It's hard to find a food with a longer history than milk, a staple of the human diet. For at least 10,000 years, milk and foods made from milk have nourished children and adults in nearly every culture on earth.
During the 1930s, pasteurization was introduced as means of making the milk supply safe from careless handling and contamination, much as irradiation is being used today to compensate for the careless and improper handling of meat.
Proponents of raw milk claim that pasteurization destroys not only the bad bugs that may be present in milk but also the good bugs and much of the nutritional power as well. With modern handling and equipment on the farm and refrigeration in the home (which was not always available in the 1930s), today's raw milk can be safe and far more nutritious than the industrialized version.
During the 1940s, Francis Pottinger, M.D,experimented with two groups of cats; one group fed raw milk exclusively, the other pasteurized milk. The raw-milk group did well, living long and happy lives through at least three generations. The other group suffered acute illnesses such as vomiting and diarrhea and ultimately succumbed to a variety of degenerative diseases. By the third generation, the vast majority of these cats were infertile and exhibiting antisocial behavior.
In other words, medically speaking they were like an increasing number of modern Americans.