What is selenium and what does selenium do?
In the past, selenium was viewed as a toxin. However, it is now considered an essential trace mineral for humans which means that we need it for survival, but only in small quantities. Selenium is present in organic and inorganic compounds, both of which are good dietary sources of selenium.
Selenium is needed for reproduction, for the proper function of the thyroid glands and for the production of DNA. It protects our body from free radical damage and infections. (1)
Tissues and blood of tuna and some other types of fish are rich in an anti-oxidant compound containing selenium called selenoneine.
Foods high in selenium
| Food | Serving | Amount of Selenium (mcg) | % of RDA for men |
Rating | % of RDA for women |
Rating |
|---|---|---|---|---|---|---|
| Brazil nuts | 1 oz (28g) | 537 | 767.1 | Excellent | 895 | Excellent |
| Oysters | 3 oysters (140g) | 107.7 | 153.9 | Excellent | 179.5 | Excellent |
| Cuttlefish, cooked | 3 oz (85g) | 76.2 | 108.8 | Excellent | 126.9 | Excellent |
| Mussel, cooked | 3 oz (85g) | 76.2 | 108.8 | Excellent | 126.9 | Excellent |
| Octopus, cooked | 3 oz (85g) | 76.2 | 108.8 | Excellent | 126.9 | Excellent |
| Clam, cooked | 3 oz (85g) | 54.4 | 77.7 | Excellent | 90.7 | Excellent |
| Swordfish, cooked | 3 oz (85g) | 52.4 | 74.9 | Excellent | 87.4 | Excellent |
| Flounder, cooked | 3 oz (85g) | 49.5 | 70.7 | Excellent | 82.5 | Excellent |
| Perch, cooked | 3 oz (85g) | 47.2 | 67.4 | Excellent | 78.6 | Excellent |
| Abalone, cooked | 3 oz (85g) | 44 | 62.9 | Excellent | 73.4 | Excellent |
| Mackerel, cooked | 3 oz (85g) | 43.9 | 62.7 | Excellent | 73.1 | Excellent |
| Snapper, cooked | 3 oz (85g) | 41.7 | 59.5 | Excellent | 69.4 | Excellent |
| Grouper, cooked | 3 oz (85g) | 39.8 | 56.8 | Excellent | 66.3 | Excellent |
| Halibut, cooked | 3 oz (85g) | 39.8 | 56.8 | Excellent | 66.3 | Excellent |
| Herring, cooked | 3 oz (85g) | 39.8 | 56.8 | Excellent | 66.3 | Excellent |
| Pollock, cooked | 3 oz (85g) | 39.8 | 56.8 | Excellent | 66.3 | Excellent |
| Tuna, cooked | 3 oz (85g) | 39.8 | 56.8 | Excellent | 66.3 | Excellent |
| Pork lean, cooked | 3 oz (85g) | 38.8 | 55.5 | Excellent | 64.7 | Excellent |
| Lobster, cooked | 3 oz (85g) | 36.3 | 51.9 | Excellent | 60.5 | Excellent |
| Salmon, cooked | 3 oz (85g) | 34.9 | 49.8 | Excellent | 58.1 | Excellent |
| Haddock, cooked | 3 oz (85g) | 34.4 | 49.2 | Excellent | 57.4 | Excellent |
| Crab, cooked | 3 oz (85g) | 34.2 | 48.8 | Excellent | 57 | Excellent |
| Shrimp, cooked | 3 oz (85g) | 33.7 | 48.1 | Excellent | 56.1 | Excellent |
| Rabbit, cooked | 3 oz (85g) | 32.7 | 46.7 | Excellent | 54.5 | Excellent |
| Cod, cooked | 3 oz (85g) | 32 | 45.7 | Excellent | 53.3 | Excellent |
| Egg large | 2 large (100g) | 31.6 | 45.1 | Excellent | 52.7 | Excellent |
| Turkey, cooked | 3 oz (85g) | 31.3 | 44.7 | Excellent | 52.1 | Excellent |
| Beef liver, cooked | 3 oz (85g) | 30.7 | 43.8 | Excellent | 51.1 | Excellent |
| Beef, lean | 3 oz (85g) | 30.4 | 43.5 | Excellent | 50.7 | Excellent |
| Crayfish, cooked | 3 oz (85g) | 29.1 | 41.5 | Excellent | 48.5 | Excellent |
| Scallops, cooked | 3 oz (85g) | 23.7 | 33.9 | Excellent | 39.5 | Excellent |
| Goose, cooked | 3 oz (85g) | 21.7 | 31 | Excellent | 36.1 | Excellent |
