Two Wheel Blogs

A few weeks ago, a well known professor of nutrition referenced this study (which was published in the AJCN) on our local cycling message board and cautioned people about using vitamin C. Her message seemed to indicate that, in general, people should follow the FDA RDI for vitamin C rigorously and that going above this value could be detrimental and dangerous.

I was quite skeptical of this study and have had some discussion with others about it. Well, now we have some results from another trial done using professional soccer players from a young pro league in Brazil. Although this trial did not show any immediate ergogenic benefits, all of the group taking the vitamin C appeared to have significantly better endurance parameters (at the end of the trial period) than the group taking a placebo.

I have still not gotten complete access to the study from the AJCN but from what I understand, the human subjects were all untrained. Now this could introduce significant variables. For example, were the subjects smokers, ex-smokers, obese, or what? I don't see any indication given. Lab rats were also used in this study. But of course, lab rats make their own vitamin C and would also create more when under stress. Giving these rats more vit C could be introducing a factor which is not well understood. What effect does it have on their own production of ascorbate and how does this effect the amount available in their blood stream?

The soccer study, on the other hand, included significant instruction on dieting and this was closely monitored. The subjects were trained athletes which reduces the variables that might effect the study (in my opinion). Notice also that the complete study is available for free. Nothing to hide (it would seem). I have a hunch that most of the really good vitamin C research is happening outside of the US since there seems to be such a strong academic bias against vit C here (and also available funding it would seem).

In my own experience I have taken lots of vitamin C on a daily bases (typically 6 to 10 grams in 24 hour period). I adjust the amount I take in relation to the amount of stress I might be under. If I get a cold or flu I can easily tolerate 20 or more grams in a 24 hour period. I have not noticed anything dramatic in terms of being slower or faster but one thing is clear. I don't get sick as much and when I do, it is shorter and milder so I recover quicker and I therefor can train more.

If there is anyone else out there who might shed more light on these studies for me, I would be very interested in hearing your thoughts.