Impact of Fat Co-ingestion With Protein on the Post-prandial Anabolic Response in Elderly Men (Pro-Fat)

Rationale: The progressive loss of skeletal muscle mass with aging, or sarcopenia, has a major impact on our healthcare system due to increased morbidity and greater need for hospitalization and/or institutionalization. One way to prevent skeletal muscle loss is to improve dietary intake of the elderly. It has already been shown that ingestion of dietary protein stimulates muscle protein synthesis and inhibits muscle protein breakdown, resulting in an overall positive net protein balance. However, the impact of fat (as part of the meal) on dietary protein-induced muscle protein synthesis remains largely unknown. Based on previous studies by other research groups, we hypothesize that fat further stimulates the muscle anabolic response to protein ingestion.

Objective: The primary objective of this study is to investigate the effect of a single meal-like amount of protein with or without fat on postprandial muscle protein synthesis rates in healthy elderly men. Furthermore, as a secondary objective, we will assess digestion and absorption kinetics.

Study design: double-blind randomized intervention study Study population: 24 healthy elderly men (55-85 y) Intervention: one group (n=12) will consume a test beverage of 350 mL containing 20 g of intrinsically labeled casein, and the other group (n=12) will consume a beverage of the same volume containing 20 g of casein plus 20 g of fat.

Main study parameters/endpoints: Primary endpoint: muscle protein synthesis rates. Secondary endpoint: digestion and absorption kinetics.