Can branched chain amino acids (BCAA) and/or glutamine improve strength and lead to muscle formation and weight gain?

sprintAmino acids are the body’s building blocks for proteins.  Leucine, isoleucine and valine are branched chain amino acids (BCAA’s), a term that refers to a particular nuance of their molecular structure. They are three of the nine “essential” amino acids that must be obtained via the diet because they cannot be synthesized by the body.

So why are branched amino acids a common supplement among weight trainers? Branched amino acids have a reputation for enhancing exercise performance and muscle recovery. But are these claims true? Studies have shown mixed results when it comes to BCAA supplementation.

In February 2011, the University of Sacred Heart in Fairfield, Connecticut released the findings of a new study on BCAA. The objective was to determine if BCAA supplementation compared to a non-caloric placebo would affect aerobic performance. In nine male volunteers with no history of training, plasma glucose and BCAA concentrations were measured before and after aerobic performance. No difference was found between the use of BCAA and placebo. More importantly, the study indicated that BCAA supplementation did not influence aerobic performance despite increased blood concentrations of BCAA and a perception of reduced exertion.

On the other hand, a study conducted in Nagoya, Japan in June 2010, sought to determine if a relationship existed between BCAA supplementation and muscle recovery. The scientists decided to induce delayed onset muscle soreness (DOMS) via squat exercises on 12 healthy, untrained females. During the trials, the participants ingested either BCAA supplements or dextrin (placebo) before squat exercises. Muscle pain and stiffness experienced after strenuous exercise, showed a peak on days 2 and 3 in both trials. However, the study revealed that BCAA supplementation greatly reduced the level of soreness when compared with the placebo. According to this study, BCAA may be beneficial in regard to reduced soreness when starting a new training program or returning from a period of rest or injury.

The drawback of the studies mentioned above, like most studies on BCAA, is the use of untrained individuals in order to determine the physiological affect of BCAA supplementation. Therefore, these findings are inconclusive in terms of their relevance to athletes. Basically, the effectiveness of BCAA supplementation is still under scrutiny, and athletes should be aware of the false-marketing claims regarding BCAA benefits for enhancing athletic performance.

Despite the limited evidence for BCAA supplementation, many athletes and body-builders tend to rely on supplements in order to gain an edge on training. Another popular supplement in the athletic world is glutamine.

Glutamine is the most abundant non-essential amino acid found in the body and has significant biochemical and physiological importance. Despite being a non-essential amino acid, glutamine at times can be “conditionally essential”, thus requiring intake from food or supplements when in state of injury or illness. Over the past ten years, many studies have concluded that glutamine is effective in treating injuries, burns, traumas and wound healing.

Exercise, which is a form of metabolic stress, can cause a depletion of glutamine in the body. This depletion is dependent upon the length and intensity of one’s training; therefore, in order to decrease the negative side effects attributed to glutamine depletion, many athletes are resorting to glutamine supplements. What does published science say about such supplementation? Unfortunately not much.

A study conducted in 1995 by TC Welbourne at Louisiana State University involved administering oral glutamine to nine healthy subjects to determine the effect on plasma bicarbonate and growth hormone, both of which are believed to have an effect on athletic performance. Two grams of glutamine were dissolved in a cola drink and ingested after breakfast. Blood samples were obtained at various time intervals, revealing that a small amount of glutamine is capable of increasing plasma bicarbonate and growth hormone. Athletic performance was not measured.

Many other controlled studies have demonstrated that there is a lack of solid evidence for enhanced physical performance as a result of glutamine supplementation. For example, a double-blind placebo controlled study performed by the University of Delaware was conducted on young male weightlifters, in order to determine the effects of high-dose glutamine ingestion on performance. The ultimate conclusion was that glutamine did not enhance weightlifting performance in resistance-trained males.

Despite a lack of scientific evidence to support glutamine supplementation, many athletes and bodybuilders prefer to continue its use in hope that dramatic muscle building effects may magically appear.  Since glutamine is a naturally occurring amino acid, it is believed to be a safe supplement. However, monosodium glutamate (MSG) hypersensitive individuals should be cautious because the body will metabolize glutamine into glutamate possibly leading to adverse reactions.

In summary, the evidence for branched chain amino acid and/or glutamine supplements for muscle formation and enhanced athletic performance is sketchy. It is unlikely that the casual athlete will derive any benefit. Short cuts don’t measure up in the long run.


Alexandra Pires-Ménard

4 responses to “Can branched chain amino acids (BCAA) and/or glutamine improve strength and lead to muscle formation and weight gain?”

  1. Steven Grandy says:

    Aren’t BCAAs available in food? None of the studies compare BCAAs against “food”.

  2. Steven Grandy says:

    Lets assume that BCAAs have a benefit. Aren’t they encoded in the proteins in all living organism and as a consequence are available in a normal diet. The control in most/all of the studies I’ve seen never compare against food.

  3. Abdul says:

    Hey Alexandra,

    I beg to differ, I mean I looked at some of the evidence behind l-glutamine and BCAA’s and I found some evidence to support supplementation with both. What do you think of these references I used in both articles?

    Look forward to hearing your thoughts 🙂

    • Joe Schwarcz says:

      it’s the old can find publications to back up is a question of weight of evidence..and that does not support the claimed benefits

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