| Chicken breast filet, cooked | 3 oz (85g) | 21.2 | 30.4 | Excellent | 35.4 | Excellent |
| Cheese ricotta, low fat | 1/2 cup (124g) | 20.7 | 29.6 | Excellent | 34.5 | Excellent |
| Duck, cooked | 3 oz (85g) | 19 | 27.2 | Excellent | 31.7 | Excellent |
| Quail, cooked | 3 oz (85g) | 18.5 | 26.5 | Excellent | 30.9 | Excellent |
| Cheese ricotta | 1/2 cup (124g) | 18 | 25.7 | Excellent | 30 | Excellent |
| Mushrooms, shiitake, cooked | 1/2 cup (72,5g) | 18 | 25.7 | Excellent | 30 | Excellent |
| Sunflower seeds | 1 oz (28g) | 15 | 21.4 | Excellent | 25 | Excellent |
| Carp, cooked | 3 oz (85g) | 13.8 | 19.7 | Good | 23 | Excellent |
| Pike, cooked | 3 oz (85g) | 13.8 | 19.7 | Good | 23 | Excellent |
| Whole wheat, cooked | 1/2 cup (50g) | 13 | 18.5 | Good | 21.6 | Excellent |
| Trout, cooked | 3 oz (85g) | 12.8 | 18.2 | Good | 21.3 | Excellent |
| Soy milk | 1 cup (250g) | 11.8 | 16.9 | Good | 19.7 | Good |
| Mushrooms, crimini, raw | 1/2 cup (43,5g) | 11.3 | 16.1 | Good | 18.8 | Good |
| Peanuts | 1 oz (28g) | 11.3 | 16.1 | Good | 18.8 | Good |
| Rye | 1 slice (32g) | 9.9 | 14.1 | Good | 16.5 | Good |
| Veal lean, cooked | 3 oz (85g) | 9.9 | 14.1 | Good | 16.4 | Good |
| Milk, cow’s | 1 cup (244g) | 9 | 12.9 | Good | 15 | Good |
| Bread, mulitgrain | 1 slice (26g) | 8.6 | 12.3 | Good | 14.3 | Good |
| Lamb lean, cooked | 3 oz (85g) | 8.6 | 12.3 | Good | 14.3 | Good |
| Cheese | 2 oz (56g) | 7.8 | 11.1 | Good | 13 | Good |
| Flaxseed | 1 oz (28g) | 7.1 | 10.1 | Good | 11.8 | Good |
| Eel, cooked | 3 oz (85g) | 7.1 | 10.1 | Good | 11.8 | Good |
| Amaranth, cooked | 1/2 cup (123g) | 6.8 | 9.6 | – | 11.3 | Good |
| Barley, cooked | 1/2 cup (78,5g) | 6.8 | 9.6 | – | 11.3 | Good |
| Soybeans, cooked | 1/2 cup (86g) | 6.3 | 9 | – | 10.5 | Good |
| White rice, cooked | 1/2 cup (79g) | 6 | 8.5 | – | 9.9 | – |
| Oats, cooked | 1/2 cup (117g) | 5.9 | 8.4 | – | 9.8 | – |
| Coconut meat | 2 oz (56g) | 5.6 | 8 | – | 9.3 | – |
| Cashew nuts | 1 oz (28g) | 5.6 | 8 | – | 9.3 | – |
| Asparagus, cooked | 1/2 cup (90g) | 5.5 | 7.9 | – | 9.2 | – |
| Pinto beans, cooked | 1/2 cup (85,5g) | 5.3 | 7.6 | – | 8.8 | – |
| Mustard seeds | 1 tsp (3g) | 4.3 | 6.1 | – | 7.2 | – |
| Lima beans, cooked | 1/2 cup (94g) | 4.3 | 6.1 | – | 7.1 | – |
| Yogurt low fat | 1/2 cup (120g) | 4 | 5.7 | – | 6.6 | – |
| Spelt, cooked | 1/2 cup (97g) | 3.9 | 5.6 | – | 6.5 | – |
| Poppy seeds | 1 oz (28g) | 3.8 | 5.4 | – | 6.3 | – |
| Mushorroms, white raw | 1/2 cup (35g) | 3.3 | 4.6 | – | 5.4 | – |
| Chickpeas, cooked | 1/2 cup (82g) | 3.1 | 4.4 | – | 5.1 | – |
| Lentils, cooked | 1/2 cup (99g) | 2.8 | 3.9 | – | 4.6 | – |
| Navy beans, cooked | 1/2 cup (91g) | 2.7 | 3.8 | – | 4.4 | – |
| Pistachios | 1 oz (28g) | 2.6 | 3.7 | – | 4.3 | – |
| Quinoa, cooked | 1/2 cup (92,5g) | 2.6 | 3.7 | – | 4.3 | – |
| Coconut water | 1 cup (240g) | 2.4 | 3.4 | – | 4 | – |
| Buckwheat, cooked | 1/2 cup (84g) | 1.9 | 2.6 | – | 3.1 | – |
| Red cabbage | 1/2 cup (75g) | 1.7 | 2.4 | – | 2.8 | – |
| Pumpkin seeds | 1 oz (28g) | 1.6 | 2.3 | – | 2.7 | – |
| Sesame seeds | 1 oz (28g) | 1.6 | 2.3 | – | 2.7 | – |
| Green peas, cooked | 1/2 cup (80g) | 1.5 | 2.1 | – | 2.5 | – |
| Walnuts | 1 oz (28g) | 1.4 | 2 | – | 2.3 | – |
