Vitamins C and E adversely affect muscle mitochondria response to 
exercise, and can cause post workout pain, and muscle fatigue.

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.

Paulsen G et al. J Physiol 2014 Feb 3.