Essential Amino Acids

What does the research say?

Research shows that EAAs, especially leucine, are critical for maximizing muscle protein synthesis [1] [17] . Consuming 6-15 grams of EAAs around resistance exercise can significantly enhance muscle growth over time [1] . Studies have shown that a dose of 1.5-3 grams of EAAs can stimulate muscle protein synthesis even at rest [7] . However, larger increases in circulating EAA concentrations are needed to drive a substantial increase in muscle protein synthesis [5] . Some studies suggest that higher protein intake (~35g of high quality protein per meal, delivering ~15g of EAAs) is needed for maximal muscle protein synthesis in older adults [8] . For plant-based proteins like soy, increasing the amount consumed or combining with other protein sources may be needed to compensate for a lower anabolic response [4] [10] . Whey protein is often more effective than other protein sources in stimulating muscle protein synthesis [11] [14] . Leucine also has a role in the formation of a molecule called HMB [13] , which has also been shown to promote muscle protein synthesis and reduce muscle breakdown [13] . The effectiveness of EAAs can be increased when combined with resistance or aerobic exercise [7] . Furthermore, they can help preserve muscle mass during caloric deficits [7] .

No known side effects in healthy individuals

EAAs are generally safe for consumption with no reported adverse effects in healthy individuals [7] .

Rare genetic metabolic disorders

Individuals with rare genetic metabolic disorders (e.g., maple syrup urine disease) may experience adverse effects [7] .

Renal disease

Individuals with renal disease may experience adverse effects [7] .

[1] International Society of Sports Nutrition Position Stand: protein and exercise.

This paper reviews the role of protein and exercise in muscle protein synthesis, highlighting the critical role of essential amino acids (EAAs) for muscle growth and repair, especially when consumed around exercise.

[2] The Health Benefits of Egg Protein.

This review discusses the health benefits of egg protein as an excellent source of essential amino acids (EAAs), focusing on its high digestibility and the role of leucine in stimulating muscle protein synthesis.

[3] Nutritional interventions to improve muscle mass, muscle strength, and physical performance in older people: an umbrella review of systematic reviews and meta-analyses.

This umbrella review looks into nutritional interventions for improving muscle mass, strength, and physical performance in older people, and the importance of essential amino acids.

[4] The Anabolic Response to Plant-Based Protein Ingestion.

This paper reviews the anabolic response to plant-based protein, particularly soy protein, and its effectiveness in stimulating muscle protein synthesis compared to animal-based proteins.

[5] Essential Amino Acids and Protein Synthesis: Insights into Maximizing the Muscle and Whole-Body Response to Feeding.

This clinical study investigates the impact of peripheral essential amino acid (EAA) concentrations on muscle and whole-body protein synthesis.

[6] Pre- and Post-Surgical Nutrition for Preservation of Muscle Mass, Strength, and Functionality Following Orthopedic Surgery.

This paper discusses the role of essential amino acids (EAAs) in preserving muscle mass, strength, and functionality before and after orthopedic surgery, especially in older adults.

[7] International Society of Sports Nutrition Position Stand: Effects of essential amino acid supplementation on exercise and performance.

This paper examines the effects of essential amino acid (EAA) supplementation on exercise and performance, with an emphasis on how EAAs stimulate muscle protein synthesis and enhance physical capabilities.

[8] Protein Consumption and the Elderly: What Is the Optimal Level of Intake?

This paper discusses protein and essential amino acid (EAA) requirements for elderly adults, noting their role in maintaining muscle health and preventing sarcopenia, also discussing the higher intake requirements for older adults.

[9] Review: Taurine: A "very essential" amino acid.

This review covers taurine, an abundant amino acid in the body, detailing its roles in the central nervous system, retina, muscle tissue and more. Although it is not a building block for proteins, it has a wide variety of functions.

[10] Protein content and amino acid composition of commercially available plant-based protein isolates.

This review analyzes the protein content and amino acid composition of various plant-based protein isolates, comparing their essential amino acid (EAA) content and suitability for muscle protein synthesis.

