The quality and nutritional value of dietary proteins are determined by the quantity, digestibility and bioavailability of essential amino acids (EAA), which play a critical role in human growth, longevity and metabolic health. Recommended daily intake (RDI) for protein for adults is 0.8 g per kg of body mass, but for athletes, protein requirements are higher (> 1.6 g·kg-1) as a result of training (i.e. due to higher protein turnover and oxidation rates).
By necessity or choice, many athletes may adopt plant-based diets because of personal, ethical, religious or philosophical beliefs, environmental concerns and/or for cost, health or performance benefits. However, compared to animal proteins the lower digestibility and an imbalanced profile of EAA of most plant proteins critically limits their nutritional value. This may be especially problematic for plant-based athletes who have higher protein requirements.
The digestible indispensable amino acid score (DIAAS) adopted by the World Health Organisation (WHO)/Food and Agriculture Organisation (FAO)/United Nations University (UNU) can be used to assess dietary protein quality and correct the protein RDI (see table below). Generally animal foods (e.g. meat, fish and dairy) are ‘high’ quality proteins, whereas plant foods, in their natural form, are generally ‘low’ quality sources of protein.
Research and development into the identification and commercial cultivation of new and novel plant proteins, industrial processing methods and gene-editing technology has led, and will lead, to higher-quality plant proteins. However, for plant-based athletes there are a few (relatively) easy ‘at-home’ strategies that can be used to enhance the dietary quality of plant proteins, such as: 1) protein complementation; 2) selection of protein-dense plant proteins; 3) minimising non-enzymatic browning of plant proteins during cooking (e.g. roasting, frying or grilling); 4) supplementation of EAA (e.g. leucine, lysine and tryptophan). Further details of these strategies are detailed and available to read in this open access paper.
Davies, R.W. and Jakeman, P.M., 2020. Separating the Wheat from the Chaff: Nutritional Value of Plant Proteins and Their Potential Contribution to Human Health. Nutrients, 12(8), p.2410. https://pubmed.ncbi.nlm.nih.gov/32806532/
Dr. Robert W. Davies is a lecturer in exercise physiology the Department of Physical Education and Sport Sciences. Contact: Robert.Davies@ul.ie. Research Profiles: Researchgate ORCID