Student guest post: A Push for Pasteurization

Student guest post by Molly Stafne

Nothing could be worse than watching your seven-year-old lying in a hospital bed fighting for his life after being diagnosed with hemolytic uremic syndrome. Unfortunately, Mary McGonigle-Martin experienced it first hand as her son, Chris, fought for his life after being poisoned by E. coli 0157:H7 found in contaminated raw milk. Like many mothers, Mary was coerced into believing the inaccurate “facts” given to her by the farm she purchased raw milk from. Too often across the US, parents are given incorrect information about the safety of the milk they drink and unfortunately, it is often children that pay the price.

Few people today know of a time when they didn’t have the choice to drink anything but raw milk. Now there is an overwhelming argument that pasteurization is decreasing the nutritional value and safety of the milk. During the 1800s, Louis Pasteur developed the germ theory which claimed that germs outside the body, like those found in raw milk, have the ability to cause infection. As a result, he developed the process of pasteurization which is used in many foods we consume today, including milk, to kill bacteria. In the past couple decades, many consumers have decided that they would rather consume more natural and organic foods rather than those that were produced by more modern methods. It is frequently believed that these natural foods, such as raw milk, are healthier which is not the case.

Pasteurizing milk has had many benefits through history. One of its major contributions is the massive reduction in human tuberculosis cases as the bacteria that causes bovine tuberculosis can also infect humans. Bovine tuberculosis can be spread to humans through contact with an infected animal but most commonly through ingestion of raw milk. Although the prevalence of tuberculosis in humans in the US has significantly reduced since pasteurization began, there are still a number of other zoonotic pathogens that can be transmissible from milk to humans including salmonella, campylobacter, listeria, and E. coli 0157:H7, all of which can have dangerous or unpleasant consequences or even potentially be fatal. E. coli is possibly the most dangerous since it only needs less than 100 organisms to cause infection. It can lead to a dangerous condition called hemolytic uremic syndrome (HUS) which may cause kidney failure. According to the CDC, there have been 148 dairy product-associated outbreaks from 1998 – 2011 that were a result of consumption of raw milk or cheese which resulted in 2,384 illnesses, 284 hospitalizations, and 2 deaths. Today, milk is heated to 161°F for 15 seconds to destroy the bacteria. This is called high temp, short time pasteurization. Another form of pasteurization is low temp, long time, 145°F for 30 minutes.

Proponents of raw milk often argue it has a greater nutritional value than pasteurized milk. There have been numerous studies that have de-bunked this myth according to the CDC. Many factors are involved when determining the nutritional value of a product. One thing that is analyzed is how readily a body breaks down and utilizes a nutrient. If a mineral or vitamin is passed through the body quickly, any loss would be irrelevant. A second analysis would be the percent contribution of the nutrient to the recommended daily intake. If people don’t rely on a certain product as the main source of an essential nutrient, the loss of the nutrient is almost negligible. It is true that some nutrients or enzymes are slightly reduced during pasteurization. For example, lysine is the most relevant essential amino acid found in milk. After heating the milk, only 1-4% loss of the amino acid was observed1,5,7. But like what was previously alluded to, reduction of nutrients like vitamin C is not considered a significant concern as milk is not a major source of vitamin C. It would take 20 liters of milk to consume the daily requirement of vitamin C, regardless if it was raw or pasteurized milk3. The availability of nutritionally relevant vitamins such as B2 or B12 were found to be affected minimally or not at all by most common heat treatments2,5. Finally, while milk is a significant source of calcium and phosphorus, neither were affected by heating the milk3.

Another raw milk marketing tool some farmers use is to claim that their cattle are grass fed. When cattle were first domesticated, they were raised on a grass diet. As the understanding of animal nutrition grew, farmers discovered that cattle would gain weight faster if they fed them grain which is economically beneficial. Proponents of grass fed cattle argue that grain is not their natural food and the growth at a faster than normal rate is unhealthy. A grass-fed animal does not mean the animal is healthier. Nutritionally speaking, it was hypothesized that grass fed cattle have a lower milk fat content. The amount of grain does play some role in the fat development but energy and dietary protein intake and the current state of pasture the cattle are being grazed on must also be accounted for. In addition, milk fat content is also determined by the genetics of the individual animal, whether or not it currently has or had infections in her udder, and her stage of lactation3.

In addition, grass-fed cattle don’t necessarily carry a lower bacterial load. Even at the most sanitary facilities, milk is often contaminated by fecal material carrying pathogens during the milking process. According to Dr. Jim Kazmierczak, a Public Health Veterinarian with the Wisconsin Department of Health Services, there have been numerous studies that proved grass-fed cattle shed E. coli 0157:H7 in the feces longer than grain-fed cattle4 and that “cattle fed a forage diet were 0157:H7 culture-positive longer and with higher numbers of bacteria in their feces than cattle fed a grain diet.6” This means that E. coli 0157:H7 remained alive in their feces longer than grain-fed cattle.  In addition to being found in fecal material, E. coli 0157:H7 can be found where cattle are grazing, can live on different environmental reservoirs for many months, such as gates, walkways, or water troughs, and is found more frequently during the summer.

