Vitamin E and C Pills Have Negative Impact on Endurance Training

A new Norway study suggests that intake of certain vitamin supplements can hamper muscle cell response to exercise.

The study reported in the Journal of Physiology claims that, vitamin E and C supplements hinder the improvement of muscular endurance by interrupting cellular adaptations in exercised muscles.

According to the study authors at the Norwegian School of Sport Sciences, access to Vitamin E and C supplements is easy. They are also used on a large scale. Hence it is crucial to identify if these vitamins affected people exercising for health or athletic purposes.

Led by Dr. Goran Paulsen, the 11 week double blind randomized controlled trial was conducted on 54 young healthy men and women. The subjects were given either a 1000 mg vitamin C and 235 mg vitamin E or a placebo.

The subjects then had to complete an endurance training program of primary running that was held three-four times per weeks.

In order to examine how well the subjects' bodies adapted to the training program, researchers carried out fitness tests, collected blood samples and conducted muscle biopsies before and after interventions.

No difference was spotted in the subjects' performance during the running test, which required them to run fast between two points set 20m apart, source BBC. However, blood samples and muscle biopsies revealed that the group receiving placebo had excess muscle mitochondria production when compared to those receiving the supplements.

Dr Paulsen says, "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. A significant trend has been identified, but the molecular process requires further research. Future studies are needed to determine the underlying mechanisms of these results, but we assume that the vitamins interfered with cellular signalling and blunted expression of certain genes."

According to the National Health Service (NHS) consuming less than 540 mg of vitamin E and 1000 mg of vitamin C supplements per day does not trigger any harm.