Any of numerous large, complex naturally-produced molecules composed of one or more long chains of amino acids, in which the amino acid groups are held together by peptide bonds.
A food rich in protein, often a meat or meat substitute.
One of three major classes of food or source of food energy (4 kcal/gram) abundant in animal-derived foods (i.e. meat) and some vegetables, such as legumes.
An atom of this isotope.
The lightest and most common isotope of hydrogen, having a single proton and no neutrons: ¹₁H