BCAAs vs EAAs

Dr Francesca Alves, PhD

Most people are aware of the importance of adequate protein intake to maintain and build muscle mass. Just like carbohydrates are broken down into glucose to fuel energy, proteins are broken down into amino acids to fuel muscle synthesis and a range of other important biological functions depending on the composition of amino acids. Understanding the structure and function of amino acids can help you personalize amino acid supplement profiles to achieve maximum health benefits.

First, let's understand the basic structure and amino acid groupings. There are 20 common amino acids that can be grouped according to their chemical compositions. All amino acids consist of an amino acid backbone with a central carbon atom (called the alpha carbon) bonded to four groups: a hydrogen atom, an amino group, a carboxyl group, and a side chain (R group), which varies among amino acids. Three of these amino acids—leucine, isoleucine, and valine—have a ‘branched’ R group. These are called "branched-chain" amino acids (BCAAs) because of this unique chemical structure. BCAAs primarily promote muscle protein synthesis and reduce muscle breakdown during exercise1. Leucine, in particular, plays a critical role in stimulating muscle growth2.

Another way to group amino acids is based on their availability. The human body can synthesize a subset of amino acids—called ‘non-essential’ amino acids—but 9 other amino acids must be sourced from the diet. These ‘essential’ amino acids (EAAs) sourced from diet and supplements include the BCAAs. An EAA supplement will cover all essential amino acids, which is great for supporting a broader range of physiological functions, including tissue repair, nutrient absorption, and neurotransmitter synthesis (e.g., tryptophan is a precursor for serotonin—a neurotransmitter required for healthy cognition)3. EAA supplements are particularly beneficial for individuals with restricted diets (i.e., vegetarians and vegans) as it is more difficult to achieve adequate EAA absorption. However, the level of BCAAs in a general EAA supplement may not be maximized for the specific function of muscle protein synthesis and repair1. Thus, stacking a BCAA supplement may be necessary (or ‘essential’) for active or metabolically stressed (i.e., age-related disorders) individuals to enhance exercise performance, reduce fatigue, and aid in muscle recovery4.