Selenium
Also known as Se
Selenium is an essential trace mineral that is a structural component of selenoproteins, which function in antioxidant defense, thyroid hormone metabolism, DNA synthesis, and reproduction. The selenium content of food depends heavily on the selenium level of the soil where crops are grown or animals are raised. Requirements are set as an RDA in micrograms, with the same value for adult men and women.
The recommended intake sits at about 14% of the level considered the safe daily ceiling, leaving comfortable headroom.
Why it matters
What it does in your body
- Antioxidant defense
- Thyroid hormone metabolism
- DNA synthesis
- Reproduction and sperm formation
- Immune function
By age, sex, and life stage
How much you need
Selenium uses an RDA for children and adults (AI for infants 0 to 12 months). The adult requirement is 55 mcg with no difference between men and women. Pregnancy rises to 60 mcg and lactation to 70 mcg.
Recommended intake across life
in mcg/dayBars scale to the highest recommendation shown. Where men and women differ, both values are listed.
Full reference table
| Life stage | Male | Female |
|---|---|---|
| Infants 0-6 mo | 15 (AI) | 15 (AI) |
| Infants 7-12 mo | 20 (AI) | 20 (AI) |
| Children 1-3 | 20 | 20 |
| Children 4-8 | 30 | 30 |
| Children 9-13 | 40 | 40 |
| Teens 14-18 | 55 | 55 |
| Adults 19+ | 55 | 55 |
| Pregnancy | n/a | 60 |
| Lactation | n/a | 70 |
Values in mcg/day. AI marks an Adequate Intake, used when there is not enough evidence for a formal recommendation.
What moves the number
What changes your needs
Age
Needs rise from 20 mcg in toddlers to 55 mcg by the teen years and hold steady through adulthood.
Sex
No difference between adult men and women; both need 55 mcg.
Body weight / size
Adult requirements are set equally for both sexes; childhood values scale with growth.
Pregnancy and lactation
Requirements rise to 60 mcg in pregnancy and 70 mcg during lactation to support the fetus and breast milk.
Soil and region
Soil selenium content drives food levels, so intake varies by geographic region regardless of diet type.
Running low
Signs you might not get enough
Most at risk: People living in low-selenium regions such as parts of China and Russia, individuals undergoing kidney dialysis, and people living with HIV are at higher risk.
Too much
Can you get too much?
Chronic selenium toxicity, called selenosis, most often results from over-supplementation. Brazil nuts are so selenium-dense that eating them daily can exceed the UL.
Where to get it
Best food sources
The bottom line
A little selenium goes a long way, and just one or two Brazil nuts a day can cover the entire requirement. Most people in selenium-rich regions get plenty from ordinary food. Because the gap between adequate and toxic intake is narrow, avoid stacking high-dose supplements on top of Brazil nuts.
Track selenium automatically
Selenium is one of the 92 nutrients Vora reads from a photo of your meal, so you can see where you stand without weighing or logging by hand.
Sources and method
The recommended intakes, upper limits, and food-source amounts on this page come from the primary references below. Numbers were checked against the current NIH Office of Dietary Supplements fact sheets and the Institute of Medicine (now the National Academies) Dietary Reference Intakes.
- NIH Office of Dietary Supplements, Selenium Fact Sheet for Health Professionals
- Institute of Medicine (IOM/NASEM), Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids
This page is for general education, not medical advice. Reference intakes are population averages for healthy people and do not replace guidance from your doctor or a registered dietitian, especially if you are pregnant, managing a health condition, or considering supplements.