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.
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Matthew Nagra is a Naturopathic Doctor and is a passionate advocate for evidence-based nutrition as medicine. I have a particular passion for plant-based/vegan nutrition, physical medicine, and chronic disease. With additional training in nutrition, I hold a Plant-Based Nutrition Certification from Cornell University and the T. Colin Campbell Center for Nutrition Studies where I’ve authored multiple articles on the subject.