In 2024, the worldwide supplement industry surpassed $485 billion, with about 60% of adults consuming at least one dietary supplement each month, according to the U.S. Centers for Disease Control and Prevention.

While popular options include vitamin D, magnesium, fish oil, vitamin C, and zinc, selenium is also gaining traction as a vital mineral for health.

In this article, we will explore what selenium is, the health benefits it offers, and the risks of excessive intake.

What is Selenium?

Selenium is a nutrient found naturally in various foods. It can also be added to other foods and comes in supplement forms such as pills, powders, and liquids, according to Perri Halperin, a nutritional scientist and registered dietitian. It is classified as an essential trace mineral since the body requires only a tiny amount for optimal functioning but cannot produce it on its own.

Food sources rich in selenium include seafood like shrimp, cod, and tuna, various types of red meat including pork and beef, as well as eggs and dairy products like yogurt and milk. Other sources include oatmeal, mushrooms, pasta, beans, spinach, bananas, and whole-wheat bread.

Most individuals derive sufficient selenium from a balanced diet; however, “those suffering from specific health issues, such as Crohn’s disease or severe gastrointestinal disorders, or individuals living in areas with selenium-poor soil might face a higher risk of selenium deficiency and may benefit from supplements with medical guidance,” states Amy Goodson, a registered dietitian and nutrition expert at The Sports Nutrition Playbook.

Is Selenium Beneficial? What Are Its Functions in the Body?

Selenium is crucial for various bodily functions, including hormone regulation, maintaining a healthy metabolism, DNA production, and protecting against oxidative stress and infections, according to the U.S. National Institutes of Health (NIH) Office of Dietary Supplements.

This nutrient from food or supplements can bolster your immune system, help balance hormones, and safeguard cells from damage, claims Goodson. “It may also lower the risk of chronic conditions like heart disease and specific cancers,” she adds, “as well as support aging and enhance skin health.”

Registered dietitian Vanessa Rissetto from New Jersey notes that selenium contributes to reproductive health by improving menstrual cycles in women and aiding men in producing healthy, mobile sperm.

Additionally, research suggests that selenium may lower the risk of developing Alzheimer’s disease, enhance cognitive abilities, and alleviate asthma symptoms.

Is Daily Selenium Intake Safe?

Despite its numerous health benefits, it’s crucial to maintain selenium within the recommended daily limits. For individuals aged 14 and older, the NIH recommends a daily intake of 55 micrograms. Pregnant or breastfeeding women may require slightly more, adds Halperin.

While aiming for this intake level is essential, the upper limit before experiencing toxicity is considerably higher. Considering all dietary sources and supplements, adults should not exceed 400 micrograms per day.

Going beyond this amount may lead to toxicity, presenting symptoms like “hair loss, joint discomfort, brittle hair and nails, skin rashes, nausea, diarrhea, fatigue, respiratory issues, and in severe cases, kidney failure,” states Rissetto.

Reaching toxic selenium levels through food alone is rare, unless an individual eats excessive Brazil nuts. A single ounce of Brazil nuts (approximately six to eight nuts) can contain around 544 micrograms of selenium. For this reason, “it’s advisable not to consume more than three to five Brazil nuts daily,” suggests Goodson.

Examples of foods that can help you meet selenium recommendations include cooked shrimp (42 micrograms in three ounces), spaghetti (33 micrograms in one cup), turkey (26 micrograms in three ounces), and a large hard-boiled egg (15 micrograms).