EAA's The Full Breakdown


If you want to know what essential amino acids (EAA) are and why you want them in your amino acid supplement, you want to read this article.


Essential Amino Acids (EAA’s) are vital to your ability to maintain, repair, and build muscle. Spend anytime reading fitness articles or actually training in the gym, and you’ll hear over and over again just how important essential amino acid supplementation is for making gains and avoiding the dreaded DOMS.


There was a time when branched-chain amino acids (BCAA’s) were promoted as the be-all, end-all for amino acid supplementation, but recently, research has pretty conclusively shown that EAA’s are really what you need to maximize muscle growth and accelerate recovery.


This makes perfect sense once you understand how the human body works and what’s required to construct protein and build muscle. That’s where this handy guide comes in!


We’ve got the full breakdown of what essential amino acids are and what each one does to help maximize your muscle building!


What are Essential Amino Acids (EAA’s)?


Amino acids are grouped into two main categories -- Essential Amino Acids (EAA’s) and nonessential amino acids. EAA’s are dubbed "essential" because the human body cannot produce them on its own, meaning they must be obtained through the diet (food or supplements). Nonessential amino acids, on the other hand, are amino acids the body can generate from other amino acids, carbohydrates and fats.


There are a total of nine essential amino acids. Those nine EAA’s are:


  • Histidine
  • Isoleucine
  • Leucine
  • Lysine
  • Methionine
  • Phenylalanine
  • Threonine
  • Tryptophan
  • Valine

Why you NEED Essential Amino Acids (EAA’s)


Simply put, EAA’s are required for protein synthesis, meaning that if you’re lacking in any one of the nine essential amino acids, your body won’t do much in the way of protein construction, muscle repair, or muscle building. While protein synthesis is absolutely critical for your fitness goals, that only begins to scratch the surface of the many roles and functions EAA’s perform in the body.


EAA’s also support energy production, cellular repair, and aid in nutrient digestion and absorption. Additionally, EAA’s also protect and safeguard the mitochondria of each cell in your body. Remember, mitochondria are the “mini power plants” inside of each cell to produces ATP.[1] Without EAA’s your body doesn’t have the raw materials needed for basic human function, let alone building slabs of lean muscle.


This is why consuming ample amounts of EAA’s is absolutely critical for everyday life. For bodybuilders, athletes, and even recreational lifters, the requirement for EAA’s is significantly greater due to the increased wear and tear their bodies are subjected to on a daily basis from weight lifting. While you could get all the EAA’s you need from your diet alone, oftentimes, a person’s diet isn’t diverse enough, setting them up for certain amino acid deficiencies. This is when its beneficial to have a complete amino acid product, one containing all of the EAA’s not just the BCAA’s!




Benefits of EAA’s


  • Increased muscle protein synthesis
  • Reduced muscle protein breakdown
  • Enhanced performance
  • Improved metabolism and energy production
  • Accelerated recovery
  • Better muscle growth 
  • Enhanced mitochondrial function

EAA’s Up Close


Ok, so EAA’s are essential, but do you know what each one actually does in the body? Yes, they’re involved heavily in building proteins and muscle, but each mighty little amino has something else to bring to the party too!


Let’s take a deeper look at each individual essential amino acid, beginning with the “king” of aminos in:



The best known, most studied, of the amino acids is Leucine. It’s also the primary reason BCAA’s have gotten so much hype over the years.

Leucine is a potent stimulator of the mechanistic target of rapamycin (mTOR).[2]FYI, mTOR previously stand for mammalian target of rapamycin.

mTOR is a cellular signal pathway that functions as the main regulator of cell metabolism, survival, growth, and multiplication.[3] There are several different mTOR pathways in the body, but the one we’re primarily interested in when discussing muscle growth is mTOR1. This particular pathway is the driver of muscle protein synthesis (i.e.muscle building).

Leucine is also beneficial for combatting catabolism too, making it extremely useful for staving off excessive muscle protein breakdown during training.




Leucine’s weaker “younger brother”, Isoleucine can also stimulate protein synthesis in the body, but not to the degree that Leucine can. Isoleucine really shines in its ability to enhance glucose uptake and utilization use during intense exercise, such as weightlifting or high intensity interval training (HIIT).[4]




The third leg of the BCAA triumvirate is Valine. While it hasn’t been as heavily studies as Leucine, Valine has been well documented to improve glycogen synthesis in skeletal muscle, prevent catabolism, and support energy production.[4]




Histidine is a precursor to histamine and essential for cognitive function and wakefulness, as it’s required for the production and maintenance of the myelin sheaths that envelop nerve cells.[9] Histidine also supports signal transmission from the brain to the various regions of the body.


On top of that, this essential amino acid also aids carnosine production[10], a powerful intracellular buffer. Histidine binds to beta alanine to form carnosine, which enhances your ability to remove metabolic waste products, such as lactic acid, during training, allowing you to train longer before succumbing to fatigue.


L-Lysine HCl

L-Lysine is best known as an amino that enhances calcium absorption and recovery from injury, most likely due to its role in protein construction.[5] It’s also required for carnitine production, making it essential to fat metabolism. Remember, carnitine is a substance that aids the conversion of fat into useable energy.

One other thing to note about lysine is that it is a key player in the formation of cartilage, collagen, skin, and tendons.


