What is selenium?

What do Brazil nuts, shrimp and whole-wheat bread have in common? They’re all good sources of selenium. This essential mineral is used by the body in a variety of ways, from reproductive health to thyroid function and more, and researchers are still investigating other potential benefits. But much like free pizza in the office, too much can backfire. Here’s the full scoop on selenium, including recommended daily amounts and what may happen when someone goes beyond that limit.

In this article:

What is selenium and what does it do?

Selenium is an essential mineral. It supports thyroid and reproductive functions, and it offers other benefits, too. Selenium also helps create deoxyribonucleic acid (DNA) and protects the body from cell damage and infection. Selenium is naturally found in a variety of foods. It is also available as a dietary supplement.

Potential health benefits of selenium

The primary benefits of dietary selenium revolve around thyroid and reproductive functions. However, it is also used in other areas of the body. 

Thyroid health

The thyroid plays a major role in metabolism, growth and development. It also contains more selenium than any other part of the body. That selenium is used to create proteins, or selenoproteins, which keep things working properly. It also helps protect against cell damage since selenium also has antioxidant properties.

Reproductive health

Pregnancy increases the demand for nutrients like selenium. Upping intakes can help prevent deficiencies in both the pregnant person and their baby. Selenium also plays a role in creating healthy sperm. Eating a healthy diet and selenium-rich foods is what’s recommended here. More research is needed on whether supplements alone can actually improve male fertility.

Heart health

The link between selenium and heart health is complex. It’s often described as “U-shaped” because both too little and too much can be harmful. It’s true that maintaining a healthy selenium level is important for cardiovascular function. But supplementation isn't generally recommended for preventing heart disease. Any benefits from supplements are mostly limited to people with pre-existing deficiencies or low baseline selenium.

What is the daily recommended amount of selenium?

For adults, the recommended daily intake is between 55 and 70 micrograms. For kids and teens, it varies by age, ranging from 15 to 55 micrograms. For pregnant and lactating people, the recommended daily intake is between 60 and 70 micrograms. These guidelines help ensure everyone gets enough selenium without overdoing it.

Food sources of selenium

A single Brazil nut typically contains 68 to 91 micrograms of selenium. That means it only takes one to exceed someone’s daily intake. And lots of other foods are high in selenium, too. Organ meats and seafood like yellowfin tuna, sardines and shrimp are all high in selenium. Other options might include:

• Baked beans
• Beef
• Chicken
• Cottage cheese
• Eggs
• Lentils
• Oatmeal
• Turkey
• Whole-wheat bread

An important note: People should speak to a health care provider before adding more selenium to their diet. The same goes for anyone thinking of starting selenium supplements or other over-the-counter (OTC) products.

Selenium side effects

The body doesn’t need that much selenium, so it’s not uncommon to overdo it once in a while. Adults can start experiencing effects if they regularly consume high amounts of selenium. Symptoms of chronically high selenium intake can include:

• A metallic taste in the mouth
• Brittle nails
• Diarrhea
• Fatigue
• Garlicky breath
• Hair loss
• Nausea
• Skin rashes

Key takeaways

Selenium is an essential mineral that is especially important for thyroid and reproductive health. When taken in recommended doses, selenium rarely leads any serious side effects. However, taking too much can cause issues ranging from brittle nails to garlicky breath and more. That’s why it’s important to speak to a health care provider before adding more selenium to the diet (or taking supplements).

FOR VITAMINS AND SUPPLEMENTS: Check with your health care provider before taking any vitamins or supplements. Certain statements have not been evaluated by the Food and Drug Administration (FDA). Check products for more details.