Long-lasting improved amino acid bioavailability associated with protein pulse feeding in hospitalized elderly patients: a randomized controlled trial.

OBJECTIVE

Aging is associated with a blunted anabolic response to dietary intake, possibly related to a decrease in systemically available amino acids (AAs), which in turn may stem from increased splanchnic AA metabolism. Splanchnic sequestration can be saturated by pulse feeding (80% of daily protein intake in a single meal), enabling increased protein synthesis. The aim of this study was to explore whether protein pulse feeding increased postprandial AA concentrations, and if so whether this increase persisted after 6 wk of dietary treatment.

METHODS

This prospective randomized study enrolled 66 elderly malnourished or at-risk patients in an inpatient rehabilitation unit. All were given a controlled diet for 6 wk. In a spread diet (SD) group (n = 36), dietary protein was spread over the four daily meals. In a pulse diet (PD) group (n = 30), 72% of dietary protein (averaging 1.31 g/kg body weight daily) was consumed in one meal at noon. The patients were evaluated on day 1 and at 6 wk for plasma postprandial (five times from 0 to +180 min) AA concentrations (expressed as area under the curve above baseline).

RESULTS

Protein pulse feeding was more efficient than protein spread feeding at increasing plasma postprandial AA concentrations, notably of essential AAs. This increased postprandial AA bioavailability was maintained after 6 wk.

CONCLUSIONS

This study demonstrates that increased postprandial AA bioavailability induced by protein pulse feeding persists after 6 wk (i.e., that there is no metabolic adaptation blunting AA bioavailability).