Dairy products like milk, butter and cheese should be eaten in moderation. Man is the only animal on this planet that depends on milk for food after growing up. Dairy products make you sluggish and creates excess phlegm. It requires extra 'prana' or life force to process dairy.
Ayurveda recommends buttermilk (yogurt after removing the fats) and ghee (clarified butter) highly as digestive aids. These are rich in lactobacillus and can help in the absorption of food easily.