Why can I tolerate goats' milk when I cannot tolerate cows' milk?

Research has indicated that it has much to do with the protein structure in the milks. They are called caseins and the absence of alpha-s1 casein and a higher proportion of beta-casein in goats' milk means that the casein profile of goats' milk is closer to human milk than that of cows' milk. These proteins form a softer curd in the stomach and the fat particles are also smaller, which is a great aid to digestion for many who cannot tolerate cows' milk.