Vegetarianism is Compatible With Muscle in Older Adults

Vegetarian diets yield muscle mass gains similar to omnivorous diets in older adults who engage in resistance training.

Overview

• What did they test? In this study, researchers compared a lacto-ovo vegetarian (VEG) diet with an omnivorous diet (OMN) in older adults who did resistance training and consumed at least 1.2 g of protein per kilogram of body weight per day, measuring protein intake, muscle mass, and strength.  
• What did they find?  Participants following the OMN diet consumed more protein than the VEG group, but this did not translate into statistically significant differences in muscle mass gain or strength over 12 weeks. Protein intake was significantly related to muscle mass gains only in the VEG group.  
• What does it mean for you? A VEG diet can lower protein intake compared to an OMN diet, but it doesn’t seem to affect muscle mass much in the short term, especially among people with a higher protein intake of >1.2 grams per kilogram of body weight. This study provides further evidence that VEG diets are not inferior to OMN diets when protein intake is adequate. 

What’s the Problem?

In recent decades, more people have chosen not to eat meat, and public health agencies have increasingly recommended plant-based diets for environmental, health, and ethical reasons 1. This has raised concerns about sarcopenia risk among older adults, since plant protein sources tend to have lower protein density, digestibility, and essential amino acid levels than animal-based protein sources 2. 

Previous research comparing plant and animal protein sources has found no difference in muscle mass gain between soy-based protein sources and animal protein when given as supplements, but some studies report lower muscle gains with other plant protein sources 3. Currently, research on whole-diet interventions is limited, especially among older adults who are most at risk for sarcopenia. To date, two studies have conducted whole-diet interventions: one showed greater muscle mass gain among men who were resistance training and followed a self-selected OMN vs. VEG diet 4. The other study found no difference, but participants received textured vegetable protein to increase protein intake 5. 

There is currently a lack of research on whole-diet VEG interventions performed in free-living conditions with both older men and women undergoing resistance training. 

Purpose

The purpose of this study was to compare the effects of following a lacto-ovo vegetarian diet that provided >1.2 g/kg/bw of protein to an omnivorous diet that also provided >1.2 g/kg/bw of protein on protein intake, muscle mass, and strength in adults over 55 years old engaging in resistance training. 

Hypothesis

The authors did not present a hypothesis in this study. 

What Did They Test and How?

Participants

Participants were eligible to join the study if they were at least 55 years old with a BMI of 18.5 to 30 kg/m², living independently, and they could not abuse alcohol  (<14 and 21 glasses per week for female and male participants, respectively), or have cognitive decline or another chronic disease that would interfere with study participation. 

Study Procedures