Nope. Only more data that supports the leucine hypotheses our lab believes in. We have several exciting experiments coming up which are going to tell us a lot more about our theories, though. This is an abstract of our latest experiment, which we are almost done analyzing.
Leucine is a critical regulator of muscle protein synthesis (MPS) and has been demonstrated to be responsible for the majority of the anabolic effects of a meal (J. Nutr. 133:1553S-6S, 2005). It is unclear if isonitrogenous protein sources containing different levels of leucine will produce differential MPS responses in animals adapted to meal feeding. This study examined 4 different protein sources (wheat, soy, egg, and whey) containing different leucine contents (6.8, 8.0, 8.8, and 10.9% respectively) on the potential to activate translation factors and MPS. Male rats (250g) were trained for 14d to eat 3 meals/d consisting of 16/54/30% calories from their respective protein sources, carbohydrates and fats. Rats were sacrificed on experiment day 90 min after consuming their normal breakfast meal or fasted. Measurements include plasma insulin and amino acids, MPS via D5-Phe incorporation, and phosphorylation of translation factors 4E-BP1 and S6K. Wheat and soy did not stimulate MPS above fasted levels whereas egg and whey significantly increased MPS, with whey being significantly greater than egg. The MPS responses were closely related with changes in plasma leucine and phosphorylation of 4E-BP1 and S6K. These finding suggest that leucine content of protein sources is a critical factor in determining protein quality as it relates to changes in post prandial MPS responses.
Gabriel "Venom" Wilson, Ph.D. Nutritional Sciences
B.S. (Hons) & M.S. in Kinesiology, CSCS
Vice President, ABCbodybuilding
Co-Editor. of JHR
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