Should athletes supplement with BCAAs

Should athletes supplement with BCAAs?

BCAA stands for Branched Chain Amino Acids. Amino acids are the building blocks of proteins, which are required for almost every chemical reaction and function within the human body.

BCAAs have become a very popular sports supplement due to their ability to promote muscle protein synthesis, which is essential for the body’s ongoing growth, repair and maintenance of skeletal muscle. BCAAs are named because of their appearance (“branched”) and there are three of them – leucine, isoleucine and valine.

Leucine is considered the primary BCAA due to it bringing about the most popular benefit of BCAAs – muscle growth. Leucine has been tested quite a lot in isolation, so there is more data about this BCAA compared to isoleucine and valine. Although leucine has been found to increase muscle protein synthesis (the formation of muscle), it is important to note that this has predominately been found in people who consumed less protein overall in their everyday diet.

All three BCAAs are “essential” amino acids. This means our bodies cannot create them and therefore must obtain them from food. The best foods to find BCAAs are high-quality protein foods such as:
  • - Lean meats
  • - Poultry
  • - Fish
  • - Dairy products
  • - Eggs
Generally, the highest concentrations of BCAAs are found in the dairy proteins whey and casein.

Plant sources of BCAAs include:
  • - Soybeans
  • - Baked beans and lima beans
  • - Lentils
  • - Brown rice
  • - Almonds and cashews. 


As mentioned above, BCAAs are popular with exercising individuals who want to build and/or maintain lean muscle mass. Again, many of the studies that found a benefit with BCAA supplementation occurred on the background of minimal protein intake from food. Nevertheless, possible benefits of BCAAs that could lead to performance gains include:
  • - Stimulation of muscle protein synthesis (via leucine)
  • - Prevention of muscle protein breakdown
  • - Reduction in markers of muscle damage
  • - Acting as a fuel source for muscles during exercise
  • - Extending the time it takes for the body to feel fatigued during exercise, and hence the individual can train for longer and/or harder. This occurs via BCAAs possibly
  •    interfering with the transport of tryptophan to the brain, which results in the reduced synthesis of serotonin – a neurotransmitter involved in the regulation of the
  •    sleep/wake cycle. (Please note: this finding occurred when BCAAs were loaded before exercise in beginner athletes, hence it may not have the same effect in experienced
  •    athletes)


All three BCAAs are required for the growth and production of lymphocytes, which are white blood cells involved in the immune response (the “good guys”).

One study found that surgery patients who had a higher BCAA intake post-surgery had a higher level of post-surgery lymphocytes, higher immune parameters, and better recovery. The mode/s in which BCAAs bring about improved immunity are still undetermined; however possible explanations include:
  • - Decreasing exercise-induced muscle damage
  • - Preventing a decrease in the concentration of plasma glutamine (another amino acid particularly important for wound healing and recovery from illness)
  • - Acting directly on lymphocyte metabolism (giving nourishment to the “good guys”)
  • - Or a combination of all the above.


Recently there has been hot debate about whether or not BCAAs may be of benefit with regard to maintaining lean body mass during dieting. In particular, a 2016 study claimed that supplementing with BCAAs helped maintain lean body mass during a reduced calorie diet, as compared to supplementing with carbohydrates. The reported results however, appeared to be at odds with the actual data presented. It actually appeared that the carbohydrate group lost more fat and the “preservation” of lean body mass in the BCAA group was most likely attributable to their minimal loss of body fat and not BCAA consumption.

On the subject of maintaining lean mass, many proponents of intermittent fasting drink BCAAs when they wish to perform intense or enduring exercise. The theory behind this is that the body will use the BCAAs for energy instead of breaking down muscle. This is because BCAAs are oxidised (broken down) in the skeletal muscle – whereas most other amino acids are oxidised in the liver. This is certainly a rational theory.

There is also the argument however, that because whey protein has a stronger anabolic and anti-catabolic effect compared to its equivalent in BCAA supplements, it would be more beneficial to consume whey before, during and/or immediately after exercise. The body is no longer fasting with the consumption of BCAAs anyway, so why not get the best “bang for your buck” and consume whey protein, which contains all Essential Amino Acids – not only the branched type.


There are many, many health benefits from consuming BCAAs within the diet – most of which extend beyond the scope of this article. Our bodies have an essential need for them. But is supplementation necessary for athletes?

Due to research predominately finding that BCAAs are of benefit when overall protein intake is low, it is sensible to assume that an athlete eating adequate dietary protein would gain no further benefit from supplementing with additional BCAAs. Obtaining BCAAs from real food is cheaper, tastier and more nutrient-packed.

If you are involved in very heavy training however, and are finding it difficult to eat the required amount of protein needed to fuel, repair and grow, then BCAAs might be required. Speak to our qualified sports dietitian, Hannah, who can assist you to find the best foods and supplements for you as an individual!

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