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If you’re an athlete or are in the process of trying to change your body for the better, you may have heard of the benefits of BCAAs (Branched Chain Amino Acids—leucine, valine, and isoleucine). They sound great—the BCAAs are known to reduce muscle soreness, improve fat burning, and reduce the breakdown of muscle cells.

But what do these claims mean in real life?

After all, BCAAs aren’t cheap and they’re amino acids that can be gotten through food, so why not just eat a lot of protein and get the same benefits?

In some cases that’s the perfect plan. In others, BCAA supplementation can make a world of difference in body composition and performance. This article will discuss the pros and cons of BCAAs so you can get the most out of your efforts.

Pros of BCAAs
#1: BCAAs have a branched chain that makes it easier for the body to convert each amino acid into energy.

The BCAAs are essential amino acids, which means that the body is unable to synthesize them out of other amino acids. They must be ingested through food or other supplements. This may seem like a downer, but the good news is that the “branched chain” composition makes it easier for the body to utilize the amino acid building blocks during intense exertion.

#2: BCAAs trigger protein synthesis and inhibit the breakdown of muscle cells.

Based on the availability of amino acids, the body is constantly in a fluctuating state of muscle loss and gain. Any time you replenish that pool of building blocks by eating protein that contains the BCAAs, it’s a good thing, promoting muscle development.

Combining BCAA intake with weight training results in maximal protein synthesis because they both trigger a key muscle-building pathway in the body called mTORC1.

Theoretically, this means that supplementing with BCAAs during exercise would maintain serum BCAA levels and lead to greater protein synthesis. However, if you eat a high-BCAA containing protein before and after your workout, supplementing with BCAAs is unlikely to lead to any measureable differences in muscle mass gains.

BCAA supplementation becomes valuable for maintaining muscle in the following situations:

You are training fasted or are doing very long-duration endurance exercise. For example, supplementing with BCAAs during an Ironman or even a marathon would provide simultaneous nutritional support to prevent muscle tissue loss.

You don’t have time to eat pre- or post-workout. Quite simply, BCAAs are convenient and can be taken in capsule form or gotten in a BCAA or whey protein powder.

You are a vegetarian. Vegetarians are hard pressed to get enough of one particular BCAA, leucine, which has the most powerful stimulating effect on protein synthesis. Seeds, soy, and some vegetables like watercress do contain leucine, but the concentration is miniscule compared to whey protein, meat, or eggs.

#3: BCAAs play an important role in energy production during exercise.

Besides keeping your muscles from “cannibalizing” themselves, BCAAs can be burned as energy to maintain ATP energy levels during glycogen-depleting exercise.

Isoleucine helps the body use energy by facilitating glucose uptake into cells. This, combined with the fact that leucine increases fat oxidation, allows for a more flexible metabolism, which is great for fat loss but also key for peak endurance performance.

Supplementation is most relevant if you’re doing endurance exercise with a high catabolic component and no additional weight training. In this situation you want to take every advantage to spare muscle loss, and a BCAA supplement is convenient during workouts and easy on the stomach if appetite is suppressed.

#4: BCAAs & taurine reduce muscle soreness from intense exercise.

A series of studies on both trained and untrained individuals show that BCAAs are worth the time and money to reduce (not prevent) DOMS muscle soreness in response to both resistance and endurance exercise.

For example, taking 100 mg/kg of BCAAs reduced muscle soreness at 48 hours and allowed for faster recuperation of strength in untrained women—the population most at risk of suffering from severe DOMS.

A more recent study found that BCAAs have a synergistic effect when paired with the amino acid taurine. Untrained men took either a placebo, just taurine, just BCAAs, or 2 grams of taurine and 3.2 grams of BCAAs 3 times a day for 2 weeks. Then they did a muscle damaging eccentric workout.

The group that took taurine and BCAAs experienced much less muscle damage and had less muscle pain over the 4-day recovery period after the workout than all of the other supplementation groups.

Together, taurine and BCAAs convey three benefits:

First, they improve the water content in muscle fibers, which leads to less muscle damage.

Second, providing a greater pool of amino acids may improve sensitivity in the contractile part of the muscle fiber to calcium, while inhibiting the production of creatine kinase, a waste byproduct that accumulates and promotes the feeling of muscle fatigue.

Third, taurine and the BCAAs decrease oxidative stress. Simply, this dynamic duo reduces the “garbage” produced during intense training, which means less DOMS and faster recovery.

#5: Reduce fatigue in long duration exercise.

One of the most exciting effects of BCAAs is how they reduce fatigue in the central nervous system. As intense training progresses and serum BCAA levels fall, you experience an influx of the amino acid tryptophan into the brain. This leads to the production of the neurotransmitter serotonin, causing fatigue.

Scientists who study the limits of human performance believe that the real limiting factor in performance is when the brain tells you “I’m done.” BCAAs are one solution to keep your brain from giving up on you. For example, in one study, subjects who took 300 mg/day of BCAAs for 3 days and then completed in an exhaustive exercise trial had 17.2 percent greater resistance to fatigue compared to a placebo.

Cons Of BCAAs
#1: They deplete B vitamins.

The B vitamins are critical for amino acid metabolism and can become depleted when you take high doses of the BCAAs. This can cause serious health issues since the B vitamins are essential for everything from managing anxiety and cognition to energy metabolism and avoiding food cravings.

