Selenium Supplement Benefits, Uses and More

Vitamin and mineral supplements have long been a cornerstone of maintaining our overall health. Among these essential nutrients, selenium stands out as a vital trace mineral with remarkable significance in our bodies.

Despite being required in minute quantities, selenium plays a crucial role as an antioxidant, protecting our cells from oxidative stress, among other important functions, such as immune system and thyroid support.

Maintaining optimal selenium levels is important for health and longevity and can be achieved through the food we eat as well as selenium supplementation.

Here's a guide to understanding the role selenium plays in the body—and how to ensure we're getting enough of it to stay healthy.

What is selenium?

Selenium is an essential trace mineral that is naturally present in many foods and is added to others. It is also available as a dietary supplement. Trace minerals, also known as trace elements, are essential nutrients that the human body needs in very small amounts for various physiological and biochemical functions. Trace elements also include iron, zinc, copper and iodine, to name a few.

Selenium plays a key role in various biological processes. This nutrient is a vital component of several selenoproteins that are important to reproduction, thyroid function, DNA synthesis and preservation or function, immune system support and more.

How to get selenium

There are many good food sources of selenium, including plant-based, dairy-free, soy-free and yeast-free options. High-selenium foods include Brazil nuts, seafood and organ meats. In fact, some studies show that Brazil nuts are so selenium-rich, they have about 544 mcg of selenium per ounce (about 6-8 nuts), which is more than enough (too much!) selenium for your optimal health. The tolerable upper limit for selenium is 400 mcg daily.

Other selenium-containing foods include dairy products, whole-wheat cereals and other grains, including gluten-free options like brown rice and gluten-free oatmeal. Many grain products, such as macaroni and other pastas, are selenium-enriched.

Selenium supplements can also help fill in nutrient gaps and maintain healthy selenium status. Some studies show that vitamin E, an antioxidant, may work synergistically with selenium, so select supplements with vitamin E along with selenium for optimized health and longevity support. The selenium-vitamin E combo has many potential health benefits, including supporting the body against oxidative stress, helping maintain normal thyroid and immune function in healthy individuals, and promoting heart health, brain health and healthy cell division.

What are selenium supplements good for?

Selenium supplementation has many potential health benefits. For one, this nutrient plays a key role in thyroid function. The thyroid is a small, butterfly-shaped gland located in the front of the neck. Though it is small in size, it has a big job: helping to regulate the body's metabolic processes.

Selenium helps an enzyme that is responsible for converting the thyroid hormone into its most active form. So it is important to maintain a healthy selenium status for healthy thyroid hormone levels and healthy function of the thyroid.

Selenium also plays a role in immune system function by encouraging the development, maturation and function of immune cells. Selenium also helps protect immune cells from oxidative stress thanks to its antioxidant properties, which helps to combat free radicals. The antioxidant action of selenium is also important for the brain. One study found that selenium may support neuroprotection and contribute to optimal brain health.

There is an impressive body of evidence to show the important functions of selenium and its selenoproteins in the cardiovascular system—also mainly attributed to its antioxidant properties that protect cells and tissues from oxidative stress.

Another clinical study demonstrated health benefits and telomer lengthening (see below—longer telomeres are associated with longer lifespans) when selenium supplementation was combined with CoQ10 (another antioxidant), with particular benefits for heart health.

How to take a selenium supplement

Before starting any supplement regimen, you should talk with a healthcare professional, such as a doctor or registered dietitian. They can help determine if you have low selenium levels and provide personalized guidance on your supplement needs.

In terms of how to take a selenium supplement, always follow the directions on the supplement label. Remember that like other supplements, it is possible to consume too much. Also consider other supplements in measuring your selenium intake. For example, some multivitamin and mineral supplements may already contain selenium, and this may affect your selenium levels. Certain medications can also affect selenium levels.

Who should not take selenium?

While selenium is an essential trace element necessary for many bodily functions, including antioxidant protection against free radicals and immune system support, there are certain individuals who should exercise caution when taking selenium supplements, such as pregnant and breastfeeding women. Additionally, those with adequate selenium intake will not benefit from a selenium supplement. For example, those who consume Brazil nuts regularly are likely to have sufficient selenium levels already.

Talk with a healthcare provider about your selenium levels before starting selenium supplementation. As with any supplement, we recommend testing to determine your vitamin and mineral levels before adding any dietary supplements to your daily routine.

References

• Alehagen U, et al. "Reduced Cardiovascular Mortality 10 Years after Supplementation with Selenium and Coenzyme Q10 for Four Years: Follow-Up Results of a Prospective Randomized Double-Blind Placebo-Controlled Trial in Elderly Citizens." PLoS One. December 2015. https://pubmed.ncbi.nlm.nih.gov/26624886/
• Avery JC, Hoffmann PR. "Selenium, Selenoproteins, and Immunity." Nutrients. September 2018. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6163284/
• Cardoso BR, et al. "Supranutritional Sodium Selenate Supplementation Delivers Selenium to the Central Nervous System: Results from a Randomized Controlled Pilot Trial in Alzheimer's Disease." Neurotherapeutics. January 2019. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6361071/
• Schomburg L. "Selenium Deficiency Due to Diet, Pregnancy, Severe Illness, or COVID-19—A Preventable Trigger for Autoimmune Disease." Int J Mol Sci. August 2021. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8395178/
• Winther KH, et al. "Selenium in thyroid disorders - essential knowledge for clinicians." Nat Rev Endocrinol. March 2020. https://pubmed.ncbi.nlm.nih.gov/32001830/
• "Selenium." Harvard School of Public Health. March 2023. https://www.hsph.harvard.edu/nutritionsource/selenium/
• "Selenium." National Institutes of Health. March 2021. https://ods.od.nih.gov/factsheets/Selenium-HealthProfessional/