Don’t Take Those Vitamins!

It seems obvious that we should take supplements to prevent free-radical formation and reactive oxygen species (ROS). Exercise produces ROS by activating mitochondrial metabolism, but exercise also improves insulin sensitivity. These researchers examined how antioxidant vitamins alter the insulin-sensitizing effects of exercise in 40 healthy men (mean age, 26) who were either active (exercising >6 hours/week) or sedentary (exercising <2 hours/week).

All participants were randomized to receive placebo or vitamin E (400 IU/day) plus vitamin C (500 mg twice daily) and underwent an exercise regimen for 4 weeks (5 days/week: biking or running, 20 minutes; circuit training, 45 minutes; warm-up/cool-down, 20 minutes).

At baseline and after 4 weeks, …