BCAAs — What are they and should you be supplementing them?

The short answer: Don’t waste your money

The longer answer:

Very briefly, proteins, as in the the food we eat, but also in our body, and made up of chains of amino acids. These can be considered the “building blocks” of protein. When many amino acids join together (100s) they form proteins.

When we eat food, during digestion, we have enzymes that break down protein to its building blocks, amino acids, and then we can use these amino acids (AAs) for various functions, include building new tissue (muscle).

There are 20 amino acids in foods we eat, 8 of which are essential (meaning we cannot make them in the body), and of them 8, 3 are the branched chain amino acids, Leucine, IsoLeucine & Valine.

The branched-chain amino acids (BCAA), isoleucine, leucine and valine, are unique in that they are principally metabolized extrahepatically (not in the liver) in the skeletal muscle.

So, why do some supplement with them? Well, we know that consuming protein after training can help augment (increase) the muscle building response (increase MPS) [1]. Just as a side note, that does not mean you need protein immediately after your workout [2] . And… recent evidence has shown that one of the BCAAs, Leucine, is a key AA in “triggering” that response. So, supplement companys saw the $$$. Another tangent, somewhere between 2–3g of leucine seems to be the sweet spot for most [3].

So, that’s the background, but do BCAAs work?

First of all, I am not aware of any evidence showing BCAAs having any benefit on hypertrophy, or strength, in people consuming adequate protein (at least 1.6g/kg) already.

Secondly, the BCAAs all share common intestinal transporters, so consuming BCAAs instead of just leucine can interfere with Leucine uptake in the gut, and Leucine is the important trigger, remember.

Finally, any time you consume for example 25 of whey protein, you are getting roughly 2.5–3g of Leucine, plenty of BCAAs and about 10g of EAAs (those other AAs that you also *need*). So a simple whey shake will give you the benefits, plus more! And this has been tested [4]. The study looked a little like this:

(25g whey) vs (6.25g whey + 5g Leucine) vs (6.25g whey + BCAAs w/ 5g Leucine) vs (6.25g whey + 3g leucine).

The result? 25g whey had the greatest response, with only the whey + 5g leucine matching it. So the 2–3g leucine trigger is not enough by itself.

A chicken breast (100 g) contains 470 mg valine, 375 g isoleucine, and 656 mg leucine, the equivalent of about 7 BCAA tablets. One quarter of a cup of peanuts (60 g) contains even more BCAA and is equivalent to 11 tablets [5].

One final note worth mentioning. People often are of the belief BCAAs are calorie free, and consume them during periods of fasting or low calorie. The BCAAs are probably the highest calorie proteins there are, with metabolizable energy of 5.5, 6, & 6kcal/g respectively. Compare that with your typical 4kcal/g protein. So if you are taking 10g of BCAAs to get your 5g Leucine (assuming it is dosed 2:1:1), that’s about 60kcal right there, with very little satiating effect compared to a whey shake.

Any questions, fire away. I don’t recommend BCAAs for most people, though there can always be the exception to the rule.

If you want to learn more about BCAAs, try reading some of the references. If research papers are a bit much, Joseph Agu wrote an excellent series on BCAAs starting here.

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1. Cermak, N. M., de Groot, L. C., Saris, W. H., & van Loon, L. J. (2012). Protein supplementation augments the adaptive response of skeletal muscle to resistance-type exercise training: a meta-analysis. The American journal of clinical nutrition, 96(6), 1454–1464.

2. Schoenfeld, B. J., Aragon, A. A., & Krieger, J. W. (2013). The effect of protein timing on muscle strength and hypertrophy: a meta-analysis. J Int Soc Sports Nutr, 10(1), 53.

3. Breen, L., & Churchward‐Venne, T. A. (2012). Leucine: a nutrient ‘trigger’for muscle anabolism, but what more?. The Journal of physiology, 590(9), 2065–2066.

4. Churchward-Venne, T. A., Breen, L., Di Donato, D. M., Hector, A. J., Mitchell, C. J., Moore, D. R., … & Phillips, S. M. (2014). Leucine supplementation of a low-protein mixed macronutrient beverage enhances myofibrillar protein synthesis in young men: a double-blind, randomized trial. The American journal of clinical nutrition, 99(2), 276–286.

5. Gleeson, M. (2005). Interrelationship between physical activity and branched-chain amino acids. The Journal of nutrition, 135(6), 1591S-1595S.

6. Hulmi, J. J., Lockwood, C. M., & Stout, J. R. (2010). Review Effect of protein/essential amino acids and resistance training on skeletal muscle hypertrophy: A case for whey protein.

Originally published at physiquebyscience.com on June 14, 2015.

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