protein

any of a large group of nitrogenous organic compounds that are essential constituents of living cells; consist of polymers of amino acids; essential in the diet of animals for growth and for repair of tissues; can be obtained from meat and eggs and m

बहुत से लोगों के लिए दूध ही जानवर प्रोटीन का मुख़्य स्रोत है.

Vitamin A is an essential protein for eyes.