The mineral selenium aids in the proper functions of your immune system and thyroid function. Your body does not naturally make selenium therefore you need to consume small amounts to maintain adequate health. Selenium may also have benefits as an antioxidant and preventive for viral infection, certain cancers or heart disease. Research is inconclusive and ongoing, however.
Daily Allowance
The daily recommended dietary allowance for selenium in adults is 55 micrograms. Pregnant or lactating women require increased dosage at 60 to 70 micrograms per day. The safest tolerable upper intake limit should not exceed 400 micrograms per day. According to the Linus Pauling Institute, the tolerable upper intake set for selenium includes sources from food or supplements. However, most adults in the United States do not exceed 100 micrograms of selenium in the diet per day. Supplemental use should be monitored carefully so you do not exceed the tolerable upper intake, which can result in selenium toxicity.
Toxicity
Selenium toxicity is not common in the United States. However, high blood levels of selenium results in a condition called selenosis or rapid high dose can cause fatal toxicity. Over time, selenosis occurs with higher dose use of selenium exceeding the safe tolerable upper limit and symptoms include hair loss, brittle nails, fatigue and stomach upset. Fatal toxicity can occur from exorbitant doses upward of thousands of micrograms, notes the Linus Pauling Institute. Before using a selenium supplement consult your physician for dosing recommendations.
Food Sources
A well-balanced diet can provide you with adequate daily intake of selenium. Brazil nuts are an abundant selenium source with a 1-oz. serving yielding 544 micrograms. Walnuts and sunflower seeds at servings of 1 oz. yield 5 to 10 micrograms of selenium. Tuna, salmon, cod, crab or shrimp has 32 to 63 micrograms per 3 oz.-serving and beef, turkey and chicken provides 20 to 35 micrograms for a 3 1/2-oz. serving. Rice, oatmeal at 1/2-cup serving and one slice of whole wheat bread are rich in selenium with 10 to 12 micrograms.
Antioxidant and Disease Prevention
As an antioxidant, selenium works along with vitamin E to prevent free radicals from causing damage to your molecules and organs. Adequate dietary intake prevents you from experiencing selenium deficiency diseases including heart enlargement, osteoarthritis and neurological deficits. The American Cancer Society notes that selenium may protect your body from cancer cell growth and spread but this research is ongoing and inconclusive.
Supplements and Drug Interaction
Selenium may be included in multivitamin supplements or as an individual supplement. Selenium can cause drug interactions with blood thinners and chemotherapy medications. Anticonvulsant medications for seizures may also have an interaction with selenium. Consult your physician before taking selenium supplements.
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