Small amounts of selenium, a trace element naturally found in the soil and food products, are nutritionally essential for human health. In the body, selenium clusters known as selenoproteins play a critical role in reproduction, thyroid hormone metabolism, immune support and DNA synthesis. In its function as an antioxidant, selenium plays an important role in oxidative damage protection and infection prevention. Selenium is required for the proper activity of glutathione peroxidases, a group of enzymes that provide protection from oxidative stress and facilitate the recycling of vitamins E and C, helping to optimize the performance of the antioxidant system. They also play a key role in the body’s detoxification system, aiding in the elimination of heavy metal toxicity symptoms.
Chronic low selenium intake is associated with an increased risk for heart disease, cancer and depressed immune function. Those most susceptible to selenium deficiencies include those with rheumatoid arthritis, eczema, psoriasis, inflammatory conditions and those with certain types of cancer. Others who may have low levels of selenium include those who smoke cigarettes, drink alcohol, take birth control pills or have digestive health issues such as celiac or Crohn’s disease that prevent absorption of the mineral.
In addition to potent antioxidant activity, selenium stimulates the immune system and shows promise in cancer prevention by its ability to inhibit tumor growth. Because of its antioxidant properties and its positive effects on DNA repair and the endocrine and immune systems, the importance of selenium in cancer prevention is the basis of ongoing scientific studies. A substantial amount of research indicates that selenium plays a role in regulating cytokines, cell signaling molecules that stimulate the immune response, while deficiencies are associated with impaired immune function.
Selenium can be found in the highest concentration in the thyroid gland. Much like iodine, selenium has important roles to play in thyroid hormone synthesis and thyroid gland function. The transformation of a less active thyroid hormone known as thyroxine (T4) into the more active triiodothyronine (T3) is one way that selenium partners with iodine to keep thyroid function strong and consistent. While selenium supports efficient thyroid hormone synthesis and metabolism, it also protects the thyroid from the damaging effects of excessive iodine exposure.
Although true selenium deficiency is rare in the U.S., selenium intake and blood concentrations can vary by region depending on soil content and amounts found in local foods. The amount of selenium a plant food contains is dependent on the soil content, soil pH, the health of the soil, the amount of organic material in the soil and whether the plant is able to extract the selenium from the soil. The soil also affects the amount of selenium in an animal’s diet, so amounts found in dietary animal products can fluctuate. Good food sources of selenium include brazil nuts, sunflower seeds, organ and muscle meats, whole grains, cold water fish, shellfish, dairy and cruciferous vegetables. Eating a diet rich in whole foods is preferable to processed foods, as processing destroys much of the nutrient content. Most refined and processed foods, which often make up a large percentage of many American’s diets, are very low in selenium.
Making sure your selenium intake is optimal may boost both thyroid and immune function. While the importance of selenium in the diet is well documented, you can have too much of a good thing. While most adults average less than 100 mcg per day from foods, exceeding the recommended daily allowance of 400 mcg is not recommended.
Here are some great recommendations for selenium supplementation:Selenium (Selenomethionine) by Pure Encapsulations – This easily assimilated supplement provides 200 mcg of selenium per capsule in a hypo-allergenic, gluten and soy free formula. Aqueous Selenium by Biotics Research – This product provides supplemental selenium in an easy to take liquid formula. One drop provides 95 mcg of elemental selenium. Reacted Selenium by Ortho Molecular – This gluten and soy free supplement provides 200 mcg of selenium per natural vegetable capsule. Selenium by Innate Response Formulas – Crafted exclusively from 100% whole food nutrients, this non-GMO, gluten and soy free formula provides 50 mcg of selenium per tablet.