Whey proteins inhibit food intake and tend to improve oxidative balance in obese zucker rats.

BACKGROUND/AIMS Whey proteins (WP), obtained from milk after casein precipitation, represent a heterogeneous group of proteins. WP are reported to inhibit food intake in diet-induced experimental obesity; WP have been proposed as adjuvant therapy in oxidative stress-correlated pathologies. This work evaluates the effects of WP in comparison with casein, as a source of alimentary proteins, on food intake, weight growth and some indexes of oxidative equilibrium in Zucker Rats, genetically prone to obesity. METHODS We monitored food intake and weight of Zucker Rats during the experiment, and some markers of oxidative equilibrium. RESULTS WP induced significant decrease of food intake in comparison to casein (WP 80.41 ± 1.069 ml/day; CAS: 88.95 ± 1.084 ml/day; p < 0.0005). Body weight growth was slightly reduced, and the difference was just significant (WP 128.2 ± 6.56 g/day; CAS 145.2 ± 3.29 g/day; p = 0.049), while plasma HNE level was significantly lower in WP than in CAS (WP 41.2 ± 6.3 vs CAS 69.61 ± 4.69 pmol/ml, p = 0.007). Mild amelioration of oxidative equilibrium was indicated by a slight increase of total glutathione both in the liver and in the blood and a significant decrease of plasma 4-hydroxynonenal in the group receiving WP. CONCLUSIONS The effect of WP on food intake and weight growth in Zucker Rats is particularly noteworthy since the nature of their predisposition to obesity is genetic; the possible parallel amelioration of the oxidative balance may constitute a further advantage of WP since oxidative stress is believed to be interwoven to obesity, metabolic syndrome and their complications.