Introduction to Vitamin C

Vitamin C, also known as ascorbic acid, is a water-soluble vitamin. Vitamin C is required for the synthesis of collagen, an important structural component of tendons, ligaments and so on. Vitamin C also plays an important role in the synthesis of the neurotransmitter, norepinephrine (noradrenaline). In addition, vitamin C is required for the synthesis of carnitine, a small moleculeessential for the transport of fatty acids to cellular organelles called mitochondria (powerhouses of cell), for conversion to energy. Vitamin C is also a highly effective antioxidant. It protects various molecules in the body from damage by free radicals and reactive oxygen species that can be generated during normal metabolism (especially during physical exercise) as well as through exposure to toxins and pollutants.

Vitamin C, Muscle Soreness and Oxidative Stress

A recent study at the University of South Carolina examined if high-dose vitamin C supplementation before and after eccentric exercise could reduce muscle soreness, oxidative stress and muscle function. The investigators randomly assigned 18 healthy men to either a placebo (fake supplement) or vitamin C (3 grams per day) treatment group. The subjects took pills for two weeks prior and four days after performing 70 eccentric elbow extensions with their non-dominant arm. Muscle soreness increased in both groups with significantly reduced muscle soreness for the first 24 hours with vitamin C. Furthermore, vitamin C supplementation attenuated muscle damage after exercise. In sum, this study suggests that high-dose vitamin C supplementation may be of some benefit for serious athletes.

Vitamin C & Fat Burning

Recently, Dr. Carol Johnston and colleagues at the Arizona State University conducted a preliminary trial to evaluate the impact of vitamin C status on fat burning during submaximal exercise. Seventy-eight men and women from a campus population were screened for blood (plasma) vitamin C status. Suprisingly, nearly 40 percent of the sample had marginal vitamin C status and 15 of these individuals were willing to participate in exercise testing, i.e., maximal oxygen consumption (VO₂ max) was measured using a graded walking protocol. An additional seven of the screened individuals with adequate vitamin C status were included as the vitamin C adequate (control) group.

Interestingly enough, the results of this study indicated that individuals with marginal vitamin C status burned 25 percent less fat per kilogram (2.2. pounds) bodyweight during a 60-minute treadmill walk as compared to individuals with adequate vitamin C status.

Furthermore, fat burning during exercise was enhanced in these individuals by normalizing blood vitamin C concentrations. The authors concluded, "These preliminary results show that low vitamin C status may reduce fat oxidation [burning] during submaximal exercise and that reduced fat oxidation during exercise was related to fatigue. It's possible that increased fatigue and less reliance on fat as a fuel during activity may influence eventual weight gain. Thus, in addition to emphasizing calorie control and physical activity, attention to specific diet components such as vitamin C may be necessary for effective weight management."

Vitamin C & Upper Respiratory Tract Infections

There's solid evidence that vitamin C supplementation can prevent the common cold in physically active individuals. In fact, five trials found a 45 percent to 91 percent reduction in common cold incidence in the vitamin C group.

About the Author

Anssi Manninen holds an MHS in sports medicine from the University of Kuopio Medical School. His numerous cutting-edge articles in MD firmly established his reputation as a leading authority on hardcore sports nutrition. Anssi´s articles have also been published in scientific journals, including The British Journal of Sports Medicine, The Journal of International Society of Sports Nutrition, Metabolic Syndrome and Related Disorders, Nutrition & Metabolism, and Journal of Sports Science and Medicine. Anssi is also an associate editor for Nutrition & Metabolism, a leading scientific journal in the area of nutritional biochemistry.

References:

• 1. Bryer SC, Goldfarb AH. Effect of high dose vitamin C supplementation on muscle soreness, damage, function, and oxidative stress to eccentric exercise. Int J Sport Nutr Exerc Metab, 2006 Jun;16(3):270-80.
• 2. Johnston C et al. Marginal vitamin C status is associated with reduced fat oxidation during submaximal exercise in young adults. Nutr Metab (Lond), 2006 Aug 31;3:35.
• 3. Hemila H. Vitamin C supplementation and respiratory infections: a systematic review. Mil Med, 2004 Nov;169(11):920-5. Review.