Pasteurized milk is heated to a specific temperature for a set period to slow the growth of harmful pathogens. Some enzymes are destroyed, but "the enzymes in raw animal milk are not known to be important in human health," said Dr. Michele Jay-Russell, a veterinarian who is a food safety and security specialist at the Western Institute for Food Safety at UC Davis. "Vitamin C is also reduced by heat treatment, but even raw milk is not a good source of vitamin C."
The Weston A. Price Foundation — which advocates for community-supported farms, pasture feeding of livestock and universal access to clean, certified raw milk — disagrees. It also argues that pasteurization has outlived its usefulness.
"Modern stainless steel tanks, milking machines, refrigerated trucks and inspection methods make pasteurization absolutely unnecessary for public protection," its website states.
"Not true," responded Tauxe, who says that the dairy environment is inherently dirty. "Animals and bacteria are natural companions. Normal-looking and -tasting milk from a healthy cow can still be contaminated."
Research supporting the health benefits of raw milk is limited. Proponents often cite a European study that suggests it may have a protective effect against asthma and eczema in children. But the study authors note that other factors might be at play, including the farm environment, and concluded that the risk of pathogens in raw milk outweighs its potential benefits.
Taking a chance
More than three years ago, Mary McGonigle Martin, 51, believed many of the claims she found on the site of the Weston A. Price Foundation. A health-conscious mother who ate organic, she bought some raw milk from a California health food store for her son Chris, then 7.
For two weeks, Chris' chronic congestion eased, she said. But the third week he became violently ill; the milk had been contaminated with E. coli. Chris ultimately developed a serious complication called hemolytic uremic syndrome, marked by prolonged renal failure and pancreatitis. Although he has recovered, he may need a kidney transplant in the future, and the entire family is still shaken, McGonigle Martin said.
"People can drink raw milk their whole life and not get sick," said the Murietta, Calif., mother, who tells her story on realrawmilkfacts.com, a site started by health professionals and researchers. "But the reality is that you don't know when a pathogen is in there. And it's promoted to children and infants, which I think is a crime.
"I support people's right to choose it," she added. "I would never condone it."