Selenium: what it does and how much you need
Selenium helps with reproduction, thyroid function and making DNA, and helps protect the body from damage and infection. Adults need 55 micrograms a day, and the upper limit is 400 micrograms a day.
General information, not medical advice. Check with a doctor or pharmacist before taking a supplement, especially if you are pregnant or breastfeeding, take any medicine, or are under 18.
In the UK
In the UK, adults need 75 micrograms a day for men and 60 micrograms for women, and the NHS says up to 350 micrograms a day from supplements is unlikely to cause harm.
How much you need and the upper limit
| US (NIH) | UK (NHS) | |
|---|---|---|
| Adults need | 55 micrograms a day | 75 micrograms a day for men and 60 micrograms for women |
| Upper limit | 400 micrograms a day | Up to 350 micrograms a day from supplements |
The UK figure is the amount the NHS says is unlikely to cause harm. Figures are for adults.
Cautions
- Brazil nuts are very high in selenium, so a few a day on top of a supplement can add up.
Food sources
- Brazil nuts
- Seafood
- Meat and poultry
- Eggs
- Dairy
- Bread and cereals
Dose questions
Quick answers
- What does selenium do?
- Selenium helps with reproduction, thyroid function and making DNA, and helps protect the body from damage and infection.
- How much selenium do adults need?
- Adults need 55 micrograms a day (US, NIH). In the UK: 75 micrograms a day for men and 60 micrograms for women (NHS).
- What is the upper limit for selenium?
- US: 400 micrograms a day. UK (NHS): up to 350 micrograms a day from supplements is unlikely to cause harm.
- Which foods have selenium?
- Brazil nuts, seafood, meat and poultry, eggs, dairy, bread and cereals.
- What should I watch out for with selenium?
- Brazil nuts are very high in selenium, so a few a day on top of a supplement can add up.
Sources
- NIH Office of Dietary Supplements fact sheet
https://ods.od.nih.gov/factsheets/Selenium-HealthProfessional/ - NHS vitamins and minerals guidance
https://www.nhs.uk/conditions/vitamins-and-minerals/others/
Ask Supplement Check yourself
Type a vitamin, mineral or supplement, a dose, or a product name, and get the daily need, the upper limit and any cautions. Open Supplement Check, free, no sign-up.
In Claude or any app that takes MCP connectors, add https://goodturn-mcp.pages.dev/supplementcheck/mcp and ask: “Is 200 mcg of selenium too much?”