EAA Science Essentials

An in depth look at the science behind essential amino acid supplementation

By Dr.Dwayne N. Jackson, Phd, CSO ATP LABORATORIES

Before we begin, we would like to clarify something ----Branched chain amino acids are ESSENTIAL AMINO ACIDS (EAAs). In fact, the BCAAs: Leucine, Isoleucine, and valine, are just 3 of the 9 EAAs. However, because the science tells us that BCAAs are the most important trio of essential amino acids we, as supplement formulators, delineate BCAA supplements from EAA supplements. But please note, an EAA supplement should contain an abundance of BCAAs, otherwise it is not a full spectrum EAA supplement.

If you are interested in how to get the most out of EAA and BCAA supplements, read on as we explain the science behind essential amino acids as performance enhancing agents.

What are the EAAs?

The Essential amino acids are: the BCAAs (leucine, isoleucine, and valine), histidine, lysine, methionine, phenylalanine, threonine, tryptophan.  All of which cannot be produced by the body, so you must get them in the diet. Data show that if we lack any of these EAAs in the diet, our health, performance, and gains suffer. Many past research studies focused only on BCAA supplementation to promote increased protein synthesis; however, the latest research shows that including a full spectrum EAA supplement, enriched with BCAAs and high levels of leucine, promotes protein synthesis better than BCAAs alone.

So why have a standalone BCAA supplement? 

Well, simply because when you use a BCAA supplement in conjunction with a full spectrum EAA supplement, you can take advantage of the energy boosting and mood enhancing effects of BCAAs, while driving anabolism through the roof---- the science shows that high blood levels of BCAAs synergize with full spectrum EAAs.

What makes BCAAs so “special”?

The BCAAs, leucine, isoleucine and valine, share a unique branched chain structure and are, therefore, transported and metabolized by common means. Of the nine essential amino acids, BCAAs play a key role in protein synthesis and energy metabolism and account for approximately 20% of our total protein intake (dairy has an abundance of BCAAs). Additionally, BCAAs make up about 35% of the essential amino acids in muscle proteins and 40% of the human requirement for preformed amino acids.

Of the three BCAAs, leucine has been definitively shown to have the greatest anabolic effect in humans. It is a truly rate limiting BCAA for protein synthesis and thus is commonly taken on its own. However, the increase in anabolic drive with leucine supplementation is dependent on adequate caloric (protein and carbohydrate) consumption and, as such, those in caloric deficit will not reap leucine’s muscle-building properties. Studies have shown that leucine supplementation on its own can deplete the body’s stores of BCAA’s, thus it is best to supplement all three BCAA’s together to ensure maximum results under any condition.

BCAAs make up a great proportion of the total amino acid content in skeletal muscle, but they are selectively broken down (catabolized) during exercise. The status of BCAA breakdown is dependent on the branched-chain α-keto acid dehydrogenase complex (BCKDH) activity, which is relatively dormant under resting conditions and becomes activated with exercise. During exercise stress, BCAAs are reduced to their basic components and are eventually used as fuel for energy production.

BCAAs and Brain Function

Recently there has been some very intriguing past BCAA research, illustrating their role in the regulation of central fatigue [1, 2, 3]. It has been shown that exercise increases 5-hydroxytryptamine (5-HT, A.K.A serotonin) release, thus contributing to exercise-induced fatigue (5-HT affects mood, arousal, and sleepiness). During exercise BCAAs are metabolized (as discussed above) which causes plasma BCAA levels to decrease. As exercise progresses, plasma free fatty acids become elevated which promotes increases in free tryptophan. This throws off the free tryptophan to BCAA ratio and enables enhanced tryptophan uptake into the brain. 5-HT synthesis is very sensitive to changes in plasma tryptophan levels and the transport of tryptophan across the blood-brain barrier. Ingestion of BCAAs prior to exercise ensure BCAA homeostasis and, in turn, decreases the transport of tryptophan across the blood-brain barrier, subsequently decreasing 5-HT synthesis and delaying fatigue [1,3]. The plasma concentration ratio of free tryptophan to BCAAs has been shown to increase by 45% during cycling exercise and by 150% 5 min after exercise (3). The ratio remains unchanged or even decreased when BCAAs are ingested immediately prior to or during exercise. Furthermore, subjects undergoing BCAA supplementation report significantly lower ratings of perceived exertion and mental fatigue at a given work rate.

An interesting effect of BCAA supplementation, is its ability to augment cognitive function via balancing brain tryptophan levels (as described above). Those who regularly ingest BCAAs before exercise find that mood and mental clarity are enhanced. In fact, subjects that underwent the Stroop Word Color test (a test of mental attention and flexibility) after exercise performed significantly better with BCAA supplementation than with a placebo [3].

Immune Function

Our immune cells rely on BCAAs for their structure and function. BCAAs are necessary for lymphocytes to synthesize proteins and to promote cell proliferation. It has been shown that BCAA restriction results in increased susceptibility to pathogens, leading to greater frequency of infection [4]. Therefore, knowing that exercise can deplete BCAA stores, supplementation of these essential amino acids seems obligatory to ward off sickness, keep you out of the doctor’s office and in the gym.

