Note: This article is supporting content to the Optimum Nutrition for Health and Performance course.
Author: Dr. Crionna Tobin, PhD
There is a lot of controversy and myth surrounding how much protein the body can absorb from one single serving. It has been incorrectly claimed that the body can only absorb and use 30g of protein from one meal, implying that any other protein contained within the serving is oxidised or broken down and excreted as waste. Firstly, regardless of the amount of protein consumed it is all digested and absorbed by the body. However, the amount of protein digested and absorbed is far greater than the amount of protein the muscle needs to grow and repair.
Protein is digested in the small intestine into smaller particles known as amino acids of which 50% are taken up by the gut and 50% are released into the circulation for use by the muscle and other tissues in the body. Although we focus primarily on the athletic benefits of consuming protein, it is also used to produce hormones, enzymes, antibodies and is a major structural component of many tissues in the body such as hair, nails, skin and many more. So although the muscle is the largest depot for amino acids, not all the amino acids released into circulation become incorporated into skeletal muscle.
Therefore, it is important to choose a high quality protein source such as whey protein so the protein that is delivered to the muscle is optimal to support muscle growth and repair around exercise. Lower quality proteins such as beans, peas or wheat which lack or are low in some of the essential amino acids will not stimulate the growth of muscle to the same degree as the same amount of whey protein which is higher in essential amino acids particularly leucine.
Secondly, a 2016 study from Sterling University found that 40g of whey protein stimulated muscle protein synthesis 20% more that 20g of whey protein in resistance trained men after a whole body workout. Previous studies which recommended 20-30g of protein only used single leg extenders as the mode of exercise. As the majority of people workout using their upper and lower body it is safe to speculate that 40g of protein provides greater muscle support for growth and repair after training.
Take Home Message:
Consuming more that 30-40g of protein in one serving provides the body with amino acids for muscle repair and growth and a wide range of other beneficial functions within the body, none of the protein is ‘wasted’. Choosing protein with an optimal amino acid profile such as any animal protein or a combination of plant protein sources at higher doses will promote skeletal muscle recovery after exercise training. Are you a PT, coach or fitness professional and want to better your nutrition knowledge? Sign up to our online nutrition course today! The course consists of ten online modules and on completion of these you will receive an accredited certificate in Nutrition by the Association for Nutrition (AfN) and earn CPD points from your professional body.
- Stokes et al 2017. Recent Perspectives Regarding the Role of Dietary Protein for the Promotion of Muscle Hypertrophy with Resistance Exercise Training. https://www.ncbi.nlm.nih.gov/pubmed/29414855
- Macnaughton et al 2016. The response of muscle protein synthesis following whole-body resistance exercise is greater following 40 g than 20 g of ingested whey protein. https://www.ncbi.nlm.nih.gov/pubmed/27511985