&ampnbsp;&ampnbsp;Amino acids are the subunits that make up proteins.&ampnbsp; They are necessary for the function of all cells, for tissue repair, and for the production of enzymes and neurotransmitters.&ampnbsp; The body uses 20 amino acids to construct proteins.&ampnbsp; People with limited diets or poor digestion may not get enough essential amino acids from their diet.