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Monday, March 10, 2014
Mineral Supplements and Diabetes
Is zinc chromium and selenium essential for a diabetic ? What is the recommended maximum dose of these supplements?
Zinc, chromium and selenium are all nutrients needed by everyone in adequate amounts, with or without diabetes. If they are lacking in the diet, deficiency results. For an adult over the age of 18, the Dietary Reference Intakes (DRI) recommends that women receive 8 mg of zinc per day and 11 mg for men. The Selenium DRI is 55 ug (micrograms) for both men and women. Chromium has an established "AI" or adequate intake of 25 ug for women and 35 ug for men between the ages of 31 -50 years old and 20 and 30 respectively for those over 50 years old.
The tolerable upper limit or UL (those levels that are unlikely to pose a risk of adverse effects) has been established for many nutrients. The UL represents total intake from food, water and supplements sources. Levels (taken from supplements) above the DRI can lead to toxicity and can cause deficiencies of other nutrients in the body (for example, too much zinc can cause a copper deficiency.) The UL for zinc is 40 mg/day and for Selenium 400 ug/day. The UL for chromium has not been established yet; however up to 200 ug of supplemented inorganic chromium appears to be safe.
As for the role of these nutrients specifically in people with diabetes, the research is inconclusive. According to the book Diabetes Management Therapies from the American Association of Diabetes Educators, "The ADA (American Diabetes Association) concluded that the potential benefits of chromium supplementation in persons with diabetes have not been conclusively demonstrated. Until larger clinical trials are conducted in countries similar to the U.S. and where chromium deficiency is not of concern, it is prudent to avoid chromium supplementation. Long-term benefits from pharmacological doses of chromium on glycemia and lipids are unknown." This text also states, "Deficiency of certain minerals such as potassium, magnesium, and possibly zinc and chromium may aggravate carbohydrate intolerance. Potassium and magnesium assessment can be done, but the need for zinc and chromium in persons with diabetes has not been established."
My advice? Eat a well balanced diet with a lot of variety and color to obtain adequate amounts of all your essential nutrients. Self prescribing supplements without knowing the long-term safety and effectiveness can be very risky business. For more help, speak with a RD (registered dietitian) and your physician to discuss your medical nutrition concerns. They will know your specific medical history and dietary needs and can give more individualized guidance.
Jane Korsberg, MS, RD, LD
Senior Instructor of Nutrition
School of Medicine
Case Western Reserve University