Different types of fatty acid and carbohydrate are metabolized at different rates, but what about protein? In the first study of its kind, one group has looked at the effect of milk proteins — whey protein and casein — on whole-body protein metabolism. They find that when people are given whey protein, the concentration of amino acids in the blood plasma increases, and there is a concomitant increase in protein synthesis. But a casein meal leads to a much slower accumulation of amino acids, and only a slight increase in protein synthesis.
