Mineral

Selenium

Selenium supports the immune system, reproduction and thyroid function, and acts as an antioxidant. It is found in brazil nuts, fish, meat and eggs.

Written by Meds Global Health Clinical Team · Clinically reviewed by Dr Muhammad Suffyan, MB BS, Founder & Clinical Director · Last reviewed · How we review

What it is

Selenium is an essential trace mineral needed only in small amounts, which the body uses in several important proteins.

What it does

It helps the immune system work, supports reproduction and thyroid function, and acts as an antioxidant that protects cells from damage.

Good sources

Brazil nuts (very rich), fish and shellfish, meat, eggs, and bread and other foods depending on the selenium in the soil where they were grown.

Deficiency and who is at risk

Deficiency is uncommon in the UK but possible with a limited diet or in areas with low soil selenium. It can affect immunity and thyroid function.

Balance

Can you have too much?

Too much selenium — for example from eating many brazil nuts daily or high-dose supplements — can cause hair loss, nail changes, digestive upset and, in extreme cases, nerve problems, so intakes should stay moderate.

Education and reference only. This is general nutrition information, not personal advice, and does not give doses. Ask a pharmacist, GP or registered dietitian before starting supplements, especially with a health condition or in pregnancy.

Answers

Selenium: frequently asked questions

How many brazil nuts should I eat for selenium?

Brazil nuts are very rich in selenium, so just one or two a day usually provides plenty. Eating large numbers every day can lead to too much selenium, so moderation is best.

Do I need a selenium supplement?

Most people in the UK get enough from a varied diet and do not need a supplement. High-dose selenium supplements can be harmful, so they should only be taken if advised.

Related

More on minerals and nutrition

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Sources

Where this is drawn from

  • NHS — Vitamins and minerals
  • British Dietetic Association (BDA)
  • UK Scientific Advisory Committee on Nutrition (SACN)

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