Selenium: A Nutrient of Increasing Interest
The global supplement market exceeded $485 billion in 2024, and roughly six in ten adults reported taking at least one dietary supplement monthly, according to the U.S. Centers for Disease Control and Prevention (CDC). Vitamin D, magnesium, fish oil, vitamin C, and zinc are still the most commonly used, but another mineral is gaining recognition: selenium.
Selenium is a trace mineral that the body needs in small amounts to be healthy, but cannot synthesize itself. Therefore, we have to get it through our diet or supplements. Although selenium is less popular than other nutrients, it has a critical role in several body functions and, therefore, should not be missed in the diet.
Selenium, by nature, is found naturally in many kinds of food sources and is further supplemented through its pill, powder, and liquid forms. This nutritional scientist as well as being a registered dietitian, “Perri Halperin further indicates that sea foods such as shrimp, cod, and tuna are rich with selenium, so also red meat sources like pork chops, ham, and even beef steak contain this mineral, too. Dairy products, such as cottage cheese, yogurt, and milk, also contain selenium, along with plant-based sources like oatmeal, mushrooms, pasta noodles, beans, spinach, bananas, and whole-wheat bread.
For most people, a balanced diet is enough to provide adequate selenium. However, those with conditions like Crohn’s disease or severe gastrointestinal disorders, or living in areas where the soil is deficient in selenium, are at greater risk for deficiency. Supplementation under medical guidance may be helpful in these cases, according to Amy Goodson, a nutritionist and registered dietitian at The Sports Nutrition Playbook.
Selenium is involved in many body processes, such as hormone regulation, metabolism, DNA synthesis, and protection against oxidative damage and infections. The U.S. National Institutes of Health’s Office of Dietary Supplements states that selenium supports the immune system, aids in the smooth functioning of hormones, and protects cells from damage.
According to Goodson, selenium is also associated with a lower risk of chronic diseases like heart disease and some cancers. Selenium may also play a role in slowing down the aging process and improving skin health. Its role in hormone balance also promotes reproductive health, including the regulation of the menstrual cycle in women and the development of healthy sperm in men, says Vanessa Rissetto, a registered dietitian at Culina Health.
It has also been associated with reducing the risk of Alzheimer’s disease, for improved cognitive function, and reduced asthma symptoms, thus making it an important nutrient for optimal wellness.
With so many advantages of selenium, consumption must be within bounds. The NIH suggests that adults older than 14 years should consume 55 micrograms daily. However, pregnant and breastfeeding women require slightly higher doses.
Although dietary sources generally provide adequate selenium, it is crucial not to exceed the daily upper limit of 400 micrograms. Consuming excessive selenium, particularly from supplements, can lead to toxicity, resulting in symptoms such as hair loss, joint pain, brittle nails, skin rashes, nausea, diarrhea, fatigue, breathing difficulties, and, in severe cases, kidney failure, warns Rissetto.
Selenium poisoning through food alone is extremely rare. Brazil nuts are the exception, however. A single ounce—about six to eight nuts—contains 544 micrograms of selenium, well above the daily recommended allowance. Goodson cautions to limit Brazil nut intake to three to five nuts per day.
For people requiring diet-based fulfillment of daily selenium, seafood such as cooked shrimp provides 42 micrograms in three ounces, pasta like spaghetti noodles gives up 33 micrograms in a cup, and turkey meat offers 26 micrograms in three ounces. Hard-boiled eggs also provide 15 micrograms per egg. All these can be achieved through beneficial, varied food intake without the need for supplements.
