Although maintaining strong immunity is important during the winter to avoid colds and flu, a healthy immune system is one of the foundations for optimal health all year round.

While necessary to every cell in the body, the antioxidant mineral selenium is particularly valuable to the immune system. Selenium plays a key role in our antioxidant system, helping to make glutathione, and regenerating major antioxidants like vitamins C and E so that they can be reused again and again. One way immune cells kill pathogens is with oxidative poisons. Without the protection of selenium, these poisons can harm the immune cells themselves, weakening them and making them less effective—sometimes even killing them. Selenium has also been shown to keep viruses from mutating into forms that are many times more destructive.

Cumulative oxidative damage to immune cells over time causes the immune system to weaken with age. However selenium and other antioxidants can prevent and even reverse age-related decline. For example, when extra selenium was given to aged mice, their immune systems responded to a challenge as if they were young adult mice again.

Although we don’t yet know all the ways in which selenium supports immunity and research is ongoing, people who get levels of selenium well above the RDA of 55 micrograms (mcg) a day just seem to do better.

How much selenium is optimal?

Most studies on selenium supplementation have used 200-300 mcg a day.

It’s been estimated that Americans get about 100 mcg of selenium in their daily diet, however this may be overly optimistic since levels of selenium have been declining in soils and hence in our food. Also, like other antioxidants, selenium is depleted by environmental toxins as well as chronic illness. All things considered, it is not possible to count on diet alone to provide adequate selenium.

We believe supplementing the diet with 75-400 mcg a day is about right for most people. If you’re young and healthy, 75 mcg a day may be enough; if you’re older and/or experiencing health challenges, higher amounts are recommended.

Even at daily doses up to 900 mcg, organic selenium is very safe. Beyond Health uses the preferred form of organic selenium, L-selenomethionine, the form found in plant foods. Another organic form, selenocysteine, found in animal foods, is also acceptable; but according to selenium researcher Raymond F. Burk, MD, selenomethionine is more effectively utilized by the body and produces higher levels of selenium in the blood and tissues.

Inorganic forms of selenium, such as sodium selenite and sodium selenate, are not recommended.

These forms are only about 50% bioavailable (our L-selenomethionine is 95% bioavailable), and are not as bioactive or well utilized as organic forms. Beware also of some forms of selenomethionine that are simply inorganic forms grown on yeast.

A strong immune system is one of the foundations for optimal health. Make sure yours is in tip-top shape with adequate amounts of high-quality selenium!