United States raw milk debate
The United States raw milk debate concerns issues of food safety and claimed health benefits of raw (un-pasteurized, un-homogenized) milk, and whether authorities responsible for regulating food safety should prohibit sale of raw milk for consumption.
Raw milk, commonly and historically consumed by farm families, makes up a small proportion of US general population milk consumption.[1] However, some claim the demand for raw milk has "considerably increased in recent years".[1] Raw milk advocates claim a variety of health benefits attributable to untreated dairy products; government officials and scientific researchers stress that there are substantial food safety risks associated with raw milk and that claims of health benefits provided by raw milk are unsupported by scientific evidence.
Homogenization
Unprocessed milk consists of globules of milk fat suspended in a watery base containing dissolved proteins, sugars, vitamins, and minerals. If the globules are large enough, as with unprocessed milk from cows, the fat globules float upwards until they form a distinct cream layer at the top. Some animals, such as goats, produce smaller fat globules that remain mixed unless mechanically separated by centrifugation.
Homogenization is a process that reduces the size of fat globules by forcing pressurized, hot milk through small holes, causing turbulence that breaks up the larger fat globules so that they remain suspended rather than separating in a cream layer at the top.[2] The purpose of homogenization is to make milk more convenient to process, store and consume, eliminating the need to shake or stir the milk container to remix the separated cream layer and increasing the shelf-life of the product.[2]
Those opposed to homogenization argue that decreasing the size of fat globules may have unhealthy effects, including allowing steroid and protein hormones to bypass normal digestion and increase their levels in the body. Concerns that uptake of the protein xanthine oxidase is increased by homogenization, leading to hardening of the arteries (atherosclerosis), were raised in the 1970s. Subsequent research "failed to substantiate, and in many cases has refuted"[3] a plausible effect of xanthine oxidase from homogenized milk on cardiovascular disease.[3][4]
Scientific studies are somewhat limited but do not currently support claims that milk homogenization affects the development of atherosclerosis, coronary heart disease, milk allergy and milk intolerance, Type I diabetes or Type II diabetes.[2]
Pasteurization
Pasteurization is a sanitation process in which milk is heated briefly to a temperature high enough to kill pathogens, followed by rapid cooling. While different times and temperatures may be used by different processors, pasteurization is most commonly achieved with heating to 161 degrees Fahrenheit (71.7 degrees Celsius) for 15 seconds.[5][6] Milk is tested following pasteurization to confirm that bacteria have been killed to an acceptable level. Pasteurization kills pathogenic bacteria which occasionally may be present in milk, including those causing tuberculosis (Mycobacterium bovis), listeriosis (Listeria monocytogenes), Q fever (Coxiella burnetii), brucellosis (Brucella), campylobacteriosis (Campylobacter), salmonellosis (Salmonella), and several other foodborne illnesses (e.g., Escherichia coli O157:H7).[6] Pasteurization may not kill some resistant bacteria, which can eventually cause souring and spoilage of fresh milk[citation needed]. UHT pasteurization (Ultra High Temperature) is a more extreme form of pasteurization heating milk to a temperature high enough to kill spoilage organisms also.
Pasteurization is widely accepted to improve the safety of milk products by reducing the exposure to pathogens.[6] Opponents of pasteurization argue that unpasteurized milk has benefits associated with superior taste, nutritional qualities and certain health benefits over pasteurized milk. While pasteurization of milk kills off bacterial pathogens, other bacteria species with possible health benefits are also destroyed[citation needed]. A 2009 systematic review of the food safety of unpasteurized milk concluded that science-based data to substantiate claims of health benefits "are lacking or do not exist" and the risks associated with disease outbreaks as a result of raw milk consumption are "considerably higher".[7]
History
Pasteurization was first used in the United States in the 1890s after the discovery of germ theory to control the hazards of highly contagious bacterial diseases, including bovine tuberculosis and brucellosis, that could be easily transmitted to humans through the drinking of raw milk.[8] Initially after the scientific discovery of bacteria, no product testing was available to determine if a farmer's milk was safe or infected, so all milk had to be treated as potentially contagious. After the first test was developed, some farmers actively worked to prevent their infected animals from being killed and removed from food production, or would falsify the test results so that their animals would appear to be free of infection.[9]
In the United States, milk pasteurization became "widespread" in the 1920s and it was considered "one of the major breakthroughs in public health".[5] Pasteurization is credited with reducing infectious-disease rates in the U.S. "more than 90% over the past century".[10] In 1924, "Grade A Pasteurization" became recommended federal policy, but interstate commerce of unpasteurized dairy products was only limited via federal legislation in 1987.[6]
Legal status
