Comprehensive Analysis of Branched Chain Amino Acids


If you’ve been involved in the fitness community for a length of time, you have likely heard of something a lot of people would consider an important component to their fitness success; namely, Branched Chain Amino Acids. As popular as Branched Chain Amino Acids have been, there has been quite some controversy on their effectiveness and even if found effective, if BCAAs have enough of an effect on our physiology to impact us to any noticeable degree. Now, before we begin dissecting the details of Amino Acids, I would like to mention that there is a sizeable amount of research on the subject, and while it would be nice to cover everything there is to know about Branched Chain Amino Acids in one article, the scope of the article would be far too broad (knowing myself, it would turn into a book); so, for the sake of this article, we will only discuss its effect in exercise performance and body composition.

What are Branched Chain Amino Acids?

Amino Acids are known as the “building blocks of protein” as they make up quality protein.
Simply, there are 20 Amino Acids.
11 of those are considered non-essential amino acids (body produces them naturally)
The remaining 9 are labeled as essential amino acids (not produced by the body)
Of those 9, we are concerned with 3.
Those 3 amino acids belong to the subclass Branched Chain Amino Acids.
Those 3 BCAAs are Leucine, Isoleucine, and Valine.

Let us leave it at that for this article.


What do these Branched Chain Amino Acids do?

BCAAs are thought to increase protein synthesis and decrease fatigue in beginner lifting populations if necessary protein requirements through normal nutrition practices are not met. Individually, each of these three Amino Acids has a role.

Leucine, the most understood of the three, has shown to have benefits in protein synthesis and anti-catabolic effects with respect to muscle (1)(2)(4). So, Leucine, due to mechanisms I won’t go into in this article (I will in following, more detailed articles) reduces loss of muscle and promotes the growth of new muscle.

Isoleucine may help in glucose uptake, independent of insulin uptake, which aids in muscle functionality during exercise (3).

Valine, on the other hand, has comparatively low effect on protein synthesis and glucose uptake while possibly having a significant effect on glycogen synthesis (3). Essentially, of the BCAAs, Valine is most responsible for glycogen production (stored glucose = stored energy).

So, in combination, all the Branched Chain Amino Acids have important roles in one extent or another. That being said, although there is evidence to say that these Amino Acids work, it matters on if they work well enough to be worth your time.

Do they work?
The research is a bit muddled on this subject. In certain respects, the intuitive understanding of Branched Chain Amino Acids from the information provided above in respect to function in physiology would indicate BCAAs do have an impact.

In respect to exercise performance, BCAAs have some research substantiating their effectiveness (5)(6). That being said, they may work for post exercise recovery (7)(10). Of course, the same, if not better post workout recovery would come from consuming complete protein as opposed to a BCAA supplement. Still, the research does indicate that BCAAs do reduce muscle damage, decrease muscle protein catabolism (9) and promote muscle synthesis (11) as well as possibly reducing DOMS (Delayed Onset Muscle Soreness) (8).

What is the recommended intake?

Easily, I could give a general number to shoot for, but I don’t want to do that, because it helps to know if you are buying a quality BCAA supplement (if you are buying a BCAA supplement) by knowing the exact quantities are optimal for each Branched Chain Amino Acid’s function in the body. That being said, here is a brief examination of the three.


According to Dr. Layne Norton and his extensive research on the subject, Leucine intake should be around 3 grams per meal, every 4-5 hours, for optimal effectiveness on muscle protein synthesis (MPS)(12). Other opinions, such as that of Dr. Jeff Volek, substantiate that an amount of 2.5 grams of Leucine is optimal (13). I should note that these recommendations were based on athletes. So, it is relatively safe to assume that anything 2.5-3 grams per meal would be sufficient for optimal MPS.

