Is Animal Protein Better than Plant Protein for Lean Muscle Mass and Strength?

There is plenty of evidence to suggest that a plant-based diet is healthier than an animal-based diet, not to mention the planetary benefits. One of the principal reasons a plant-based diet is healthier stems from the fact that these types of diets generally have less calories from protein than do animal-based diets. However, recent evidence shows that it is more about the quantity of protein consumed than it is about the quality of the protein.

A recent analysis of randomized controlled trials comparing plant protein and animal protein suggests that for maintenance of lean muscle mass, as well as strength, particularly in younger individuals, the better choice is animal protein.

Animal Protein versus Plant Protein in Supporting Lean Mass and Muscle Strength: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

When considering the effects of protein, independent of source, it is important to understand the metabolic functions of skeletal muscle and the factors that influence skeletal muscle homeostasis. The main metabolic functions of skeletal muscle include its critical role in the maintenance of normal plasma glucose concentration and it role in supplying the body with an energy source (amino acids) particularly during periods of prolonged fasting. Loss of muscle mass is associated with poor quality of life as well as increased morbidity and mortality.

In addition, low muscle strength has been shown to be a significant and independent predictor of mortality risk.

Declines in both muscle mass and strength is a common observation associated with aging and is evident across different populations. Maintenance of muscle mass is a dynamic balance between muscle protein synthesis and muscle protein breakdown. Muscle protein synthesis is increased after resistance exercise, yet protein balance remains negative as the rate of muscle protein breakdown is also elevated as a result of exercise.

Because the protein quality of animal protein is considered superior to that of plant protein for building muscle mass. However, as indicated plant-based diets are healthier than animal-based diets, particularly with respect to decreasing the risk of cardiovascular diseases.

When the investigators performed their meta analysis of the results from multiple publications they discovered that the total protein intake by the participants across these multiple studies was generally above the recommended dietary allowance at both the beginning and the end of the studies. When certain parameters were examined, such as the overall lean muscle mass, percent lean muscle mass, and level of muscle strength, the mean values were all higher for animal protein than for plant protein. However, these difference did not tend to be statistically significant. Thus, it appears that protein source may not affect changes in absolute lean muscle mass or muscle strength. Nonetheless, the meta analysis does show that there is a favoring effect of animal protein on percent lean mass. Where the results were most significant was in adults younger than 50 years of age. In this cohort the consumption of animal protein was associated with a gain in absolute and percent lean mass.

The results of this meta analysis suggest that, at least in younger adults, animal protein tends to be more beneficial than plant protein for lean mass.

It is important to keep in mind that ones diet, whether plant-based or animal-based, includes not only protein but also carbohydrates and lipids. Two major benefits of plant-based diets, with respect to health, are that these diets are lower in total protein and also lower in the types of lipids that are found in animal-based diets that are correlated to adverse cardiovascular health.