In 2009, 29 U.S. states allowed sales of raw milk in some form.[7] In other parts of the world, raw milk can often be bought directly from the farmer. Arizona, Utah, California and Washington allow raw milk sales in retail stores with appropriate warning labeling. As of May 2010, Massachusetts only allows direct sales from farm to consumer, resulting in "buying clubs" where consumers pool transportation resources to obtain raw milk more conveniently.[11]
In late 2007, the debate received media attention in California, where limits on the bacterial counts legally allowed in commercial raw milk came up for legislative review.[12] Reuters named the raw milk debate as first on a list of the top eight health issues of 2008.[13] The FDA has also offered financial assistance to state departments of health to help reduce raw milk consumption.[11]
Health effects of pasteurized milk
Pasteurization is credited with dramatically reducing pathogens found in milk. This improves the shelf-life and safety of the processed milk. Advocates of drinking raw milk claim various health benefits they attribute to raw milk that are lost in the pasteurization process,[14] and claim that raw milk can be produced as hygienically as pasteurized milk.[15] Raw milk advocates may go as far as to claim that untreated milk is a "miracle cure" for illnesses such as asthma or gastrointestinal disorders.[16] A 2006 systematic review of infections associated with raw milk contends that pasteurized milk is substantially safer than raw milk, and comparably nutritious to raw milk, therefore there is no scientific reason for choosing raw milk products.[17]
Pasteurization opponents say that raw milk contains bacteria beneficial to the human digestive system,[18] but pasteurization is not selective and impacts all bacteria whether beneficial or infectious. These bacteria include species considered to be probiotics, such as Lactobacillus acidophilus, useful for the culturing of yogurt and cheese. Milk products with L. acidophilus, have been associated with decreased incidence of pediatric diarrhea, decreased levels of toxic amines in the blood of dialysis patients with small bowel bacterial overgrowth, aided lactose digestion in lactose-intolerant subjects, and a reduction in coronary heart disease risks.[19][20] However, food scientists and FDA officials maintain that such "good bacteria" can be found in pasteurized products, including yogurt,[21] and argue that the destruction of pathogens far outweighs any proposed benefit to keeping the "beneficial" microbes alive.[22]
Pathogens and public health concerns
According to a 2009 review, milkborne disease outbreaks made up approximately 25% of all food and water contamination disease outbreaks in 1938; pasturization is largely credited for a dramatic decrease in milkborne disease outbreaks, which made up less than 1% of food and water contamination disease outbreaks by 2005.[1]
According to the Center for Disease Control and Prevention, more than 300 people in the United States got sick from drinking raw milk or eating cheese made from raw milk in 2001, and nearly 200 became ill from these products in 2002. "Drinking raw milk or eating raw milk products is like playing Russian roulette with your health," says John Sheehan, director of the Food and Drug Administration's Division of Dairy and Egg Safety. "We see a number of cases of food-borne illness every year related to the consumption of raw milk."[22]
In 2006, the California Department of Food and Agriculture temporarily quarantined milk and cream from Organic Pastures, California's largest raw milk producer, after four children were stricken with E. coli O157:H7 bacterial illness. The department determined that the common link in all four cases "was consumption of raw milk or raw colostrum from Organic Pastures in the week prior to symptom onset."[23]
Milk collected or stored in unsanitary conditions may harbor a host of disease-causing organisms (pathogens), such as tuberculosis (Mycobacterium bovis), the bacteria Campylobacter (Campylobacteriosis), Escherichia E. coli O157:H7), Listeria (Listeriosis), Salmonella (Salmonellosis), Yersinia (Yersinia enterocolitica), and Brucella (Brucellosis). Pasteurization consistently removes all of these pathogens, though they can be reintroduced if the product is handled carelessly. Thus dairy farms that pasteurize their milk can have unsanitary facilities without the attendant outbreaks of disease that would occur if a raw milk dairy kept its herds in similar unsanitary conditions.
People with weakened immune systems, such as elderly, children, and those with certain diseases or conditions, are most at risk for severe infections from pathogens that can contaminate raw milk. In pregnant women, Listeria monocytogenes-caused illness can result in miscarriage, fetal death, or illness or death of a newborn infant, and Escherichia coli (E. coli) infection has been linked to hemolytic uremic syndrome, a condition that can cause kidney failure and death. Other groups, such as the Center for Food Safety and Applied Nutrition[24] and American Academy of Pediatrics, also warn that raw milk is dangerous, especially for children.[6]
The Centers for Disease Control (CDC) cite numerous cases of serious or fatal infections caused by raw milk, with E. coli O157:H7 being the most important because it can cause hemolytic-uremic syndrome, a life-threatening condition.[25] In a CDC report, numerous cases were traced to raw milk from a cow-share program in Cowlitz County, Washington. After five children were hospitalized, a court order was issued to bring the farm into compliance.[26] In 2007, Kansas State University published a list of outbreaks[27] associated with consuming raw milk or dairy products and an article[28] about the investigation of raw milk outbreaks.
