Indexed on: 27 May '10Published on: 27 May '10Published in: Mediterranean Journal of Nutrition and Metabolism
In the field of biology, free radicals which are derived from the incomplete reduction of oxygen take on great importance; they belong to the so called reactive oxygen species, whose production in the organism is an inevitable consequence of various external or internal factors to which it is exposed. Once free radicals are generated they are often capable of giving rise to chain reactions. A lot of biological molecules are susceptible to the attack by free radicals including lipids, proteins, carbohydrates and nucleic acids. Molecular alterations caused by the radical reactions have been frequently studied and are considered as pathogenetically main passages in the development of many diseases and ageing. In order to face a radical attack, living organisms have developed several biological defensive systems against it: the main ones are represented by anti oxidizing molecules and by enzymatic anti oxidizing systems. Among the various defence systems, glutathione stands out as the principal guarantor of homoeostatic intra-cellular oxidation–reduction. One of glutathione’s most important functions is to act as cysteine “tank”; this amino acid is extremely unstable in the extra-cellular environment and it rapidly auto-oxidates. Whey proteins (WP) are particularly rich in cysteine (cys) and in glutamine (glu) and therefore potentially capable of increasing the organism’s antioxidant defences. It is thought that the principal mechanism which allows WPs to exert their properties is through the contribution of cys and glu, which is rich in these proteins and is used intra-cellularly for the synthesis of glutathione. A diet based on milk serum proteins which supplies a superior quantity of cys, allows for a greater synthesis of hepatic glutathione in oxidative stress conditions. The use of ultra-filtrated WP could represent a useful tool in the control of oxidative stress in numerous pathological situations.