Dietary Protein & Muscle Building in Younger Adults

There are a total of 20 amino acids that comprise human muscle protein; 9 of which are considered to be ‘essential’, meaning they cannot be produced by the body in physiologically significant amounts, and therefore must be consumed through diet. For the synthesis of new muscle protein, all 20 amino acids must be present in adequate amounts. The physiological regulation of skeletal muscle mass is determined and maintained, in large, by dietary protein intake and muscle contraction. These two factors act as the main stimuli for upregulating a process called muscle protein synthesis, which is how the body constructs new muscle tissue.

A growing body of research suggests that increasing dietary protein consumption above current recommended amounts, can aid in the maintenance of skeletal muscle mass and optimise tissue reconditioning in response to exercise, as noted in both young healthy participants and older adults1.

9 essential amino acids

Quorn mycoprotein contains all nine essential amino acids in good quantities and is highly bioavailable. This makes Quorn mycoprotein a ‘complete protein’, and comparable to more traditional sources of protein such as egg, beef and fish.

Research Spotlight: Focus on muscle protein synthesis

Quorn mycoprotein is high in fibre and protein, low in total and saturated fat, and contains no cholesterol. It is also comparatively low energy relative to animal protein sources. This makes it a great addition to an individual’s healthy, sustainable and balanced diet.

For over 35 years, Quorn has been conducting research on the health benefits of Quorn mycoprotein, collaborating with world-class academic institutions such as the University of Exeter. Exploring the impact of Quorn mycoprotein on muscle protein synthesis forms a large part of our research programme.

What does the science say about Quorn mycoprotein?

Due to a limited range of non-animal protein sources having been investigated in the past, there has long been a common misconception that animal-based protein sources were superior for muscle tissue synthesis.

PDCAAS (protein digestibility-corrected amino acid score) is a method of evaluating the quality of a protein based on both the amino acid requirements of humans and their ability to digest that protein. Quorn mycoprotein is considered to be a complete protein source and has a high PDCAAS of 0.9962. To put this into context, beef has a score of 0.92 and soy has a score of 0.913. For more information, visit our Amino Acid Lowdown Factsheet.

Animal-derived dietary protein sources, such as whey, milk, beef, and egg have all been shown to stimulate post-exercise muscle protein synthesis rates, and non-animal-based dietary protein sources have traditionally been assumed to be inferior in their capacity to stimulate muscle protein synthesis rates2.

This is considered to be due to their typically slower digestibility, lower bioavailability, and lower essential amino acid (EAA) and leucine content. However, much of this narrative was based on data investigating soy protein, which has been shown to stimulate a lesser muscle protein synthetic response compared to animal-derived protein sources4, 5, 6.

The research team at the University of Exeter’s Nutritional Physiology Research Group began by investigating whether the amino acids contained within mycoprotein were bioavailable; whether they appeared in the bloodstream following ingestion, meaning they had been digested and absorbed. Dunlop et al.7 provided healthy young males with a test drink containing either a bolus of mycoprotein (20, 40, 60 or 80 g) or 20g of milk. Mycoprotein ingestion resulted in slower and more sustained appearance of amino acids in the bloodstream compared with milk, indicating that Quorn mycoprotein could have the potential to robustly stimulate muscle protein synthesis rates.

This was a promising start, so the research team then investigated whether Quorn mycoprotein could stimulate muscle protein synthesis rates8 - in this instance, compared to milk protein, which can be considered a ‘gold-standard’ protein source.

Using a randomised, double-blind, parallel-group study design, researchers assessed the muscle protein synthetic response to the ingestion of a single bolus of Quorn mycoprotein compared with a bolus of milk protein, that was leucine-matched (the EAA leucine is particularly important for stimulating muscle protein synthesis).

Twenty healthy, resistance-trained young men were given either 31g milk protein or 70g Quorn mycoprotein following a bout of resistance exercise. The rate at which they were building new muscle was then measured using “tracers” in the hours following protein consumption. Results showed that Quorn mycoprotein ingestion robustly stimulated protein synthesis rates in resting and exercised muscle. While those who ingested milk protein increased their muscle growth rates by an average of 60%, those who had Quorn mycoprotein increased their muscle growth rates by more than double this. This study suggests that Quorn mycoprotein is a more effective source of protein to support post-exercise muscle protein synthesis when compared to milk protein, in healthy young men8.

