The main role of dietary amino acids is as components of body proteins. There has been growing interest in identifying functional benefits of individual amino acids beyond their role as constituents of proteins. While there are more than 300 common amino acids, only 20 different amino acids are incorporated into body proteins. Of those 20 amino acids, 9 are considered essential” amino acids (EAAs) because they are not synthesized in the body.
Amino Acids Drive Protein Turnover
Proteins in the body are in a constant state of breakdown and resynthesis (turnover). Some of the amino acids released from protein breakdown are irreversibly oxidized (damaged) and therefore not available for reincorporation into newly synthesized protein. Dietary amino acids are therefore necessary as precursors for the production of new protein so that the rate of protein synthesis can be stimulated sufficiently to balance the rate of protein breakdown, thereby maintaining the protein mass of the body constant.
So, the question isn’t if you need dietary amino acids—we can’t live without them. The question is if we need to supplement our normal dietary intake of protein food sources with an amino acid supplement.
Why Essential Amino Acid Supplements Are a Must-Eat
EAAs are the only macronutrients required for survival. EAAs are the “active” components in dietary protein that help activate protein synthesis. A normal diet containing high-quality proteins should deliver adequate amounts of EAAs to meet minimal requirements. However, dietary supplements of EAAs can provide benefits not achievable with even high-quality protein food sources.
Essential amino acid supplements can play an indispensable role in optimal amino acid and protein nutrition. EAAs stimulate muscle protein synthesis to a greater extent than any intact protein can. On a gram-for-gram basis, EAAs are at least three times as effective as whey protein in stimulating muscle protein synthesis. This is due in part to the rapid and complete absorption of free EAAs—peak concentrations of EAAs are much higher and more rapid than concentrations of intact protein. Further, the relative amounts of each EAA in a dietary supplement can be formulated to optimally stimulate muscle protein synthesis in specific circumstances, such as during exercise or recovery from surgery.
The beneficial effects of amino acid supplements can be achieved with minimal caloric intake so you can stay on track with your healthy weight goals. Beneficial effects of essential amino acid supplements have been demonstrated with doses less than 4 grams, which is equivalent to only 16 calories. In contrast, even high-quality dietary protein food sources contain 50% or more non-protein calories in the form of carbohydrate and/or fat, and also contain more than half nonessential amino acids that have little value in terms of stimulating protein synthesis. Consuming approximately 4 grams of EAAs in the context of high-quality intact protein requires 100 kcal, or about five times the calories of an amino acid supplement.
The Best Amino Acid Supplement for Muscle Growth
Clinical trials have shown benefits of supplementing the diet with EAA formulations designed to increase muscle strength and muscle mass, control plasma lipids and reduced liver fat, and accelerate recovery from serious injury or surgery. But the composition of an essential amino acid supplement is vital, not only in terms of stimulating protein synthesis but also maintaining an ideal balance of all EAAs in the blood.
It is crucial that all EAAs be provided in a dietary supplement. Consumption of supplements containing only some of the EAAs, such as BCAA supplements (leucine, isoleucine, and valine) have minimal effect on protein synthesis. The synthesis of complete proteins requires adequate availability of all the EAAs. Further, the many other functions of amino acids in the blood, including the production of neurotransmitters, blood flow regulation, immune function, and improvement of plasma lipid profiles are contingent on a balanced composition of the blood amino acids. For this reason, a balanced formulation containing all the EAAs is the optimal amino acid supplement.