Is Milk an Overprocessed Food? How Milk Processing Has Changed Since the 1940s

Per capita milk consumption has plummeted since the 1940s. Does it have anything to do with processing? Data from USDA-ERS.

As someone who spends a lot of time studying the past, I’ve found it very interesting to compare today’s movement against overprocessed foods to the natural foods movement of the 1940s. There are a lot of similarities, but one major difference is that today’s movement seems excessively focused on beef and beef tallow, which weren’t considered “protective foods” in the 1940s because they’re not exceptionally high in vitamins. While the nutritionists back then all agreed that it was important to have some animal products in the diet, they believed that the most important protective foods from animals were milk and butter, preferably from pastured cows.

Today, except in the dairy lobby, milk seems to have lost its status as a healthy food. One reason for that is because the milk typically sold in grocery stores makes a lot of people sick. Not majorly ill, just mild gastric discomfort. They say they’re lactose intolerant or have a milk allergy, but most haven’t had that verified by a doctor. They just stop drinking milk. In contrast, I’ve never met anyone who thinks they have a beef allergy. Some people don’t eat beef for religious or ethical reasons, but not because it makes their stomach upset.

What’s going on? Why are an increasing number of people today unable to comfortably consume what was considered a high-quality protective food eighty years ago? The most common explanation is that the US population is more diverse now than it was then, and people from cultures that didn’t traditionally drink milk have lost the ability to digest lactose as adults. But that doesn’t explain why huge numbers of people whose ancestors came from regions that historically drank milk—including Europe, the Middle East, Africa, and India—feel icky when they drink milk today.

Back in the 1940s, milk was minimally processed and delivered quickly to consumers.

No, the real problem is that what we call “milk” today isn’t the same as what they called “milk” in the 1940s. Back then, most milk in the US came from local milksheds—the small dairy farms that surrounded each city and usually pastured their cows in the summer. The only processing done at the local processing plant was pasteurization (already mandated by law) and bottling. Then the milk was delivered three times a week right to people’s front doors. It went from cow to consumer in two or three days or less and rarely, if ever, sat around for a week or longer.

Modern milk processing systems significantly alter the fatty acid profiles of milk by homogenization.

Contrast that to today’s milk distribution system, where milk from an enormous number of cows is all pooled together and trucked to huge, centralized processing plants. The cream is separated out and added back in at specific percentages (a process called standardization). Then, the milk is forced through tiny openings at incredibly high pressures (over 2000 psi) to break up fat molecules so that the cream won’t rise to the top (homogenization). Homogenized milk will go rancid in less than an hour because of changes in the fatty acid structure, so it’s immediately pasteurized at temperatures far above the minimum legal requirement. Then it’s put into cartons and shipped hundreds or even thousands of miles to grocery stores, where it can sit on the shelf for a couple weeks and in someone’s fridge for another week or two before they finally drink it.

It's worth noting that per capita milk production in the US started declining in the late 1950s, right when standardization and homogenization started becoming commonplace. As milk processing has altered milk more and more from its natural state, fewer and fewer people have been able to drink it—a decline that no “Got Milk?” campaign or mandatory milk for school lunches has been able to reverse. The dairy industry says it’s a coincidence, but I’m not so sure.