Plant -v- Animal Protein

The protein experiment you need to know about...

Have you ever heard that plant protein is inferior to animal protein for building muscle and strength? A co-worker’s comment about being cautious with protein as a vegan sparked my curiosity about how vegan and plant-based diets compare with omnivorous diets regarding muscle strength and hypertrophy. Let’s dive into this fascinating study and see if it challenges the concept that plant protein is inferior to animal protein.

Title:

High-protein plant-based diet versus a protein-matched omnivorous diet to support resistance training adaptations: A comparison between habitual vegans and omnivores. ¹

Population:

Nineteen habitual vegan (VEG) men and 19 habitual omnivores (OMN were defined as having consumed their nominated diets for at least 12 months before enrolment in the study. None of the participants were well-versed with resistance training.

Intervention:

Both groups underwent a 12-week resistance training program. The protein intake was adjusted to ensure that they each consumed 1.6g/kg per day with whole foods and “topped up” with either soy protein isolate (VEG group) or whey protein isolate (OMN group). They assessed baseline protein intake using 6 x 24-hour recalls for each group. They then monitored this with three additional 24-hour recalls for each group. They trained twice per week on non-consecutive days.

The exercise program:

- 5-minute warm-up

- 2 x submaximal sets of leg-press (8 reps at 50% & 3 reps at 70% of last training load registered)

- It started at 12-15 rep max (RM) and decreased to 8-10 RM with 2-4 sets increasing to the end of the training period.

- They performed leg presses and leg extensions.

The VEG group was supplemented with 0.79g/kg of soy protein isolate, and the OMN group with 0.52g/kg of whey protein isolate per day.

an anthropomorphic broccoli lifting weights

Comparison:

The researchers looked to assess muscle hypertrophy using biopsies (muscle fiber surface area), ultrasound (muscle cross-sectional area), and DEXA scans to evaluate muscle mass changes. They also assessed strength using a 1RM leg press. There were no initial baseline anthropogenic differences between the two groups apart from vitamin D being statistically significantly lower in the vegan group. For assessment of dietary intakes at baseline, the VEG group had a statistically significantly lower intake of total protein, g/kg protein, essential amino acids, and fat but had higher intakes of fiber and carbohydrates. All measures for protein showed no difference during the intervention period.

Outcome:

There was no difference in any of the outcomes assessed. Strength, muscle mass, and adherence to the training program showed no difference between the groups.

30,000ft view:

There is a pervasive thought process that would have folks believe that plant protein is inferior to animal protein when it comes to growing big, strong muscles. You often hear statements like – “protein you get from beef is a complete protein (has all the necessary amino acids in perfect proportions),” or “plant protein is non-digestible, and therefore not accessible by the body to make muscles stronger and bigger.” The paper's discussion points out that this could be an issue for vegan folks trying to achieve 1.6g/kg with whole foods without protein powders, given that whole plant foods contain anti-nutrients, making it more challenging to access the protein in that food. Each group needed to supplement with protein powders, with the vegan group needing to take two servings per day and the omnivorous groups needing around 1.5 servings per day. Pointing out all of these possible issues, this study would make it seem that if you hit your 1.6g/kg target per day – you will be no worse off eating a plant-exclusive diet, regardless of the possible downsides discussed above. This is not a new concept either; esteemed protein expert Professor Stuart Phillips (@mackinprof) outlines muscle protein synthesis optimization once you hit this 1.6g/kg target per day. ²

How should this modify your practice:

If you are vegan, eating a mixed diet, and want to achieve muscle strength and hypertrophy gains, you will likely want to hit 1.6g/kg of protein daily. You may need a supplement to hit this number, which is fine (the OMN group also had to take a supplement). Don’t be afraid of eating a plant-exclusive diet to build muscle and strength – just hit your protein targets. Also, hit the mute button on those folks who shout from their soap box that animal proteins are superior – it’s just inaccurate.

Author: Dr Adrian Cois, MD

Assistant Professor
Emergency Medicine

@dr_cois

Extend Yourself:

This was a great video from Simon Hill (@theproof) discussing how much protein we need. It’s an excellent primer for this work. Simon also talks with the study's senior author on his podcast, which this paper discusses. ³

References:

1. Hevia-Larraín V, Gualano B, Longobardi I, et al. High-Protein Plant-Based Diet Versus a Protein-Matched Omnivorous Diet to Support Resistance Training Adaptations: A Comparison Between Habitual Vegans and Omnivores. Sports Med Auckl NZ. 2021;51(6):1317-1330. doi:10.1007/s40279-021-01434-9

2. Medicine BPGL and BA of S and E. Correction: A systematic review, meta-analysis, and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. Br J Sports Med. 2020;54(19):e7-e7. doi:10.1136/bjsports-2017-097608corr1

3. How Much Protein Do We Need? | Drs Stuart Phillips and Christopher Gardner | The Proof Podcast EP228.; 2022. Accessed February 28, 2024