Don’t Count On Vitamin C To Boost Your Exercise Performance

Orange juice or other sources of vitamin C (ascorbic acid), may (or may not) benefit you in terms of health and exercise, but contrary to what many people thought previously, ascorbic acid doesn’t seem to help physical exercise performance. And in terms of such endurance exercise as running, walking or cycling, whereas vitamin C reduces physiological “oxidative stress,” that reduction didn’t help performance for either men or women, whether they were in their 20s or 60s.
http://www.sciencedaily.com/releases/2005/01/050110121926.htm