress (which leads to cellular and tissue damage)
- Enhancing immune system defenses
- Supporting reproductive health
- Optimizing cognitive health
- Promoting cardiovascular health
Selenium continues to draw scientific interest for its wide-ranging roles in the body. Ongoing research explores how selenium affects chronic diseases and overall health (2).
Thyroid Health
Despite its small size, the thyroid gland contains more selenium per gram of tissue than any other organ. This is because many of the body’s 25 known selenoproteins are active in the thyroid.
Low selenium levels have been linked to thyroid dysfunction, especially those associated with autoimmune disorders. Research shows that selenium supplementation may help reduce thyroid antibody levels and improve quality of life in individuals with Hashimoto’s thyroiditis, an autoimmune condition that leads to hypothyroidism (underactive thyroid). There’s also evidence that selenium may support people with Graves’ disease, an autoimmune condition that causes an overactive thyroid. Overall, adequate selenium is crucial for optimal thyroid function, and it may have therapeutic benefits for autoimmune thyroid disorders.
Cognition: Protecting the Aging Brain
Selenium’s antioxidant power also benefits the brain. Selenoproteins help reduce oxidative stress in brain cells, a key contributor to age-related cognitive decline and neurodegenerative conditions like dementia and Alzheimer’s disease. Selenium could play a protective role against cognitive decline, especially when combined with a balanced diet rich in antioxidants (3).
Health: A Role in Cardiovascular Protection
Oxidative stress and inflammation are two major contributors to heart disease—and selenium may help combat both. According to the Harvard School of Public Health, imbalanced selenium levels can lead to an increased risk of cardiovascular disease and cardiac events such as heart attacks. While selenium won’t replace traditional heart-healthy practices, maintaining optimal levels may provide an extra layer of cardiovascular protection, particularly in populations with selenium deficiency.
Type 2 Diabetes: A Delicate Balance
Research suggests that the right amount of selenium may help with blood sugar control and insulin function, both of which are extremely important for patients with type 2 diabetes. Selenium also helps reduce inflammation and oxidative stress, both of which are commonly elevated in people with diabetes. Some studies suggest that selenium may enhance insulin sensitivity and lower the risk of developing diabetes (4).
Reproductive Health
Selenium plays a crucial role in reproductive health for both women and men. By protecting sperm and eggs from oxidative stress, selenium helps prevent infertility and pregnancy loss. In men, selenium deficiency can impair sperm quality, reduce sperm count, and affect motility. In women, selenium deficiency may lead to ovulation problems and reduced egg quality (5,6).
Getting Selenium from Your Diet
For most people, the best way to meet your selenium needs is through food. Selenium from dietary sources is well-absorbed and less likely to cause toxicity compared to high-dose supplements. Brazil nuts are one of the most selenium-rich natural sources, with about 68–91 mcg per nut. Consuming just 1 or 2 Brazil nuts a day can meet or even exceed the recommended daily intake. Daily intake is dependent on age, but for most adults, 55 mcg is ideal per day (7).
While many individuals can meet their selenium needs through a balanced diet, certain health conditions may require higher therapeutic doses. The appropriate amount depends on individual health status and the body’s specific physiological needs (8).
Other selenium-rich foods include:
- Fin fish (tuna, cod, halibut, salmon, anchovies) and shellfish (shrimp)
- Eggs
- Whole grains
- Beans
- Lentils
- Poultry, turkey, beef
By Dr. Anthony Salzarulo DC PT and Rachel Kessler MS
- https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/selenoprotein
- https://nutritionsource.hsph.harvard.edu/selenium/
- Ferdous KA, Knol LL, Park HA. Association between selenium intake and cognitive function among older adults in the US: National Health and Nutrition Examination Surveys 2011-2014. J Nutr Sci. 2023 May 10;12:e57. doi: 10.1017/jns.2023.43. PMID: 37180486; PMCID: PMC10173086.
- Casanova P, Monleon D. Role of selenium in type 2 diabetes, insulin resistance and insulin secretion. World J Diabetes. 2023 Mar 15;14(3):147-158. doi: 10.4239/wjd.v14.i3.147. PMID: 37035226; PMCID: PMC10075028.
- Mistry HD, Broughton Pipkin F, Redman CW, Poston L. Selenium in reproductive health. Am J Obstet Gynecol. 2012 Jan;206(1):21-30. doi: 10.1016/j.ajog.2011.07.034. Epub 2011 Jul 29. PMID: 21963101.
- https://www.sciencedirect.com/science/article/abs/pii/S0946672X14001345
- https://ods.od.nih.gov/factsheets/Selenium-Consumer/
- https://www.stanfordchildrens.org/en/topic/default?id=selenium-19-Selenium
Much of the information regarding dietary fat intake is confusing and conflicting. Many people attempt to avoid all fats because they are misinformed. Approximately 95% of the U.S. population does not consume the right kinds of fats and oils to stay healthy. They eat refined, processed, overheated, hydrogenated and solvent-ridden oils and fats.