This is probably one of the most controversial issues in modern medicine.
XIII Milk It must be noticeable to the reader that although the fact that Canaan is a land flowing with milk and honey is so often mentioned as one of its advantages, very little fuss is made about milk. Even in the nourishment which God gave to the people as a sign of His special kindness are enumerated fine flour, oil and honey, but not milk. Nevertheless, it is considered a sign of wealth if the vessels are full of milk, and a sign of luck if wine and milk can be procured free.
A particular delicacy seems to have been goats’ milk. The Romans also considered it to be the most easily digestible type of milk, because the goat lives more from foliage than from plants. A remark of Galen which asserts the opposite, but which allows the combination of “milk and honey” to be also considered in the medical-dietetic sense, will only be conveyed here but not commented upon. He teaches that one should always give goats’ milk together with honey because it curdles in the stomach, is distressing to a person, and can lead to death by suffocation.
The milk of a clean animal is white, that of an unclean animal is yellow; the former curdles, the latter does not. The same is mentioned by Plinius: the milk of animals who are fully teethed in both jaws produces no cheese, for it does not curdle. Nevertheless, he himself speaks of mare’s cheese, hippace. It was already mentioned above that the Rabbis considered milk to be a sexual stimulant, whereas physicians specifically prescribe milk as part of a “bland diet” for irritating conditions of the urogenital apparatus. If both opinions are correct, that of the Rabbis and ours, then one must assume that their cattle breeding, and in particular their fodder, was basically different from ours. The difference of opinion cannot relate to a difference in the species of animal, for the Rabbis only spoke of milk derived from ruminant animals (which chew their cud), for all other animals (camel, donkey, mare, pig) are unclean, and “that which is derived from an unclean animal is unclean”. Since milk was also considered to be an intoxicant, it is possible it was imbibed in the form of a kumys or kefir. Young girls who drink milk and eat fowl during their years of maturation develop a bright complexion. Warmed animal milk is beneficial for people with illnesses of the chest.
Preuss, Julius. Biblical and Talmudic Medicine (p. 562). Jason Aronson, Inc.. Kindle Edition.