While this applies to cheese and yogurt too, I will discuss milk and why it should be raw, organic and non homogenized. I will list them in order of least importance in my opinion but still should be strived for.
Unless you buy milk from a co-op farm, you will be drinking pasteurized milk. As for as I know, it is illegal for grocery stores to sell raw milk. While pasteurization does kill bacteria, it also kill the healthy variety and healthy parts of milk. The stores are required not to allow the sale of raw milk. Doctor Joseph Mercola gives a great link about why milk should be raw.
If your milk is not organic, you are almost surely risking it having strains of bacteria that isn't anywhere near as pure. Although organic is more expensive, it doesn't cheapen your health. Organic milk let's you break the milk down better in the stomach and allow for smoother digestion. Non organic milk will damage their intestinal tract more and wear out proper cell functioning to make it easier to get sick. Organic milk is worth it.
Homogenized milk has the cream and milk mixed together and this is dangerous for our blood in forming platelets sticking to arterial walls easier and it is unnatural for our body to drink milk where the cream is not on top. The cream should always be separated from the milk. When together, these globules start bursting apart in our blood because the body was not designed to break them down while connected but on a 1 by 1 phase process. Shame on our food companies only valuing cost and not being health incentive for people.
Please make an effort to only drink raw, organic non homogenized milk. It is the best milk you can drink.
Being raw is not as vital as the other 2 but shoot for this order first in my opinion:
1st: non homogenized
The 1st 2 are musts for me but I try to get all 3 if available.
Thanks for reading.