Amino Acids

Amino acids are often referred to as the building blocks of proteins. There are 20 amino acids that link together in thousands of ways to form thousand of unique proteins, each with specific functions and roles in the body. When you consume protein-rich foods, the digestive juices in your stomach and intestine break down the protein into amino acids, which are then used to preserve muscles, bones, and organs, and perform other vital functions.

Nonessential vs Essential Amino Acids

Eleven amino acids are nonessential; they’re made inside the body in a large enough quantity to meet the body’s needs. Nine amino acids are essential because the body can’t make enough to meet its needs.

If you have a rare genetic disorder such as Phenylketonuria (PKU), certain metabolic problems, or experience a trauma or critical illness, your body might not be able to make any or enough of the nonessential amino acids it can normally create.

Animal and plant sources of protein vary in their amino acid content. Animal sources of protein are considered complete proteins because they contain all the essential amino acids. On the other hand, most plant sources of protein are considered incomplete proteins because they lack one or more essential amino acids; soybeans are the exception and contain all the essential amino acids. Different plant proteins with different amino acid profiles can be consumed over the course of the day (and not necessarily at each meal as was once believed) to provide the body with more complete, high-quality proteins that can then perform their many vital functions.

People who are vegans rely on plant foods and consume no animal foods, so they need to consume a variety of plant foods such as soybean products (such as tofu or soy milk), often each day, to get enough essential amino acids.

Phenylketonuria (PKU) is an inherited disorder caused by a lack or deficiency of the enzyme that converts phenylalanine (an essential amino acid) to tyrosine (a nonessential amino acid).