Some of the best dietary sources of selenium are Brazil nuts, seafoods and organ meats.
There are many other good food sources that can be used to increase intake of this mineral, including vegan and vegetarian options.
Dietary supplements containing L-selenomethionine are another popular source. Supplements may also contain the inorganic form sodium selenite.
Selenium (Se) is a trace element that is fundamental for human health and plays a role in multiple biological processes. However, it is required only in small amounts, and too much selenium can be toxic.



- Cofactor for antioxidant enzymes
- Supports thyroid function & metabolism
- Promotes immune function & fertility
Role of Selenium in the Body
In humans, selenium occurs as a constituent of more than two dozen selenoproteins. Selenoproteins function in the body in various ways including the following: [1]
- Protect cells from excessive H2O2 (hydrogen peroxide);
- Detoxify heavy metal accumulations;
- Regulate immune system activities;
- Facilitate proper thyroid function;
- Support fertility and healthy reproduction;
Preliminary clinical evidence also suggests that selenium possesses anticancer properties against some types of cancer. [2]
In 2009, a health claim petition was reviewed by the FDA asserting that selenium may reduce the risk of prostate, bladder, urinary tract, lung, respiratory tract, colon, digestive tract, thyroid, liver, brain and breast cancer.
Data from previous research is inconclusive and significantly more research is required to determine the efficacy of selenium in human cancer prevention and/or treatment. [3]
The benefits of this mineral for human health are believed to be mainly due to its antiviral, anti-inflammatory and antioxidant properties.
Research suggests that supplementation may also “enhance male fertility; decrease cardiovascular disease mortality, and regulate the inflammatory mediators in asthma.” [4]
It is not common for people to be deficient in this nutrient, but there are some cases in which increasing selenium intake may have benefits for human health.
Best Sources of Selenium in Diet
In the United States, the most common dietary sources of selenium are breads, grains, muscle meats, cereals, eggs, fish and poultry.
The following are some rich food sources:
- Saltwater and freshwater fish like salmon, tuna, swordfish, halibut and sardines;
- Shellfish like oysters, lobster, shrimp and scallops;
- Dairy products like milk, cheese and yogurt;
- Beef and fowl liver and kidney;
Some other animal-based sources of selenium include sea lion, pork, lamb, veal, goose and snails.
In most geographic locations, selenium is not found in nutritionally significant amounts in drinking water.
Vegan and Vegetarian Sources
Although organ meats are some of the most concentrated sources of selenium, there are plenty of plant-based selenium sources available to ensure adequate intake of this important micronutrient.
Some of the most concentrated sources of selenium come from plant-based foods. Brazil nuts have the highest concentrations known – roughly 550 micrograms per 1-ounce serving.
Other vegan sources of selenium include brewer’s yeast, wheat germ, corn and mushrooms. Green leafy vegetables like spinach, kale and Swiss chard are also good sources. Other plants high in this mineral include:
- Sunflower, flax, chia and sesame seeds;
- Lima, pinto and other types of beans;
- Walnuts, almonds and pistachios;
- Sprouted brown rice;
- Red grapes;
- Molasses;
Herbal Sources
Various herbaceous plants also contain good amounts of this mineral. Some of the most notable herbal sources include ginger, ginseng, turmeric, chili peppers and garlic.
Others include nettle, alfalfa, lemongrass, rosehips and peppermint. Selenium is also found in chamomile, catnip, fenugreek and burdock root.
The selenium content in any food source will vary significantly depending on several factors. The main factor is the soil in which a plant was grown. If the soil lacks selenium, then plants grown in that soil will likewise have low levels of this trace mineral.
Other factors that affect content in food sources include soil pH, how much organic matter is in the soil, and the form(s) of selenium found in the soil. Because of these factors, selenium content in plants can vary greatly between different geographic areas.
Animals that eat selenium-poor plants will be low in this mineral. However, larger variances are found in plant foods relative to animal food sources. This difference is largely because many animals are raised on livestock feed which is fortified with this compound.
Vegans and vegetarians should be mindful of the selenium concentrations in the food sources they select. Selenium deficiencies can cause side effects including hair loss, fatigue, brain fog and hypothyroidism.
Water Supplies
Water supplies in certain areas may be contaminated with substances including selenium. This element is contained in small amounts in at least 40 other minerals that are commonly mined.
Anthropogenic contamination of wastewater can occur due to agricultural irrigation, power plants fueled by coal – and other processes like surface mining operations.
While this mineral is of basic importance for animal health at low levels, excessive selenium concentrations can be toxic. When there is too much selenium in a water supply, fish and other aquatic animals can suffer reproductive impairments, stunted growth and increased overall mortality.
Selenium poisoning in animals can deformity, dysfunction and deterioration over time. According to the EPA and the US Forest Service, animals, including humans, that eat aquatic animals that contain toxic levels of selenium may develop signs of toxicity as well.
Selenium RDA
The RDA (Recommended Daily Allowance) for selenium according to the FDA is 55 mcg daily for healthy adults over 14 years of age. Younger children need less while pregnant and nursing women need more.
The National Institutes of Health (NIH) provides a detailed guide for all ages:
Age | Male | Female | Pregnancy | Lactation |
---|---|---|---|---|
Birth to 6 months | 15 mcg* | 15 mcg* | ||
7–12 months | 20 mcg* | 20 mcg* | ||
1–3 years | 20 mcg | 20 mcg | ||
4–8 years | 30 mcg | 30 mcg | ||
9–13 years | 40 mcg | 40 mcg | ||
14–18 years | 55 mcg | 55 mcg | 60 mcg | 70 mcg |
19–50 years | 55 mcg | 55 mcg | 60 mcg | 70 mcg |
51+ years | 55 mcg | 55 mcg |
Caution is necessary if trying to increase your dietary intake of this mineral through foods or suplements. According to a 2016 review of clinical data, “Slight differences in the selenium content can result in excess or deficiency, therefore supplementation has to be done carefully and cautiously.” [2]
If you are considering increasing your consumption of dietary sources of selenium, or taking a supplement, then it is best to speak to a health professional first.
- Brown KM1, Arthur JR. Selenium, selenoproteins and human health: a review. Public Health Nutr. 2001 Apr;4(2B):593-9.
- Kieliszek M1, B?a?ejak S2. Current Knowledge on the Importance of Selenium in Food for Living Organisms: A Review. Molecules. 2016 May 10;21(5). pii: E609. doi: 10.3390/molecules 21050609.
- Vinceti M1, Dennert G, Crespi CM, Zwahlen M, Brinkman M, Zeegers MP, Horneber M, D'Amico R, Del Giovane C. Selenium for preventing cancer. Cochrane Database Syst Rev. 2014 Mar 30;(3):CD005195. doi: 10.1002/14651858.CD005195.pub3.
- Wrobel JK1, Power R2, Toborek M1,3. Biological activity of selenium: Revisited. IUBMB Life. 2016 Feb;68(2):97-105. doi: 10.1002/iub.1466. Epub 2015 Dec 30.
- Kieliszek M1, B?a?ejak S. Selenium: Significance, and outlook for supplementation. Nutrition. 2013 May;29(5):713-8. doi: 10.1016/j.nut.2012.11.012. Epub 2013 Feb 16.
Article last updated on: July 15th, 2018 by Nootriment