Health Dangers of BCAA in Protein Supplements

Branched-chain amino acid (BCAA) supplements are often used by athletics and fitness fanatics to increase muscle mass and enhance performance.

Protein Powder

Image Credit: Nick Starchenko/

However, research suggests that excessive consumption supplements may pose health risks.

What are BCAAs?

Food-derived proteins are broken down during digestion releasing amino acids which are then used by the body to create proteins required by bodily organs, tissues, and cells.

The body can code for 20 different types of amino acids. However, some amino acids are considered to be essential whereby they cannot be synthesized in large enough quantities by the body. Therefore, they must be consumed as part of a balanced diet. Non-essential amino acids are produced by the body.

There are nine types of essential amino acids: phenylalanine, histidine, threonine, isoleucine, leucine, tryptophan, lysine, valine, and methionine.

Of the nine essential amino acids, leucine, valine, and isoleucine are referred to as branched-chain amino acids. Generally, all three BCAAs act as a substrate to produce protein and energy.

Leucine plays an additional role as an intercellular signaling regulator for the mechanisms of protein production. Typically, BCAAs are found in foods rich in proteins such as eggs, fish, red meat, dairy and chicken as well as soy proteins, nuts, and lentils.

Research has found that as the production of protein is continuous, there is a need to replace lost protein. This need for continued protein intake has increased the popularity of BCAA supplements.

For example, the inclusion of BCAA supplements into the diets of bodybuilders, athletes, and gym-goers has increased due to their proposed muscle-building benefits and ability to enhance performance.

Health Dangers of BCAA Protein Supplements

Despite their proposed benefits on muscle growth, research has suggested that BCAA protein supplements may cause adverse health consequences if taken in excess.

The researchers used a mouse model to investigate the effects of consuming BCAAs as well as other essential amino acids.

The mice were separated into four main conditions: those who were to consume the standard amount of BCAAs; those required to consume twice the recommended amount; those to consume half the standard amount; and those to consume 20% of the recommended amount over their lifetime.

The researchers found that overall the consumption of BCAA supplements led to an increase of blood branched-chain amino acid levels. This resulted in a BCAA competing with tryptophan for brain transportation. When both amino acids access the brain, they then cause different effects. Tryptophan is considered to be one of the only precursors for serotonin, a hormone that improves mood and aids sleep amongst other roles.

In instances where there is an increase in BCAA blood levels, BCAA takes tryptophan’s position within the brain, which results in reduced synthesis of serotonin, decreasing mood.

In addition to serotonin’s role in mood enhancement, it also plays a role in the regulation of appetite. Within the study, due to lower serotonin levels and excess BCAAs, the researchers noted that the mice that consumed twice the standard dosage of BCAA overate and became obese, shortening their lifespan.

BCAA and Cardiovascular Diseases

In addition to the effects on mood, the excess consumption of BCAA supplements may be linked to an increased susceptibility to cardiovascular disease.

Research has shown that the metabolism of amino acids is potentially involved in the development of heart disease. For example, those with heart issues have been found to have increased concentrations of BCAAs.

BCAA and Diabetes

Similarly, to cardiovascular diseases, high levels of BCAA are correlated to the onset of type 2 diabetes. Currently, it is unclear whether increased BCAAs are purely markers of the disease, or their increase is a consequence of a loss of insulin or whether raised BCAA levels are responsible for insulin resistance.

Do BCAA Supplements Increase Muscle Mass?

There is mixed evidence regarding the effectiveness of BCAA supplements to increase muscle mass in its users.

Research investigating such effects between those who took BCAA supplements and a placebo found that those who took the supplement reported increase energy metabolism and reduced levels of substances attributed to muscle damage.

However, other researchers proposed there is a lack of consensus regarding the effects of BCAAs as a nutritional supplement.

Despite disagreement in the scientific literature, it is indicated that potential overconsumption of BCAAs may pose health risks. However, more research is needed to further investigate the impact of both typical and excessive consumption.


  • Wolfe, R. R. (2017). Branched-chain amino acids and muscle protein synthesis in humans: myth or reality? Journal of International Society of Sports Nutrition. DOI: 10.1186/s12970-017-0184-9
  • Solon-Biet, S. M., Cogger, V. C., … Simpson, S. J. (2019). Branched-chain amino acids impact health and lifespan indirectly via amino acid balance and appetite control. Nature Metabolism. DOI:
  • Holecek, M. (2018). Branched-chain amino acids in health and disease: metabolism, alterations in blood plasma, and as supplements. DOI:
  • Bifari, F., & Nisoli, E. (2016). Branched-chain amino acids differently modulate catabolic and anabolic states in mammals: a pharmacological point of view. British Journal of Pharmacology. DOI: 10.1111/bph.13624

Further Reading

Last Updated: Mar 12, 2020


Please use one of the following formats to cite this article in your essay, paper or report:

  • APA

    Bennett, Chloe. (2020, March 12). Health Dangers of BCAA in Protein Supplements. News-Medical. Retrieved on June 19, 2024 from

  • MLA

    Bennett, Chloe. "Health Dangers of BCAA in Protein Supplements". News-Medical. 19 June 2024. <>.

  • Chicago

    Bennett, Chloe. "Health Dangers of BCAA in Protein Supplements". News-Medical. (accessed June 19, 2024).

  • Harvard

    Bennett, Chloe. 2020. Health Dangers of BCAA in Protein Supplements. News-Medical, viewed 19 June 2024,


The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News Medical.
Post a new comment

While we only use edited and approved content for Azthena answers, it may on occasions provide incorrect responses. Please confirm any data provided with the related suppliers or authors. We do not provide medical advice, if you search for medical information you must always consult a medical professional before acting on any information provided.

Your questions, but not your email details will be shared with OpenAI and retained for 30 days in accordance with their privacy principles.

Please do not ask questions that use sensitive or confidential information.

Read the full Terms & Conditions.