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Unpasteurized milk poses health risks without benefits

December 17, 2008

With disease outbreaks linked to unpasteurized milk rising in the United States, a review published in the January 1, 2009 issue of Clinical Infectious Diseases examines the dangers of drinking raw milk.

Milk and dairy products are cornerstones of a healthy diet. However, if those products are consumed unpasteurized, they can present a serious health hazard because of possible contamination with pathogenic bacteria. An average of 5.2 outbreaks per year linked to raw milk have occurred in the United States between 1993 and 2006-more than double the rate in the previous 19 years, according to co-authors Jeffrey T. LeJeune and Päivi J. Rajala-Schultz of the College of Veterinary Medicine in Columbus, Ohio.

Contamination can occur at the time of collection, processing, distribution, or storage of milk, the authors write. Many pathogens can be found in the dairy farm environment, which can contaminate the teat skin of dairy cows and consequently the milk at the time when cows are milked. For example, Salmonella and E. coli have been reported in pooled milk collected from farms., Outbreaks of salmonellosis, campylobacteriosis, and E. coli related to raw milk consumption have been reported since 2005.

Although the sale of raw milk was illegal in 26 states as of 2006, the authors note that those who are opposed to pasteurization have found ways to circumvent the law and obtain raw milk. For example, participants in "cow-share" programs pay for the upkeep of the cow and receive raw milk in exchange, rather than buying raw milk outright.

Raw milk advocates claim that unpasteurized milk cures or prevents disease, but no scientific evidence supports this notion. Testing raw milk, which has been suggested as an alternative to pasteurization, cannot ensure a product that is 100 percent safe and free of pathogens. Pasteurization remains the best way to reduce the unavoidable risk of contamination, according to the authors.

Infectious Diseases Society of America