| Parsnip, cooked | 1/2 cup (78g) | 1.3 | 1.9 | – | 2.2 | – |
| Turnip greens | 1 cup (144g) | 1.3 | 1.9 | – | 2.2 | – |
| Banana | medium (118g) | 1.2 | 1.7 | – | 2 | – |
| Broccoli florets, cooked | 1/2 cup (78g) | 1.2 | 1.7 | – | 2 | – |
| Brussels sprouts, cooked | 1/2 cup (78g) | 1.2 | 1.7 | – | 2 | – |
| Adzuki beans, cooked | 1/2 cup (100g) | 1.2 | 1.7 | – | 2 | – |
| Pecans | 1 oz (28g) | 1.1 | 1.6 | – | 1.8 | – |
| Black beans, cooked | 1/2 cup (86g) | 1.1 | 1.5 | – | 1.8 | – |
| Kidney beans, cooked | 1/2 cup (88,5g) | 1.1 | 1.5 | – | 1.8 | – |
| Macadamia | 1 oz (28g) | 1 | 1.4 | – | 1.7 | – |
| Millet, cooked | 1/2 cup (87g) | 0.8 | 1.1 | – | 1.3 | – |
| Cocoa powder | 1 tsp (5g) | 0.7 | 1 | – | 1.2 | – |
| Almonds | 1 oz (28g) | 0.7 | 1 | – | 1.1 | – |
| Hazelnuts | 1 oz (28g) | 0.7 | 1 | – | 1.1 | – |
| Wild rice, cooked | 1/2 cup (82g) | 0.7 | 0.9 | – | 1.1 | – |
| Beetroot, cooked | 1/2 cup (85g) | 0.6 | 0.9 | – | 1 | – |
| Corn, cooked | 1/2 cup (82g) | 0.6 | 0.9 | – | 1 | – |
| Kale, cooked | 1/2 cup (65g) | 0.6 | 0.9 | – | 1 | – |
| Mung bean sprouts | 1 cup (100g) | 0.6 | 0.9 | – | 1 | – |
For Table Legend & Data Sources Information click here.
Brazil nuts are the best food source of selenium. To see the complete list of health benefits of Brazil nuts click here.
Selenium benefits
Selenium is an antioxidant that works best if combined with vitamin E. It protects the body from free radicals (particles that damage the membranes of the cells) and from DNA damage. This action may be responsible for its protective properties against cancers, ageing and cardiovascular diseases. (2)
- Selenium benefits related to cancer
The intake of selenium is associated with a reduced risk of developing bladder and prostate cancers, due to its important anti-cancer properties. (3, 4) . It is believed that these effects derive from selenium’s antioxidant properties and effects on DNA repair, apoptosis (dying of cells) and immune and endocrine systems. (5) - Selenium benefits related to cardiovascular diseases
The antioxidant properties of selenium may play a role in the prevention of cardiovascular diseases. However, more research is needed to prove this link. (6, 7)
- Selenium benefits related to thyroid
Selenium is an important component in the production of thyroid hormones and may be beneficial in the treatment of autoimmune thyroid conditions. In Hashimoto’s disease, supplementation of selenium reduces local inflammation, although the progress of this disease cannot be avoided. In Graves’ disease, selenium supplementation helps the thyroid to function normally. (8) - Selenium benefits related to immunity
Selenium can improve some immune functions, such as protection against some pathogens and the immunity response to aging. However, selenium is not useful in the immune reaction to parasites or in the case of allergic asthma. (9)
Selenium deficiency signs and symptoms
Selenium deficiency is rare in the U.S. and many developed countries. Lack of selenium in the soil is often solved by either adding selenium salts to the fertilizers or importing selenium rich staple foods. Selenium deficiency can lead to: (10)
- Juvenile heart disease also known as Keshan disease which is caused by severed selenium deficiency.
