The Health Benefits of Branch Chain Amino Acids


BCAAs (branch chain amino acids) consist of three essential amino acids: leucine, isoleucine, and valine. In combination, these three amino acids make up approximately 1/3 of skeletal muscle tissue in the human body. BCAAs play an integral role in muscle protein synthesis. Amino acids are the building blocks of protein. When an individual consumes food(s) containing protein, the food is digested through the intestines and stomach. During this process the protein is broken down into individual amino acids and short chains of amino acids which are then absorbed into the bloodstream. Once the amino acids are absorbed into the bloodstream, they have far reaching effects across the entire body.  They are involved in muscle repair (lean muscle building), essential brain functions, hair growth and more. BCAAs have been found to:  increase protein synthesis, potentially maintain lean muscle and support fat loss, prevent diabetes and improve insulin sensitivity, improve the testosterone to cortisol ratio, increase strength gains, and improve mood.

When adequate amounts of BCAAs are ingested, they create a metabolic pathway which results in increased protein synthesis. A clinical study in the journal Medicine and Science in Sports and Exercise found that BCAA supplementation contributed to an anabolic environment in the body. The study maintained that Leucine-enriched BCAAs (a BCAA mixture comprised of 40 percent leucine) was shown to elevate and prolong protein synthesis after resistance training. This means that more muscle tissue will be grown and muscles will be repaired faster. Now let’s examine the effects of resistance training. After a bout of intense strength training, the body shifts into a catabolic (the breaking down of muscle tissue) state, with a protein synthesis deficit. This occurs because the MAPK signaling pathway is activated post-exercise. The MAPK signaling pathway is the body’s own way of signaling muscle growth. It is at this moment that there is increase or decrease protein synthesis depending on timely consumption of the necessary macro-nutrients. The MAPK pathway is not at peak effectiveness for signaling muscle growth until it is combined with the BCAAs. Because of this, when adequate amounts of BCAAs are ingested post workout (usually in the form of a post-workout drink) the body is placed in an elevated state of hypertrophy with a positive amount of protein synthesis. This is becomes increasingly extremely for athletes because it decreases muscle recovery time while increasing the rate at which lean body mass is gained.

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One potential benefit of BCAAs is that it could potentially minimize muscle loss. A clinical study in the European Journal of Applied Physiology examined the effects of BCAA supplementation on rats who had their hind-limbs immobilized for six days and discover that the supplementation process helped to preserve protein synthesis that regulated cell growth. The BCAAs did not completely prevent protein degradation and muscle atrophy in the rats’ hind limbs, but definitely helped preserve the muscle to a greater extent when compared to the placebo group.

BCAAs have also been linked to improved body composition. Research indicates that individuals with a higher BCAA intake in their diets tend to have lower rates of obesity, lower body weight, and better body composition. At this juncture, studies suggest that leucine increases energy expenditure and improves glucose tolerance. A review in the journal Aging found that BCAAs, and in particular leucine, “appear to have unique obesity-reducing effects” because they decrease food intake and body weight by increasing the gene signaling of the mTOR pathway, an enzyme that that regulates cell growth, cell proliferation, cell motility, cell survival, protein synthesis, and transcription. A study of 4429  animal and human subjects examined the beneficial effects of supplementation with BCAAs, including leucine, isoleucine, and valine on body weight. The objective of this study was to examine the association between dietary BCAA intake and risk of overweight status/obesity across multi-ethnic populations. INTERMAP, The International Study of Macro-/Micronutrients and Blood Pressure, conducted it’s cross-sectional epidemiological investigation in China, Japan, the UK, and the US and discovered that the group with greater amounts of BCAAs in their diets were leaner and had significantly less chance of being overweight than those with lower BCAA intake. Based on findings, researchers hypothesized that leucine supplementation in conjunction with the other BCAAs, could be the “magic bullet” for a lean body composition.

