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A low dietary intake of cod protein is sufficient to increase growth, improve serum and tissue fatty acid compositions, and lower serum postprandial glucose and fasting non-esterified fatty acid concentrations in obese Zucker fa/fa rats

Drotningsvik, Aslaug, Mjøs, Svein Are, Høgøy, Ingmar, Remman, Tore, Gudbrandsen, Oddrun Anita
European journal of nutrition 2015 v.54 no.7 pp. 1151-1160
adipose tissue, adiposity, blood serum, body weight, casein, cholesterol, cod (fish), comorbidity, diet study techniques, dietary protein, fasting, fatty acid composition, fatty acid metabolism, food intake, free fatty acids, glucose, healthy diet, homeostasis, liver, males, muscles, polyunsaturated fatty acids, protein content, protein intake, rats
PURPOSE: Studies in rats suggest that fish proteins may improve lipid and glucose regulation and could thus be a potential tool in the treatment of obesity-related comorbidities. To date, all published rat studies on dietary fish protein have been designed with 50 or 100 % of dietary proteins from fish. As it is not common, nor advised, to consume fish as the only protein source in a healthy diet, mechanistic studies on the effects of diets with low dose fish proteins are needed. Here, we investigate whether a low dose of cod protein would affect glucose homeostasis and lipid metabolism in obese Zucker fa/fa rats. METHODS: Twelve male obese Zucker fa/fa rats consumed diets where cod proteins accounted for 25 % of the total protein intake with the remaining 75 % from casein (COD) or 100 % of protein as casein (CAS) for 4 weeks. RESULTS: Rats fed COD achieved a higher body weight without affecting adiposity and thigh muscle mass after 4 weeks, but liver weight and hepatic cholesterol level were higher than in CAS-fed rats. Fasting serum level of non-esterified fatty acids and 2 h postprandial glucose level were lower in COD than in CAS. The fatty acid metabolism was beneficially affected by the COD diet, with e.g., higher ratio of n-3/n-6 PUFAs in serum, liver and adipose tissue when compared to CAS. CONCLUSIONS: A low intake of cod protein (25 % of protein intake) was sufficient to beneficially affect lipid metabolism and postprandial glucose regulation in obese fa/fa rats.