According to the study authors, one argument against pasteurization is its association “with destruction of selected vitamins present in raw milk.” This statement is not completely accurate, and we will return to it in a moment. Nonetheless, the direct effect of pasteurization on vitamin levels is important to know. The researchers looked at studies measuring vitamins A, B1, B2, B6, B12, C, E and folate, eliminating many for various reasons, some or all of which seem frivolous—such as not published in English, not reporting sample size, not including a standard deviation, not reporting mean values. Nevertheless, even after leaving out over half the studies looking at vitamins levels published between 1936 and 2003, the researchers came up with interesting results.
Starting with the fat-soluble vitamins, studies on vitamin A were inconsistent, with two studies reporting a reduction and—strangely—two reporting an increase in vitamin A after pasteurization. (The suspicion is that vitamin A was added to the pasteurized milk.) The available data did not allow the researchers to make important conclusions about vitamin E, although “pasteurization appeared to qualitatively reduce concentrations” of vitamin E. They did not examine vitamin D “because secreted bovine milk is deficient in vitamin D based on human nutrition needs.” Vitamin K2 was not on the radar screen until very recently, so the researchers did not look at this fat-soluble vitamin either.
Looking at the water-soluble vitamins, researchers found a significant decrease for vitamins B12, B2 and folate, with a slight decrease in vitamins B1 and B6. As for vitamin C, “In the majority of trials, a numeric decrease in vitamin C was found after heat treatment.”
These results are pretty shocking. Every water-soluble vitamin decreased, some significantly. But not to worry, say the researchers, since “milk is not an important source of vitamin C and folate,” nor of vitamin B12! Only the reduction of B2 has them a little worried: “With the exception of vitamin B2, pasteurization does not appear to be a concern in diminishing the nutritive value of milk because milk is often not a primary source of these studied vitamins in the North American diet.” Put another way, “The effect [of pasteurization] on milk’s nutritive value was minimal because many of these vitamins are naturally found in relatively low levels.”
Note the word “often.” Milk “is often not a primary source of these studied vitamins. . . “ For someone not drinking milk, or drinking little milk, this statement is true. But what about babies and toddlers? Milk is often a primary source of these nutrients for this group. And what about a mom worried about her children’s junk food habits or pickiness, who wants to ensure that her children at least get the basics of what they need. Raw milk can be a primary source of these nutrients for these children. And what about vegetarians depending on milk for vitamin B12? The destruction of B12 by pasteurization could be disastrous for these folks.
But let’s go back to the premise that people are opposed to pasteurization because it destroys vitamins in the milk. Indeed, it does, but this is only half the story. What pasteurization completely destroys is the enzymes—after all, the test for effective pasteurization is the destruction of the enzyme phosphatase–and many of these enzymes act as carriers for the vitamins and minerals in the milk. This explains why levels of some vitamins in milk seem low—since the enzymes in raw milk ensure that they are completely absorbed, the levels do not need to be high.
The researchers did not even examine vitamin D levels on the assumption that there is not enough vitamin D in milk to satisfy human needs. If this is the case, where do infant humans and animals get their vitamin D? The fact is that vitamin D is very difficult to measure in foods, and also vitamin D levels vary widely depending on the diet of the human mother—and presumably depending on the diet of the animal mother also.
Pasteurization destroys the enzymes and carrier proteins needed to absorb calcium, folate, B12, B6, vitamins A and D, iron and many other minerals. To absorb these nutrients in pasteurized milk, the body has to produce its own enzymes, something that takes a lot of energy to do, especially in amounts required to ensure 100 percent assimilation.
|Vitamin C||Raw milk but not pasteurized can resolve scurvy. “. . . Without doubt. . . the explosive increase in infantile scurvy during the latter part of the 19th century coincided with the advent of use of heated milks. . .” Rajakumar, Pediatrics. 2001;108(4):E76|
|Calcium||Longer and denser bones on raw milk. Studies from Randleigh Farms.|
|Folate||Carrier protein inactivated during pasteurization. Gregory. J. Nutr. 1982, 1329-1338.|
|Vitamin B12||Binding protein inactivated by pasteurization.|
|Vitamin B6||Animal studies indicate B6 poorly absorbed from pasteurized milk. Studies from Randleigh Farms.|
|Vitamin A||Beta-lactoglobulin, a heat-sensitive protein in milk, increases intestinal absorption of vitamin A. Heat degrades vitamin A. Said and others. Am J Clin Nutr . 1989;49:690-694. Runge and Heger. J Agric Food Chem. 2000 Jan;48(1):47-55.|
|Vitamin D||Present in milk bound to lactoglobulins, pasteurization cuts assimilation in half. Hollis and others. J Nutr. 1981;111:1240-1248; FEBS Journal 2009 2251-2265.|
|Iron||Lactoferrin, which contributes to iron assimilation, destroyed during pasteurization. Children on pasteurized milk tend to anemia.|
|Minerals||Bound to proteins, inactivated by pasteurization; Lactobacilli, destroyed by pasteurization, enhance mineral absorption. BJN 2000 84:S91-S98; MacDonald and others. 1985.|
So despite assurances by apologists for pasteurization, heat treating Nature’s perfect food does have a negative effect on the amount of nutrients and their availability—a profoundly negative effect.
One more thing: most of the studies the researchers had available were for regular pasteurization, not for ultra-high temperature (UHT) pasteurization—and most milk today, even organic milk, is ultra-pasteurized. It is not beyond the realm of possibility that the additional heat pretty much kills everything.
What emerges is a story of the most colossal waste—think of the nutrients that our growing children are not getting, but should be getting, because we pasteurize!