16 January 2009

4 minute read

North America

In a new peer-reviewed scientific publication, Ohio State University food safety expert Jeff LeJeune reviews the dangers of drinking raw milk and argues that, contrary to claims from advocates, there is no scientific evidence supporting the notion that raw milk cures or prevents disease.

The article, "Unpasteurized Milk: A Continued Public Health Threat," was published in the Jan. 1 issue of the journal Clinical Infectious Diseases.

"Although milk and dairy products are important components of a healthy diet, if consumed unpasteurized, they can present a health hazard due to possible contamination with pathogenic bacteria," said LeJeune, a microbiologist and veterinary researcher with the university’s Ohio Agricultural Research and Development Center (OARDC) in Wooster. "These bacteria can originate even from clinically healthy dairy cows or from environmental contamination occurring during collection and storage of milk."

In 2006, the sale of raw milk was illegal in 26 states. In states where unpasteurized milk sales are outlawed, various strategies have been developed to circumvent these restrictions — including selling raw milk labeled as "animal or pet food" across state lines and selling "shares" in cows or "leasing" cows, which helps avoid the buying and selling of raw milk per se.

The raw milk trade has led to recent legal disputes. For example, the Food and Drug Administration (FDA) recently filed an injunction to stop a California raw milk dairy from shipping raw milk for human consumption out of state. Meanwhile, the Ohio Department of Agriculture (ODA) has prosecuted several farmers for allegedly selling raw milk to consumers in the past couple of years.

In the article, LeJeune documented the increasing number of cases of foodborne illnesses related to unpasteurized milk consumption in the United States since 2005 — including outbreaks of salmonellosis, campylobacteriosis and E. coli infection. One of those incidents resulted in eight cases of infection with E. coli O157:H7, mostly among children younger than 14, in Oregon and Washington State. Five of the affected children, aged 1-13 years, were hospitalized, four developing hemolytic uremic syndrome (HUS) — a rare disorder frequently associated with E. coli infection that can lead to kidney failure and damage to other organs.

Despite research and management efforts that have contributed to the reduction of foodborne pathogens in cattle and milk, LeJeune said, "the risk of milk-borne disease has not, and cannot, be fully eliminated." He noted that dairy cows can be a source of microorganisms that sicken people while remaining clinically healthy and maintaining near-optimal milk production. In fact, studies have found the frequency of pathogen contamination in pooled farm milk to be as high as 8.9 percent for Salmonella species, as high as 3.8 percent for Shiga toxin-producing E. coli, and as high as 12.3 percent for Campylobacter jejuni.

"Pasteurization is still the most effective method for enhancing the microbiological safety of milk," insisted LeJeune, who is also a specialist with Ohio State University Extension.

According to LeJeune, pasteurization does not change the nutritional value of milk. Raw-milk advocates claim that pasteurization robs milk of nutrients that can prevent and treat a wide spectrum of diseases, including heart disease, kidney disease, cancer and lactose intolerance. But in his article, LeJeune presented scientific data that refutes such a claim.

For example, it has been determined that the nutritive value of milk proteins such as caseins and whey and milk’s vitamin content are largely unaffected by pasteurization. Also, pasteurization has not been typically found to lead to high levels of lactulose — an indigestible carbohydrate in milk that may cause digestive upset in lactose-intolerant individuals.

"Pasteurization is not the same as sterilization," pointed out LeJeune, who added that although testing raw milk has been suggested as an alternative to pasteurization, this method cannot ensure a product that is 100 percent safe and free of pathogens.

Finally, LeJeune encouraged public health workers to get a better understanding of the science behind this highly debated topic so that they can enhance their communication with clients in an effort to reduce the incidence of infections associated with the consumption of unpasteurized dairy products.

OARDC and OSU Extension are the research and outreach arms, respectively, of Ohio State’s College of Food, Agricultural, and Environmental Sciences.

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