Bounous-whey protein-antioxidant defense

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Rivista Italiana di Nutrizione Parenterale ed Enterale / Anno 22 n. 4, pp. 193-200

Wichtig Editore, 2004

Rassegna - Review

The role of whey protein in antioxidant defense S.G. SUKKAR1, G. BOUNOUS2 1 2

Clinical Nutrition Unit, Azienda San Martino University Hospital Genova - Italy Research and Development Department, Immunotec Research Ltd, Vaudreuil-Dorion, Quebec - Canada

ABSTRACT: Whey protein concentrates (WPC) are a heterogeneous group of proteins (β-lactoglobulin, α-lactalbumin, serum albumin and immunoglobulins) obtained in milk after casein (CAS) precipitation. WPC also contains bioactive substances, such as hormones, growth factors (insulin-like growth factors (IGFs), transforming growth factor-β (TGF-β) platelet derived growth factor) and cytokines, which can have an important physiological role. In in vitro studies, WPC demonstrate anticancer actions such as the inhibition of cancer cell growth and antimutagenic effects while, in experimental tumor animal models, tumor burden reduction. Furthermore, WPC present immuno-enhancing properties due to glutathione (GSH) synthesis of lymphocytes, which can represent a possible tool in oxidative stress related diseases. Finally, WPC consumption in adults is associated with a significant increase in protein synthesis, with no change in protein catabolism when compared with CAS, according to their different enteric absorption. The physiological mechanisms by which WPC interact with the antioxidant system, cancer prevention and metabolism, as well as the possible role of WPC in immunonutrition are discussed. In conclusion, WPC could be an interesting integrative protein source in clinical nutrition. Human clinical trials are required to verify the efficacy of WPC in counteracting oxidative stress and in favoring protein anabolism in protein-energy malnutrition syndromes. (RINPE 2004; 22: 193-200) KEY WORDS: Antioxidants, Whey protein, Cancer, Immune system, Immunonutrition, Oxidative stress, ROS PAROLE CHIAVE: Antiossidanti, Proteine del siero di latte, Cancro, Sistema immunitario, Immunonutrizione, Stress ossidativo, Radicali liberi

The current interest in complementary medicine has led to the increasing use and misuse of terms such as “free radicals” and “antioxidants”. A free radical can be defined as any species that contains one or more unpaired electrons, an unpaired electron being one that is alone in an orbital. Most biological molecules contain only paired electrons. A radical either can donate its unpaired electron to another molecule or can acquire an electron from another molecule in order to pair. The characteristic of events involving free radicals is the development of a chain reaction with subsequent damage to adjacent biological structures, which could be involved in the pro-in-

flammatory cascade (Fig. 1). The majority of free radicals originate in the final stage of cell respiration, in which electrons flow from organic substrates to oxygen, yielding energy. When mitochondria are functioning, an electron passing through the respiratory chain can leak directly onto the oxygen molecule resulting in superoxide radical formation: O2 + e- O.-2. Figure 2 demonstrates the sequence of biochemical events following the appearance of O.-2. Overall, antioxidants include endogenous and exogenous elements such as antioxidant enzymes (superoxide dismutase catalase), vitamins (vitamin C and vitamin E), the glutathione (GSH) system and non-vitamin substances such as catechins and β-carotene (1). More▼

INTRODUCTION

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