Vitamin C and E Supplements may hamper Endurance Training

Too much of vitamins C and E supplements may interfere with endurance training.

Researchers at the Norwegian School of Sport Sciences, have found that taking vitamin C and E supplements may interfere with endurance training. High doses of vitamins C and E act as antioxidants, which is why athletes are attracted to them, but removing this oxidative stress, may block muscular endurance development.

In an eleven week, double-blind trial, 54 healthy young men and women were randomly allocated to receive either 1000mg vitamin C plus 235mg vitamin E, or a placebo pill containing no active ingredients. The participants then undertook an endurance training programme, consisting of three to four sessions per week, primarily of running. Fitness tests, blood samples and muscle biopsies were taken before and after the programme.

In endurance training, an adaptation is normally observed in the exercised muscles; this adaptation is characterised by an increase in mitochondrial proteins to improve muscular endurance. The results of this trial however, showed that in the group taking the vitamins, this increase was blunted.

Dr Gøran Paulsen, who led the study, 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. Future studies are needed to determine the underlying mechanisms of these results, but we assume that the vitamins interfered with cellular signalling.

(Journal of Physiology, on-line 3 February 2014.)

Robin’s note: If you wish to address free radical generation during exercise, then instead try using food to do it. You need food with a high ORAC (oxygen radical absorption capacity) rating. Prunes are top of the list, followed by things like raisins, blueberries, blackberries, strawberries, kale and spinach.