BCAA supplementation has become increasingly common as a possible treatment for diabetes. A primary way that BCAAs prevent aging and support a lean body composition is by improving insulin sensitivity and glucose tolerance. High insulin levels accelerate aging and nerve/cell damage, making it essential to control this hormone. Researchers are currently using BCAAs as a treatment for diabetes. A recent study in the journal Diabetologia found that the individuals who were in a weight loss study who lost the most weight had the highest BCAA levels. What they also found was a stronger correlation between improvements in insulin sensitivity and BCAA levels than weight loss. Another clinical study found that rats that were given BCAAs in conjunction with a high-glucose solution, had higher levels of glucose tolerance when compared to the placebo group. The BCAA group was able to process the glucose for energy more effectively than the less tolerant placebo rats.

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Another potential benefit of BCAA supplementation is that it may help minimize the cortisol response induced from stress of exercise. As a stress hormone, cortisol degrades muscle which can lead to adipose fat gain in the long-term. However, less cortisol would lead to more favorable conditions of elevated testosterone which will result in faster muscle tissue recovery and increased muscle development.  Two clinical studies highlighted the role of BCAAs in decreasing muscle protein degradation. A 2010 study compared a placebo group and BCAA group, both of which were involved in a resistance training program. The results found that the group taking BCAAs in conjunction with resistance training produced significantly higher testosterone levels than a placebo group. In addition, the participants who took BCAAs had a lower cortisol response. This finding is considered significant because both strength gains and a decrease in protein degradation are more closely correlated with a better testosterone to cortisol ratio than with total testosterone levels.

A recent study in the Chinese Journal of Physiology tested the effect of a drink of BCAAs, arginine, and carbs (BCAA drink) on hormone response and psychological state after a single bout of exhaustive exercise. Testosterone was up significantly and the testosterone to cortisol ratio was much more favorable with the BCAA drink than with a placebo. Testosterone peaked at the 120-minute recovery point, which was indicative of a prolonged anabolic effect. In addition, participants were given a mood states evaluation to measure psychological condition after the extremely intense workout. Participants who received the BCAA drink recovered much more quickly and had a lower fatigue score on the evaluation than the participants that received the placebo.  Further research was conducted to determine the effects of BCAA concentrations on muscle break down.  Comparing a drink that was 10 grams of protein with 18 percent leucine to a similar drink that was 35 percent leucine, results suggest that higher leucine concentrations could possibly elicit greater anabolic protein signaling, which would mean less muscle breakdown from the degrading effects of cortisol.

Physical benefits aside, BCAAs have also been discovered to have neurological benefits. Researchers note that for older individuals who sometimes have difficultly eating enough high-quality protein, BCAA supplementation is essential. Supplementation of BCAAs will improve production of the neurotransmitters, boosting cognitive function. In addition, BCAAs have been shown to play an important role in the synthesis of the neurotransmitters glutamate and GABA, which help to generate energy and drive for an individual when needed and suppress energy and drive when it is not needed. Studies have shown that supplementing 10 grams of essential amino acids, which include BCAAs, can help to improve depressive symptoms and overall physical performance in an elderly population. Currently, BCAAs have been hypothesized to increase levels of brain serotonin, improving mood and decreasing depression.

Although there may be slight contradictions in pre-existing research regarding BCAA supplementation there is enough positive third party scientific evidence to warrant its application. Based on numerous clinical studies, it is evident that BCAA’s have a significant role in increasing  protein synthesis (muscle recovery), maintaining lean muscle while supporting fat loss, improving insulin sensitivity in diabetics, improving the body’s testosterone to cortisol ratio, and improving mood through the release of certain neurological chemicals. There may also be strength increases accompanied by BCAA supplementation; however, further research is needed to determine whether this is a direct or indirect effect of BCAA supplementation. According to which is an independent testing company, there is no apparent toxicity or danger associated with BCAA supplementation. ConsumerLab  recommends anywhere from 1 to12 grams. The typical ratio of BCAA’s is 50% leucine, 25% isoleucine, and 25% valine. This ratio lines up with current research on BCAA supplementation. For optimal benefit, BCAAs should be taken with water before and after training with any other pre or post workout supplement or meal.