Plant Protein vs Animal Protein For building Muscle (science-based)

Michelle Solace
ILLUMINATION
Published in
4 min readJul 13, 2022
Photo by Alora Griffiths on Unsplash

Due to the increased interest in veganism emphasizing global sustainability, ethical or health reasons, many fitness enthusiasts wonder, can plant protein replace animal protein without undesirable changes in muscle growth.

In this article, you will learn the basics of muscle gain, what contributes and what is necessary to grow muscle. Additionally, I will present two scientific studies in simple words that you will be able to put into practice immediately.

A simplified explanation of what is protein.

Protein is a complex substance that consists of different numbers and types of molecules, called amino acids. Imagine that these molecules stick together one by one, curl up, form many bonds and create a protein. However, proteins differ in number and diversity of amino acids, so here we run into a problem because we need all amino acids. Although some we can synthesise in our body, other amino acids we can get only from our diet ( so-called essential amino acids (EAAs)).

How are we building muscle tissue?

The total muscle mass is balanced via changes in muscle protein synthesis (MPS) and muscle protein breakdown (if there is not enough “fuel” for our bodies to work, then muscle protein is broken down). MPS is the main factor responsible for muscle gain, depending on food intake and physical activity.

It is important to note that MPS response to food intake lasts only 4–5h after a meal. Correspondingly, we should consume protein sources regularly and perform consistent resistance training. For instance, one should be eating 20 g of protein in a meal every 4 hours.

Which protein sources suit muscle building better and why?

Dietary protein quality relates to the ability of a protein to assist the increase in muscle protein synthesis (MPS) after food ingestion. MPS stimulation depends on dietary protein digestion, amino acids absorption rate and amino acids variety, focusing on leucine, lysine and methionine ( essential amino acids (EAAs)).
Animal protein and plant protein considerably differ in protein digestion rate. For instance, animal-based protein sources, including dairy, eggs, and meat, are highly digestible (>90%), whereas, plant-based sources such as maize, oat, bean, and pea have lower digestibility, ranging from 45% to 80%. That does not include purified plant protein sources such as soy protein isolate that reaches up to 90%, which is a big plus.
What’s more, that amino acids derived from soy and wheat are more readily converted to urea than milk proteins, relating to “unbalanced” essential amino acids. Plant-derived proteins lack essential amino acids such as lysine, methionine and leucine.

Better options:

  • Spirulina has 5,2 % of lysine and 2% of methionine.
  • Mycoprotein, a fungus protein, has a lysine content of 6,7%, but only 1,5% of methionine.
  • Quinoa has lysine of 6,5% and methionine of 2,6%.

In comparison, animal products have a 7–10% lysine content and methionine>2,2%.

A recent study reported that a high-protein (1,6 g/kg) plant-based diet (vegan diet including soy protein isolate supplementation) is as effective as a mixed diet for muscle gain. However, the researchers noted that in a vegan diet, a person needed about 58g a day of soy protein to get 1,6g/kg, in comparison, an omnivore diet-based individual only needed 41g.

Can we improve plant-based proteins?

Selective breeding

Scientists created “quality maize protein” (QMP) — maize with a single gene mutation that doubled lysine and increased tryptophan content. Unfortunately, the lysine content was relatively lower than an animal protein source.

Protein blends

Ingestion of either 17,7g of whey protein or 19,3g of a protein blend (containing 25% whey, 25% soy, and 50% casein) demonstrated no remarkable difference. As was foreseeable, these two protein blends had almost equal amounts of essential amino acids.

Lysine, methionine and leucine fortification

One study showed that the supplementation with crystalline leucine depleted valine and isoleucine (other amino acids). Some studies demonstrated that supplementation with leucine, isoleucine, and valine slightly improved muscle protein synthesis; however, this strategy needs more research.

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