Essential nutrient
An essential nutrient is a nutrient required for normal physiological function that cannot be synthesized by the body (e.g., niacin, choline), and thus must be obtained from a dietary source.
Fatty acids
Essential fatty acids (EFAs) are fatty acids that humans and other animals must ingest because the body requires them for good health but cannot synthesize them.
Amino acids
An essential amino acid or indispensable amino acid is an amino acid that cannot be synthesized de novo (from scratch) by the organism being considered, and therefore must be supplied in its diet. The nine amino acids humans cannot synthesize are phenylalanine, valine, threonine, tryptophan, methionine, leucine, isoleucine, lysine, and histidine (i.e., F V T W M L I K H).
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