Let’s start with the basics: amino acids are the building blocks of proteins. When these functional subunits, or monomers, come together in a linear fashion they form what is called a peptide.

At a certain point, when enough subunits have come together, this formation becomes what is known as a polypeptide. Proteins are the functional entities of these products, consisting of one or more polypeptides in an active conformation (a non-linear shape which allows proteins to carry out a specific function).

Although there are twenty-two basic amino acids and a variety of other non-basic amino acids, only twenty of them are found naturally in and utilised by the human body. Those which we can synthesise, eleven in total, are known as non-essential. The other nine must be consumed as part of your diet and thus, are considered essential.

Essential Amino Acids

These essential amino acids are: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. The best sources of these amino acids are found in what are known as complete proteins. Milk, dairy products, eggs, fish, and meat are examples of complete proteins, or those which contain all twenty amino acids.

It is for these reasons why they have become bodybuilding staples, and are an important part of any diet, regardless of supplementation.

Over the years, research has focused on a specific class of amino acids known as BCAAs and how they may enhance athletic abilities.

What Are BCAAs?

Branch chain amino acids (or BCAAs) are a special class of amino acids included among the previously mentioned essential amino acids. They are: leucine, isoleucine and valine.

BCAAs account for approximately 35 per cent of the essential amino acids found in muscle proteins and approximately 40 per cent of the preformed amino acids required by mammals (1).

During exercise these BCAAs are oxidised (broken down) as an energy source for the body by an enzyme known as BCKDH (branched-chain alpha-keto acid dehydrogenase). This process mainly occurs in skeletal muscle and, since these amino acids are essential to protein synthesis and maintenance, muscle wasting occurs (2).

Exercise has been found to increase levels of BCKDH, ultimately increasing the body’s requirement for BCAAs. This protein complex is directly responsible for increased rates of metabolic catabolism. However, under normal conditions it helps the body maintain homoeostasis by disposing of excess BCAAs and their toxic intermediates in the blood (3).

Why Should You Supplement With BCAAs?

Here are the top four reasons why BCAA supplements should become part of your nutritional foundation.

Enhanced Recovery

A study done by MacLean, et al. evaluated the effectiveness of BCAA supplementation before and after exercise on muscle wasting. Here, subjects were given an oral BCAA supplement and were then asked to performed knee extensions for one hour.

Findings showed that supplementation resulted in higher intracellular and arterial BCAA levels both before and during exercise and suppression of endogenous muscle protein breakdown.

These results are confirmed by a similar study, which also found that supplementation reduced the muscle soreness that sometimes follows vigorous exercise, commonly known as DOMS or delayed onset muscle soreness (4).

Increased Muscle Protein Synthesis

Leucine has been found to stimulate protein synthesis in skeletal muscle. This is achieved by the enhancement of both the activity and the synthesis of the proteins involved in mRNA translation (messenger RNA are the sequences or blueprints that cells use to produce proteins – this process is known as translation).

Further still, they are also intensified by leucine and insulin’s co-stimulatory effects on mTOR (mammalian Target of Rapamycin) which is a kinase enzyme that regulates cell growth and proliferation (5). The end result is an increase in skeletal muscle.

Anabolic Edge

Prolonged and intense exercise often results in a long lasting decrease in serum testosterone levels, due to its metabolisation within skeletal muscle (6).

To study the effects that BCAAs may have on exercise-induced hormone responses, Carli et al. provided long-distance runners with a BCAA supplement and drew blood samples at specified intervals following exercise.

They concluded that these amino acids had the positive effect of maintaining and elevating testosterone levels following a workout. Testosterone, as you may know is an anabolic hormone which stimulates the growth of skeletal muscle, thus elevated levels lead to an increase in muscle mass.

Fat Loss

BCAAs, leucine in particular, have been found to enhance changes in body composition by sparing muscle mass. This is achieved through improved glucose recycling resulting in the stabilisation of fasting and postprandial (post meal) blood glucose levels (7).

