Selenium Facts and Health Benefits
Selenium is a trace element that is essential in small amounts. Humans require selenium for the function of a number of selenium-dependent enzymes needed to form a functional protein. Selenium is important to growth and immune system function.
Selenium plays several key functions necessary to our optimum health, including:
- – Thyroid Health.Selenium plays a role in regulating thyroid function. The thyroid gland needs selenium to circulate thyroid hormones in the bloodstream. Inadequate selenium intake can affect your metabolism and growth. Researchers believe that selenium deficiency may worsen the effects of iodine deficiency on thyroid function, and that adequate selenium nutritional status may help protect against some of the neurological effects of iodine deficiency.
- – Immune System Health. Selenium affects how well your immune system functions through its ability to help the development of your body’s white blood cells. White blood cells work together to fight infections within your body.
- – Antioxidant. Selenium is incorporated into proteins to make selenoproteins, which are important antioxidant enzymes. The antioxidant properties of selenoproteins help prevent cellular damage from free radicals. Free radicals are natural by-products of oxygen metabolism that may contribute to the development of chronic diseases such as cancer and heart disease.
- – Prostate Health. Some studies have reported that low dietary selenium intakes are associated with increased risk of prostate cancer. Some studies have found the risk of developing prostate cancer was 50% less in men with serum selenium levels in the highest quartile compared to those in the lowest quartile.
Natural Food Sources of Selenium
Some research suggests that selenium supplements are harder for the body to absorb than natural organic forms of selenium, such as selenomethionine, high-selenium yeast or natural food sources.
Natural sources of Selenium include brazil nuts, yeast, oats, brown rice, eggs, chicken, dairy, most whole grains, wheat, seafood, onions, garlic and molasses. The selenium content of vegetables is generally not high, but can vary dependent on soil selenium content. Yeast is a good source of Selenium as Yeast are able to naturally metabolize inorganic minerals like Selenium into organic forms, similar to what plants do. Selenium from Yeast does not carry the toxicity concerns as Selenium from supplements.
| Selected Food Sources of Selenium | Micrograms (mcg) | Percent DV* |
|---|---|---|
| Brazil nuts, dried, unblanched, 1 ounce | 544 | 777 |
| Tuna, light, canned in water, drained, 3 ounces | 68 | 97 |
| Herring, 100 grams, 3 ½ ounces | 46.8 | 74 |
| Pork, lean roast, 100 grams, 3 ½ ounces | 43.2 | 60 |
| Turkey leg, 100 grams, 3 ½ ounces | 37.8 | 53 |
| Cod, cooked, 3 ounces | 32 | 46 |
| Turkey, light meat, roasted, 3 ounces | 27 | 39 |
| Bagel, egg, 4 inch | 27 | 39 |
| Lamb, 100 grams, 3 ½ ounces | 26.2 | 39 |
| Chicken breast, meat only, roasted, 3 ounces | 24 | 34 |
| Beef chuck roast, lean only, roasted, 3 ounces | 23 | 33 |
| Sunflower seed kernels, dry roasted, 1 ounce | 23 | 33 |
| Duck, roast, 100 grams, 3 ½ ounces | 20 | 28 |
| Anchovies, canned in oil, 1 ounce | 19.3 | 27 |
| Egg noodles, enriched, boiled, ½ cup | 19 | 27 |
| Macaroni, enriched, boiled, ½ cup | 19 | 27 |
| Ground beef, cooked, broiled, 3 ounces | 18 | 26 |
| Egg, whole, hard-boiled, 1 large | 15 | 21 |
| Oatmeal,cooked, 1 cup | 12.6 | 17 |
| Cottage cheese, low fat 2%, ½ cup | 11 | 16 |
| Bread, whole-wheat, commercially prepared, 1 slice | 11 | 16 |
| Rice, brown, long-grain, cooked, ½ cup | 10 | 14 |
| Rice, white, enriched, long-grain, cooked, ½ cup | 6 | 9 |
| Walnuts, black, dried, 1 ounce | 5 | 7 |
| Cheddar cheese, 1 ounce | 4 | 6 |
*DV = Daily Value. DVs are reference numbers developed by the Food and Drug Administration (FDA) to help consumers determine if a food contains a lot or a little of a specific nutrient. The DV for selenium is 70 micrograms (mcg)
Selenium Recommended Daily Intake
Recommended Dietary Allowances (RDAs) for Selenium in micrograms (mcg) per day, for children and adults.
| Age (years) | Males and Females (mcg/day) | Pregnancy (mcg/day) | Lactation (mcg/day) |
|---|---|---|---|
| 1–3 | 20 | N/A | N/A |
| 4–8 | 30 | N/A | N/A |
| 9–13 | 40 | N/A | N/A |
| 14–18 | 55 | 60 | 70 |
| 19+ | 55 | 60 | 70 |
There is insufficient information on selenium to establish a RDA for infants. An Adequate Intake (AI) has been established that is based on the amount of selenium consumed by healthy infants who are fed breast milk. The Table below lists the AIs for selenium, in micrograms (mcg) per day, for infants.
| Age (months) | Males and Females (mcg/day) |
|---|---|
| 0–6 months | 15 |
| 7–12 months | 20 |
* Adequate Intake (AI)
Selenium Deficiency and Toxicity
Deficiency. Selenium deficiency can occur areas where soil concentration of selenium is low. There is evidence that selenium deficiency may contribute to development of a form of heart disease, hypothyroidism, and a weakened immune system.
Toxicity. As with all mineral supplements, taking selenium supplements carries toxicity risk and might in large amounts over periods of time cause health problems. Dietary intake of Selenium from natural food sources is the healthiest way of Selenium intake. Taking Selenium supplements can affect your bleeding and clotting times. Selenium supplements can also have adverse reactions with a variety of medications, including blood thinners. Additionally, Selenium can cause you to bleed more than normal during surgery. Tell your doctor about the dietary supplements you take that contain selenium before any medical tests or procedures.
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