Whey protein is the liquid portion that remains after whole cow’s milk is fermented into cheese (curds and whey).  This nutritious source of protein is considered to have an ideal amino acid content & balance, making it a highly valued protein source.  Nature’s Variety uses a high protein, low carbohydrate whey protein that is US sourced and human edible.  (Our whey protein is also lower in fat and lactose than whole milk powder or sweet dairy whey.)