On the use of carnosine and antioxidants: A letter from Russia

Sir, Carnosine, an endogenously synthesized dipeptide found in muscular and other tissues, was reported to possess antioxidant properties. Favorable actions of carnosine were explained by its effects against reactive oxygen species (ROS), against peroxynitrite damage and different types of viral injury [1-6]. Moreover, one of the mechanisms of detoxification from aldehydes, accumulating in inflammation, ischemia, and other pathological conditions was reported to be conjugation with carnosine [7-10]. Among other potential applications, carnosine-containing eye drops have been recommended for the treatment, dissolution and prevention of cataracts, in particular, senile cataracts [5,11]. From the viewpoint of biochemistry, it is difficult to envisage how carnosine can contribute to the dissolution of cataracts, regarded to be the end stage of metabolic and structural transformations including conformational changes and aggregation of proteins [12]. To decide whether a local or general supplementation of a substance is indicated, the question should be answered whether there is a local or general deficiency. Such deficiency is prima facie improbable for substances that are supplied with food and can be synthesized in different cells and tissues of the body. Tissue carnosine concentrations are influenced by the diet being lower in vegetarians [1,4,13]. If the presence of carnosine in body fluids is important for the preservation of the lens transparency [5,11] or some physiological functions [4,14], the incidence of cataracts or other pathological conditions among vegetarians/vegans would be higher than in the general population. On the contrary, vegetarians have been reported to have a lower risk of cataract than meat eaters: There was a strong relation between the cataract risk and a diet group, with a progressive decrease in risk of cataracts in high meat eaters to low meat eaters, fish eaters, vegetarians, and vegans [15]. Admittedly, the topic is not without controversy [16], probably confounded by geographical (exposure to sunlight) and other factors. Furthermore, it has been suggested that carnosine is an anti-aging substance with a beneficial effect on the cardiovascular system [3,17,18]. There is, however, evidence that vegetarians have lower rates of coronary heart disease, hypertension, etc. Overall, their cancer rates appear to be moderately lower than in other people living in the same communities, and life expectancy appears to be greater [19]. A very low meat intake was reported to be associated with greater longevity [20]. However, benefits from the vegetarian versus carnivorous diet [9] are beyond the scope of this letter. Carnosine has been used in sports …