For example, vitamin B6 is necessary for the production of an enzyme called Branched Chain Keto Acid Dehydrogenase, which is required for the body to effectively break down and utilize BCAAs.

Another enzyme involved in BCAA metabolism requires four other B vitamins: thiamin (B1), riboflavin (B2), niacin (B3), and pantothenic acid (B5).

These enzymes are limiting factors in BCAA metabolism. If you’re mega-dosing BCAAs during training, they will eventually be affected, as will the hundreds of other biological processes that rely on the different B vitamins.

The solution is to avoid mega-dosing BCAAs and eat plenty of vitamin B-foods. Here are some of the top vitamin B containing plants: spinach, parsley and other leafy greens, broccoli, beets, asparagus, lentils, bell peppers, papaya, orange, cantaloupe.

The B vitamins are also present in animal products so varying your diet to include fish, meat (especially liver) and eggs is recommended.

#2: May lead to low serotonin levels.

Serotonin is a calming, relaxing neurotransmitter that boosts mood and aids sleep. It can become easily depleted on high-protein low carb diets, and evidence suggests supplementation of BCAAs around exercise may be problematic for serotonin levels as well (though good for work capacity and endurance performance).

It works like this. As mentioned above, tryptophan is a precursor that is used by the body to manufacture serotonin. The presence of BCAAs will inhibit tryptophan influx into the brain, reducing serotonin levels. Low serotonin is linked with depression and low mood.

Those most at risk of low serotonin are anyone on a low-carb diet who is getting a very high protein intake. The simple solution is to include carbs in your evening meal to provide the body with what it needs to manufacture serotonin and give you a lift. Try beans, fruit, or starchy vegetables.

The most well known (but incorrect) serotonin-raising trick is having milk before bed. Although it does contain tryptophan, milk is also packed with BCAAs, which compete for passage across the blood brain barrier and reduce tryptophan influx. People who swear by milk for sleep are most likely getting a psychological effect, which is just as good in real life.

#3: BCAAs aren’t a supplement for high-quality protein foods.

Although most people aren’t going to be relying on BCAAs in the absence of foods for their amino acid needs, research shows there is a trend among young men to do just this. Scientists have identified a new eating disorder profile where men are favoring supplements over real food.

This is a bad choice and it sets you up for nutrient deficiencies. Everyone needs to include protein foods in their diet to get the 19 other essential and non-essential amino acids that the body needs for tissue repair and peak function. Although the 3 BCAAs account for about 35 percent of the amino acids in muscle proteins, studies consistently show that protein foods or supplements that contain a larger array of total amino acids trigger greater protein synthesis.

Protein foods also provide other nutrients that are paramount for athletic performance and health such as carnosine, carnitine, glutamine, creatine, and vitamin B12.

Finally, protein has a major effect on keeping you satisfied and without hunger, which is key for weight management and useful for fat loss.

Now, someone might wonder if the near absence of calories in BCAAs might make them a good tool for creating a calorie deficit.

It’s never been tested, but it’s probably a bad idea: The process of chewing food has a primary effect on the release of hunger-reducing hormones and feelings of satiety. Plus, you’d miss out on all the extra nutrition provided in protein, and while BCAAs are a great tool in certain situations, they aren’t cheap.

Final Words: BCAAs are an effective tool for supporting the body in athletic performance and recovery. Avoid pitfalls to a high BCAA intake by getting plenty of B vitamins, cycling carbs post-workout and pre-bedtime, and get the majority of protein from whole protein sources.

References

Audhya, Tapan. Role of B Vitamins in Biological Methylation. Health Diagnostics and Research Institute. Retrieved 30 May 2015. http://www.hdri-usa.com/assets/files/role_of_b_vitamins_in_biological_methylation.pdf.

Ra, S., et al. Additional Effects of Taurine on the Benefits of BCAA Intake for the Delayed-Onset Muscle Soreness and Muscle Damage Induced by High-Intensity Eccentric Exercise. Advances in Experimental Medicine and Biology. 2013. 776, 179-187.

Bajotto, G., Sato, Y., et al. Effect of BCAA Supplementation During Unloading on Regulatory Components of Protein Synthesis in Atrophied Soleus Muscles. European Journal of Applied Physiology. 2011. 111, 1815-1828.

Borgenvik, M., Nordin, M., et al. Alterations in Amino Acid Concentrations in the Plasma and Muscle in Human Subjects during 24 Hour of Simulated Adventure Racing. European Journal of Applied Physiology. 2012. Published Ahead of Print.

Da Luz, Claudia, Nicastro, H., et al. Potential Therapeutic Effects of BCAA Supplementation on Resistance Exercise-Based Muscle Damage in Humans. Journal of the International Society of Sports Nutrition. 2011. 8(23).

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Hsu, M., Chien, K., et al. Effects of BCAA, Arginine, and Carbohydrate Combined Drink on Post-Exercise Biochemical Response and Psychological Condition. Chinese Journal of Physiology. April 2011. 542), 71-78.

Jackman, S., et al. Branched-Chain Amino Acid Ingestion Can Ameliorate Soreness From Eccentric Exercise. Medicine and Science in Sports and Exercise. 2010. 42(5), 962-970.

Shimomura, Y., et al. Branched-Chain amino acid Supplementation Before Squat Exercise and Delayed-Onset Muscle Soreness. International Journal of Sport Nutrition and Exercise Metabolism. 2010. 20(3), 236-244.