GLYCINE Overview Information. Glycine is an amino acid, a building block for protein. It is not considered an “essential amino acid” because the body can make it from other chemicals. A typical diet contains about 2 grams of glycine daily.The primary sources are protein-rich foods including meat, fish, dairy, and legumes.t is not considered an “essential amino acid” because the body can make it from other chemicals. A typical diet contains about 2 grams of glycine daily. The primary sources are protein-rich foods including meat, fish, dairy, and legumes.