Jonathan Silver, MD

Vitamins C and E adversely affect muscle mitochondria response to exercise.

Several studies have shown that vitamins C and E impair glucose regulation (NEJM JW Psychiatry Jun 8 2009) and raise risk for Alzheimer disease (NEJM JW Psychiatry Apr 23 2012). Here is another study to relate to our patients who believe that these antioxidant vitamins “can't hurt.”

In a double-blind study partially funded by supplement manufacturers, 54 individuals (28 women; mean age, 24) were randomized to receive placebo or vitamin C (1000 mg/day) plus vitamin E (DL-alpha-tocopherol acetate, 235 mg/day) while they participated in an 11-week endurance training program. The two groups did not differ in change in performance over time (VO2max, submaximal running, and a shuttle run test). However, only the placebo group showed improvement at 11 weeks in mitochondrial markers (obtained via muscle biopsy). Only the placebo group had significantly improved fat oxidation and reduced heart rates at submaximal workloads.

Citation(s):

Paulsen G et al. Vitamin C and E supplementation hampers cellular adaptation to endurance training in humans: A double-blind randomized controlled trial. J Physiol 2014 Feb 3; [e-pub ahead of print].