Colorado State University Extension
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Raw Milk: Why Pasteurize?
Edited by: Stephanie Wallner, M.S., Mary Schroeder, M.S., R.D, Pat Kendall, Ph.D., R.D., Colorado State - Fall 2006
In recent years, we have seen a growing interest in raw milk among some consumers. Proponents of raw milk suggest that pasteurization destroys nutrients, enzymes that facilitate calcium absorption, and beneficial bacteria present in milk; another claim is that pasteurized milk is associated with allergies. A quick search on the internet using the key words "raw milk" brings up several websites devoted to the far-reaching virtues of raw milk, from calming nerves to reversing malnutrition. Is raw milk the answer to our health issues, or is drinking raw milk a potentially dangerous practice that can cause serious foodborne illness?
Milk and other milk-based products naturally contain both beneficial and pathogenic bacteria. Beneficial bacteria, like Lactobacillus, help produce yogurt and other dairy foods and have a role in promoting gastrointestinal health. Harmful bacteria, such as Campylobacter jejuni, E. coli O157:H7, Listeria monocytogenes, and Salmonella, may get into milk through cross-contamination and grow in the nutrient-rich environment milk provides. Infections from these pathogens, especially in persons with compromised immune systems, can cause severe diarrhea, cramps, fever, nausea, vomiting, headache and dehydration, as well as more serious complications like hemolytic uremic syndrome.
Because of the dangers of pathogenic bacteria, most milk is treated by pasteurization, a heat treatment originally developed to kill the bacterium that causes tuberculosis. Pasteurization is effective in destroying the bacteria in milk that cause tuberculosis, salmonellosis, diphtheria, typhoid fever, and other illnesses without adversely affecting the milk's nutritional content, flavor or quality. Rapid cooling of the milk and storage below 40 degrees F. following treatment help prevent milk spoilage and keep treated milk safe to drink. Despite the claims of raw milk advocates, the FDA and other public health agencies maintain that there are no known significant nutritional differences between unpasteurized and pasteurized milk and that pasteruized milk provides all the nutrients found naturally in raw milk. According to the FDA, the benefits of destroying harmful bacteria far outweigh any potential health benefits claimed by raw milk advocates, and recent outbreaks of foodborne illness associated with untreated milk have helped to renew public awareness of the dangers of raw milk consumption.
These outbreaks include one caused by Salmonella Typhimurium in 2002-03 in which 62 people in Illinois, Indiana, Ohio, and Tennessee became ill after consuming raw milk sold in Ohio. More recently, an outbreak in late 2005 of E. coli O157:H7 infection in Washington state caused serious illness in 8 people and was linked to locally sold raw milk. The unlicensed provider of the milk was ordered to close. In another recent case, five people became ill with campylobacteriosis early this January after drinking raw milk linked to a dairy in Larimer County, Colorado. Although the direct sale of raw milk is illegal in Colorado, consumers may buy shares in dairy cows; raw milk from a shared cow was likely the cause of this outbreak, according to the Colorado Department of Public Health and Environment. In cases such as these, raw milk can cause severe illness and related complications.
Federal law requires that milk shipped across state lines for sale at retail stores must be pasteurized. However, within each state, the regulation is up to local governments, and some states allow the sale of raw milk. In some states where the sale of raw milk is illegal, consumers can get around the law by "cow sharing" - groups pay a fee to a farmer to purchase a cow and use the raw milk. Other states, like Wisconsin where an outbreak of Campylobacter jejuni infection was linked to raw milk from cow sharing, have banned cow sharing programs.
Despite the possible health benefits touted by raw milk advocates, the FDA and other public health officials recommend taking precautions to avoid foodborne illness from raw milk or other unpasteurized dairy products. Recommendations advise consumers to avoid drinking beverages or eating foods made with unpasteurized milk, including raw milk soft cheeses from any source. Those at increased risk of foodborne illness, including the young and elderly, pregnant women, or those with diseases that compromise immune function, should especially be advised to avoid raw milk products and to have the best information available from their healthcare providers regarding the risks of raw milk.
Sources:
- Why pasteurize? The dangers of consuming raw milk. Cornell University Dairy Science Factsheets. Department of Food Science, Ithaca, NY. 2002.
- Got milk? Make sure it's pasteurized. FDA Consumer. http://www.fda.gov/fdac/features/2004/504_milk.html. Accessed January 2006.
- Multistate outbreak of Salmonella serotype Typhimurium infections associated with drinking unpasteurized milk - Illinois, Indiana, Ohio, and Tennessee, 2002-2003. MMWR Weekly. 2003: 52(26); 613-615.
- E. coli outbreak in southwestern Washington highlights risks of raw milk. Washington State Dept. of Health News Release. http://www.doh.wa.gov/Publicat/2005_news/05-164.htm. Accessed January 2006.
- Raw milk sickens five: Larimer dairy implicated. The Daily Reporter-Herald, Loveland, CO. January 21, 2006.
