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)

 

 

Castrating sheep with teeth: not a good idea (with video!)

Just a quick post as I’m in end-of-semester hell. Via Maryn McKenna on Twitter, the CDC has released a report of Campylobacter illnesses due to not food consumption, but because of castrating lambs. With their teeth.

On June 29, 2011, the Wyoming Department of Health was notified of two laboratory-confirmed cases of Campylobacter jejuni enteritis among persons working at a local sheep ranch. During June, two men had reported onset of symptoms compatible with campylobacteriosis. Both patients had diarrhea, and one also had abdominal cramps, fever, nausea, and vomiting. One patient was hospitalized for 1 day. Both patients recovered without sequelae.

During June, both patients had participated in a multiday event to castrate and dock tails of 1,600 lambs. Both men reported having used their teeth to castrate some of the lambs.

Among the 12 persons who participated in the event, the patients are the only two known to have used their teeth to castrate lambs.

Sadly, this wasn’t the first time I’ve heard of such a procedure. This was on Dirty Jobs a few years back (and yes, Mike Rowe participated–not for the squeamish).

On a related note, my grandma always had sheep on her farm. I helped to shear but never castrate. Now I’ll have to ask my dad and uncles what method they used…

Campylobacter jejuni-Associated Guillain-Barré Syndrome: It’s No Picnic

Student guest post by D.F. Johnston

As the year marches forward, ever closer to that summer sun we missed so much during dreary winter days, we also get closer to the traditional summer picnics and barbecues. Sometimes, in our hurry to enjoy quality time with friends and family, we get distracted from our usual practices for proper food handling. We might try to get little Billy his hamburger before he has time for a full-fledged temper tantrum, so we hurry it along, figuring a tiny bit of pink in the middle won’t be the end of the world. Or we might realize that we’re short a couple of serving spoons and re-use the meat fork for the raw fruit or veggie tray. After all, even if we’re thinking about foodborne illness, a little diarrhea is our biggest worry, right?

Actually, amongst the wide range of microbes that can cause foodborne illness, one of the more common is a Gram-negative bacterium called Campylobacter jejuni, which lives in the intestines (where the name “jejuni” comes from) and it is most often encountered in undercooked poultry or via cross-contamination. This bacterium does cause the well-known symptom of short-term diarrhea and usually resolves on its own over the course of two to ten days or with antibiotic treatment (1). Many people who worry about foodborne illness worry about the well-known salmonellosis or the dreaded E. coli O157:H7. According to the National Center for Zoonotic, Vector-Borne, and Enteric Diseases estimates for the number of cases of shiga-toxin producing E. coli, enterohemorrhagic E. coli, salmonellosis and an Institute of Medicine estimate for enterotoxigenicE. coli, the combined total number of cases occurring each year in the United States is approximately 880,000 (2-5). Ironically, cases of Campylobacter are over 2.5 times more common, as there are approximately 2.4 million cases in the United States each year (6). Campylobacter probably isn’t as infamous as it tends to occur in small clusters like at family picnics, rather than in high-profile outbreaks and recalls.

Unfortunately, discomfort and dehydration are not the only possible consequences of campylobacteriosis. Lindsay mentions temporary arthritis and hemolytic uremic syndrome, which can result in renal failure, as potential consequences of C. jejuni infection (7). Additional chronic conditions associated with prior infection with C. jejuni are mentioned by the Food Research Institute at the University of Wisconsin-Madison and include appendicitis, carditis, Reiter syndrome, and Miller Fisher syndrome, which is a subtype of Guillain-Barré syndrome (8). There are several forms of Guillain-Barré syndrome (GBS), making the range of symptoms wide as well, but some of the more commonly encountered effects are limb and respiratory weakness, and loss of reflexes (9). Several organisms may precipitate GBS, in addition to C. jejuni, such as cytomegalovirus, Epstein-Barr virus, and Mycoplasma pneumoniae, although Campylobacter-associated forms may be more severe in clinical presentation (10, 11). Typically, GBS associated with C. jejuni follows 1-3 weeks after infection and patients generally recover within weeks to months (11). However, there is a 2-3% mortality rate and 20% of GBS cases may have significant and lasting neurologic effects (12). Between 30-50% of all GBS cases are linked to C. jejuni infection (12).

