amino acids

“I know it may seem small and insignificant, but it’s not about what it is, it’s about what it can become.”

Branched, essential, complete, incomplete… there are many types and combinations when it comes to amino acids, but no matter how you get them, these relatively small molecules are by no means insignificant due to the many roles they play in the human body.  

A famous quote from Dr. Seuss’s The Lorax sums up amino acids perfectly: “I know it may seem small and insignificant, but it’s not about what it is, it’s about what it can become.” 

That’s because all the amino acids (there are 20 standard amino acids) are building blocks. They have different structures and link together in specific sequences to form proteins. The order and type of amino acids determine the unique shape and function of each protein.

This incredible versatility allows proteins to perform numerous tasks within the body. For instance, they act as neurotransmitters, signal hormone release, and form components of various cells and structures like haemoglobin, cell membranes and fibrin (for clotting). 

These roles mean amino acids are also closely linked with disease prevention, mental health and the optimal functioning of our internal, endocrine and musculoskeletal systems.

Among the 20 standard amino acids important for muscle gain, nine are considered essential amino acids (EAA) because our bodies cannot create them from other compounds.

As such, we need to supply our bodies with these important amino acids, which include:

  1. Histidine
  2. Isoleucine
  3. Leucine
  4. Lysine
  5. Methionine
  6. Phenylalanine
  7. Threonine
  8. Tryptophan
  9. Valine

A complete protein contains all nine EAAs, which are usually animal-derived sources like meat and dairy. An incomplete protein lacks one or more EAAs or may have them in limited quantities. Most plant-based proteins like legumes (beans, lentils, peas), nuts, seeds, and whole grains are considered incomplete.

Among the nine EAAs, three play important roles in muscle building – the branched-chain amino acids (BCAA). BCAAs get their name from their unique structure – a basic tree with branches. The three BCAAs include:

  1. Leucine
  2. Isoleucine
  3. Valine

In addition to the various roles already mentioned, we need amino acids to build and repair muscle tissue. The body breaks down the different protein sources we get from our diet into amino acids, providing the body with the structural elements needed to make new muscle proteins.

In addition, the body can metabolise some amino acids directly in the muscle to convert them into energy (a process known as gluconeogenesis), including the EAAs lysine, phenylalanine, threonine and tryptophan.

To simplify how we provide our bodies with these important amino acids and limit muscle damage, supplement manufacturers have created products that help us conveniently meet these nutritional requirements.

EAA supplements provide all nine amino acids our body requires to spare muscle during training and build new tissue during the recovery phase.

The International Society of Sports Nutrition’s position stand on protein and exercise¹ affirms that you need an abundant supply of all the EAAs to stimulate muscle protein synthesis (MPS), stating that: “Rapidly digested proteins that contain high proportions of essential amino acids (EAAs) and adequate leucine, are most effective in stimulating MPS.”

By supplying free-form amino acids to working muscle tissue, EAA and BCAA supplements have a high bioavailability as the body does not need to digest complete proteins.

As such, these products can support MPS and reduce muscle loss through their muscle-sparing effect.

BCAAs can also boost the muscle repair process after exercise, particularly leucine, which is a more potent MPS stimulator than the other two BCAAs because it activates an anabolic (muscle-building) pathway.

A study² published in Frontiers in Physiology confirmed that ingesting 5.6 g of BCAAs after a strength-training session led to 22% greater MPS.

Higher leucine levels indicate to the body that there is sufficient dietary protein to create new muscle. This signals a specific gene to create more of an anabolic cell signalling messenger called mTOR, which is why many standalone BCAA supplements include higher leucine contents in various ratios.

The industry standard is usually a 2:1:1 leucine:isoleucine:valine ratio, but products aimed at bodybuilders or other high-level athletes that may have higher recovery demands go as high as 8:1:1 and 12:1:1.

Both BCAA and EAA supplements can support muscle growth and recovery from training. EAAs are better suited for someone who struggles to meet their daily protein targets and could benefit from additional nutritional support as all these amino acids play key roles in repairing and building muscle.

BCAAs offer targeted support for serious athletes and gym-goers who already have their total daily protein needs covered through their diet and protein supplements.

However, supplement manufacturers now also produce combined products that offer the full spectrum of EAAs to deliver energy, with additional BCAAs to support muscle growth and recovery.

The ultimate decision whether to use EAAs, BCAAs or a combination of both boils down to your individual needs, your goals and your budget as both forms of amino acids work!

  1. Jäger R, Kerksick CM, Campbell BI, Cribb PJ, Wells SD, Skwiat TM, Purpura M, Ziegenfuss TN, Ferrando AA, Arent SM, Smith-Ryan AE, Stout JR, Arciero PJ, Ormsbee MJ, Taylor LW, Wilborn CD, Kalman DS, Kreider RB, Willoughby DS, Hoffman JR, Krzykowski JL, Antonio J. International Society of Sports Nutrition Position Stand: protein and exercise. J Int Soc Sports Nutr. 2017 Jun 20;14:20. doi: 10.1186/s12970-017-0177-8. PMID: 28642676; PMCID: PMC5477153.
  2. Jackman SR, Witard OC, Philp A, Wallis GA, Baar K and Tipton KD (2017) Branched-Chain Amino Acid Ingestion Stimulates Muscle Myofibrillar Protein Synthesis following Resistance Exercise in Humans. Front. Physiol. 8:390. doi: 10.3389/fphys.2017.00390.