Selenium and Type 2 Diabetes Have Special Relationship
You may want to add Brazil nuts and button mushrooms to your diet sometime soon. Both of these foods, along with selected others, are a rich source of selenium, and a new study indicates that selenium is a good mineral to have if you want to reduce your risk of type 2 diabetes.
What's the relationship between selenium and type 2 diabetes?
Selenium is a critical mineral that plays many roles in the body, from protecting cells against damage from free radicals (selenium is an antioxidant) to facilitating the production and levels of the thyroid hormone T3 (triiodothyronine) thyroid hormones and reducing the risk of joint inflammation.
Selenium also has demonstrated some cancer-fighting abilities, as it's been shown to help repair DNA, inhibit the spread of cancer cells, and induce cell suicide (apoptosis). When it comes to a relationship between selenium and type 2 diabetes, however, the research has been limited and produced mixed results.
A new effort from researchers at Yeungnam University and Harvard evaluated data from two different US cohorts: 3,630 women (1982-1983) and 3,535 men (1986-1987). None of the study participants had diabetes or heart disease at the start of the investigation.
Follow-up was continued through 2008, and during that time 780 cases of type 2 diabetes were identified. After adjusting for multiple variables, the authors found that the highest average levels of selenium in toenails was associated with a 24 percent lower risk of type 2 diabetes.
The concentration of selenium found in human toenails has long been used as an indicator of long-term (6-12 months) selenium levels in the body. Selenium is one of the most important substances that make up human nails.
How much selenium do you need?
The recommended dietary allowance (RDA) for selenium for males and females age 14 years and older is 55 micrograms daily. In addition to Brazil nuts (which contain about 544 micrograms per ounce) and button mushrooms, other excellent to very good sources of selenium include lobster, cod, tuna, shrimp, salmon, and sunflower seed kernels.
The amount of selenium in foods depends on the selenium content of the soil in which plants are grown or animals are raised. Selenium content in fish comes from the water, sediment, and aquatic plants.
Excessive amounts of selenium, however, are unhealthy. The tolerable upper intake levels for selenium are 280 micrograms for children 9 to 13 years old and 400 micrograms for males and females age 14 years and older. Too much selenium can cause selenosis, which is characterized by gastrointestinal upset, hair loss, fatigue, mild nerve damage, and white blotchy nails.
According to the authors of this latest study, "At dietary levels of intake, individuals with higher toenail Se [selenium] levels are at lower risk for [type 2 diabetes]." This relationship between selenium and type 2 diabetes is one to consider when making your menu plans.
Office of Dietary Supplements
Park K et al. Toenail selenium and incidence of type 2 diabetes in US men and women. Diabetes Care 2012 Jul; 35(7): 1544-51
Image: Wikimedia Commons