- A type of osteoarthritis called Kashin-Beck. The symptoms are loss of motion in the joints, pain and swelling. Kashin-Beck is caused by a severe selenium deficiency.
- Infertility in males.
- Problems with thyroid (such as goiter), especially in women.
- Increased iodine deficiency, increasing the risk of cretinism in infants.
- An increased risk of developing cancers such as bladder, colorectal, esophagus, lung, prostate, skin and stomach. (3)
- An increased risk of cardiovascular disease. However, more evidence is needed.
- A decline in brain function. Since the level of blood selenium normally declines with age, elderly people may be in the risk group. The studies on this subject, however, are conflicting. Therefore, more evidence is needed.
Who is at risk of selenium deficiency?
- Populations in selenium-deficient areas, especially those who eat mostly plant foods, grown in selenium depleted soils (e.g. Finland or some parts of China). (11, 12)
- People undergoing long term hemodialysis due to dietary restrictions, with the removal of some selenium from the blood and uremia.
- People with HIV due to inadequate diet, malabsorption and selenium losses through diarrhea.
- People with malabsorption problems such as in Crohn’s disease or ulcerative colitis.
- Cigarette smoking, alcohol consumption and oral contraceptives reduce the concentration of selenium in blood and may lead to selenium deficiency in people who are already nutritionally compromised. (2, 13, 14)
Recommended daily intake of selenium (mcg/day)
| Life Stage | Age | RDA for men | UL for men | RDA for women | UL for women |
|---|---|---|---|---|---|
| Infants | 0-6 months | 15 (AI) | 45 | 15 (AI) | 45 |
| Infants | 6-12 months | 20 (AI) | 60 | 20 (AI) | 60 |
| Children | 1-3 years | 20 | 90 | 20 | 90 |
| Children | 4-8 years | 30 | 150 | 30 | 150 |
| Children | 9-13 years | 40 | 280 | 40 | 280 |
| Adolescents | 14-18 years | 55 | 400 | 55 | 400 |
| Adults | 19-50 years | 55 | 400 | 55 | 400 |
| Adults | 51-70 years | 55 | 400 | 55 | 400 |
| Adults | > 70 years | 55 | 400 | 55 | 400 |
| Pregnancy | 14-18 years | – | – | 60 | – |
| Pregnancy | 19-50 years | – | – | 60 | – |
| Breast-feeding | 14-18 years | – | – | 70 | – |
| Breast-feeding | 19-50 years | – | – | 70 | – |
For Table Legend & Data Sources Information click here.
Side effects of excessive selenium
Selenium toxicity is not uncommon and usually occurs form long term consumption of supplements or large amounts of high selenium foods, such as Brazil nuts. (read more..)
The most common symptoms of selenium toxicity are:
- Early signs are garlic breath odor and metallic taste in the mouth
- Weakness and fatigue
- Gastrointestinal disorders (e.g. diarrhea)
- Hair loss
- Nail loss, discoloration and brittleness
- Skin rashes and lesions
- Bronchial irritation
- Abnormalities in the nervous system such as peripheral neuropathy
- Nausea
- Mottled teeth
- Irritability
Extremely high levels of selenium may cause:
- Breathing difficulty
- Kidney failure
- Tremors
- Heart attack
- Heart failure
Some reports state that long term selenium supplementation (200mcg of selenium per day during 7 years) may increase the risk of diabetes. More studies are required to confirm these findings. (8, 15)
Selenium supplements
You should only take selenium supplements under medical supervision. Selenium supplementation may lead to type 2 Diabetes (more studies are needed to prove this) and interact with certain medications such as Cisplatin.
NUTRITION FACTS VS NUTRITION MYTHS
You will find a summary of the most common nutrition myths and evidence-based nutrition facts here.