There is a question that often follows when a person reveals they live on a plant-based diet: are you sure you get enough protein?

 

Can You Get Enough Protein When You On Plant-Based Diet?

When a person reveals they live on a plant-based diet: are you sure you get enough protein?

There persists a misconception that plant foods are missing certain essential amino acids (eAAs). For reference: amino acids are the building blocks of protein; there are nine eAAs we must consume in our diet because we cannot produce them ourselves.

 

The claim that plant foods are missing eAAs is false. All plant foods contain all of the eAAs in varying amounts. The only way a person would be deficient in a specific amino acid is by only living off of a single food or non-varied diet.

 

For example, eating only beans or only rice would lead to deficiency in methionine or lysine respectively. Fortunately, that is not the diet that anyone is advocating for.

 

Some individuals focus on “protein combining,” which is also not necessary. While variety is important to ensure adequate amounts of all eAAs, there is no need to focus on meal-by-meal intake. Our bodies are smart enough to combine proteins for us!

 

We maintain pools of certain amino acids in our bodies, so that when we consume proteins, break them down into amino acids, and absorb them, they can combine with our amino acid pools and produce complete proteins. There is no need to focus on combining at each meal if you’re eating an overall varied diet.

 

The true irony is that the only food completely missing an essential amino acid is actually an animal product, collagen/gelatin, which is lacking tryptophan.

 

Are Animal Proteins More Digestible Than Plant Proteins?

Another myth is that animal proteins are significantly more digestible than plant proteins.

 

There are two main scoring systems for protein digestibility: PDCAAS and DIAAS. The methods used for each limit their applicability to humans.

 

The best measurement of protein digestibility is true ileal digestibility in humans, which only demonstrates a “few percent” difference, according to a 2019 review, between the digestibility of animal and specific plant proteins. Some whole plant foods may be less, however, the data is limited, and these differences are inconsequential outside of marginal protein intake.

 

Another set of arguments for animal protein proponents is around muscle gain and athletic performance. They point to acute muscle protein synthesis (MPS). MPS is a short-term boost in muscle production post meals, and it is true that animal protein typically results in more MPS than plant proteins. However, MPS is a debatable marker for muscle growth, and the difference diminishes when the leucine content of plant and animal protein is matched.

 

Another claim is that animal protein raises blood amino acid levels more than plant proteins. However, the very study that is typically cited clearly states that there is evidence of a rapid rise in blood levels with plant protein, but the proteins were simply “used up” quicker than animal proteins, which gives the illusion of lower serum levels.

 

The question is whether or not animal protein leads to greater muscle gains than plant protein. The answer is no.

 

We have a meta-analysis of soy protein, and several studies involving pea or rice protein directly comparing them to what would be considered “high quality” animal proteins that result in no difference in muscle mass or athletic performance.

 

We only see a difference when there is less total protein. If you consume the same amount of protein overall, it doesn’t matter if it comes from animals or plants.

 

Any proposed differences in plant protein digestibility, muscle protein synthesis, blood amino acid levels, etc. do not result in greater gains.

 

Several 2020 studies show that the evidence does not support the choice of animal protein over plant protein for athletic endeavours. But studies strongly suggest that making the switch from animal to plant protein can increase your chances of living a long and healthy life.

 

If you have any questions about plant-based diet, please reach us to our Vancouver Naturopathic Doctor.

 References

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Gardner, CD. Maximizing the intersection of human health and the health of the environment with regard to the amount and type of protein produced and consumed in the United States. Nutrition Reviews. 2019.⁣
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Melina, V. Position of the Academy of Nutrition and Dietetics: Vegetarian Diets. J Acad Nutr Diet. 2016.⁣
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Munro, HN. Mammalian Protein Metabolism: Volume IV. 1970.

Schaafsma, G. The protein digestibility-corrected amino acid score. J Nutr. 2000.⁣
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Tome, D. Digestibility issues of vegetable versus animal proteins: Protein and amino acid requirements – functional aspects. Food and Nutr Bulletin. 2013.⁣

 

Monteyne, AJ. 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. Am J Clin Nutr. 2020.⁣
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Monteyne, AJ. A mycoprotein based high-protein vegan diet supports equivalent daily myofibrillar protein synthesis rates compared with an idonitrogenous omnivorous diet in older adults: a randomized controlled trial. Br J Nutr. 2020.⁣
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Messina, M. No Difference Between the Effects of Supplementing With Soy Protein Versus Animal Protein on gains in Muscle Mass and Strength in Response to Resistnace Exercise. In J Sports Nutr Exer Metabol. 2018.⁣

 

Moon, JM. Effects of daily 24-gram doses of rice or whey protein on resistance training adaptations in training males. J Int Soc Sports Nutr. 2020.⁣

 

Babault, N. Pea proteins oral supplementation promotes muscle thickness gains during resistance training: a double-blind, randomized, Placebo-controlled clinical trial vs. Whey protein. J Int Soc Sports Nutr. 2015.⁣

 

Li, CY. Amount rather than animal vs plant protein intake associated with skeletal muscle mass in community-dwelling middle-aged and older Chinese adults: Results from the Guangzhou nutrition and health study. J Acad Nutr Diet. 2019.⁣
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Morton, RW. 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. British J Sports Med. 2018.

 

Chen, Z. Dietary protein intake and all-cause and cause-specific mortality: results from the Rotterdam Study and a meta-analysis of prospective cohort studies. Eur J Epidemiol. 2020.⁣
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Huang, J. Association Between Plant and Animal Protein Intake and Overall and Cause-Specific Mortality. JAMA Intern Med. 2020.⁣
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Naghshi, S. Dietary intake of total, animal, and plant proteins and risk of all-cause, cardiovascular, and cancer mortality: systematic review and dose-response meta-analysis of prospective cohort studies. BMJ. 2020.

 

Hevia-Larrain, V. 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. 2021.