Selenium is a trace mineral that is essential to human health. It works as an antioxidant alongside the enzyme, glutathione peroxidase to protect cells from damage caused by free radicals. Selenium is also crucial for cognition, immune function, cell growth, reproduction, thyroid gland function and DNA production.
How much selenium do you need?
The amount of selenium you need depends on your age and gender. In the UK, national guidelines recommend that women get 60 micrograms (mcg) of selenium daily and men 75 mcg. The recommendations for Americans are summarised in the table below.
|Life Stage||US recommendations (mcg)|
|Birth to 6 months||15|
|Infants 7-12 months||20|
|Children 1–3 years||20|
|Children 4–8 years||30|
|Children 9–13 years||40|
|Teens 14–18 years||55|
|Adults 19–50 years||55|
|Adults 51–70 years||55|
|Adults 71 years and older||55|
What are the sources of selenium?
Selenium is present in food largely as the selenium-containing amino acids selenomethionine and selenocystenine. The selenium content of the soil in any region has a major effect on the selenium content of the food grown in that area and, thus, the dietary intakes of the people who live there.
Dietary sources of selenium include meats, whole grain cereals, pulses, brazil nuts and shellfish. The richest sources of selenium are fish, kidneys, and liver.
|Food Item and Amount||Selenium (micrograms)||% RDA for UK Adults|
|Brazil nut, 1||96||160%|
|Tuna, yellowfin, cooked (3 oz.)||92||153%|
|Beef liver, cooked (3 oz)||30||50%|
|Ham, roasted (3 oz)||22||36%|
|Chicken, white meat (3 oz)||21||35%|
|Egg, 1 large||15||25%|
|Whole-wheat bread (1 slice)||8||13%|
|Brown rice, cooked (1/2 cup)||6||10%|
Are you getting enough selenium?
Most UK and US adults get enough selenium from their diet because they eat food grown or raised in areas with sufficient selenium in the soil. People in certain parts of China may be at risk of selenium deficiency because of poor selenium levels in the soil.
That said, other groups of people may be at increased risk of selenium deficiency. They include:
- People living with HIV
- People undergoing kidney dialysis
What are the consequences of selenium deficiency?
Selenium deficiency is very rare in the UK and US. Deficiency, however, can cause a type of heart disease (Keshan disease) or a type of arthritis (Kashin-Beck disease) that causes pain, swelling and loss of movement in your joints. Also, due to its role in thyroid hormone metabolism, selenium deficiency may impair thyroid function, thereby limiting growth.
Low blood levels of selenium have been linked to increased incidence of prostate cancers, although more evidence is needed.
What are the consequences of excess selenium?
Getting too much selenium can cause brittle hair and nails, diarrhoea, irritability, nausea, skin rashes, metallic taste in the mouth, bad breath, discoloured teeth, and nervous system disorders. Extremely high intakes of selenium can cause kidney failure, heart attacks and heart failure.
The daily upper limit of selenium intake from all food, beverages and supplements is 400 mcg for day for people ages 14 and older, including pregnant and breastfeeding women.
Does selenium interact with medication?
Selenium can interact with a chemotherapy drug, cisplatin. It lowers selenium levels, but the effect this has on this body is well understood.
And there you have it, everything you need to know about selenium including sources, functions, and consequences of too little and excess intakes.
Check out these selenium-rich recipes:
- Rayman, M.P. (2000) The importance of selenium to human health. The Lancet, 356(9225): 233–41.
- Rayman, M.P. (2012) Selenium and human health. The Lancet, 379(9822): 1256–68.
- Kielczkowska, M., Kocot, J., Pazdzior, M., Musik, I. (2020) Selenium – a fascinating antioxidant of protective properties.Advances in Clinical and Experimental Medicine, 27(2): 245–255.
- Shreenath, A.P., Ameer, M.A., Dooley, J. (2021) Selenium deficiency. Available: https://www.ncbi.nlm.nih.gov/books/NBK482260/. Accessed: August 18, 2021.
- Aldosary, B.M., Sutter, M.E., Schwartz, M., Morgan, B.W. (2011) Case series of selenium toxicity from a nutritional supplement. Clinical Toxicology, 50(1): 57–64.
- Lobb, R.J., Jacobson, G.M., Cursons, R.T., Jameson, M.B. (2018) The interaction of selenium with chemotherapy and radiation on normal and malignant human mononuclear blood cells. International Journal of Molecular Sciences, 19(10): 3167.