In the quest for optimal health, many people engage in regular physical activity and take a vitamin just for “insurance.” But if you exercise to lower your risk of developing diabetes, a new study says you may want to avoid taking antioxidant vitamins C and E.
During exercise, the body produces free radicals. Free radicals are generally formed in unhealthful environments like smoking and pollution. If not controlled, free radicals can wreak havoc on the body by increasing oxidation (read: inflammation) and risk of disease. Although it is well established that exercise is good for us, the free radicals produced may too be harmful. Because antioxidant vitamins like C and E have been shown to blunt free radical damage, researchers wanted to know if supplementing exercisers with the vitamins would have an effect on risk of developing diabetes.
It is well established that engaging in regular physical activity increases the body’s sensitivity to insulin, which helps to lower diabetes risk. Researchers supplemented exercising healthy men with antioxidant vitamins E (400 IU/day) and C (1000 mg/day) for four weeks and measured their insulin sensitivity before and after the exercise intervention. They received surprising results: the group taking the vitamins showed no improvement in insulin sensitivity and their bodies natural defense against oxidative damage was not activated. It appears that the antioxidants actually blunted insulin sensitivity and interrupted the body’s natural ability to fight off free radical damage.
There is surely more research to be done in this area, but the overall message is clear: instead of supplementing your way to good health, EAT your antioxidants, which have shown no detrimental side effects, only positive ones. Enjoy a variety of fruits, vegetables, legumes, and whole grains and don’t forget to engage in regular, sustained aerobic activity to improve insulin sensitivity.
Written by Melissa Ohlson, MS, RD, LD, Preventive Cardiology and Rehabilitation.
Get more information on nutrition strategies. To make an appointment with a registered dietitian, call the Cleveland Clinic Preventive Cardiology - 216.444.9353 or 800.223.2273 ext. 9353. Or, get a nutrition consultation online with our private and secure MyConsult Nutrition Consultation.
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