Effect of supplementing meals with soluble milk proteins on plasma leucine levels in healthy older people: A randomized pilot study.

BACKGROUND: The muscle protein synthetic response to food intake is reduced in aging, contributing to a progressive muscle loss. This anabolic resistance results from a decreased sensitivity to anabolic signals, especially leucinemia, a potent activator of protein synthesis. Nutritional strategies are needed to reach the anabolic threshold of leucinemia and stimulate muscle anabolism. OBJECTIVES: This study sought to evaluate the effect of supplementing meals with soluble milk proteins (SMP) on postprandial leucinemia in elders. METHODS: During 3 successive experimental sessions, 6 healthy older men (66.7±0.7y) consumed a standardized lunch (27 g of proteins; 2.2 g of leucine) supplemented with a beverage containing 0 g, 5 g or 8.2 g of SMP (0 g, 0.6 g and 1.1 g of leucine, respectively). RESULTS: The supplementation with 5 g or 8.2 g of SMP induced an increase of 1.9? and 2.5? in plasma leucine levels, compared to the control meal (without additional SMP). The leucine area under the curve over 3h20 had an increase of 2.1? and 2.3?, respectively, as compared to the control meal. CONCLUSIONS: Ingesting SMP in addition to a meal strongly increased postprandial plasma leucine, and could be an effective strategy to reach anabolic thresholds and optimize the anabolic effect of each meal. [ABSTRACT FROM AUTHOR]