Amount: 2.5-3.0g per meal




Again, there simply is not enough research on Isoleucine to definitively say a certain amount is optimal – unlike Leucine. Now that disclaimer is out, here is what the research does tell us: as most of the research was done on rats and pigs, we have to be able to extrapolate information from those studies (which, in its own right, gives inconclusive data on application to humans) in conjunction with what we have on human trials. So, in rats, the maximum intake of .45g/kg of weight led to optimal increases in glucose uptake and no amount greater than .45g/kg (>.45g/kg) showed any benefits. In limited human trials, an intake of 12.1g of total Isoleucine (along with trace amounts of other amino acids) led to statistically significant glucose uptake. Now, because we understand what Isoleucine does we can assume that glucose uptake was impacted by the large amount of Isoleucine and not the other AAs, but again, we need more research on Isoleucine isolated.

So, having disclosed all that information, what is a decent number to aim for in light of the need for more research? According to the reputable Examine (16), you should aim for .072g/kg of Isoleucine. For now, let us aim for that marker.

Amount: .072g/kg

If research is hard to come by for Isoleucine, that is a compounded statement for Valine. Basically, there is not enough research on the amino acid to come up with a valid, reliable number for optimizing benefits. While a few studies have been done in animal trials, as I’ve explained before, it is impossible to assume, with any real certainty, that those numbers would convert correctly to human trials.

Amount: Unknown

Now that we’ve discussed each BCAA and broken down their recommended intake for optimal function, I can quickly discuss a solid total amount of BCAA to consume as BCAA supplements tend to combine the three into one dose, although it is possible to buy individual BCAAs, as well.

If you are to take a BCAA supplement, it is thought that a ratio of Leucine : Isoleucine : Valine should look roughly like this 2 : 1 : 1 if bought in a supplement. Again, there is no real evidence that this ratio is “superior” to any other ratio, but it is the one most supplement companies will sell you. If you want to get accurate, you can use the individual measures I listed for each (except Valine). Now that you know the optimal amounts of each, you should look at the supplement label and see if they are overcharging you for a high amount of one or more BCAAs that has no added benefit if taken in higher doses than the doses detailed above.

Should I buy Branched Chain Amino Acids?

Now that we understand that these BCAAs do have an impact on your physiology, we need to bring this home and put things in perspective. For you to understand this, you need to understand that just because something aids or hinders you on a micro level (cells, molecules, etc.) does not mean you will see or feel the effects on a macro level (your conscious self, limbs, muscle performance, etc).

You might be thinking, “BCAAs are essential to life”, and you are completely correct, but that does not mean supplementing them in your nutrition is going to do you any good. So, what’s the word? Is supplementing them worth it?

As I’ve briefly explained, BCAAs are necessary and you get them from complete protein sources (meats, eggs, etc), but some of their added benefits can be achieved by supplementation, as well. There is a decent amount of debate on the subject, actually. One camp believes that BCAA supplementation throughout the day, especially during a caloric deficit, is useful for all. Another camp believes BCAA supplementation is useful, but only for top tier performers (athletes, bodybuilders, elite lifters, etc). The third camp believes that although they may have physiological benefits, those benefits do not extend into enough visible results to be considered worth your worry.

Again, BCAAs are essential and we must consume them to live, build muscle, etc, but the debate is over their increased intake through supplementation, not their foundational intake through regular diet.

There are a few studies that look at amino acid intake and its impact on various factors (muscle soreness, recovery, and performance) and found some results stating that amino acids do aid in all categories (15). Still, this does not tell us if additional BCAAs help create a difference between no BCAA supplementation and BCAA supplementation. So, based on the expertise of Eric Helms, Dr. Layne Norton, among others, I would say that if your goal is to achieve general health or to achieve goals that are noncompetitive, then just focus on your protein intake and do not worry about BCAA supplementation. If your goal is to be elite and one of the best in the business, it might be useful to supplement with BCAAs to be on the safe side while taking advantage of the possible small benefits.










Writer: Nicolas Verhoeven

Bottom line, the supplementation of BCAAs versus non-supplementation needs further research, but the likelihood is low that BCAAs make a dramatic difference one way or another if a person’s nutrition is already complete. 


