Our newsletter this week featured a guest column from a friend of the store, Dr. Ralph Hall. Dr Hall is a professor emeritus of medicine at the University of Missouri at Kansas City. Additionally, he is a fellow of the American College of Physicians and American College of Sports Medicine. He is the co founder of the Hospital Hill run in Kansas City and has run the Pikes Peak Ascent eleven times.
Updates in Health and Fitness
By Ralph R Hall M.D. FACSM
SYNOPSIS: Oral vitamin C prevents improvement in VO2 max and endurance capacity.
SOURCE: The American Journal of Clinical Nutrition. Jan 2008.
BACKGROUND: Runners and bikers often take vitamin C supplements because intense running and biking can result in oxidative stress. Peroxidation is the result of increased free radicals and they are thought to lead to increases in heart disease, cancer and other degenerative diseases. Free radicals are molecules with an odd number of electrons. They are created by normal activity and because of their molecular structure are toxic. There is considerable debate regarding the beneficial health effects of the antioxidant activity of supplemental vitamin C.
STUDY DESIGN: The human study was double-blinded and randomized. Fourteen men (27-36 years old) were trained for 6 weeks. Five of the men were supplemented daily with an oral dose of 1 gram of vitamin C daily. Twenty-four rats were exercised under two different protocols for 3 and 6 weeks. Twelve of the rats were supplemented with a comparable dose of vitamin C calibrated for their body surface area.
RESULTS: The administration of vitamin C significantly (P=0.014) hampered endurance capacity. Vitamin C also prevented the exercise induced increases of markers of increased fitness such as cytochrome C (a marker of mitochondrial content) and of the body’s own powerful antioxidant enzymes superoxide desmutase and glutathione peroxidase.
Vitamin C levels were measured in all the human and animal experimental subjects to confirm that levels were consistent for both the supplemented and the unsupplemented subjects.
Training significantly increased the running time in the rats. However, this increase was prevented by vitamin C supplementation. The running time increased from a mean of 99 minutes to 284 minutes in the un-supplemented rats, but only from 101 to 128 minutes in the supplemented rats. The VO2 max increased more in the un-supplemented subjects. In the human subjects VO2 max was increased by 17% in the unsupplemented group and 4.7 % in the supplemented group. This was not statistically significant -perhaps because of the small number of subjects.
Editorial Comment: The unsupplemented subjects had significantly higher tissue levels of two of the body’s important antioxidants and statistically higher levels of markers for mitochondrial content. (Mitochondrial content is the amount of the energy producing machinery (mitochondria) in a cell.) The mitochondrial content is more closely related to endurance capacity than the maximum oxygen uptake (VO2 Max) and the anaerobic threshold.
Endurance athletes have higher levels of the very protective antioxidant, superoxide desmutase, than sedentary people. It is there to protect against free radicals and inflammation around the clock. It not only protects against the free radicals produced by exercise but also those produced by other factors such as improper diet, environmental toxins, etc.
It seems likely that vitamin E will have the same adverse effects as vitamin C, since both prevent free radical formation. The consensus of those working in this research area is that a few free radicals are beneficial and lead to the body generating its own protective antioxidants.
The reasoning behind taking antioxidants is they act as scavengers for superoxides or free radicals generated by foods, exercise and environmental toxins which lead to inflammation, atherosclerosis and cancer. To date the studies in which these supplements have been given are still controversial.
The amount of vitamin C we get from diet is obviously healthy and necessary, but taking excess vitamin C is not justified by current evidence.
This was a carefully done study, however, since this is the first report to note these adverse effects of vitamin C it will need to be verified by additional studies.
Until further studies are done the best advice to runners and bikers is to get your vitamin C from fruits and vegetables. As always, they are the best supplements.