Similarly, subsequent work by the same research group9 conducted in healthy young males found that a 35 g dose of branched chain amino acid (BCAA) enriched mycoprotein stimulated muscle protein synthesis rates at rest and postexercise but to a lesser extent than the 70 g mycoprotein bolus (matched in BCAA, and leucine, content). This suggests that consuming more mycoprotein, as opposed to a smaller-fortified dose, may confer the most benefit to muscle growth.

Incorporating Quorn mycoprotein into a dietary plan

A healthy diet, alongside training, is important in building muscle strength in young adults. As recent research has demonstrated, Quorn mycoprotein can indeed stimulate resting and post-exercise muscle protein synthesis rates to a greater extent than milk protein when matched for leucine1, 8. Further to this, Quorn mycoprotein is one of the only vegan protein sources, where ingestion has been shown to acutely stimulate muscle protein synthesis rates to a comparable extent as an animal-derived comparator.

Quorn® products can play a role in a healthy and balanced diet for vegans, vegetarians, and meat-eaters aiming for a more plant-based diet alike. Thanks to its meat-like texture, it’s easy to swap out meat for Quorn in family favourites such as Spaghetti Bolognese, Chilli or Tikka Curry.

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Last updated February 2023. Next review due February 2025.

  • 1 Monteyne, A.J., Dunlop, M.V., Machin, D.J., Coelho, M.O., Pavis, G.F., Porter, C., Murton, A.J., Abdelrahman, D.R., Dirks, M.L., Stephens, F.B. and Wall, B.T. 2020. A mycoprotein-based high-protein vegan diet supports equivalent daily myofibrillar protein synthesis rates compared with an isonitrogenous omnivorous diet in older adults: a randomised controlled trial. British Journal of Nutrition. [online]. pp.1-11. Available at:
  • 2 Edwards, D. and Cummings, J. 2010. The protein quality of Quorn mycoprotein. Proceedings of the Nutrition Society. [online]. 69(OCE4). Available at:
  • 3 Schaafsma, G., 2000. The Protein Digestibility–Corrected Amino Acid Score. The Journal of Nutrition, [online]. 130(7), pp.1865S-7S. Available at:
  • 4 Tang, J.E., Moore, D.R., Kujbida, G.W., Tarnopolsky, M.A. and Phillips, S.M. (2009). Ingestion of whey hydrolysate, casein, or soy protein isolate: effects on mixed muscle protein synthesis at rest and following resistance exercise in young men. Journal of Applied Physiology, 107(3), pp.987–992. Available at:
  • 5 Wilkinson, S.B., Tarnopolsky, M.A., MacDonald, M.J., MacDonald, J.R., Armstrong, D. and Phillips, S.M. (2007). Consumption of fluid skim milk promotes greater muscle protein accretion after resistance exercise than does consumption of an isonitrogenous and isoenergetic soy-protein beverage. The American Journal of Clinical Nutrition, [online] 85(4), pp.1031–1040. Available at:
  • 6 Yang, Y., Churchward-Venne, T.A., Burd, N.A., Breen, L., Tarnopolsky, M.A. and Phillips, S.M. (2012). Myofibrillar protein synthesis following ingestion of soy protein isolate at rest and after resistance exercise in elderly men. Nutrition & Metabolism, [online] 9(1). Available at:
  • 7 Dunlop, M., Kilroe, S., Bowtell, J., Finnigan, T., Salmon, D. and Wall, B., 2017. Quorn mycoprotein represents a bioavailable and insulinotropic non-animal-derived dietary protein source: a dose-response study. British Journal Nutrition. [online]. 118(9), pp.673-685. Available at:
  • 8 Monteyne, A., Coelho, M., Porter, C., Abdelrahman, D., Jameson, T., Jackman, S., Blackwell, J., Finnigan, T., Stephens, F., Dirks, M. and Wall, B., 2020. Quorn 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. The American Journal of Clinical Nutrition. [online]. 112(2), pp.318-333. Available at:
  • 9 Monteyne, A.J., Coelho, M.O.C., Murton, A.J., Abdelrahman, D.R., Blackwell, J.R., Koscien, C.P., Knapp, K.M., Fulford, J., Finnigan, T.J.A., Dirks, M.L., Stephens, F.B. and Wall, B.T. (2023). Vegan and Omnivorous High Protein Diets Support Comparable Daily Myofibrillar Protein Synthesis Rates and Skeletal Muscle Hypertrophy in Young Adults. The Journal of Nutrition. [online] Available at:

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