Impact of protein pulse feeding on lean mass in malnourished and at-risk hospitalized elderly patients: A randomized controlled trial

Background & aims: 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. This splanchnic sequestration can be saturated by pulse feeding (80% of daily protein intake in a single meal), enabling increased protein synthesis. This study aimed to evaluate the efficacy of a new nutritional strategy, termed protein pulse feeding. Methods: This prospective randomized study (ClinicalTrials.gov registration number NCT00135590) enrolled 66 elderly malnourished or at-risk patients in an inpatient rehabilitation unit. All were given a controlled diet for 6 weeks. 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 (1.31 g/kg weight/d on average) was consumed in one meal at noon. The patients were evaluated at admission and at 6 weeks for body composition [lean mass (LM), appendicular skeletal muscle mass (ASMM), and body cell mass (BCM) indices, measured by X-ray absorptiometry combined with bioelectrical impedance analysis] (primary outcome), hand grip strength, and activities of daily living (ADL) score. Results: Protein pulse feeding was significantly more efficacious than protein spread feeding in improving LM index (mean changes from baseline for PD group: +0.38 kg/m(2); 95% confidence interval (CI), [0; 0.60]; for SD group: -0.21 kg/m(2); 95% CI, [-0.61; 0.20]; p = 0.005 between the two groups), ASMM index (+0.21 kg/m(2); 95% CI, [0; 0.34] and -0.11 kg/m(2); 95% CI, [-0.20; 0.09]; p = 0.022), BCM index (+0.44 kg/m(2); 95% CI, [0.08; 0.52] and -0.04 kg/m(2); 95% CI, [-0.09; 0.10]; p = 0.004). There was no significant effect for hand-grip strength or ADL score. Conclusions: This study demonstrates for the first time that protein pulse feeding has a positive, clinically relevant effect on lean mass in malnourished and at-risk hospitalized elderly patients. (C) 2012 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.