“The idea is to show EAA supplementation has a great deal of research behind it and demonstrate the efficacy of EAAs in the maintenance of muscle and body protein,” lead author on the paper Dr. Arny Ferrando told NutraIngredients-USA. His lab at the Center for Translational Research in Aging and Longevity at the University of Arkansas for Medical Sciences provided much of the foundational research for the paper.
This work was supplemented with an extensive literature review conducted by a team of leading human performance and exercise science experts to provide a scientific reference for athletes, dietitians, trainers and other practitioners on the benefits of stimulation of muscle protein synthesis (MPS) by EAAs in both healthy and resistant (aging/clinical) populations.
The nine essential amino acids
Humans acquire the nine essential amino acids—histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine—through food and supplemental protein. These indispensable nutrients are crucial components of protein intake since the body cannot produce them on its own, and they are required for the synthesis of body protein and other important nitrogen-containing compounds, such as creatine, peptide hormones and some neurotransmitters.
“The necessity of consuming all the EAAs has been well established over the last 100 years, and there are accepted daily requirements for each EAA as part of normal dietary intake,” the authors stated.
Beyond the prevention of deficiencies, research has since expanded to consider the added benefits of supplementing in amounts above minimal requirements and with all EAAs as opposed to products with single free amino acids such as leucine or lysine. Only compositions containing the nine EAAs in free form were considered in the review.
“Also, rather than supplements containing only a single compound, such as creatine, there are almost limitless combinations of the nine EAAs that can be made depending on the physiological demand,” the paper noted.
The 10 official conclusions
The following conclusions represent the official position of the ISSN:
1. Initial studies on EAAs’ effects on skeletal muscle highlight their primary role in stimulating muscle protein synthesis (MPS) and turnover. Protein turnover is critical for replacing degraded or damaged muscle proteins, laying the metabolic foundation for enhanced functional performance. Consequently, research has shifted to examine the effects of EAA supplementation—with and without the benefits of exercise—on skeletal muscle maintenance and performance.
2. Supplementation with free-form EAAs leads to a quick rise in peripheral EAA concentrations, which in turn stimulates MPS.
3. The safe upper limit of EAA intake (amount), without inborn metabolic disease, can easily accommodate additional supplementation.
4. At rest, stimulation of MPS occurs at relatively small dosages (1.5–3.0 g) and seems to plateau at around 15–18 g.
5. The MPS stimulation by EAAs does not require non-essential amino acids.
6. Free-form EAA ingestion stimulates MPS more than an equivalent amount of intact protein.
7. Repeated EAA-induced MPS stimulation throughout the day does not diminish the anabolic effect of meal intake.
8. Although direct comparisons of various formulas have yet to be investigated, aging requires a greater proportion of leucine to overcome the reduced muscle sensitivity known as “anabolic resistance.”
9. Without exercise, EAA supplementation can enhance functional outcomes in anabolic-resistant populations.
10. EAA requirements rise in the face of caloric deficits. During caloric deficit, it’s essential to meet whole-body EAA requirements to preserve anabolic sensitivity in skeletal muscle.
Source: Journal of the International Society of Sports Nutrition
“International Society of Sports Nutrition Position Stand: Effects of essential amino acid supplementation on exercise and performance”
doi: 10.1080/15502783.2023.2263409
Authors: Arny A. Ferrando et al.