The Weston A. Price Foundation has been active in promoting raw milk with its "Real Milk" campaign.[14] The organization claims that of 15 milkborne disease outbreaks cited by the FDA, not a single one demonstrated that pasteurization would have fixed the problem, that 93% lacked either a valid statistical correlation with raw milk or a positive sample, and half lacked both; they further claimed that, even with the FDA's numbers, raw milk was no more dangerous than deli meats.[29] In response, the director of the FDA's division of plant- and dairy-food safety, John Sheehan, called the organization's claims on the health benefits and safety of raw milk "false, devoid of scientific support, and misleading to consumers".[30]
In 2008, scientists discovered that raw milk contains more species of bacteria than previously thought, and identified Chryseobacterium oranimense as well as C. haifense and C. bovis, but the amount found in raw milk has not been proven harmful.[31]
Nutrients in milk
Advocates of drinking raw milk claim raw milk contains desirable substances, such as enzymes, that cannot survive the heating process and may be destroyed during pasteurization; specifically, immunoglobulins and the enzymes lipase and phosphatase, which are inactivated by heat, are believed to be beneficial.[citation needed] In contrast, food scientists and FDA officials assert that most "beneficial" enzymes survive pasteurization and that humans do not use animal enzymes to metabolize nutrients.[22]
Raw milk contains vitamin B6, but the heat treatment may cause as much as 20% of the vitamin to be lost.[18][unreliable source] Pasteurization does cause the loss of several vitamins, but only approximately 0–10%.[22] Raw milk contains very little vitamin D, which is added to processed milk.[14][22]
Protection against non-infectious disease
Two studies found a statistically significant inverse relationship between consumption of raw milk and asthma and allergies.[32][33]
Sensory experiences of pasteurized and un-pasteurized products
Many raw milk consumers cite a preference for the taste of raw milk products.[14]
The Raw Milk Cheesemakers Association hold that cheeses produced from raw milk have distinctive complexity and depth of flavor absent from pasteurized-milk cheeses.[34]
The FDA considers hard, aged cheeses, such as parmesan and cheddar, made from raw milk to be generally safe for consumption; soft cheeses made from raw milk are considered unsafe.[35] These cheeses are currently legally sold if aged for 60 days or more.[30] Over this period, the salt and acid characteristics of aging cheeses generally eliminate the growth of pathogenic bacteria.[36]
Personal choice
Raw milk advocates cite libertarian and personal choice arguments against government interference concerning the sale of raw milk.[37][38] Some such advocates may feel resentment towards the government's efforts in limiting the distribution and consumption of raw milk, seeing their actions as a personal choice that is not harmful to anyone else.[10] Raw milk activism can be associated with alternative medicine and anti-regulatory activism.[16]
Quality standards for milk
The methods of determining Grade A milk quality are well-established and outlined in the Grade A Pasteurized Milk Ordinance. These grades are typically related to a measurement known as the somatic cell count (SCC) and the bacteria plate count. Generally a lower somatic cell count indicates better animal health, while the bacteria plate count indicates improved equipment sanitation.
Somatic cells originate only from inside the animal's udder, while bacteria are usually from external contamination, such as insufficient cleaning of the milk transport equipment or insufficient external cleansing of the cow’s udder and teats prior to milking. Milking equipment can also be accidentally knocked or kicked off an animal onto the floor, and contaminants on the barn floor can be sucked into the milk line by the system vacuum. A filter sock or filter disk in the pipeline prevents large particulate contaminants from entering the milk bulk tank, but cannot remove bacterial contamination once it has occurred.
For example as defined by the state of Indiana’s administrative code, Grade A milk shall meet the following standards:[39]
- The bacterial estimate classification shall be "acceptable".
- The bacteria count using the standard plate count, direct microscopic count, or plate loop count methods shall be not more than one million (1,000,000) bacteria per milliliter.
- The somatic cell count shall be not more than one million (1,000,000) cells per milliliter.
- The milk shall not contain drug residues.
