Scientific research confirms the importance of BCAA amino acids for both maintaining and increasing muscle mass in bodybuilding and sports in general, as well as for a large number of other vital processes.
One of the axioms of sports dietetics states that the benefit of any substance for the body is not proportional to the dosage in which it is taken (“the more, the better”). This is also true for BCAA amino acids.
Regular consumption of them in doses exceeding the body’s needs can lead to serious health consequences. And the need is individual for each person.
It is also important to consider that sources of BCAA are not only special sports supplements but also all protein products with high biological value (both natural products and sports proteins).
Below we will discuss the potential side effects and harm to health from the consumption of BCAA amino acids.
Main thoughts:
Reason for the potential harm of BCAA amino acids to health
First, a bit of philosophy, a few obvious truths that should be clear to anyone with common sense, but are often neglected by many in practice.
It is a common belief that if any product for enhancing muscle growth (including BCAA amino acids) is sold in a sports nutrition store, then gaining mass is the only function it performs when it enters the body.
This is not the case.
Let me explain with an analogy.
When we take a painkiller to relieve pain in a specific part of the body, after its absorption and entry into the bloodstream, it is transported to every cell in the body, not just “to the head,” having a systemic effect.
This is why the instructions for use of almost any medication contain a section with a list of possible side effects.
As for BCAA amino acids, in addition to functions related to the growth and maintenance of muscle mass, which many are aware of, they also actively participate in a large number of other metabolic processes in the body.
Excessive consumption of amino acids can disrupt the course of these processes, which explains the potential harm of BCAA and other amino acids.
In particular, the consumption of arginine – another popular amino acid in bodybuilding – in free form suppresses the actions of some other amino acids in the body. See Arginine in Sports and Bodybuilding: Benefits, Harms… Uselessness. Comparison of Views from Popular Internet Resources and Scientists.
And an excess of methionine – an amino acid known in bodybuilding for its anabolic properties – is a factor in the development of cancer.
Scientists say that taking BCAA in free form (as supplements) may increase the risk of developing certain diseases, such as diabetes and cancer.
“Beneficial for health or muscle gain” does not mean “the more, the better.” The reason for the potential harm of BCAA to health is their complex action on the body.
The question of the harm of BCAA to health resonates closely with the questions of the harm of protein and other amino acids (in particular, side effects of taking glutamine) when consumed in large doses. For a complete understanding of the topic, we recommend familiarizing yourself with these materials.
Also read What are BCAA needed for in sports and bodybuilding?, where we discuss what scientific research says about the benefits of these amino acids for athletes.
Harm of BCAA: Doctors’ Reviews
Below we will look at the reviews of some doctors and experts regarding the potential harm of BCAA.
1 BCAA and Cancer
“BCAA amino acids are a very powerful stimulant of one of the most important mechanisms of metabolic regulation – the mTOR enzyme.
Excessive amounts of protein, BCAA amino acids, and leucine, in particular, have a very negative impact on mTOR activity.
“This is acceptable when the goal is to gain muscle mass, but constant high dosages every day is a bad idea,” notes Dr. Mercola 1.
This enzyme determines sensitivity to nutrients and, consequently, the release of certain hormones that regulate metabolism, growth, cell division, and survival.
What does this mean?
“If there are many BCAA (or protein) amino acids in the diet, the activity of the mTOR enzyme increases, cells begin to divide and grow; if the activity of mTOR is low, then the process of preserving and restoring existing cells occurs.”
An important question: which cells are we talking about in terms of division and growth?
If it’s muscle cells, then this is exactly what is needed in bodybuilding and what we expect when taking amino acids and proteins: an increase in muscle mass.
The problem, however, is that there is a great variety of cells in the human body, including malignant ones, in each of us.
“An increased level of the mTOR enzyme leads to a higher risk of cancer formation because it suppresses the natural mechanism for eliminating defective cells with mutations and mitochondria.”
At the same time, it also suppresses the body’s ability to create new mitochondria, which are like “mini power plants” for cells where energy is produced.”
The issue of protein’s harm to the body in terms of stimulating the growth of cancer cells has been the subject of numerous scientific articles and books, one of the most famous being the “China Study” – a book summarizing over 20 years of research by a world-renowned scientist who has proven the existence of this relationship in numerous experiments on humans and animals (read an interview with the author of the book here).
Dr. Mercola’s review: “One of the reasons for the possible harm of BCAA to health is the stimulation of mTOR enzyme activity, which occurs with excessive concentrations of BCAA amino acids in the blood. This can lead to the development of cancer.“
“Many patients suffering from cancer experience severe muscle wasting syndrome, and to preserve muscle mass, they are prescribed BCAA amino acids.
It is important to maintain a balance where the necessary increase and maintenance of muscle mass is ensured while, at the same time, cancer tumors do not receive nourishment for growth.”
Researchers from the journal Metabolities note 2:
“In the case of cancer, meeting the body’s normal requirement for BCAAs is complicated by the fact that the tumor also feeds on these amino acids.”
We recommend: Creatine in bodybuilding: what is it and what is it for? Scientific studies on its effectiveness for muscle mass gain
2 BCAA and diabetes
Scientific studies indicate that BCAAs can either lower or raise blood sugar levels depending on certain factors.
The journal Metabolities explains the complex role of BCAAs in diabetes 2:
“Recent studies have shown that increased concentrations of BCAA amino acids in the blood are associated with decreased insulin sensitivity and subsequent development of diabetes.
It is important to avoid consuming leucine (one of the three BCAA amino acids) in free form.
According to research, intravenous administration of leucine in free form causes a strong hyperglycemic reaction and insulin resistance, which increases the risk of developing diabetes.”
For this reason, scientists and doctors categorically do not recommend taking BCAA amino acids as supplements, as well as avoiding excessive amounts of protein in the diet.
Review from scientists (Metabolities): “Excessive consumption of BCAA amino acids may stimulate the development of diabetes. This also applies to the separate intake of the amino acids that make up BCAAs in free form, particularly leucine“
We recommend: What is glutamine for in bodybuilding? Scientific studies on its effectiveness
What to do to reduce the risk of harm from BCAAs?
When it comes to taking BCAA amino acids, it is important, as in everything in life, to maintain balance: they have undeniable anabolic effects, i.e., they are beneficial for muscle growth, but can be harmful to health when regularly taken in large doses.
“BCAAs can be very beneficial if used purposefully by athletes who train for muscle mass gain, which becomes especially important with age.
The concentrate of whey protein (not isolate) is the best, fully balanced, nutritional source of BCAA. I recommend taking it specifically, rather than BCAA amino acids in free form, which are sold in sports nutrition stores.”
Recommended: Types and differences of whey proteins. Which is the best: concentrate? isolate? or hydrolysate?
It is much easier to exceed the dosage of BCAA when you take them in the form of supplements.
Especially if your menu, like that of any “normal” athlete, is rich in natural protein products and various types of sports protein nutrition: proteins, gainers, protein bars, etc.
If this is the case – you are at risk of side effects from consuming too much protein, and BCAA amino acids, as mentioned above.
BCAA amino acids can be harmful to health if regularly taken in excessive amounts. To avoid harm, scientists and doctors recommend not taking BCAA in the form of supplements and considering their content in protein products (both natural and sports nutrition).
