Science Library

Latest Clinical Research on Essential Amino Acids

The science behind EAAs is real.

The scientific journey toward the discovery of the precise ratios of Essential Amino Acids that perform best took time.  Decades, in fact, and there are more on the way.  If you’re ready to roll up your sleeves and dig into some of the best research on primary muscle building with amino acids, check these 24 out.

We recommend starting with this overview and discussion about how BCAAs, three popular essential amino acids, cannot work effectively on their own:

24 Clinical Studies on EAAs

Depending on your specific goals you can use EAAs to lose weight and tone up, gain mass or just use them as a way to prevent muscle loss, stabilize your mood and get natural energy.

  1. Biolo G, RYD Fleming, SP Maggi, RR Wolfe. Transmembrane transport and intracellular kinetics of amino acids in human skeletal muscle. Am. J. Physiol. 268:E75-E84, Jan 1995. Description of a model to quantify protein synthesis, breakdown, and amino acid transport in humans. How to measure the effect.
  2. Biolo G, BD Williams, RYD Fleming, RR Wolfe. Insulin action on muscle protein kinetics and amino acid transport during recovery after resistance exercise. Diabetes 48:949-957, May 1999. The ability of insulin to stimulate glucose uptake and alanine transport and to suppress protein degradation in skeletal muscle is increased after resistance exercise.
  3. Volpi E, AA Ferrando, CW Yeckel, KD Tipton, RR Wolfe. Exogenous amino acids stimulate net muscle protein synthesis in the elderly. J Clin Invest, 101:2000-2007, May 1998.
    Demonstrates the effects of exogenous amino acids on muscle protein anabolism.  Aminos increase muscle mass in elderly. FSR rate .44 to .92 aminos by IV solution
  4. Tipton KD, BE Gurkin, S Matin, RR Wolfe. Nonessential amino acids are not necessary to stimulate net muscle protein synthesis in healthy volunteers. J Nutr Biochem 10:89-95, Feb 1999.
    Only the essential amino acids are required to stimulate muscle anabolism. Aminos peak at 30 minutes and stay up to 2 hours, starts in 10 minutes, Net nitrogen (N) balance changed from negative (-495 +/- 128 nmol/mL) prior to consumption of EAA to a peak positive value (416 +/- 140 nmol/mL) within 10 minutes of ingestion of the drink. EAA resulted in an estimated positive net N uptake of 307.3 mg N above basal levels.
  5. Volpi E, B Mittendorfer, SE Wolf, RR Wolfe. Oral amino acids stimulate muscle protein anabolism in the elderly despite higher first-pass splanchnic extraction. Am J Physiology 277:E513-E520, Sep 1999.
    Muscle anabolism can be stimulated to the same degree in older and younger subjects with oral amino acids. This proves works at any age, 15 young and old
  6. Volpi E, M Sheffield-Moore, BB Rasmussen, RR Wolfe. Basal muscle amino acid kinetics and protein synthesis in healthy young and elderly men: New insights into the development of sarcopenia. JAMA 286:1206-1212, Sep 2001.
    Fasted muscle protein turnover is the same in young and older subjects. 26 young/elderly fractional synthesis rate, 0.0601 (0.0046) %/h vs 0.0578 (0.0047) %/h; P = 73.
  7. Tipton KD, BB Rasmussen, SL Miller, SE Wolf, SK Owens-Stovall, BE Petrini, RR Wolfe. Timing of amino acid-carbohydrate ingestion alters anabolic response of muscle to resistance exercise. Am J Physiol 281:E197-E206, Aug 2001. Greatest response of muscle anabolism to essential amino acids occurs when given just prior to resistance exercise. Take before you exercise.
  8. Borsheim E, KD Tipton, SE Wolf, RR Wolfe. Essential amino acids and muscle protein recovery from resistance exercise. Am J Physiol 283:E648-E657, Oct 2002. is a dose-dependent effect of essential amino acid ingestion on muscle protein synthesis.
