L-cysteine supplements reduce DNA damage resulting from overtraining

Severe overtraining leads to an overproduction of free radicals, which can cause muscle soreness, DNA damage and a weakening of the immune system. Free radicals are highly reactive chemicals that are produced during various metabolic processes. They can be thought of as "biological rust" that can damage carbohydrates, amino acids, fats and nucleic acids (the building blocks of DNA). Antioxidants such as glutathione, vitamin C and vitamin E bind free radicals and thus protect the body's cells from damage. Greek researchers have found that the administration of 500mg L-cysteine for one month in basketball players undergoing high-intensity training (forced overtraining) increased the levels of antioxidants in the body and reduced the rate of DNA damage compared to members of a placebo group. L-cysteine could therefore help to reduce the destructive effects of overtraining and prevent DNA damage. (Pharmacological Research, 53:386-390, 2006)