Vitamin C and E Supplements May Hinder Athletic Training

Vitamin Supplement PowderVitamins are essential for good health. However, a new study published in The Journal of Physiology suggestions that vitamin C and vitamin E supplements may hinder athletic training rather than improve performance.

The Office of Dietary Supplements of the National Institutes of Health recommends 75 milligrams for women and 95 milligrams for men of vitamin C daily and 15 milligrams of vitamin E daily for men and women. Vitamin E is naturally available in foods such as vegetable oils, nuts, and green vegetables while vitamin C is naturally available in citrus fruits and vegetables including potatoes and broccoli.

Vitamin C and vitamin E supplements are also widely available.

Because of the ease of access to vitamin C and E supplements researchers from the Norwegian School of Sport Sciences led by Dr. Gøran Paulsen recently investigated the effects, if any, of supplementation on cellular or physiological mechanisms in the body during exercise.

The researchers studied 54 young and healthy men and women for 11 weeks. The participants were randomly assigned to one of two groups. The first group took 1,000 milligrams of vitamin C and 235 milligrams of vitamin E daily, which the researchers identified as consistent with the amount of each vitamin found in commercial supplements. The second group took a placebo daily.

The participants then took part in an endurance training program that consisted of three to four training sessions each week that primarily involved running. The participants also underwent fitness tests and muscle biopsies and had blood samples taken before and after the study.

According to the study, production of new muscle mitochondria, structures that supply power to the cells, increased only in the participants who received the placebo pill. The participants who took the vitamin C and E supplements did not exhibit and increased in new muscle mitochondria production, indicated that supplementation may hinder athletic training.

Exercise increases the production of oxygen in the muscles. Both vitamin C and vitamin E are antioxidants. The researchers hypothesize that high doses of the vitamin supplements may reduce some of the oxidative stress of exercise and block the development of muscular endurance. Oxygen is necessary for muscular change. However, additional research is needed to determine underlying cause of the decrease muscular development in the athletes taking the supplements.

Comments Dr. Paulsen on the findings:

“Our results indicate that high dosages of vitamin C and E – as commonly found in supplements – should be used with caution, especially if you are undertaking endurance training. Future studies are needed to determine the underlying mechanisms of these results, but we assume that the vitamins interfered with cellular signaling and blunted expression of certain genes.”

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