  9. Tipton KD, E Borsheim, SE Wolf, AP Sanford, RR Wolfe. Acute response of net muscle protein balance reflects 24-h balance after exercise and amino acid ingestion. Am J Physiol 284:E76-E89, Jan 2003. The acute response of skeletal muscle to essential amino acids and resistance exercise reflects the cumulative daily response. Non essential aminos are not required.
  10. Volpi E, H Kobayashi, M Sheffield-Moore, B Mittendorfer, RR Wolfe. Essential amino acids are primarily responsible for the amino acid stimulation of muscle protein anabolism in healthy elderly adults. Am J Clin Nutr 78:250-258, Aug 2003. amino acids are primarily responsible for the amino acid-induced stimulation of muscle protein anabolism in the elderly. Non essential do little
  11. Miller SL, KD Tipton, DL Chinkes, SE Wolf, RR Wolfe. Independent and combined effects of amino acids and glucose on muscle protein following resistance exercise. Med Sci Sports Exerc 35:449-455, Mar 2003. intake of carbohydrate and/or amino acids does not diminish subsequent anabolic response of muscle.
  12. Paddon-Jones D, M Sheffield-Moore, XJ Zhang, E Volpi, SE Wolf, A Aarsland, AA Ferrando, RR Wolfe. Amino acid ingestion improves muscle protein synthesis in the young and elderly. Am J Physiol 286:E321-E328, Mar 2004. amino acid supplementation acutely stimulated muscle protein synthesis in both young and elderly individuals.
  13. Paddon-Jones D, M Sheffield-Moore, RJ Urban, AP Sanford, A Aarsland, RR Wolfe, AA Ferrando. Essential amino acid and carbohydrate supplementation ameliorates muscle protein loss during 28 days bedrest. J Clin Endocrinol Metab 89:4351-4358, Sep 2004. amino acid and carbohydrate supplementation ameliorated the loss of muscle mass and strength during prolonged inactivity. Works even with no exercise, FSR was higher in the EXP group on d 1 (EXP, 0.099 +/- 0.008%/h; CON, 0.075 +/- 0.005%/h) and d 28 (EXP, 0.093 +/- 0.006%/h; CON, 0.055 +/- 0.007%/h) works long term as well
  14. Borsheim E, A Aarsland, RR Wolfe. Effect of an amino acid, protein, and carbohydrate mixture on net muscle protein balance after resistance exercise. Int J Sport Nutr Exerc Metab 14:255-271, Jun 2004. After resistance exercise, a mixture of whey protein, amino acids, and carbohydrate stimulated and prolonged muscle protein synthesis more than carbohydrate alone.
  15. Paddon-Jones D, M Sheffield-Moore, A Aarsland, RR Wolfe, AA Ferrando. Exogenous amino acids stimulate human muscle anabolism without interfering with the response to mixed meal ingestion. Am J Physiol 288:E761-767, Apr 2005. Carbohydrate/Essential Amino Acid supplementation produces a greater anabolic effect than ingestion of intact protein, but does not interfere with the normal metabolic response to a meal. Ingestion of a combination of CAA supplements and meals resulted in a greater mixed muscle FSR than ingestion of the meals alone (SUP, 0.099 +/- 0.008; CON, 0.076 +/- 0.005%/h; P < 0.05)
  16. Katsanos CS, H Kobayashi, M Sheffield-Moore, A aarsland, RR Wolfe. Aging is associated with diminished accretion of muscle proteins after the ingestion of a small bolus of essential amino acids. Am J Clin Nutr 82:1065-1073, Nov 2005. Aging results in a diminished accretion of muscle proteins after ingestion of a small dose of essential amino acids, indicating that a greater amount of amino acids may be required by the elderly to enhance muscle anabolism. Take more 7 grams too little of a dose for muscle growth
