Selenium is an essential mineral built into selenoproteins, which play critical roles in thyroid hormone metabolism, DNA synthesis, reproduction and protection from oxidative damage and infection1.
Selenoproteins help convert the prohormone T4 into active T3 and help protect the thyroid gland during hormone production1.
Glutathione peroxidases and other selenoproteins help protect cells from oxidative damage and infection1.
Selenoproteins play a role in making DNA1.
Needed for reproduction, and an important nutrient for healthy sperm2.
Selenium is part of 25 human selenoproteins, including thioredoxin reductases, glutathione peroxidases and selenoprotein P1.
Food selenium, mostly selenomethionine with selenocysteine, is readily absorbed and turned into a common intermediate used to make the selenocysteine in selenoproteins; urinary excretion keeps the balance1. The liver makes selenoprotein P, which carries selenium in the blood to tissues such as the brain and testis3.
| Food and serving | Amount |
|---|---|
| Brazil nuts, 1 ounce (6–8 nuts) | 544 µg |
| Spaghetti, cooked, 1 cup | 33 µg |
| Cottage cheese, 1% milkfat, 1 cup | 20 µg |
| Baked beans, canned, 1 cup | 13 µg |
| Oatmeal, cooked with water, 1 cup | 13 µg |
| Mushrooms, portabella, grilled, ½ cup | 13 µg |
| Rice, brown, long-grain, cooked, 1 cup | 12 µg |
| Bread, whole-wheat, 1 slice | 8 µg |
| Food and serving | Amount |
|---|---|
| Tuna, yellowfin, cooked, 3 oz | 92 µg |
| Sardines, canned in oil, with bone, 3 oz | 45 µg |
| Shrimp, cooked, 3 oz | 42 µg |
| Pork chop, bone-in, broiled, 3 oz | 37 µg |
| Beef steak, bottom round, roasted, 3 oz | 37 µg |
| Turkey, boneless, roasted, 3 oz | 26 µg |
| Chicken, light meat, roasted, 3 oz | 22 µg |
| Egg, hard-boiled, 1 large | 15 µg |
Selenium in plant foods varies widely with the soil they grew in, and Brazil nut values vary widely between analyses; animal foods vary less because animals keep steady tissue levels1. Amounts per serving from1.
Plants take up selenium from soil, so plant foods grown in low-selenium regions hold less; food shipped from many regions evens this out1.
The selenium in drinking water is not nutritionally significant in most regions1.
Found in multivitamin/mineral products, in combinations with vitamin E and on its own; selenium-only products usually hold the most1.
The same reference table draws the reference lines on your charts in Ayuvo. Needs differ in pregnancy and breastfeeding, which are not covered here.
| Age | Women | Men | Upper limit |
|---|---|---|---|
| 19–30 | 55 mcg | 55 mcg | 400 mcg |
| 31–50 | 55 mcg | 55 mcg | 400 mcg |
| 51–70 | 55 mcg | 55 mcg | 400 mcg |
| 71+ | 55 mcg | 55 mcg | 400 mcg |
RDA (Recommended Dietary Allowance) is the daily amount that meets the needs of nearly all healthy people. Per day, for adults1.
Upper limit (UL) is the most per day that is unlikely to cause harm. Applies to food, drinks and supplements combined.
Signs like these have many possible causes. They are a reason to talk to a clinician, not to self-treat.
Deficiency is very rare in the U.S. and Canada and rarely causes illness on its own, but in low-selenium regions it is linked with some diseases1.
Chronically high intakes cause selenosis; Brazil nuts hold so much selenium that eating them regularly could cause toxicity1.
Plasma and serum selenium are the most common measures and reflect recent intake; whole blood, hair and nails reflect longer-term intake, and selenoprotein markers can be affected by inflammation1.
| Plasma or serum selenium | What it may mean |
|---|---|
| ≥ 8 µg/dL | Usually considered sufficient in healthy people |
Labs use different units and ranges. Your clinician reads a result alongside your history and other tests.
Selenium supplements come in several forms, and the body absorbs up to about 90% of the selenium from each of the common ones1.
The main form of selenium in food, also widely used in supplements1.
Yeast grown in a high-selenium medium; its selenium is mostly selenomethionine1.
An inorganic form found in supplements1.
Another inorganic form found in supplements1.
Supplements can interact with medicines. Talk to a clinician or pharmacist before you start one, especially at high doses.
Yes. One Brazil nut can hold about 68 to 91 micrograms of selenium, and amounts vary with where the nuts were grown. Eating them regularly and in large numbers can push total selenium above the upper limit shown on this page, and chronically high intakes can cause hair loss and brittle nails.
Some observational studies linked higher selenium status with a lower risk of several cancers, but large randomized trials found that selenium supplements did not reduce the risk of prostate cancer or cancer overall. One analysis of a large trial linked selenium supplements with a higher risk of high-grade prostate cancer in men who already had higher selenium status.
No. Deficiency is very rare in the U.S. and Canada, partly because food comes from many regions. The risk is higher for people on long-term kidney dialysis, people living with HIV, and people whose diet is mostly plant foods grown locally in low-selenium soil.
Food logging does not estimate selenium, so Ayuvo tracks it from supplements you log in Medications, and from Apple Health on iPhone or Health Connect on Android when another app saves it there. Charts by day, week, month and year use the reference lines from this page, personalised by age and sex where they differ. Free, with no account.
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Facts on this page come from these sources, checked on the dates shown. Intake numbers come from Ayuvo's shared reference table, which cites the sources marked for them.
General information, not medical advice. This guide is for healthy adults and does not cover pregnancy, breastfeeding, children or medical conditions. It cannot diagnose or treat anything. Talk to a clinician before starting high-dose supplements, or if you think you may have too little or too much of a nutrient. Spotted an error? Email us.