Quick answer
Adults need 55 mcg of selenium a day, 60 mcg in pregnancy and 70 mcg while breastfeeding. Most Americans already get about 108 mcg a day from food and drink. The US upper limit for adults is 400 mcg a day from all sources, and Europe's food safety agency uses a lower one of 255 mcg.1,2,3
Key facts
- The Daily Value printed on labels is 55 mcg, the same as the adult recommended amount.2
- Multivitamins often contain 55 mcg, while selenium-only supplements usually contain 100 to 400 mcg.2
- Most long-term trials of selenium supplements used 200 mcg a day.2
- Men in the United States average 132 mcg a day from food and drink, and women 94 mcg.2
Recommended amounts and upper limits by age
| Age or stage | Recommended amount | Upper limit |
|---|---|---|
| Birth to 6 months | 15 mcg (adequate intake) | 45 mcg |
| 7 to 12 months | 20 mcg (adequate intake) | 60 mcg |
| 1 to 3 years | 20 mcg | 90 mcg |
| 4 to 8 years | 30 mcg | 150 mcg |
| 9 to 13 years | 40 mcg | 280 mcg |
| 14 years and older | 55 mcg | 400 mcg |
| Pregnancy | 60 mcg | 400 mcg |
| Breastfeeding | 70 mcg | 400 mcg |
The recommended amount is set to cover nearly all healthy people, 97% to 98% of them, so most need a little less. The upper limit is the most you can take each day without likely harm, and it counts selenium from food as well as supplements. It does not apply to selenium a doctor is giving you.1,2
What you probably get already
An analysis of national survey data from 2017 to early 2020 put average intake at 108 mcg a day from food and drink for everyone aged 2 and over, and 116 mcg once supplements are added. Between 17% and 19% of adults take a supplement with selenium in it.2
Where you live matters less than you might expect. People in the Midwest and West have higher blood selenium than people in the South and Northeast, because soils differ, but food travels so widely that people in low-selenium areas usually still get enough.2
How much is enough to fill the selenoproteins
Two trials asked how much selenium it takes before the body's selenoproteins stop rising. They point to totals of roughly 50 to 105 mcg a day, not to the 200 mcg a day common in single-ingredient products.4,5
In a 40-week trial in adults whose food supplied only about 14 mcg a day, selenoprotein P reached its full level at about 49 mcg a day in total, and glutathione peroxidase activity at about 35 mcg a day.4
In adults in the United Kingdom who got about 55 mcg a day from food, adding 50 mcg a day was enough to bring selenoprotein P to its highest level.5
The authors of the first trial adjusted for body size and individual variation and estimated that about 75 mcg a day would allow full selenoprotein levels in adults in the United States, which average intakes already pass.2,4
What supplements contain
Many multivitamins contain 55 mcg of selenium. Products that pair selenium with vitamin E or a few other ingredients usually have 50 to 200 mcg, and selenium-only supplements 100 to 400 mcg.2
Most long-term trials of selenium supplements, including the largest, used 200 mcg a day.2
On top of the 108 mcg average from food, a 55 mcg multivitamin brings the total to about 163 mcg and a 200 mcg product to about 308 mcg. Both are under the US limit of 400 mcg, but the second is over Europe's 255 mcg.2,3
Who should stay at the lower end
In SELECT, the largest selenium trial, men whose selenium levels were already high and who took 200 mcg a day had more high-grade prostate cancer. The researchers advised men over 55 to avoid selenium supplements above recommended intakes.2
Europe's food safety agency based its 255 mcg limit on hair loss seen at 330 mcg a day in that trial. It judged that adults are unlikely to pass the limit unless they take high-dose supplements or eat Brazil nuts regularly.3
- Ask your doctor before taking selenium if you are pregnant or breastfeeding, have a thyroid condition, or are having chemotherapy
- Count every product that lists selenium, including multivitamins, before adding another
Questions people ask
Is 200 mcg of selenium a day too much?
It is under the US upper limit of 400 mcg, but food adds about 108 mcg on average, which takes the total past Europe's limit of 255 mcg. The SELECT researchers advised men over 55 not to take selenium supplements above recommended intakes.2,3
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Sources
- Office of Dietary Supplements, National Institutes of Health. Selenium: Fact Sheet for Consumers. Updated June 18, 2025. Opened 2026-10-07.
- National Institutes of Health, Office of Dietary Supplements. Selenium: Fact Sheet for Health Professionals. Updated September 4, 2025. Opened 2026-10-07.
- EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA), Turck D, et al. Scientific opinion on the tolerable upper intake level for selenium. EFSA J. 2023;21(1):e07704. Opened 2026-10-07.
- Xia Y, et al. Optimization of selenoprotein P and other plasma selenium biomarkers for the assessment of the selenium nutritional requirement: a placebo-controlled, double-blind study of selenomethionine supplementation in selenium-deficient Chinese subjects. Am J Clin Nutr. 2010;92(3):525-531. Opened 2026-10-07.
- Hurst R, et al. Establishing optimal selenium status: results of a randomized, double-blind, placebo-controlled trial. Am J Clin Nutr. 2010;91(4):923-931. Opened 2026-10-07.
This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.