Amino acids are the elemental constituents of protein. What is essential in human nutrition isn't protein, but rather the amino acids that comprise protein. Although about 20 amino acids are thought to play a role in human nutrition, only nine are considered essential. What that means is that those nine amino acids must be obtained from dietary sources and cannot be synthesized in the body. In contrast, the other eleven amino acids are often referred to as "non-essential," which is a misnomer from a scientific point of view. The so-called "unessential amino acids" also play important roles in the human body, but they can be synthesized in the body from other sources, including other amino acids. To make it even more confusing, still other amino acids are categorized as "conditionally essential." What that means is that under certain conditions, such as extreme stress, certain amino acids, such as taurine, glutamine, and arginine cannot be synthesized fast enough to meet physiological requirements, so ingesting them would be of benefit. From the perspective of helping to develop added muscle mass, what's required are the nine essential amino acids. The others are not needed for muscle protein synthesis, although having them available doesn't present any disadvantages, either. You need to ingest an average of only 10 grams of essential amino acids to maximize muscle protein synthesis (MPS). This can be obtained from consuming 20 grams of a high-quality protein source that is rich in essential amino acids, such as whey. It can also easily be obtained from food sources, such as about three ounces of beef, fish, turkey, or chicken.
One ongoing controversy about amino acids is whether supplemental amino acids are better than consuming whole-food proteins. On the surface, it would initially appear that ingesting actual amino acids would be superior to ingesting whole-food proteins. The usual stated reason for this is that amino acids are elemental; that is, they don't have to go through the digestive process and are immediately available. While it's true that food protein sources, such as beef, can take four hours or more to digest, that isn't as much of a problem as you would think. For one, while it was previously thought that the faster you can ingest essential amino acids, the greater the rate of MPS, that notion has been tempered by ongoing research. What is now known is that MPS occurs following resistance exercise over a period of 24 to 48 hours and as long as you consume sufficient protein within that time frame, your level of MPS will be maximized. From a practical point of view, this means that you don't have to rush and gulp down a protein drink immediately after training. I still see many people doing this, drinking protein drinks as soon as they leave the gym, often mixing it in the back of their cars in the gym parking lot. This . . .