Perspective published in Advances in Nutrition suggests the lower anabolic properties of plant-based foods may compromise older adults’ muscle mass and strength

Consumers are increasingly encouraged to consume more plant-based foods and lower their consumption of animal-based foods for both personal health and environmental sustainability.  In particular, vegan diets, which exclude all animal-based foods, may improve the dietary intake of important nutrients and bioactive compounds and have therefore been associated with potential health benefits, such as improved cardiovascular risk factors.

While vegan diets may be a healthy choice for many people, a Perspective published in Advances in Nutrition, “Vegan Diets for Older Adults? A Perspective on the Potential Impact on Muscle Mass and Strength,” questions whether a vegan diet can provide older adults with an adequate amount of high-quality protein.

Beginning in the fifth decade of life, people generally begin to lose muscle mass, which may result in sarcopenia, a muscle disorder characterized by low muscle strength in combination with low muscle mass or quality.  Sarcopenia increases the risk for frailty, falls, hospitalization, and mortality.  Among community-dwelling older adults, the estimated prevalence of sarcopenia ranges from 9.9% to 40.4%, depending on how the study defines sarcopenia.  The authors believe that, in view of the envisaged transition towards more plant-based dietary guidelines, it is urgent that we come to a better understanding of the potential impact of a vegan diet on muscle mass and strength at an older age.

This Advances in Nutrition Perspective focuses on the consequences of adopting a vegan diet on muscle mass and strength among adults aged 65 years and older.  Rather than focus on the impact of consuming individual plant-based protein sources, the authors focused on the impact of consuming whole meals and diets, since food components interact differently when consumed as part of a meal rather than in isolation.

Not all proteins are created equally; they differ in quality.  The quality of a protein source denotes its anabolic property.  Protein sources with higher anabolic properties can better meet the body’s metabolic demands, supporting growth and maintenance of the body’s protein mass.  The authors present evidence that the quality of most individual plant-based foods and proteins is inferior to those of animal origin.  Moreover, it is very difficult to determine the protein quality of a vegan meal consisting of several plant-based foods due to the complex interactions among the various meal components.

Increasing portion sizes has been proposed as a strategy to compensate for the lower anabolic properties of plant-based foods and proteins.  The authors, however, note that “increasing portion sizes to compensate for the proposed lower anabolic properties of vegan meals will be challenging for most older adults,” pointing to studies which suggest that older adults experience a reduction in appetite.

Though there are many important health benefits of vegan diets for several subgroups of the adult population, according to the authors, “the lesser anabolic properties of plant-based foods may compromise muscle mass and strength at an older age.  Based on this, we feel that it may not be preferred for older adults to consume a vegan diet.”

The authors do acknowledge that there are major gaps in the scientific literature.  In particular, evidence regarding the direct consequences of a vegan diet on muscle-related outcomes in older adults is limited to just two intervention studies.  They therefore call for “future studies to assess the impact of a vegan diet provided by whole foods and/or supplemented by isolated protein supplements on muscle-related outcomes.”  In addition, “future studies should target different subgroups within the older population to assess whether the consequences of adhering to a vegan diet may differ between these subgroups.”