It has already been established that muscle building in humans is augmented by eating a high-protein diet. However, there is an ongoing debate within fitness circles about whether plant-sourced protein is as good at creating muscle as protein sourced from animals. A recently published study investigated this very question.
In February 2023 results were published from a small United Kingdom study that compared the efficacy of plant-sourced protein to that of animal-sourced protein in the production of muscle. The plant-sourced protein used in this study was Quorn, a meat-free protein derived from fungi (mycoprotein). Marlow Foods Ltd., makers of Quorn, sponsored this research and the researchers were from the University of Exeter in the UK and the University of Texas in Galveston USA . (1) Quorn, first introduced in England in 1983, is a trade-marked meat substitute derived from a natural micro-fungus produced through fermentation called Fusarium venenatum. Quorn is available in products such as sausages, nuggets and minced “meat”. (2)
The 2023 randomized trial was split into two phases.
Phase 1 of the research included 16 healthy adults, half men and half women, aged 22 to 24, who were placed on a 3-day high-protein dietary intervention that derived its protein either from animal-sourced foods (omnivorous meals) or from Quorn (vegan meals). Participants performed daily leg resistance exercise on one leg only and their rates of new muscle formation was measured every day. Results showed that the rate of new protein synthesis was 12% higher in the exercised leg compared to the rested leg, regardless of which diet was being consumed. (1)
Phase 2 included 22 additional adults, half men and half women, aged 23 to 25 years, that completed a 10-week-long program of progressive daily resistance exercise along with the consumption of a high-protein diet from either omnivorous sources (animal-based foods) or from a vegan source (Quorn). Participants were analysed through assessments of their whole-body lean mass, thigh muscle volume, muscle strength, muscle function and muscle fiber cross-sectional area. Measurements were taken before the dietary intervention began, at 2 weeks, at 5 weeks and after the trial was completed. Results showed that the resistance training increased lean muscle mass in the omnivores by an average of 5.7 pounds and by an average of 6.8 pounds in the vegan eaters. In addition, the training increased thigh muscle volume by 8.3% in both groups and muscle fiber cross-sectional area by a similar amount in omnivore and vegan eaters. Both groups increased comparably in the strength of multiple muscle groups. (1)
This research concluded that both omnivorous and vegan diets support equivalent increases in muscle volume, muscle strength, and muscle fiber size in healthy young adults eating a diet higher in protein. (1)
In other words
a high-protein, completely plant-sourced diet
is as equally effective as
a diet high in animal-sourced proteins
in the development of muscle during progressive, intensive training
Of course, in your own life you don’t have to eat Quorn to get these results. The world of plants offers all the protein you need for healthful living and building muscles. Plant-sourced legumes and pulses such as beans, peas and lentils are the “heavy lifters” of protein sources. These include soy proteins (tofu, tempeh, edemame and soy milk), beans (kidney beans, black beans, navy beans, pinto beans, borlotti beans, white beans, lima beans and more), peas, chickpeas and lentils (including hummus). However, all plants contain some protein and deficiency in protein is virtually nonexistent in developed countries. If you are eating enough food to maintain your weight and you’re consuming a variety of whole plant-sourced foods, it’s almost impossible to lack protein in your diet. In fact, most adults living in North America and Europe eat substantially more than the recommended daily amount of protein. (3)
The Canadian Nutrition Facts table does not provide a recommended daily intake for protein. This is because most people get more than enough protein in their diet, so it is not a health concern for Canadians. (4) In the US, the official recommended daily dietary allowance for protein is 56 grams for adult men and 46 grams for adult women. A healthy completely plant-based diet will naturally provide about 10% of total calories from protein. So, if you are eating 2200 calories in a day and 10% of your calories are coming from protein, you’ll be easily getting 55 grams of protein. (3)
Here is the calculation for the above amount of protein. When you eat 2200 calories and 10% of those calories come from protein, that means that you are obtaining 220 calories from protein. Since protein offers 4 calories per gram, you can divide 220 by 4 and get 55 grams of protein.
If you’re a body builder looking to increase your protein to build extra muscle, it is easy to add in additional portions of the plant protein pros, beans, peas and lentils, to achieve your goals. Other great sources of protein from plants include quinoa; grains like whole wheat, spelt, brown rice and oatmeal; seeds, nuts and nut butters; nutritional yeast; and the higher-protein vegetables like broccoli, Brussels sprouts, asparagus, artichokes, spinach, potatoes and sweet potatoes. But the bottom line is that all plants contain some protein. (3,4,5,6)
Another consideration is the challenge that aging brings with it. Recent research has discovered that older adults tend to be less efficient in absorbing protein. Elders are also more likely to eat smaller meals. Consequently, seniors may want to consider getting a bit more protein in their diets. The Mayo Clinic now recommends 0.44 to 0.52 grams of protein daily per pound of ideal body weight for anyone over the age of 65. This translates into a protein goal for a senior with a body weight of 150 pounds of 66 to 78 grams of protein daily. (7,3)
Surprisingly, it is more likely that people may be suffering from too much protein rather than too little. A 2019 study revealed that those who consume more meat and other animal-based sources of protein increase their risk of death from chronic disease by 23% compared to those eating higher amounts of plant-based protein sources. (8) And an earlier study showed that participants who ate the most animal protein had a 5-fold increase in the risk of death related to diabetes; those younger than 65 who were ingesting the most animal protein had a 75% increased risk for death from any cause and a 4-fold increase in cancer-related death during a follow-up of 18 years. Researchers noted that these effects may be due to the link between higher levels of IGF-1 (insulin-like growth factor-1) and increased incidence of age-related diseases like cancer and diabetes. The more animal protein consumed, the higher the circulating IGF-1 in the bloodstream. (9)
1 Monteyne AJ, Coelho MO, Murton AJ, et al. Vegan and omnivorous high protein diets support comparable daily myofibrillar protein synthesis rates and skeletal muscle hypertrophy in young adults. J Nutr. 2023;S0022-3166(23)12680-0. doi:10.1016/j.tjnut.2023.02.023
7 Baum, J.I., Kim, I.Y., Wolfe, R.R. Protein Consumption and the Elderly: What Is the Optimal Level of Intake? Nutrients. 2016 Jun 8; 8(6): 359.Ddoi: 10.3390/nu8060359. PMID: 27338461; PMCID: PMC4924200.
8 Virtanen, H.E.K, Voutilainen, S., Koskinen, T.T., et al. Dietary proteins and protein sources and risk of death: the Kuopio Ischaemic Heart Disease Risk Factor Study. Am J Clin Nutr. Published online April 9, 2019.
9 Levine, M.E., Suarez, J.A., Brandhorst, S., et al. Low protein intake is associated with a major reduction in IGF-1, cancer, and overall mortality in the 65 and younger but not older population. Cell Metab. 2014; 19:407-417.