You should write about this, he said. I don't think our friends know this story.
Two processes define modern milk: pasteurization and homogenization.
We are raised to think that pasteurization means safety. A clean, safe product that is ready for us to consume.
But milk is not pasteurized because it's healthier, it's pasteurized because the government didn't have enough regulators to do what was good.
Milk was not consumed fresh until the late 1800s; until then, milk was soured, or clabbered, or made into cheese—all forms that are more digestible than fresh milk. But when people urbanized, the trend moved towards feeding children cow's milk, largely because mothers couldn't nurse as long as they previously had; they went to work.
A big problem, however, was that urban dairies were unsanitary. They were right on the edges of cities, and the cows were raised in confinement and fed brewery swill—not food for cows! The cows weren't let out to eat grass or be in the sun and fresh air, they were kept in their stalls for their whole lives. The barns themselves were filthy. The cows weren't healthy, the milk wasn't clean, and people were getting sick. So, starting in 1911, decisions were being made about the regulation of milk.
Among those involved in the issue, there were two main camps. On the one side was certified raw milk, which was largely recognized by studies at the time (and since) as being far healthier, but of course it was much more difficult to provide. Dairies would have to change the way they operated, farmers would have to be taught about sanitation, and they would need to be regulated to ensure that sanitation standards were upheld. (Today we can and do simply test bacteria counts in milk—if counts go over a particular level, the milk can't be consumed raw. These tests weren't yet available at the time.)
On the other side was pasteurization: this would ensure that the milk became sterile, and would eliminate the need to educate dairies about sanitation standards. The equipment to pasteurize milk was quite costly; only the largest dairies could afford it. By putting small dairies out of business, or forcing them to combine into larger conglomerates, the remaining regulation work was made . . . well, less big, at any rate.
There was debate, and in the end, pasteurization became legally required.
However, if you're going to consume milk, raw milk is much healthier! It retains enzymes and probiotic bacteria. Pasteurized products go bad faster because pasteurization kills both good and bad bacteria. The good bacteria is no longer available to crowd out the bad and as a result, the pasteurized product is a perfect host for bacteria that spoils food. In a short time, the food is no longer safe to eat. If milk were unpasteruized, instead of going bad, it would sour, or ferment, both processes which increase the amount of "good" (probiotic) bacteria and crowd out bad bacteria that spoils food and causes illness. Not only that, but probiotic bacteria is a critical component of daily diet—without "good" bacteria, we can't properly synthesize nutrients from the foods we eat.
You can read a good article about raw milk here at the NOFA MA website. (NOFA is the Northeast Organic Farmers Association, the organic certification authority for New England.)
The other part of the story of modern milk is homogenization. Homogenization breaks the fat molecules down so that they are dispersed evenly throughout the milk, instead of rising to the top as cream. Different kinds of cows produce milk with different percentages of fat—by homogenizing milk, dairy processors were able to provide a uniform product. Because the fat molecules were in suspension, milk didn't need to be shaken every time.
Now that milkfat was being standardized, there were new marketing advantages. Let's look at them individually:
"Whole" Milk - "Whole" milk isn't actually whole. It's homogenized with a standard fat content now at 3.25%. Raw milk ranges between 3.25% and 8% fat, depending on the breed of cow, her health, age, diet, etc. The processors are able to standardize at a very low percentage and sell the rest of the cream separately.
Skim Milk - Skim milk used to be a waste product; it was sold off to pig farmers for pennies per gallon and used like corn in a feedlot; pigs were given as much as they'd consume in the last few weeks before going to butcher, to fatten them up.
But with the advent of the "low-fat" movement, creative advertisers and milk processors made lots of money when people bought into the idea that drinking milk without the fat would make them skinny. Believe what they tell you on television! You'll buy the skim milk for much more than the pig farmer did, and the dairy processors get to sell the cream separately.
The truth is, skim milk will make you fat. Ask a pig farmer! It's sugar water with a bit of protein, and nothing more. No one would tell you that Kool-Aid is healthy; skim milk is essentially Kool-Aid without the color.
2% - Now that you think skim milk is skinny, everyone understands that less fat must be better. But say you don't like skim milk, what then? It's ok! They'll sell you two percent! They make money on the cream and to top it off, skim and 2% are more expensive!
So in all this, milk processors—don't think I mean farmers!—still make more money, because now they can skim the cream and sell that, and you'll still pay more for what's leftover . . . in other words, the waste product!
The most important part here, though, is that when milk is homogenized, the fat is broken down into very tiny particles that cannot rejoin, which allows them to suspend evenly in the milk, instead of floating on top. The problem is, the body doesn't digest that fat (and the protein it hangs on to) properly now; it gets through our digestive system much earlier than it is supposed to, because it has been mechanically broken down (and not because it's been digested), and enters the bloodstream in an undigested state. That is actually quite harmful for the body! There is data linking this to congested arteries, autoimmune disorders, and cancer, all because these fats and their helper-proteins are getting into the body far ahead of their turn in the process.
So, that's the story. Which means?
Well, that's up to you, the story is what it is. To me it meant, when I didn't yet realize I was allergic to casein, that I only used raw dairy products—hooray for froofy French cheeses! To you, it might mean something different . . . though, probably everyone says hooray for froofy French cheeses. ;-)