Since there are several forms of clinical presentation for GBS, the forms also differ in hypothesized mechanisms for how the disease is caused or what part of the nerve cell is directly affected (i.e. the myelin sheath versus the axon or T-cell mediated versus antibody-mediated) (11). Despite this, the current conception for all types is of GBS being caused by the immune system reacting to an external factor (such as C. jejuni) to the degree that human cells become collateral damage in one form or another. One of the more popular theories is that part of a molecule on the surface of the bacterium is very similar to those found on nerve cells in the human body, leading to an antibody attack on nerve cells even after the Campylobacter has been eliminated. This mechanism is further supported by the other agents suspected in causation of GBS since they also have a similarly-shaped molecule on their surface (11). The paralysis or muscle weakness may occur because the immune system breaks open the protective Schwann cells surrounding the nerves, allowing enzymes to begin breaking down the myelin “insulation” of nerve axons that help ensure reception and speed of nerve impulses (11).

The first causal relationship for C. jejuni and GBS was hypothesized in 1982 based on a case report and similar reports continued after this (11). Isolation and growth of Campylobacter from the stool of GBS patients also supported such a relationship, but was assumed to underestimate bacterial presence, as time from initial infection to culture and culture methodology could strongly influence recovery of the bacterium (11). Lab techniques to detect antibodies to C. jejuni have also been used to demonstrate presence of the organism in GBS patients, although this technique is subject to cross-reaction with closely related bacteria (11). That GBS appears 1-3 weeks after bacterial infection (the time it takes to produce an antibody response) also supports an infectious event leading to GBS. Animal models have strengthened support for the association, as rabbits and mice have been injected with molecules similarly shaped to those of C. jejuni and have developed high titers of antibodies that also react against nerve cells (11, 12). The NIH appears to accept the role of Campylobacter in GBS etiology and has moved to outlining steps for improving mechanistic knowledge (11); the published literature also reflects this general acceptance.

This summer, my family reunion is going to use safe food handling techniques in an attempt to lower my family’s risk for the unpleasantness of campylobacteriosis and the subsequent risk for Guillain-Barré syndrome and other Campylobacter-associated chronic conditions. Have a look at the USDA guidelines for proper food handling and enjoy your summer pursuits (13).

Works Cited

1. Ang, J.Y. & Nachman, S. 2009. “Campylobacter Infections.” eMedicine.

2. National Center for Zoonotic, Vector-Borne, and Enteric Diseases. 2009. “Escherichia coli O157:H7.” Centers for Disease Control and Prevention.

3. National Center for Zoonotic, Vector-Borne, and Enteric Diseases. 2009. “Enterohemorrhagic Escherichia coli: Technical Information.” Centers for Disease Control and Prevention.

4. National Center for Zoonotic, Vector-Borne, and Enteric Diseases. 2009. “Salmonellosis.” Centers for Disease Control and Prevention.

5. Stratton, K.R., Durch, J.S., & Lawrence, R.S (Institute of Medicine). 2000. “Vaccines for the 21st Century: A Tool for Decisionmaking–Appendix 5: Enterotoxigenic E. coli.” National Academies Press.

6. National Center for Zoonotic, Vector-Borne, and Enteric Diseases. 2009. “Campylobacter, General Information.” Centers for Disease Control and Prevention.

7. Lindsay, J.A. 1997. “Chronic Sequelae of Foodborne Disease.” Emerg Infect Dis, 3(4): 443-452. http://www.cdc.gov/ncidod/EID/vol3no4/lindsay.htm

8. Doyle, M.E. 1998. “Campylobacter–Chronic Effects.” UW-FRI Briefings.

9. Davids, H.R. & Oleszek, J.L. 2010. “Guillain-Barré Syndrome.” eMedicine.

10. Yu, R.K., Usuki, S., & Ariga, T. 2006. “Ganglioside Molecular Mimicry and Its Pathological Roles in Guillain-Barré Syndrome and Related Diseases.” Infect Immun, 74(12): 6517-6527.

11. Nachamkin, I., Allos, B.M., & Ho, T. 1998. “Campylobacter Species and Guillain-Barré Syndrome.” Clin Microbiol Rev, 11(3): 555-567.

12. Moore, J.E., Corcoran, D., Dooley, J.S.G., Fanning, S., Lucey, B., Matsuda, M., McDowell, D.A., Megraud, F., Millar, B.C., O’Mahony, R., O’Riordan, L., O’Rourke, M., Rao, J.R., Rooney, P.J., Sails, A., & Whyte, P. 2005. Campylobacter.” Vet Res, 36(3): 351-382.

13. USDA: Food Safety and Inspection Service. 2010. “Safe Food Handling Fact Sheets.”

Image from: http://en.wikipedia.org/wiki/Campylobacter