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Selenium is an essential dietary mineral. Its principal function is as a constituent of four glutathione peroxidase molecules, which are among the most powerful antioxidants and immune boosters made by the body. Studies have shown that it can help fight infections, maintain brain function in the elderly, and decrease the risk of some cancers.
Did you know?
Selenium was recognized as essential for people in 1957—relatively recently as nutrition research goes.
By itself, selenium appears to have little biological activity. However, as part of glutathione peroxidases and some proteins, it has far-reaching health benefits. Via glutathione peroxidases, it helps the body break down hydrogen peroxide, one of the most dangerous generators of free radicals, into water. Selenium also plays a crucial role in the formation of thyroid hormones.
Selenium Health Benefits
Brain function. Selenium may help keep aging minds sharp. In one study, French researchers studied approximately 1,400 older men and women for nine years. They found that cognitive function closely paralleled selenium levels, and the greatest decrease in cognitive function occurred among people with the lowest blood levels of selenium. Meanwhile, in a study of 2,000 elderly subjects, American and Chinese researchers found that high selenium levels were associated with better mental function, while poor test scores were related to low selenium levels.
Fighting infections. Almost 20 years ago, researchers reported that selenium supplements were beneficial in the treatment of HIV (human immunodeficiency virus) infection, and a 2020 research review suggested that they may also be beneficial for Covid-19 infection. As the researchers noted, “The significant body of evidence from human, animal and cell culture studies indicates that Se status is an important factor in response to viral infections, notably RNA viral infections and including respiratory virus infections.”
Did You Know?
Toxicologists have long known that adequate selenium intake helps prevent mercury toxicity.
Preventing viral mutations. Selenium also prevents mutations in coxsackie and influenza (flu) viruses, which cause symptoms similar to those of the common cold. That’s important because mutations in selenium-deficient people and animals result in much more dangerous viruses. One study found that selenium supplements help people effectively respond to the polio virus and polio vaccines, a benefit that may extend to other vaccines.
Cancer protection. One study reported that taking selenium supplements (200 mcg daily for 4.5 years) lowered the risk of prostate, lung, and breast cancers by more than one-third. Another study found that high selenium levels were associated with a relatively low risk of developing colorectal adenomas, a type of cancer.
Selenium supplements may be particularly beneficial for women who inherit mutations in the BRCA “cancer gene.” Normally, this gene helps repair damaged genes, but the mutation increases the risk of breast and ovarian cancers. In a study of 32 women with BRCA gene mutations, researchers noted that they had a high rate of chromosome breaks, a cancer risk factor. However, after taking selenium supplements for just three months, the rate of mutations decreased to that of women with normal rates.
What You Should Take
It’s prudent to take 200–300 mcg daily as a stand-alone supplement or as part of a multivitamin/multimineral. It’s also safe to go up to 600 mcg daily for short periods, such as when fighting a cold or flu. To use higher doses in the treatment of serious diseases, such as HIV infection, work with a nutritionally oriented physician.