[11] Ingestion of whey hydrolysate, casein, or soy protein isolate: effects on mixed muscle protein synthesis at rest and following resistance exercise in young men.

This study compares the effects of whey, casein, and soy protein on muscle protein synthesis at rest and after resistance exercise in young men, highlighting the superior effect of whey.

[12] Leucine supplementation and intensive training.

This paper discusses the role of leucine supplementation in intensive training, noting its importance in muscle protein synthesis and its potential to improve performance and prevent muscle breakdown.

[13] The Effects of Protein and Supplements on Sarcopenia in Human Clinical Studies: How Older Adults Should Consume Protein and Supplements.

This review discusses how protein and supplements, such as HMB, can help with sarcopenia in older adults and how older adults should consume these to get the best effect. It also details how HMB has a role in promoting muscle protein synthesis.

[14] Muscle Protein Synthesis and Whole-Body Protein Turnover Responses to Ingesting Essential Amino Acids, Intact Protein, and Protein-Containing Mixed Meals with Considerations for Energy Deficit.

This paper reviews the impact of essential amino acids (EAAs), intact protein (whey) and mixed meals on muscle protein synthesis and whole-body protein turnover, particularly during energy deficit, and the importance of leucine content in whey.

[15] Whey protein, amino acids, and vitamin D supplementation with physical activity increases fat-free mass and strength, functionality, and quality of life and decreases inflammation in sarcopenic elderly.

This clinical study investigates the effects of whey protein, amino acids, and vitamin D supplementation with physical activity on fat-free mass, strength, functionality, quality of life, and inflammation in sarcopenic elderly individuals.

[16] Perspective: Vegan Diets for Older Adults? A Perspective On the Potential Impact On Muscle Mass and Strength.

This review discusses the impact of vegan diets on muscle mass and strength in older adults, highlighting the importance of essential amino acid (EAA) intake for stimulating muscle protein synthesis.

[17] A high proportion of leucine is required for optimal stimulation of the rate of muscle protein synthesis by essential amino acids in the elderly.

This study compares the effects of different leucine concentrations in essential amino acid mixtures on muscle protein synthesis in elderly and young individuals, demonstrating the importance of leucine for older adults.

[18] Stable isotope labeling by amino acids in cell culture, SILAC, as a simple and accurate approach to expression proteomics.

This paper describes SILAC, a technique using stable isotope labeling by amino acids in cell culture, particularly deuterated leucine, to study protein expression, and provides a good understanding of how essential amino acids work in the body.

[19] Dietary essential amino acids for the treatment of heart failure with reduced ejection fraction.

This study examines the effects of a diet substituting free essential amino acids (EAAs) for protein on mitochondrial function and heart health in a mouse model of heart failure.

[20] [Prevention and treatment of sarcopenia with essential amino acids].

This paper reviews the role of essential amino acids (EAAs) in the prevention and treatment of sarcopenia, focusing on how EAAs stimulate muscle protein synthesis and improve muscle function in older adults.

[21] Loss of Muscle Mass and Strength After Hip Fracture: an Intervention Target for Nutrition Supplementation.

This review summarizes the impact of hip fracture on muscle mass and strength, as well as the evidence for nutritional supplementation to maintain muscle and improve function post-surgery.

[22] Effects of essential amino acid (EAA) and glutamine supplementation on skeletal muscle wasting in acute, subacute, and postacute conditions.

This review examines the effects of essential amino acid (EAA) and glutamine supplementation on muscle wasting in acute, subacute, and postacute conditions, with a focus on maintaining muscle size and strength.

[23] Regulation of Skeletal Muscle Function by Amino Acids, Especially Non-Proteinogenic Amino Acids.

This paper discusses how amino acids, including non-proteinogenic amino acids, regulate skeletal muscle function, specifically their role in muscle protein synthesis.

[24] Kinetic properties and essential amino acids of the 2,3-bisphosphoglycerate synthase-phosphatase from pig skeletal muscle.

This study explores the importance of histidine, arginine and lysine residues for 2,3-bisphosphoglycerate synthase-phosphatase function in pig skeletal muscle, contributing to the understanding of essential amino acid roles in muscle.