Milk not meeting these standards shall be designated as undergrade. Undergrade milk may not be sold for human consumption or processing into products for human consumption.
As established, these measurements are taken daily from the milk bulk tank and not from individual cows. This is because testing of individual animals at each milking would be expensive, but it also means that milk from a sick cow is diluted and averaged down by the healthy animals. Greater bulk tanks at very great commercial farms are accommodating of more sick animals in the herd, without the sick animals affecting the overall milk quality rating.
As discussed in the paper Guidelines for Using the DHI Somatic Cell Count Program[40]
- The results of many studies suggest that cows with SCC of less than 200,000 are not likely to be infected with major mastitis pathogens, but cows with SCC above 300,000 are probably infected (Smith, 1996).
- Herds with bulk tank SCC above 200,000 will have varying degrees of subclinical mastitis present. Data from the National Mastitis Council (1987) show that 6% of the [udder] quarters in a herd could be expected to be infected in a herd with a bulk tank SCC of 200,000.
- At 500,000 SCC, 16% of the quarters may be infected with a 6% reduction in milk production compared to a SCC of 200,000.
Bacteria in milk can come from sources other than the animal. Over time the milking pipeline and equipment can become coated with residues such as milkstone which are not removed by standard detergents and require periodic flushing of equipment with high strength corrosives. Automatic washing equipment for the bulk tank may not effectively clean all interior surfaces, and does not clean the exterior of the bulk tank at all.[citation needed]
Some buyers award producers for having the lowest SCC but this does not also lead to an increased payment for the milk quality, so there is no incentive to strive for anything more than meeting the basic grade A SCC rating.[citation needed]
See also
References
- ^ a b c Lejeune JT, Rajala-Schultz PJ (2009). "Food safety: unpasteurized milk: a continued public health threat". Clin. Infect. Dis. 48 (1): 93–100. doi:10.1086/595007. PMID 19053805.
{{cite journal}}
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ignored (help) - ^ a b c Michalski MC (2007). "On the supposed influence of milk homogenization on the risk of CVD, diabetes and allergy". Br. J. Nutr. 97 (4): 598–610. doi:10.1017/S0007114507657900. PMID 17349070.
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ignored (help) - ^ a b Clifford AJ, Ho CY, Swenerton H (1983). "Homogenized bovine milk xanthine oxidase: a critique of the hypothesis relating to plasmalogen depletion and cardiovascular disease". Am. J. Clin. Nutr. 38 (2): 327–32. PMID 6349321.
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ignored (help)CS1 maint: multiple names: authors list (link) - ^ Deeth HC (1983). "Homogenized milk and atherosclerotic disease: a review". J. Dairy Sci. 66 (7): 1419–35. doi:10.3168/jds.S0022-0302(83)81956-0. PMID 6350392.
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ignored (help) - ^ a b "Got Raw Milk?", Boston Globe, March 23, 2008
- ^ a b c d e Bradley J, Pickering L, Jareb J (December 2008). "Advise families against giving children unpasteurized milk" (PDF). AAP News. 29 (12). American Academy of Pediatrics.
{{cite journal}}
: CS1 maint: multiple names: authors list (link) - ^ a b Oliver SP, Boor KJ, Murphy SC, Murinda SE (2009). "Food safety hazards associated with consumption of raw milk". Foodborne Pathog. Dis. 6 (7): 793–806. doi:10.1089/fpd.2009.0302. PMID 19737059.
{{cite journal}}
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ignored (help)CS1 maint: multiple names: authors list (link) - ^ An Impossible Undertaking: The Eradication of Bovine Tuberculosis in the United States, ALAN L. OLMSTEAD AND PAUL W. RHODE, The Journal of Economic History (2004), 64: 734-772 Cambridge University Press, Copyright © 2004 The Economic History Association, doi:10.1017/S0022050704002955
- ^ Not on My Farm!: Resistance to Bovine Tuberculosis Eradication in the United States, Alan L. Olmstead and Paul W. Rhode, January 2005, The Journal of Economic History (2007), 67:768–809 Cambridge University Press, Copyright © 2007 The Economic History Association, doi:10.1017/S0022050707000307
- ^ a b "Got Raw Milk? Be Very Quiet", TIME, March 13, 2007
- ^ a b "Raw Milk Enthusiasts Sour on Proposed Delivery Ban". 2010-05-14. Retrieved 2010-06-28.