(1) Tom, A., & Nair, K. (2006). Assessment of Branched-Chain Amino Acid Status and Potential for Biomarkers. Journal of Nutrition, 136(1), 324-330. Retrieved January 1, 2015, from

(2): Mirza, K., Pereira, S., Voss, A., & Tisdale, M. (2014). Comparison of the anticatabolic effects of leucine and Ca-β-hydroxy-β-methylbutyrate in experimental models of cancer cachexia. US National Library of Medicine. Retrieved January 1, 2015, from of the anticatabolic effects of leucine and Ca-β-hydroxy-β-methylbutyrate in experimental models of cancer cachexia

Possible Limitations:
Study was done in mice.
Short study.

(3) Doi, M., Yamaoka, I., Fukunaga, T., & Nakayama, M. (2003). Isoleucine, A Potent Plasma Glucose-lowering Amino Acid, Stimulates Glucose Uptake In C2C12 Myotubes. Biochemical and Biophysical Research Communications, 1111-1117. Retrieved January 1, 2015, from

Possible Limitations:
Study done on rats.


(4)  Kimball, S., & Jefferson, L. (2001). Regulation of protein synthesis by branched-chain amino acids. Current Opinion in Clinical Nutrition and Metabolic Care, 39-43. Retrieved April 16, 2015, from

Possible Limitations:
Study done on fasted rats.


(5) Blomstrand, E., Hassm�N, P., Ekblom, B., & Newsholme, E. (1991). Administration of branched-chain amino acids during sustained exercise ? effects on performance and on plasma concentration of some amino acids. European Journal of Applied Physiology and Occupational Physiology, 83-88. Retrieved January 1, 2015, from

(6) Hall, G., Raaymakers, J., Saris, W., & Wagenmakers, A. (1995). Ingestion of branched-chain amino acids and tryptophan during sustained exercise in man: Failure to affect performance. Journal of Physiology, 789-794. Retrieved January 1, 2015, from

(7) Negro, M., Giardina, S., Marzani, B., & Marzatico, F. (2008). Branched-chain amino acid supplementation does not enhance athletic performance but affects muscle recovery and the immune system. Journal of Sports Medicine and Physical Fitness, 347-351. Retrieved January 1, 2015, from

(8) Shimomura, Y., Murakami, T., Nakai, N., Nagasaki, M., & Harris, R. (2004). Exercise Promotes BCAA Catabolism: Effects of BCAA Supplementation on Skeletal Muscle during Exercise.Journal of Nutrition, 134(6), 1583-1587. Retrieved January 1, 2015, from html

(9) Maclean, D., Graham, T., & Saltin, B. (1994). Branched-chain amino acids augment ammonia metabolism while attenuating protein breakdown during exercise. American Journal of Physiology, 1010-1020. Retrieved January 1, 2015, from

Possible Limitations:
Only Abstract available.

(10) Howatson, G., Hoad, M., Goodall, S., Tallent, J., Bell, P., & French, D. (2012). Exercise-induced muscle damage is reduced in resistance-trained males by branched chain amino acids: A randomized, double-blind, placebo controlled study. Journal of the International Society of Sports Nutrition, 20-20. Retrieved January 1, 2015, from


(11) Garlick, P. (2005). The Role of Leucine in the Regulation of Protein Metabolism. Journal of Nutrition, 135(6), 1553-1556. Retrieved January 1, 2015, from

(12) Norton, L., & Gabriel, W. (2008, January 1). Optimal protein intake to maximize muscle protein synthesis. Retrieved January 1, 2015, from

(13) Volek, J. (n.d.). Leucine triggers muscle growth. Retrieved January 1, 2015, from index/authors/jeff s volek phd rd/showarticle.aspx?articleid=807

(14) Wang, B., Kammer, L., Ding, Z., Lassiter, D., Hwang, J., Nelson, J., & Ivy, J. (2011, January 1). Amino acid mixture acutely improves the glucose tolerance of healthy overweight adults. Retrieved January 1, 2015, from


Possible Limitations:
Participant pool was overweight.

(15) Ratamess, N. et al (2003, May 1). The effects of amino acid supplementation on muscular performance during resistance training overreaching. Retrieved January 1, 2015, from

(16) Isoleucine - Scientific Review on Usage, Dosage, Side Effects | (n.d.). Retrieved January 1, 2015, from


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