Muscle Recovery and Muscle Sparing

BCAA supplementation has been used with great success by bodybuilders for many years and the past decade has scientifically consolidated this amino acid triad as a “must have” supplement. First, BCAA supplementation provides differential anabolic and anti-catabolic effects depending on the status of skeletal muscle. In muscles undergoing regular exercise BCAAs work as a potent anabolic aid, whereas muscles that are undergoing atrophy (e.g. with corticosteroid treatment, during injury or over training) are spared by the anti-catabolic properties of BCAA supplementation.

In a recent study BCAA supplementation was also been shown to reduce muscle soreness and fatigue induced by squatting exercise. On training day subjects ingested either a BCAA cocktail (Leucine:Isoleucine:Valine = 2:1:1)  or a placebo approximately 15 min prior to exercise. The authors reported that those who ingested BCAAs had significantly reduced duration and severity of muscle soreness and fatigue for days after exercise [5].

Molecular level support for BCAAs as anabolic activators comes from recent data illustrating their ability to “turn-on” anabolic signaling pathways via mTOR and p70 S6 kinase in human muscle in the recovery period after exercise [2]. Based on these findings, it is apparent that BCAAs are not only food for muscles, but when supplied in adequate amounts, are important “molecular switches” for turning on anabolism, blunting catabolism, and enhancing recovery.

By supplying an abundance of supplemental BCAAs preworkout, you ensure blood levels of leucine, isoleucine, and valine are elevated, which spares the BCAAs in muscle for anabolic signalling, muscle protein synthesis, and muscular gains down the road. However, maximizing anabolism requires the addition of full spectrum EAAs to your regimen (see below).

If you want to maximize anabolism, then you need to also take a full spectrum EAA supplement.

Certainly, having an abundance of BCAAs on the blood stream provide a source of amino acids necessary for cell signalling, muscle sparing (anticatabolic effects), and energy production. But, if you want to maximize muscle protein synthesis, you need all 9 EAAs fortified with BCAAs.

The most recent research shows that taking BCAAs alone will provide anti-catabolic support, as well as necessary substrates to stave off fatigue and promote energy production. However, they only promote elevated muscle protein synthesis when they are supplied with full spectrum EAAs. Therefore, we always suggest taking a high quality and full spectrum EAA supplement during your workout.

When is the best time to take BCAAs and EAAs?

Research shows that net muscle protein synthesis increases most when you take BCAAs and EAAs within the workout window, as opposed to postexercise [8].  This is because there is increased amino acid delivery and absorption in exercising skeletal muscle.


As always, we recommend taking 5-10 g of  fermented BCAAs upon waking, another 5-10 g preworkout, and another dose during the day. If you are dieting, you will find 5-10 g of BCAAs between meals will stave off hunger and give you a little spike of energy.


Take 10 g of a full spectrum EAA supplement intraworkout to provide anabolic support for recovery. If you drink a post workout whey isolate supplement like our New Zealand Whey Isolate, it contains plenty of EAAs to support postworkout anabolism. However, if you want a little extra anabolic insurance, you may add a 10 g scoop to your postworkout shake. 


  1. Curzon G, Friedel J, & Knott PJ (1973). The effect of fatty acids on the binding of tryptophan to plasma protein. Nature 242, 198-200.
  2. Blomstrand E (2006). A role for branched-chain amino acids in reducing central fatigue. J Nutr 136, 544S-547S.
  3. Blomstrand E, Hassmen P, Ek S, Ekblom B, & Newsholme EA (1997). Influence of ingesting a solution of branched-chain amino acids on perceived exertion during exercise. Acta Physiol Scand 159, 41-49.
  4. Calder PC. Branched-chain amino acids and immunity. J Nutr. 2006 Jan;136(1 Suppl):288S-93S
  5. Shimomura Y, Yamamoto Y, Bajotto G, Sato J, Murakami T, Shimomura N, Kobayashi H, & Mawatari K (2006). Nutraceutical effects of branched-chain amino acids on skeletal muscle. J Nutr 136, 529S-532S.
  6. Blomstrand E, Eliasson J, Karlsson HK, & Kohnke R (2006). Branched-chain amino acids activate key enzymes in protein synthesis after physical exercise. J Nutr 136, 269S-273
  7. Jackman SR, Witard OC, Philp A, Wallis GA, Baar K, Tipton KD. Branched-Chain Amino Acid Ingestion Stimulates Muscle Myofibrillar Protein Synthesis following Resistance Exercise in Humans. Frontiers in Physiology. 2017;8:390;
  8. Tipton K. D., Rasmussen B. B., Miller S. L., Wolf S. E., Owens-Stovall S. K., Petrini B. E., et al. Timing of amino acid-carbohydrate ingestion alters anabolic response of muscle to resistance exercise. Am. J. Physiol. Endocrinol. Metab. 281, E197–E206; 2001;

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