We are blessed in the US to have a relatively safe food supply. Sure there will be occasional food-borne illness outbreaks but we are fortunate to have the technology, sanitary methods, and capabilities to keep the food we consume free from diseases to the best of our abilities. The invention of pasteurization reduced the number of illnesses and deaths caused by contaminated dairy products while maintaining the integrity and nutritional value of the milk. But there is a misconception of pasteurized milk across the country that has led to people making deadly decisions. Mary McGonigle-Martin would have never given her child raw milk had she known that it had the potential to harm or kill him. The risks are high when consuming raw milk and people need to be properly informed before their put their families and themselves in unnecessary danger.

1. Andersson, I., and Öste, R. (1995). Nutritional quality of heat processed liquid milk. In P. F. Fox (Ed.), Heat-induced changes in milk (2nd ed.) (pp. 279e307). Brussels: International Dairy Federation.

2. Burton, H. (1984). Reviews of the progress of dairy science: the bacteriological, chemical, biochemical and physical changes that occur in milk at temperatures of 100e150 _C. Journal of Dairy Research, 51, 341e363.

3. Claeys, W. L., et. Al (2013). Raw or heated cow milk consumption: Review of risks and benefits.

4. Hovde, C. J., et al. (1999). Effect of cattle diet on Escherichia coli O157:H7 acid resistance. Appl Environ Microbiol 65:3233–32

5. Schaafsma, G. (1989). Effects of heat treatment on the nutritional value of milk. Bulletin of the International Dairy Federation, 238, 68e70.

6. Van Baale, M. J., at al. (2004). Effect of Forage or Grain Diets with or without Monensin on Ruminal Persistence and Fecal Escherichia coli O157:H7 in Cattle. Appl Envir Microbiol 70:5336-5342.

7. Walstra, P., and Jeness, R. (1984). Dairy chemistry and physics (p. 467). New York: John Wiley & Sons.

Raw milk. Raw deal?

This is the sixth of 16 student posts, guest-authored by Anna Lyons-Nace. 

Natural…unprocessed…raw.  These terms are often used by consumers, nutritionists and health experts to denote the most healthful, high-quality food options available for consumption. However, when pertaining to the recent increasing trend in raw milk consumption, can consumers be confident that they are choosing the safest and most healthful option?  Statistical data and health studies would suggest otherwise.

Before we delve into the discussion any further, we should first establish what is considered raw milk and what is not raw.  Raw milk is considered any animal milk, most often from cows, sheep and goats, which is not pasteurized, but still utilized for human consumption. Keep in mind that raw milk can also be used for producing other dairy products such as cheese and yogurt. Raw milk may also undergo a straining process, but it is otherwise unprocessed.  Sources of raw milk are typically local farming operations.  In fact, the interstate sale of raw milk for direct consumption has been prohibited in the U.S. by federal law since 1987, due to safety concerns regarding shelf life and disease risks.  However, there are many states that allow the intrastate sale of raw milk, while a few states prohibit it completely.  This means that the vast majority of what we see in our local grocery stores will have undergone the process of pasteurization, which will be clearly stated on the label.  Pasteurization involves heating the milk to very specific temperatures for short time frames in order to kill potentially harmful germs. Pasteurization was introduced in the U.S. during the first part of the 20th century, at a time when millions of people were contracting life-threatening illnesses such as typhoid, diphtheria and tuberculosis, often through milk consumption. Applying the simple process of pasteurization, along with other health advances, led to a dramatic decline in such diseases, and is considered a major public health triumph.  Decreasing or eliminating potentially harmful microbes through pasteurization, not only makes the product safer for consumers, it also increases shelf life.

So why is raw milk becoming a sought after commodity for many consumers?  This can probably be attributed to such things as a general increase in societal demand for whole, natural and sustainable food products; as well as the perceived benefits of the milk itself. Raw milk drinkers claim that the unpasteurized product is higher in nutrients, protective enzymes and immune boosting probiotics, and can help treat a variety of ailments from asthma to gastrointestinal disorders. Supporters also claim that pasteurization is the cause of milk allergies and lactose intolerance.  It is important to note that these claims remain largely unsubstantiated by published scientific studies.  In many cases these claims have been categorically refuted by direct scientific evidence.  The Food and Drug Administration (FDA) frankly states that “research shows no meaningful difference between the nutrient content of pasteurized and unpasteurized milk”.  Science has also shown that most enzymes of concern by advocates are not altered by pasteurization. For those with allergy concerns, medical experts and research agrees that it is the proteins naturally present in milk (both raw and pasteurized) that are the cause of allergic reactions to milk and have no relationship to the pasteurization process.  In regards to lactose intolerance, it needs to be understood that lactose intolerance is a genetic error of metabolism that some people are born with, and there is lactose present in both raw and pasteurized milk.  So unfortunately for the lactose intolerant, raw milk is not the solution. As for probiotics, milk does not naturally contain probiotics; so if they are detected in the raw milk they are likely from another source such as air exposure or fecal contamination.  But the good news is that we as consumers have many, safer options for experiencing the benefits of probiotics, including yogurt with active cultures and over the counter supplements.

