Protein intake distribution pattern does not affect anabolic response, lean body mass, muscle strength or function over 8 weeks in older adults: A randomized-controlled trial

Abstract

Background & aims: In our recent acute metabolic study, we found no differences in the anabolic response to differing patterns of dietary protein intake. To confirm this in a chronic study, we investigated the effects of protein distribution pattern on functional outcomes and protein kinetics in older adults over 8 weeks.

Methods: To determine chronic effects of protein intake pattern at 1.1 g protein/kg/day in mixed meals on lean body mass (LBM), functional outcomes, whole body protein kinetics and muscle protein fractional synthesis rate (MPS) over 8-week respective dietary intervention, fourteen older subjects were randomly divided into either EVEN or UNVEN group. The UNEVEN group (n = 7) consumed the majority of dietary protein with dinner (UNEVEN, 15/20/65%; breakfast, lunch, dinner), while the EVEN group (n = 7) consumed dietary protein evenly throughout the day (EVEN: 33/33/33%).

Results: We found no significant differences in LBM, muscle strength, and other functional outcomes between EVEN and UNEVEN before and after 8-week intervention. Consistent with these functional outcomes, we did not find significant differences in the 20-h integrated whole body protein kinetics [net protein balance (NB), protein synthesis (PS), and breakdown (PB)] above basal states and MPS between EVEN and UNEVEN intake patterns.

Conclusions: We conclude that over an 8-week intervention period, the protein intake distribution pattern in mixed meals does not play an important role in determining anabolic response, muscle strength, or functional outcomes. This trial is registered at https://ClinicalTrials.gov as NCT02787889.

Keywords: Aging; Essential amino acids; Protein turnover; Sarcopenia; Stable isotope tracer.

Conflict of interest statement

Conflict of interest

Dr. Wolfe has received research grants and honoraria from the National Cattleman's Beef Checkoff program. Other authors have no potential conflicts of interest.

Copyright © 2017 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

Figures

Fig. 1.

Infusion protocol utilized for each metabolic study before and after the 8 weeks of each nutritional intervention.

Fig. 2.

Changes in the rates of 20-h whole body protein synthesis (PS), protein breakdown (PB), and net protein balance (NB) from the fasted state before and after 8 weeks of each dietary intervention. Values are expressed as means ± SEM.

Fig. 3.

Muscle protein fractional synthesis rate (MPS) with EVEN or UNEVEN before and after 8 weeks of each dietary intervention. Values are expressed as means ± SEM.

Fig. 4.

Area under the curve (AUC) for plasma glucose insulin and leucine before and after 8 weeks of respective dietary intervention. Values are expressed as means ± SEM.