Pasteurization is a part of modern milk production in the United States, and kills potentially harmful bacteria in milk that could lead to illness. Salmonella is a common source of food poisoning, and one of several bacterial species that have been found in unpasteurized "raw" milk. Most public health experts and medical specialists strongly advise against consuming raw milk, largely due to the threat of infection by salmonella and other pathogens.
Milk Pasteurization
Pasteurization was originally developed in the 1800s by French scientist Louis Pasteur. The vast majority of milk sold in the United States undergoes pasteurization, a process in which it is heated to a specific temperature for a short time. Depending on temperature, the heating process may only need to last several seconds. During this time, the heat weakens or destroys potentially dangerous bacteria, virtually eliminating the risk of infectious diseases spreading via milk. Following pasteurization, the milk is rapidly cooled and bottled.
Salmonella
Salmonella describes a set of rod-shaped bacteria encompassing over 2,000 individual varieties and, according to the U.S. Department of Agriculture, is the most frequently reported source of food poisoning in the country. Salmonella infection, or salmonellosis, causes fever, diarrhea and cramping in addition to chills, headache and other gastrointestinal symptoms. A minority of salmonellosis patients suffer complicated symptoms that can last for years.
For children, pregnant women, senior citizens and anyone with a weakened immune system, salmonellosis can be fatal. The Centers for Disease Control and Prevention estimates that over 400 Americans die from salmonella infection annually.
Bacterial Infections in Milk
Raw milk can host a broad array of disease-causing organisms, including listeria, campylobacter, E. coli and salmonella. In some locations, pathogenic bacteria have been found in over 12 percent of raw milk samples, according to data collected by Cornell University. It is impossible to know in advance whether a given bottle of raw milk contains bacteria that will make people sick.
The risk of illness from unpasteurized milk has led public health authorities and medical associations to urge against drinking raw milk, especially by children and pregnant women.
Pasteurized Milk and Health
In addition to preventing the spread of diseases such as salmonella, pasteurized milk brings further health advantages. Pasteurized milk is fortified with essential nutrients such as vitamin D, which is critical to the body's ability to absorb calcium and strengthen bones. According to the National Institutes of Health, milk suppliers' fortification of pasteurized milk with vitamin D has virtually eliminated rickets, a disease of bone weakening and skeletal deformation. Vitamin D is also key to preventing osteoporosis and maintaining bone strength throughout life.
Pasteurized milk is generally the best way to get the nutritive benefits of milk, while avoiding the risk of infections caused by bacteria such as Salmonella.
References
- U.S. FDA: The Dangers of Raw Milk
- Dr. Bhushan Jayarao: Microbial Pathogens in Raw Milk
- Cornell University Food Science Department: Position Statement on Raw Milk Sales and Consumption
- U.S. Department of Agriculture: Salmonella Questions and Answers
- U.S. National Institutes of Health: Dietary Supplement Fact Sheet; Vitamin D
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