Editors Note: This is Part 4 of the Ultimate Protein Guide.  In this version, the minds at Examine.com (where brilliance is everywhere) tackle the question of amino acids. In particular, we review branched chain amino acids (BCAAs), essential amino acids (EAAs), and glutamine, and consider their role in muscle building and muscle recovery.  

The information below is a purely scientific analysis of the benefits you receive from different types of amino acids. In general, if you receive enough protein in your diet, you probably don’t “need” to supplement with additional aminos.

I’ve experienced (non-scientific) benefits from taking additional BCAAs, whether it’s with recovery or muscle growth. Therefore, they are typically part of my training routine, especially when following an Alpha-style diet, such as the one prescribed in Man 2.0

To determine if you should add amino acids to your diet, read this and decide for yourself. -AB

Do You Need To Supplement with Amino Acids?

By Kurtis Frank and Sol Orwell

Branched Chain Amino Acids (BCAAs)

Branched chain amino acids (BCAAs) are a collection of three amino acids with a side chain that is branched. They are leucine, isoleucine, and valine (usually in a 2:1:1 ratio).

They are marketed mostly to athletes during periods of caloric deprivation, as these BCAAs are found in all protein sources. Their niche lays in the fact that sometimes you only want these three amino acids and all the others merely add unwanted calories.

Leucine itself is known to be an anabolic factor and signal for muscle protein synthesis, and in the presence of inadequate nutrition (you’re eating less than normal) this anabolic signal appears to stall muscle cell loss.

This anabolic effect does, however, extend to most cell types rather than just muscle. While BCAAs tend to be high in leucine, all complete protein sources contain enough leucine to provide a benefit.

When looking at studies, comparing BCAAs to no protein intake makes it appear that BCAAs do benefit you. However, the limited studies comparing BCAAs to another protein source showed that BCAAs were no better.

While the nutritional label on BCAAs may not list any calories, this is because the FDA allows anything under 5 calories (per serving) to be listed as 0 calories.

BCAAs may have a role in preserving skeletal muscle mass during periods of severe caloric deprivation, but that is not something most people experience (and again, can be mitigated by consuming protein). The decision to use BCAAs may come down to a decision between 30 calories and 120 calories.

The bottom line: BCAAs will save you some calories, but their benefits over other protein sources is marginal, at best.

Essential Amino Acids (EAAs)

Essential amino acids are in a grey area between BCAAs and whole protein sources, and rather than giving only the three BCAAs they give all amino acids that have the aforementioned essential status.

The most practical usage of essential amino acids would be to supplement the diet of a vegan who generally under-consumes protein and is not otherwise using protein supplementation. Additionally, they confer the same benefits as BCAAs, although with a slightly higher caloric content.

Practically speaking, however, the previous choice between 30 and 120 calories has now become a pedantic 80 calories and 120 calories. Practical situations in which EAAs are useful are highly limited to times where every calorie becomes critical.

The bottom line: EAAs are useful if you have no source of protein. Otherwise, hard to see any additional benefit.


Glutamine gets special mention here due to its popularity as a standalone supplement.

When looking at isolated muscle cells, glutamine introduction above normal levels appears to cause dose-dependent increases in muscle protein synthesis. It is from this information, as well as the clinical usage of glutamine in burn victims (to aid in tissue regeneration) that glutamine is marketed as a muscle building agent.

At this moment in time, glutamine for the purpose of building muscle tissue in healthy people is wholly unsupported. (Sorry supplement industry.) Glutamine deficiency, the prerequisite for glutamine actually building muscle, is probably more uncommon in nonclinical settings than scurvy.

That being said, because the intestines sequester glutamine so much the supplement does indeed make a good intestinal health supplement (which can also just be mimicked by protein sources with a high glutamine content such as casein).

The bottom line: Do not bother with a glutamine supplement. You will get enough via protein sources. However, it might help with intestinal health and your immune system.

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