Now that we have explored some of the common myths surrounding raw and pasteurized milk, it is most important to discuss the reality of the risks involved with raw milk consumption. Real world case studies, as well as research by such reputable organizations as the Centers for Disease Control and Prevention (CDC) and the FDA, consistently show that the risks of raw milk consumption far outweigh any real or perceived benefit. A 13 year study by the CDC showed raw milk and raw milk products are 150 times more likely to cause a disease outbreak than are pasteurized dairy products. These risks come in the form of a long list of disease causing germs that can contaminate dairy products, and are the reason that pasteurization was instituted in the first place. Some of the more significant contaminants that can be present in raw milk include such pathogens as Salmonella, E. coli, Listeria, and Campylobacter.  These pathogens can cause a variety of symptoms, but most commonly produce gastrointestinal illness such as vomiting and diarrhea that can range from mild forms to fatal illnesses. The most vulnerable to becoming sick from drinking raw milk include babies, young children, those with weakened immune systems and pregnant women. But “healthy” people can become ill as well, and there are many documented cases. Data collected by the CDC from 1998-2009 documented 93 disease outbreaks due to raw milk and raw milk product consumption.  These outbreaks caused 1,837 illnesses, 195 hospitalizations, and 2 deaths.  It is important to note that for every case that is reported and diagnosed, there are many illnesses that go unreported, which means these case numbers in reality are certain to be much higher.  The most recently reported outbreak occurred in Oregon this past April.  The outbreak involved 19 people, 15 of which were children, with 4 of the children ending up in the hospital undergoing treatment for kidney failure.  Eleven of the cases were confirmed to have been caused by a very dangerous strain of E. coli that was traced back to a dairy farm that supplied the families with raw milk. In reflecting on outbreaks such as these, it is important to remember that these illnesses are preventable.   But hopefully, these sad cases will also serve to educate us as consumers, so that we can make informed and healthy choices for ourselves and our families.

References

  1. Langer AJ, Ayers T, Grass J, Lynch M, Angulo FJ, Mahon BE. Nonpasteurized dairy products, disease outbreaks, and state laws-United States, 1993-2006. Emerg Infect Dis. 2012 Mar;18(3):385-91.
  2. Oliver SP, Boor KJ, Murphy SC, Murinda SE. Food safety hazards associated with consumption of raw milk. Foodborne Pathog Dis. 2009 Sep;6(7):793-806. Review.
  3. Centers for Disease Control and Prevention, Trying to Decide about Raw Milk? Last Updated March 7, 2011, http://www.cdc.gov/foodsafety/rawmilk/decide-raw-milk.html (Accessed June 5, 2012)
  4. Centers for Disease Control and Prevention, Raw Milk Questions and Answers, Last Updated March 22, 2012, http://www.cdc.gov/foodsafety/rawmilk/raw-milk-questions-and-answers.html (Accessed June 5, 2012)
  5. Milk Facts, Heat Treatment and Pasteurization, http://milkfacts.info/Milk%20Processing/Heat%20Treatments%20and%20Pasteurization.htm (Accessed June 8, 2012)
  6. Food and Drug Administration, Raw Milk Misconceptions and the Danger of Raw Milk Consumption, Last Updated November 1, 2011, http://www.fda.gov/Food/FoodSafety/Product- SpecificInformation/MilkSafety/ConsumerInformationAboutMilkSafety/ucm247991.htm (Accessed June 5, 2012)
  7. Food and Drug Administration, Questions & Answers: Raw Milk, Last Updated November 1, 2011 http://www.fda.gov/food/foodsafety/product-specificinformation/milksafety/ucm122062.htm (Accessed June 5, 2012)
  8. Food Safety News, 19 Ill with E. Coli in Oregon Raw Milk Outbreak, Last Updated April 21, 2012, http://www.foodsafetynews.com/2012/04/post-5/ (Accessed June 5, 2012)
  9. International Association for Food Protection, Raw Milk Consumption: An Emerging Public Health Threat? Last updated 2012 http://www.foodprotection.org/events/other-meetings/3/iafp-timely-topics-symposium-raw-milk-consumption-an-emerging-public-health-threat/10/speaker-presentations/ (Accessed June 6, 2012)
  10. International Association for Food Protection, Nutritional Straight Talk on Raw and Pasteurized Milk, last updated 2012 http://www.foodprotection.org/files/timely-topics/TT_02.pdf (Accessed June 6, 2012)