5 recent studies that show the power of plant protein

It is often argued by proponents of a meat-centric diet that plants are an inferior and unsatisfactory source of protein when compared to animal-based foods. The quality and bioavailability of protein from plants is often thrown into question but the truth is, a growing body of evidence shows protein from plants is just as effective at building and maintaining muscle and strength as protein from animal sources. In fact, plant protein may be even more effective and comes without all the deleterious health effects of eating animal foods. Here are six recent studies that show the power of plant protein:

Study #1

Domic J, Pinckaers PJM, Grootswagers P et al. 2024. A well-balanced vegan diet does not compromise daily mixed muscle protein synthesis rates when compared with an omnivorous diet in active older adults: a randomized controlled cross-over trial. Journal of Nutrition. 26, S0022-3166 (24) 01246-X.

In this study, the researchers took older men and women in their seventies and had them follow a vegan diet or an omnivorous diet for 10 days. The omnivorous group got 60 per cent of their protein from animal foods and 40 per cent from plant foods. The vegan group got all of their protein from plant foods. In both groups the participants consumed the same amount of protein each day. Over the course of 10 days, there was no difference in the rate of muscle protein synthesis (MPS). This result actually went against the researchers’ initial hypothesis. They concluded:

“In contrast with our hypothesis, we demonstrate that a well-balanced vegan diet that is carefully composed to contain a feasible quantity of protein from a large variety of different plant-based protein sources does not compromise daily integrated mixed MPS rates.”

Study #2

Hevia-Larrain V, Gualano B, Longobardi I et al. 2021. High-protein plant-based diet versus a protein-matched omnivorous diet to support resistance training adaptations: a comparison between habitual vegans and omnivores. Sports Medicine. 51 (6) 1317-1330.

In this study, researchers compared already-vegan men with omnivorous men. They decided to use men who were already vegan because it makes it easier for them to comply with the diet. Both groups consumed mainly wholefood diets but the omnivorous group supplemented with whey protein powder while the vegan group supplemented with soya protein powder. Both groups consumed about the same amount of protein per day and performed resistance training twice a week. After 12 weeks there were no significant differences in muscle size or strength between the two groups. The authors concluded:

“A high-protein, exclusively plant-based diet is not different than a protein-matched mixed diet in supporting muscle strength and mass accrual, suggesting that protein source does not affect resistance training-induced adaptations in untrained young men consuming adequate amounts of protein.”

Study #3

Monteyne AJ, Coelho MOC, Murton AJ et al. 2023. Vegan and omnivorous high protein diets support comparable daily myofibrillar protein synthesis rates and skeletal muscle hypertrophy in young adults. Journal of Nutrition. 153 (6) 680-1695.

Unlike the previous trial, this time the researchers randomised the participants and included both men and women. This randomised control trial lasted 10 weeks and participants partook in a high volume resistance training programme five days a week, designed to maximise muscle growth. Participants either consumed a high-protein omnivorous or vegan diet, both getting around two grams of protein per kilogram of bodyweight. The omnivores supplemented with a milk protein and the vegans were given a mycoprotein supplement (from fungi).

The omnivores ended up consuming about 17 grams more protein each day, but even so, they didn’t outperform their vegan counterparts. In fact, the vegan group improved their incline bench press strength significantly more than the omnivores! Other than that, the researchers found that there were no significant differences in muscle protein synthesis, muscle size, strength, or body composition between the two groups. They concluded that “a carefully designed vegan diet is capable of supporting optimal skeletal muscle adaptive responses to resistance training.”

Study #4

Monteyne AJ, Coelho MOC, Porter C et al. 2020. Mycoprotein ingestion stimulates protein synthesis rates to a greater extent than milk protein in rested and exercised skeletal muscle of healthy young men: a randomized controlled trial. American Journal of Clinical Nutrition. 112 (2) 318-333.

This research was carried out by the same group of researchers as the previous study, at the University of Exeter. They compared muscle protein synthesis using mycoprotein and milk protein in 20 young men, with leucine matched. Some people believe that animal protein is superior because it contains higher amounts of leucine – an essential amino acid (EAA) necessary for muscle protein synthesis. The researchers found, to their surprise, that even though blood levels of leucine in the mycoprotein group were slower to rise and remained lower than the milk protein group, those who consumed the mycoprotein actually had higher levels of muscle protein synthesis. The researchers concluded:

“Mycoprotein ingestion resulted in slower and lower rises in plasma amino acid (and leucine) concentrations compared with the ingestion of milk protein. Despite this, and contrary to our secondary hypothesis, we report that mycoprotein ingestion stimulated muscle protein synthesis rates to a greater extent when compared with milk protein.”

Other, more recent studies have also brought the leucine hypothesis into question, demonstrating that leucine may not play as important a role in stimulating muscle protein synthesis as once thought. The researchers suspect that when you are eating a varied high-protein wholefood diet, the EAAs in isolated proteins become less important and other factors come into play.

Study #5

Arentson-Lantz EJ, Von Ruff Z, Connolly G et al. 2024. Meals containing equivalent total protein from foods providing complete, complementary, or incomplete essential amino acid profiles do not differentially affect 24-h skeletal muscle protein synthesis in healthy, middle-aged women. Journal of Nutrition. 154 (12) 3626-3638.

This study – funded by the National Cattlemen’s Beef Association – further drives home the point that the protein quality of plant foods is perfectly adequate for muscle protein synthesis. Using the outdated notion of ‘incomplete proteins’ researchers fed middle-aged women beef (considered a complete protein), beans and bread (complementary protein), or just beans or bread (considered an incomplete protein). Despite their expectations, the researchers found all meals stimulated muscle growth in exactly the same way.

The researchers concluded that “meals containing a moderate serving of total protein from foods providing complete, complementary, or incomplete essential amino acid profiles do not differentially stimulate muscle protein synthesis after a meal.” In other words, regardless of their amino acid profile, as long as foods contain a decent amount of protein, they will stimulate muscle growth.

Based on the overwhelming and ever-growing body of evidence, there is no solid ground from which to argue that plant protein is inferior to animal protein. Some will still try to claim that plant protein is incomplete, of inferior quality and less bioavailable than meat and dairy but when it’s actually put to the test it performs just as well as any other source of protein.

Not only is plant protein just as effective as animal protein when it comes to building and maintaining muscle strength, but it is superior when you look beyond bulging biceps and consider disease prevention. A 2023 systematic review and meta-analysis is just one of many that found “a shift from animal-based to plant-based foods is beneficially associated with cardiometabolic health and all-cause mortality.”

So, if plant protein is just as effective at building and maintaining muscle mass and strength, would you rather get your protein from meat, which is linked to heart disease, high blood pressure, type 2 diabetes and some cancers, or from plants, which can lower and reverse your risk of these diseases? The answer should be clear: choose the power of plants.