  17. Paddon-Jones D, M Sheffield-Moore, CS Katsanos, XJ Zhang, RR Wolfe. Differential stimulation of muscle protein synthesis in elderly humans following isocaloric ingestion of amino acids or whey protein. Exp Gerontol 41:215-219, Feb 2006. Both essential amino acids (EAA) and whey supplements stimulated muscle protein synthesis; however, EAAs may provide a more energetically efficient nutritional supplement for elderly individuals. EAAs are better, increase was greatest in the EAA group with values of 0.088 +/- 0.011% h-1 (EAA) and 0.066 +/- 0.004% h-1 (WY), 15 elderly in study
  18. Katsanos CS, H Kobayashi, M Sheffield-Moore, A Aarsland, RR Wolfe. A high proportion of leucine is required for optimal stimulation of the rate of muscle protein synthesis by essential amino acids in the elderly. Am J Physiol Endocrinol Metab 291:E381-E387, Aug 2006. Increasing the proportion of leucine in a mixture of EAA can reverse the blunted response of muscle protein synthesis in elderly.
  19. Fitts RH, JG Romatowski, JR Peters, D Paddon-Jones, RR Wolfe, AA Ferrando. The deleterious effects of bed rest on human skeletal muscle fibers are exacerbated by hypercortisolemia and ameliorated by dietary supplementation. Am J Physiol Cell Physiol, 293:C313-320, Jul 2007. An essential amino acid/carbohydrate supplement preserves muscle function during periods of relative inactivity.
  20. Borsheim E, QU Bui, S Tissier, H Kobayashi, AA Ferrando, RR Wolfe. Effect of amino acid supplementation on muscle mass, strength and physical function in elderly. Clin Nutr 27:189-195, Apr 2008. Supplementation of the diet with essential amino acids + arginine improves lean body mass, strength and physical function compared to baseline values in glucose intolerant elderly individuals.
  21. Borsheim E, QU Bui, S Tissier, MG Cree, O Ronsen, B Morio, AA Ferrando, H Kobayashi, BR Newcomer, RR Wolfe. Amino acid supplementation decreases plasma and liver triglycerides in elderly. Nutrition, 25:281-288, Mar 2009. Supplementation of diet with essential amino acids lowers plasma triglycerides, total cholesterol, very low-density lipoprotein cholesterol concentrations, and liver lipid content in impaired glucose tolerant elderly. Plasma TG decreased approximately 20% from the initial value of 1.45 +/- 0.18 nmol/L (mean +/- SE, 128 +/- 16 mg/dL), with the greatest decrease in the subjects starting out with the highest concentrations (r = 0.83). Similarly, liver fat content (liver TG/intralipid standard) decreased approximately 50% from the initial value of 0.34 +/- 0.06 (P = 0.021, n = 8),
  22. Katsanos CS, A Aarsland, MG Cree, RR Wolfe. Muscle protein synthesis and balance responsiveness to essential amino acids ingestion in the presence of elevated plasma free fatty acid concentrations. J Clin Endocrinol Metab 94:2984-90, Aug 2009. PMCID: PMC2730875. Elevated plasma fatty acid concentrations mimicking insulin resistance do not interfere with the response of muscle protein synthesis to a bolus ingestion of essential amino acids.
  23. Ferrando AA, D Paddon-Jones, NP Hays, P Kortebein, O Ronsen, RH Williams, A McComb, TB Symons, RR Wolfe, W Evans. EAA supplementation to increase nitrogen intake improves muscle function during bed rest in the elderly. Clin Nutr 29:18-23, Feb 2010. Increasing protein intake above the RDA with essential amino acids preserves muscle function in the elderly during compulsory inactivity.
  24. Ferrando AA, MM Bamman, SE Schutzler, HJ Spencer, AM Dawson, RP Evans, RR Wolfe. Increased nitrogen intake following hip arthroplasty expedites muscle strength recovery. J Aging Res Clin Practice 2:369-375, May 2013. Increased nitrogen intake via amino acid supplementation improves the rate of recovery of leg muscle strength following THA.

Find out how muscles are formed,  the solution to maintaining and gaining quality muscle and how you can achieve your health and wellness goals.

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