- ^ "Bid in Assembly to repeal tough new raw milk standard", San Francisco Chronicle, January 16, 2008
- ^ "Top Health Issues of 2008", Reuters, December 20, 2007
- ^ a b c d "Should This Milk Be Legal?", New York Times, August 8, 2007
- ^ Raw Milk and Raw Milk Products: Safety, Health, Economic, and Legal Issues, Weston A. Price Foundation
- ^ a b "'Raw milk' advocates, health officials step up dispute", USA Today, April 15, 2010
- ^ Leedom JM (2006). "Milk of nonhuman origin and infectious diseases in humans". Clin. Infect. Dis. 43 (5): 610–5. doi:10.1086/507035. PMID 16886155.
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ignored (help) - ^ a b Abstracts on the Effect of Pasteurization on the Nutritional Value of Milk, Weston A. Price Foundation
- ^ Sanders ME, Klaenhammer TR (2001). "Invited review: the scientific basis of Lactobacillus acidophilus NCFM functionality as a probiotic". J Dairy Sci. 84 (2): 319–331. doi:10.3168/jds.S0022-0302(01)74481-5. PMID 11233016.
- ^ "Effect of Fermented Milk (Yogurt) Containing Lactobacillus Acidophilus L1 on Serum Cholesterol in Hypercholesterolemic Humans". Retrieved May 25, 2010.
- ^ "The history of raw milk", Matthew DeFour, Wisconsin State Journal, December 5, 2009
- ^ a b c d e "Got Milk? Make Sure it's Pasteurized" Linda Bren, FDA Consumer, FindArticles.com. 15 Oct, 2010.
- ^ "CDFA Lifts Quarantine of Organic Pastures Raw Milk and Cream," California Department of Food and Agriculture, September 2006
- ^ "FDA Warns Consumers to Avoid Drinking Raw Milk" (Press release). FDA News. December 16, 2005. Retrieved August 10, 2008.
- ^ "Raw Milk and Cheeses: Health Risks are Still Black and White", CDC
- ^ "Escherichia coli O157:H7 Infection Associated with Drinking Raw Milk --- Washington and Oregon, November--December 2005". Morbidity and Mortality Weekly Report, March 2, 2007, 56(08);165-167
- ^ List of Raw Milk Outbreaks
- ^ "The Epidemiology ofRaw Milk-Associated Foodborne Disease Outbreaks Reported in the United States, 1973 Through 1992", American Journal of Public Health, August 1998, Vol. 88, No. 8
- ^ FDA rebuttal, Weston A. Price Foundation
- ^ a b "A Clash Over Unpasteurized Milk Gets Raw", Wall Street Journal, March 30, 2010
- ^ EurekAlert. New bacteria discovered in raw milk.
- ^ Perkin MR, Strachan DP (2006). "Which aspects of the farming lifestyle explain the inverse association with childhood allergy?". J. Allergy Clin. Immunol. 117 (6): 1374–81. doi:10.1016/j.jaci.2006.03.008. PMID 16751000.
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ignored (help) - ^ Waser M; Michels KB; Bieli C; et al. (2007). "Inverse association of farm milk consumption with asthma and allergy in rural and suburban populations across Europe". Clin. Exp. Allergy. 37 (5): 661–70. doi:10.1111/j.1365-2222.2006.02640.x. PMID 17456213.
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ignored (help); Unknown parameter|month=
ignored (help) - ^ Raw Milk Cheesemakers’ Association. "American Raw Milk Cheese Presidium Mission & Protocol".
- ^ "The Dangers of Raw Milk: Unpasteurized Milk Can Pose a Serious Health Risk", FDA
- ^ "Raw-Milk Cheese", About.com
- ^ "Pasteurization Without Representation", The Atlantic, May 13, 2010
- ^ "Raw Milk Rebellion", Jacob Grier, Cato Institute, Reason Magazine, May 16, 2008
- ^ State of Indiana Administrative Code, TITLE 345 INDIANA STATE BOARD OF ANIMAL HEALTH, ARTICLE 8. DAIRY PRODUCTS, 345 IAC 8-2-3 Manufacturing grade dairy farms; construction; operation; sanitation, page 11 http://in.gov/legislative/iac/T03450/A00080.PDF
- ^ Guidelines for Using the DHI Somatic Cell Count Program, Author: G.M. Jones, Professor of Dairy Science and Extension Dairy Scientist, Milk Quality & Milking Management, Virginia Tech, Publication Number 404-228, posted March 1998 http://www.ext.vt.edu/pubs/dairy/404-228/404-228.pdf
External links
- Pasteurized and Raw Milk
- Sale/Consumption of raw Milk-Position Statement, U.S. FDA Center for Food Safety and Applied Nutrition
- Presentation on the safety of raw milk by the FDA