What are amino acids? How do they work? Why are they so important to your health and fitness? Why are they so important as you age?



Your body consists of about 60% water. If you remove the water, about half of what remains would be made of protein. Amino acids are the building blocks of protein.



Every day, about 250-300 grams of the protein that builds your body breaks down. That’s the amount of protein you'd get from six chicken breasts!



When you get sick or injured, you break down even more.



Amino acids (AAs) are made of nitrogen, hydrogen, carbon, and oxygen.





Types of Amino Acids



Amino acids are either proteinogenic (protein-forming), or non-proteinogenic (non-protein-forming).



Some non-proteinogenic amino acids provide health benefits, but are not required for building tissues in the body. Some of these amino acids include carnitine, ornithine, citrulline, glycine, and beta-alanine. I'll address some of these in separate articles.



For the sake of this article, I'll focus on the proteinogenic amino acids. There are 22.



Proteinogenic AAs fall into three different categories:




Non-essential amino acids are important for your health, but they're called non-essential because you produce them on your own.



Conditionally essential amino acids can usually be produced by your body. However, under certain circumstances, your body’s production cannot keep up with its demand, so you must get them through your diet or supplements. Glutamine is a “conditionally essential” amino acid. Under high levels of stress, injury or when someone is severely burned, glutamine stores drop considerably, and and you'd need to eat or supplement glutamine to keep up with your body's needs. Glutamine is often recommended to support gut health, especially in those who may experience a leaky gut.



Essential amino acids (EAAs) are "essential" because they cannot be made by the body. You must get them through diet or supplementation.




Of the EAAs, three are superstars. These are the branched-chain amino acids (BCAAs): leucine, isoleucine, and valine. BCAAs make up about 35% of your muscle tissue.



NON-ESSENTIAL AMINO ACIDSESSENTIAL AMINO ACIDSAlanineHistidineArginineIsoleucine**Aspartic AcidLeucine**Cysteine*LysineGlutamic AcidMethionineGlutamine*PhenylalanineGlycine*ThreonineProline*TryptophanSerine*Valine**Tyrosine* Asparagine* Selenocysteine *Conditionally Essential Amino Acid**Branched-Chain Amino Acid



Protein Synthesis and Breakdown



Your ability to maintain, or build lean body mass, or muscle, is based on the levels of protein synthesis and protein breakdown throughout the day. As you age, protein breakdown tends to accelerate. Of course, there is much you can do to slow the protein breakdown, including eating more protein and/or supplementing with EAAs.



Lean Body Mass = Protein Synthesis – Protein Breakdown



When protein breakdown exceeds protein synthesis, your body is in a “catabolic” state. Think of someone with anorexia, cancer, or sarcopenia. They quickly lose muscle tissue because breakdown is greater than protein synthesis.



On the other hand, think of an 18-year-old boy going through the later stages of puberty. He goes from being lanky and awkward, to developing biceps and shoulders. In this case, protein synthesis exceeds protein breakdown.



Because your level of muscle mass plays a significant role in longevity, anything that increases protein synthesis or decreases protein breakdown can support your quality of life throughout your lifespan.



Since amino acids play such an essential role in building and maintaining lean body mass, they must be a consistent part of a healthy diet. You can either supplement with them as amino acids, or eat them in protein rich foods like protein shakes, meat, fish, eggs, and poultry.




What should I look for in an amino acid supplement?



First, look for the branched-chain amino acids (leucine, isoleucine, and valine) in a 2:1:1 ratio.