- Physical exercise increases insulin sensitivity through the generation of free radicals, which can help prevent diabetes.
- Antioxidant supplements such as vitamins C and E can counteract this beneficial effect by blocking the oxidative stress response induced by exercise.
- A study observed that men taking antioxidant supplements did not show increased insulin resistance, unlike those who didn’t take such supplements. This change reversed a month after they stopped consuming the supplements.
- While taking antioxidant supplements may possibly impede the beneficial effects of exercise on insulin sensitivity, the benefits of antioxidants found naturally in food aren’t disputed.
- The potential benefits and harms of antioxidants as supplements remain unclear, hence more research is needed.
Research indicates that regular physical exercises enhance insulin sensitivity, playing a vital role in preventing diabetes. However, consuming antioxidant supplements such as vitamins C and E may counteract these beneficial effects, according to some studies.
How Does Exercise Effect Insulin Sensitivity?
Physical exercise increases the body’s insulin sensitivity by generating reactive oxygen species, also known as “free radicals”. Although free radicals are generally perceived as cell-damaging and accelerators of aging, they serve a vital purpose. Post-exercising, your body utilizes these free radicals to prevent cellular damage, recent studies have shown.
“Physical exercise indeed helps improve your insulin sensitivity, a beneficial factor when there’s a risk of diabetes,” said researcher Dr. C. Ronald Kahn, Mary K. Iacocca Professor at the Joslin Diabetes Center and Harvard Medical School.
The Role of Exercise-Induced Oxidative Stress
Exercise-induced stress leads to increased insulin sensitivity. This process is facilitated through the generation of free radicals by muscles reacting to the stress. Hence, antioxidant intake (like vitamins C and E) can block this oxidative stress response, simultaneously blocking the beneficial effects of exercise on insulin sensitivity, adds Dr. Kahn.
The research findings were released in a recent online edition of the Proceedings of the National Academy of Sciences.
Insight from a Study on Exercise and Antioxidants
In an investigation into the role of exercise on insulin resistance, Dr. Kahn’s team studied 39 young men, nearly half of whom were consuming additional vitamins C and E. The results brought new attention to the interaction between antioxidants and exercise.
While the group consuming vitamin supplements did not show any change in insulin resistance, men without vitamin supplement intake showed an increase in free radicals, prompting increased insulin resistance. Moreover, insulin sensitivity was restored a month after ceasing vitamin supplement consumption, the researchers pointed out.
Dr. Kahn advised, “If your exercise regimen is partly geared towards diabetes prevention, consuming vitamin C and E supplements is not recommended, as it can hinder some positive effects of exercise in diabetes prevention.”
The Debate on Antioxidants
Dr. David L. Katz, Director of the Prevention Research Center at Yale University School of Medicine, acknowledges that the research raises questions about the benefits of taking antioxidant supplements – but not about the benefits of these vitamins found in the food we eat.
“Our hopes have long been that antioxidant supplements, such as vitamin C, vitamin E, beta carotene, lycopene and others, would help prevent a variety of diseases,” Dr. Katz stated. However, most current research does not support this hopeful perspective.”
The study concludes on a seemingly counter-intuitive note, indicating that antioxidant supplements might, in fact, impede the positive effects exercise has on insulin sensitivity. Dr. Katz emphasized that due to the study’s limited size and short duration, it doesn’t conclusively establish anti-diabetic harm from antioxidant supplements. Yet, it does suggest this as a possibility.
For now, the health benefits and potential harms of antioxidants as supplements remain uncertain, according to Dr. Katz. However, he advocates that “we have no doubt about the powerful health-promoting effects of wholesome, mostly plant-based diets and regular physical activity.”
For further information on antioxidants, visit the U.S. National Library of Medicine.