Like all of the other EAA’s, Methionine is involved in countless essential functions in the body, but the most well-known of these is as a lipotropic -- a compound that aids fat digestion in the liver. Methionine also serves as a precursor to the amino acid / antioxidant L-Cysteine, which the body uses to combat free radicals and oxidative stress that can accumulate as a byproduct of exercise.[11]


Phenylalanine is key to proper Central Nervous System (CNS) function. Upon entering the body, phenylalanine crosses the blood-brain barrier (BBB) where it’s used to synthesize important neurotransmitters including adrenaline (epinephrine), noradrenaline (norepinephrine), and dopamine.[6] These three neurotransmitters govern how you view and interact with everything around you. Plus, these three neurotransmitters also enhance mood, energy, and focus, three key factors for a productive workout.


The last amino acid to be discovered was Threonine.[6] As one of the EAA’s, threonine is necessary for protein synthesis, but more specifically, it’s used to produce glycine and serine, which drive muscle protein synthesis in the body. Also worth noting is that threonine works alongside aspartate and methionine to support fat digestion in the liver, a process also known as lipotropic function.



L-tryptophan is the lone precursor to serotonin, a key neurotransmitter for behavior, mood, and cognition.[7] Unfortunately, tryptophan is the least plentiful amino acid in the body, which makes supplementing with it that much more important.[8] Without adequate tryptophan you can suffer from serotonin deficiency, setting you up for some serious bouts of depression!


Your EAA Solution!


EAA’s are essential to protein synthesis, muscle growth, and optimal day-to-day function. They’re also the superior choice for peri-workout (intra workout) nutrition, which is why Primeval Labs has created EAA Max. Each scoop of EAA Max provides your muscles with all nine EAA’s required for muscle repair and growth, including a full 5g of 2:1:1 BCAA’s!


And don’t worry about the typical “off” flavor that amino acid products usually have. Primeval Labs has sourced the highest quality aminos so you’ll never get that “amino funk” when drinking EAA Max. Premium quality, superior formulation, and industry-leading taste make EAA Max the best EAA supplement on the market!




  1. Corsetti G, Stacchiotti A, D’Antona G, Nisoli E, Dioguardi FS, Rezzani R. Supplementation with essential amino acids in middle age maintains the health of  rat kidney. Int J Immunopathol Pharmacol. 2010;23(2):523-533. doi:10.1177/039463201002300214. http://journals.sagepub.com/doi/pdf/10.1177/039463201002300214

  2. Lynch CJ. Role of leucine in the regulation of mTOR by amino acids: revelations from structure-activity studies. J Nutr. 2001;131(3):861S-865S. http://jn.nutrition.org/content/131/3/861S.long

  3. Laplante M, Sabatini DM. mTOR signaling at a glance. J Cell Sci. 2009;122(Pt 20):3589-3594. doi:122/20/3589 [pii] 10.1242/jcs.051011. http://jcs.biologists.org/content/122/20/3589

  4. Doi M, et al. Isoleucine, a potent plasma glucose-lowering amino acid, stimulates glucose uptake in C2C12 myotubes . Biochem Biophys Res Commun. (2003) http://www.ncbi.nlm.nih.gov/pubmed/14651987

  5. Dort J, Leblanc N, Maltais-Giguère J, Liaset B, Côté CH, Jacques H. Beneficial Effects of Cod Protein on Inflammatory Cell Accumulation in Rat Skeletal Muscle after Injury Are Driven by Its High Levels of Arginine, Glycine, Taurine and Lysine. Blachier F, ed. PLoS ONE. 2013;8(10):e77274. doi:10.1371/journal.pone.0077274. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3790733/

  6. UDENFRIEND S, COOPER JR. The enzymatic conversion of phenylalanine to tyrosine. J Biol Chem. 1952;194(2):503-511. http://www.jbc.org/content/194/2/503.long

  7. Richard DM, Dawes MA, Mathias CW, Acheson A, Hill-Kapturczak N, Dougherty DM. L-Tryptophan: Basic Metabolic Functions, Behavioral Research and Therapeutic Indications. International Journal of Tryptophan Research : IJTR. 2009;2:45-60. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2908021/

  8. Young LS, Stoll S. Proteins and amino acids. In: Matarese LE, Gottschlich MM, editors. Contemporary Nutrition Support Practice. 2nd ed. Vol. 1. New York: Saunders; 2003. pp. 94–104.

  9. Van Ruitenbeek P, Sambeth A, Vermeeren A, Young S, Riedel W. Effects of L-histidine depletion and L-tyrosine/L-phenylalanine depletion on sensory and motor processes in healthy volunteers. British Journal of Pharmacology. 2009;157(1):92-103. doi:10.1111/j.1476-5381.2009.00203.x. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2697785/

  10. Salah, E, Garbilla, Alan j. Sinclair, Carnosine: physiological properties and therapeutic potential. Age and Ageing; 2000; 29: 207-210. http://www.ncbi.nlm.nih.gov/pubmed/10855900

  11. Brosnan JT, Brosnan ME. The Sulfur-Containing Amino Acids: An Overview. J Nutr. 2006;136(6):1636S-1640. http://jn.nutrition.org/content/136/6/1722S.full

  12. Moberg M, Apro W, Ekblom B, van Hall G, Holmberg H-C, Blomstrand E. Activation of mTORC1 by leucine is potentiated by branched-chain amino acids and  even more so by essential amino acids following resistance exercise. Am J Physiol Cell Physiol. 2016;310(11):C874-84. doi:10.1152/ajpcell.00374.2015. https://www.ncbi.nlm.nih.gov/pubmed/27053525