Amino Acids Are Essential Protein Building Blocks

3. Nonessential Amino Acids

Since our bodies can produce certain amino acids, scientists in the early 20th century assumed that dietary sources were dispensable. Hence, these amino acids were classified as "nonessential." However, growing evidence suggests that humans and other species require these compounds from foods for optimal growth, reproduction, and well-being. In some cases, people who cannot produce enough of nonessential amino acids require dietary supplements.

These amino acids are traditionally labeled as nonessential:

• alanine
• asparagine
• aspartic acid
• cysteine
• glutamic acid
• glutamine
• glycine
• proline
• serine
• tyrosine