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Selenium is an essential trace mineral that is important for many bodily processes, including cognitive function, a healthy immune system, and fertility in both men and women.

It contributes to thyroid hormone metabolism and DNA synthesis and helps protect against oxidative damage and infection, according to the United States Office of Nutritional Supplements .

It is found in human tissue, mostly in skeletal muscle.

Dietary sources are varied. Includes Brazil nuts, seafood, and meats.

The amount of selenium in foods often depends on the concentration of selenium in the soil and water where farmers grow or grow the food.

Fast facts on selenium

  • Selenium is a mineral that plays a role in many body functions.
  • It may protect against cancer , thyroid problems, cognitive decline and asthma, but more research is needed.
  • Brazil nuts, some fish, brown rice, and eggs are good sources.
  • The best source of food is food. The use of any supplement should first be discussed with a doctor.

Possible health benefits

  • Selenium can help prevent cardiovascular diseases, thyroid problems, cognitive decline, which means disorders related to thinking, cancer, and others.

Cardiovascular disease:

According to the Office of Dietary Supplements, selenoproteins can protect against cardiovascular disease as they prevent the oxidative modification of lipids or fats in the body.

This reduces inflammation and prevents platelet formation.

However, clinical evidence does not support the use of selenium supplements for this purpose.

Cognitive decline:

Selenium’s antioxidant activity may help reduce the risk of cognitive or mental decline as people age.

However, the evidence from studies is mixed, and selenium supplements have not yet been prescribed for people at risk of disease such as Alzheimer’s, but may have a role still under investigation in prevention.

Thyroid disorders:

Selenium has an important role in the production and metabolism of thyroid hormone.

There is some evidence that women with higher selenium levels have fewer thyroid problems, but this has not been proven for men and other studies have shown mixed results.

There are more studies underway to decide whether selenium supplements may support thyroid health.


The role selenium plays in DNA repair and other functions could mean that it can help prevent cancer. However, studies have shown mixed results.

The US Food and Drug Administration (FDA) came to the following conclusion in 2003:

“Some scientific evidence shows that selenium consumption may reduce the risk of certain types of cancer.”

Studies have suggested that selenium can also help:

  • Preventing HIV from progressing to AIDS
  • Reducing the risk of miscarriage
  • Protect against asthma

While selenium is clearly an element for many aspects of human health, there is little evidence to suggest that supplements can be beneficial in preventing these conditions.

Recommended Taking

The recommended Daily Value (DV) or daily allowance for selenium is 55 micrograms (mcg) per day for adults.

A woman should consume 60 mcg during pregnancy and 70 mcg per day for breastfeeding women.

Selenium deficiency is rare worldwide. It usually takes years to develop and is usually only seen in areas with very low selenium content in the soil.

Some regions in China have low soil selenium content, but deficiencies in the population have been eliminated through fortification programs.

Selenium supplements are available, but it’s best to get any vitamins or minerals through your diet .

It’s not just the vitamins or minerals alone that make certain foods an essential part of our diet, but the way nutrients work together.

Isolating certain nutrients in supplement form does not provide the same health benefits as consuming the nutrient from a whole food.

The daily requirements of any nutrient must come first from food.

Food Sources

Selenium is most likely found in whole grains and animal products, not fresh fruits and vegetables.

  • Brazil nuts: 1 ounce provides 544 micrograms (mcg), or 777 percent of the daily recommended value (DV).
  • Tuna: 3 ounces yellowfin tuna, dry-cooked, contains 92 mcg, or 131 percent of the DV.
  • Halibut, cooked: 3 ounces, dry-cooked, contains 47 mcg, or 68 percent of the DV
  • Brown rice, cooked: 1 cup contains 19 mcg
  • Egg: One large egg contains 15 mcg
  • Bread, white: 1 slice provides 10 mcg

The amount of selenium in cereals and grain-based foods depends on the soil content in which the grains grow.

Possible Health Risks

The daily upper limit for selenium is 400 mcg for adults.

Selenium toxicity due to overdose is rare, especially from dietary sources, but overdose of highly concentrated supplements can have adverse effects.

These can include:

  • A garlic-like smell in the breath and a metallic taste in the mouth
  • Brittle nails
  • Mottled or decaying teeth
  • Gastrointestinal problems such as nausea
  • Neurological abnormalities
  • Fatigue and irritability
  • Skin lesions and rashes
  • Hair loss
  • In extreme cases, it can lead to kidney failure, heart failure and death.

Selenium supplements can also interact with some medications, including cisplatin, a chemotherapy drug. The use of this drug can reduce selenium levels in the body.

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