Although fat loss is a relatively new claim with regard to the beneficial aspects of BCAA supplementation, limited research and empirical links have been made.

Despite this, the results look quite promising.

The Supplements

The Supplements below are some of the most popular in the industry. BCAAs come in both powder and pill forms and additional ingredients can vary by manufacturer. These additional ingredients can include electrolytes, stimulants and antioxidants and vary in their BCAA ratios:

  • Myprotein Bcaa PowderMyprotein Bcaa Powder
  • Myprotein Ibcaa Instantised Branch Chain Amino AcidsMyprotein Ibcaa Instantised Branch Chain Amino Acids
  • Myprotein Bcaa PlusMyprotein Bcaa Plus
  • Instant BcaaInstant Bcaa
  • Bcaa ComplexBcaa Complex
  • Reflex BcaasReflex Bcaas
  • Optimum Nutrition bcaa PowderOptimum Nutrition bcaa Powder
  • Cnp Pro Bcaa CapsulesCnp Pro Bcaa Capsules
  • Musclepharm BcaaMusclepharm Bcaa
  • Phd Nutrition BcaasPhd Nutrition Bcaas
  • Bsn Amino XBsn Amino X
  • Maxiraw Primary BcaasMaxiraw Primary Bcaas

Further studies are needed to clarify the optimum ratio and dose of BCAAs that are most effective at producing the desired effects. It may be noted that most of the studies mentioned used a ratio of 2:1:1 leucine, isoleucine, and valine respectively.

You’ll find that some supplements have higher ratios of leucine compared to the other two as leucine has been linked, as can be seen above, to having a larger impact on muscle protein synthesis.

However, this should be taken with a grain of salt as some believe that excessive imbalances in the ratios may have negative side effects – more isn’t always better.

That being said, there are no real ‘windows’ for BCAA dosing and supplements can be consumed throughout the day whilst training. For an extra kick, try stacking a flavoured supplement with micronized creatine.


(1) Harper, A. E., Miller, R. H., & Block, K. P. (1984). Branched-chain amino acid metabolism. Annual Review of Nutrition, 4, 409-454.

(2) Rennie, M. J. (1996). Influence of exercise on protein and amino acid metabolism. In: Handbook of Physiology, Sect. 12: Exercise: Regulation and Integration of Multiple Systems (Rowell, L. B. & Shepherd, J. T., eds.), chapter 22, pp. 995–1035. American Physiological Society, Bethesda, MD

(3) Shimomura, Y., Murakami, T., Nakai, N., Nagasaki, M., & A. Harris, R. (2004). Exercise promotes bcaa catabolism: Effects of bcaa supplementation on skeletal muscle during exercise. The Journal of Nutrition, 104(6), 15835-15875.

(4) Nosaka, K., Sacco , P., & Mawatari, K. (2006). Effects of amino acid supplementation on muscle soreness and damage. International Journal of Sports Nutrition and Exercise Metabolism, 16(6), 620-635.

(5) Anthony, J. C., Anthony, T. G., Kimball, S. R., & Jefferson, L. S. (2001). Signaling pathways involved in translational control of protein synthesis in skeletal muscle by leucine. The Journal of Nutrition, 131(3), 856-860.

(6) Di Pasquale, M. G. (2007). Amino acids and proteins for the athlete: The anabolic edge, second edition. Boca Raton, Florida: CRC Press.

(7) Layman, D. K. (2003). The role of leucine in weight loss diets and glucose homeostasis. The Journal of Nutrition, 133(1), 261-267.

MacLean, D. A., Graham, T. E., & Saltin, B. (1994). Branched-chain amino acids augment ammonia metabolism while attenuating protein breakdown during exercise. The American Journal of Physiology, 267(6), 1010-1022.

Carli, G., Bonifazi, M., Lodi, L., Lupo, C., Martelli, G., & Viti, A. (1992). Changes in the exercise-induced hormone response to branched chain amino acid administration. European Journal of Applied Physiology, 64(3), 272-277.