ABSTRACT

The role of dietary antioxidants, and particularly vitamin C, in general health have been the subject of considerable debate. The rapid turnover of vitamin C, its interaction with other physiological antioxidants and its rapid depletion during imposed oxidative stress (such as would likely occur during exercise), make study of this important vitamin complex. While the effects of acute vitamin C deficiency are well known and characterized (scurvy) and can be readily “treated” with relatively small amounts of supplements, the levels of vitamin C that may be optimal for long-term health are difficult to determine. There is considerable evidence, though not completely unequivocal, that high levels of

I. Introduction .................................................................................................. 149 II. Chemical Structure and Purification/Synthesis ............................................ 150

A. Chemical Structure ............................................................................... 150 B. Synthesis ............................................................................................... 151

III. Basis for biochemical Deficiency in Humans and Other Primates .............. 152 IV. Physiological Functions of Vitamin C .......................................................... 152

A. Collagen Biosynthesis ........................................................................... 153 B. L-Carnitine Biosynthesis ....................................................................... 153 C. Iron Absorption ..................................................................................... 153 D. Conversion of Dopamine to Norepinephrine ........................................ 154 E. Role as a Key Biological Antioxidant ................................................... 154

V. Vitamin C Transport ..................................................................................... 156 VI. Measurement of Vitamin C .......................................................................... 156 VII. Role in Exercise ............................................................................................ 158

A. Vitamin C and General Effects on Exercise .......................................... 158 B. Vitamin C and Exercise in Middle Age ................................................. 158

VIII. Body Reserves .............................................................................................. 158 IX. Dietary and Supplemental Sources ............................................................... 159 X. Possible Toxicity ........................................................................................... 159 XI. Interactions with Other Nutrients and Drugs ............................................... 159 XII. Future Research Needs ................................................................................. 161 XIII. Conclusions ................................................................................................... 161 References .............................................................................................................. 162

vitamin C may have some beneficial effect in preventing biological damage and can thus be a potentially important element of strategies to promote good health. Vitamin C has several known biological roles, all of which are of relevance to exercise and good health. In addition, vitamin C has some surprising physiological functions that have recently been described and these too may be relevant for exercise and aging.