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 it helps protect against oxidative damage and infection, according to the United States Office of Dietary Supplements.
It is present in human tissue, mostly in skeletal muscle.
Dietary sources are varied. They include Brazil nuts, seafood, and meats.
The amount of selenium in food often depends on the selenium concentration of the soil and water where farmers grew or raised the food.
Selenium is part of many important enzymes, which are substances that speed up reactions in our bodies. The amount of selenium in a plant food varies depending on how much is in the soil the plant is grown in.
In the UK, recommended daily intakes of selenium for adults are 60mcg (micrograms) for women and 75mcg for men, which are based on the assumption that a higher intake is required for people with higher body weight. It is important to avoid eating too much selenium because it can cause a condition called selenosis.
The recommended Daily Value (DV), or daily allowance, for selenium is 55 micrograms (mcg) per day for adults.
During pregnancy, a woman should consume 60 mcg, and lactating women should consume 70 mcg a day.
Selenium deficiency is rare worldwide. It often takes years to develop, and it usually only occurs in regions with severely low selenium content in the soil.
Several regions in China have low soil selenium content, but deficiencies in the population have been eradicated through supplementation programs.
Sources of selenium
The selenium content of Brazil nuts is variable but tends to be high. And eating just two a day might meet your body’s needs. Alternatively, you could use a supplement to guarantee a reliable selenium intake.
The Vegan Society markets a daily vitamin and mineral supplement designed for vegans called VEG 1, providing reliable intakes of vitamins B12 and D, iodine, and selenium.
Please discuss the use of supplements with a health professional to help ensure that they are suitable for you.
Possible health risks
The upper limit per day for selenium is 400 mcg for adults.
Selenium toxicity due to overdose is rare, especially from dietary sources, but an overdose of highly concentrated supplements could have negative effects.
These may include:
- a garlic-like smell on 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
- skins lesions and rashes
- hair loss
In extreme cases, it could 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.
Selenium supplements are available, but it is best to obtain any vitamin or mineral through food.
It is not the individual vitamin or mineral alone that make certain foods an important part of our diet, but the way the nutrients work together.
Isolating specific nutrients in supplement form does not necessarily provide the same health benefits as consuming the nutrient from a portion of whole food.
The daily requirements of any nutrient should first come from food.