Whether urban legends, deceptive marketing, or beliefs held by raw milk proponents under a siege mentality, there are more microbiological and nutritional myths about raw milk than nearly any other food.
After reviewing the myths, I looked for information from scientists and consumer advocates and busted the Top Ten 21st Century Raw Milk Myths. Here are the results:
Myth #1. Raw milk has been consumed for thousands of years without a problem.
This myth reflects a lack of understanding about the historical impact of infectious diseases transmitted by raw milk for centuries, especially tuberculosis, brucellosis (undulant fever), and scarlet fever (1-5). Raw milk has caused numerous deaths of infants throughout history. Pasteurization was developed to prevent these well-documented illnesses and deaths from contaminated raw milk. In developed countries, the use of pasteurization has been directly correlated to reduced infant mortality (6). In developing countries today, from India to Africa, raw milk is routinely boiled before being fed to babies, children, and other family members to protect them from deadly milk-borne infections.
Myth #2. Pasteurization destroys all the nutrients in milk.
Since the dawn of pasteurization (using heat to kill pathogens), this myth has prevailed without scientific evidence. When pasteurization started to become more mainstream early last century, some people were suspicious of the technology. Subsequent analyses of the nutritional components of raw and pasteurized milk revealed no significant differences for the major nutritional components such as proteins, carbohydrates, and vitamins (7-10). View comparison of raw and pasteurized organic whole milk labels:
Myth #3. Homogenization produces dangerous changes in milk.
This is another old myth dating back to the first years of milk processing during the last century. Homogenization is simply the process of physically breaking up the fat globules in cow’s milk to make a “homogenous” fluid milk beverage (11-12). Unhomogenized cows milk will develop a cream layer at the top of the container. Goat’s milk is “naturally homogenized” and does not form a cream layer during storage. There is no proven health difference between mechanically homogenized cow’s milk and naturally homogenized goat’s milk.
Myth #4. Raw milk kills pathogens.
This myth evolved from a partial truth based on experimental data where researchers inoculated “bad” bacteria into raw milk and measured its survival. In one experiment, a few strains of the bacteria Campylobacter died sooner in raw milk compared with sterile milk (13), but most strains survived long in enough in both types of milk to make someone sick. Other experiments have shown survival and even growth of E. coli O157, Salmonella, and Listeria in raw milk and raw milk products (14-17). Live bacterial pathogens are routinely found in bulk tank milk on farms, which proves that “bad” bacteria are not reliably killed by “good” bacteria, enzymes or other components of raw milk (18-21). Raw milk also does not kill or reduce foodborne viruses or parasites.
Myth #5. It is safe to leave raw milk at room temperature.
This myth appears to come from a revival in the interest in traditional diets and practices. Clabbered milk is raw milk allowed to naturally sour and thicken (22). The raw milk is allowed to warm, which can be very dangerous if the milk was accidently contaminated with pathogenic bacteria that grow at warm temperature (e.g., Salmonella, E. coli O157, Staphylococcus aureus). Bacterial pathogens thrive on the nutrients in fresh milk and can outgrow the “good bacteria” once given the advantage of increased temperature. Not all raw milk contains pathogens, but because you can’t see or smell them, there is no way to know if it is safe to take this chance. A safer alternative is to buy cultured dairy products such as buttermilk, yogurt, and kefir made with pasteurized milk. View charts of pathogen growth from experiments conducted at room temperature and under refrigeration:
Raw milk activists in developed countries, especially the United States, mostly perpetuate this myth. In contrast, most parents in developing countries recognize the dangers of raw animal milk and boil milk to destroy pathogens before feeding to babies or young children. Numerous studies show that breastfeeding is the healthiest option for infants (23). A human mother’s milk is designed to be the best source of nutrition and immune-giving factors for her baby. When breastfeeding is not an option, there is nearly unanimous agreement in the medical and public health communities worldwide that only pasteurized animal milk should be given to infants and young children (1-2, 24).
Myth #7. Millions of people purchase raw milk every year in the United States.
This myth appeared recently in an intense marketing campaign by raw milk advocates. Their estimate is based on a 2007 CDC FoodNet survey that found ~3% of people surveyed in 10 states reported drinking raw milk in the last 7 days (25). The survey did not differentiate between raw milk consumed on the farm vs. purchased by a customer. Most raw milk is consumed by rural dairy farm families and their workers who drink raw milk directly from their own animals (26-27). Estimates of non-farm, urban and suburban consumers who purchase raw milk from stores or farmers markets are drastically lower compared with farm family consumption. Commercial raw milk sales make up less
than 1% of milk sales overall (28). Retail commercial raw milk is a highly specialized niche product that is legal in only a few states and sold mostly in small natural food stores and co-ops. Major retailers do not sell raw milk because of the well-documented food safety risks. Whole Foods discontinued sales of raw milk in 2010 due to liability concerns (29).
Myth #8. Deaths attributed to drinking raw milk were from “bathtub cheese” and factory farms, not legal or “certified” raw milk.
This myth goes back to at least the 1980s when a single certified raw milk dairy in California was ultimately shut down after numerous illnesses and deaths from Salmonella Dublin (30). These deaths included immunosuppressed persons with AIDS, a then newly recognized syndrome. From 1980-1983, 15 deaths from salmonellosis in California from certified raw milk were documented (31). Stricter federal regulations were put in place during the 1980s to curb the high rate of illnesses and deaths from legal raw milk (4). There are also documented deaths from listeriosis and salmonellosis due to contaminated Mexican-style cheese (e.g., queso fresco) made with raw milk, and processed milk contaminated after pasteurization (32-33). No deaths in the last decade have been attributed to legal raw milk, but E. coli O157:H7 infections and hemolytic uremic syndrome (HUS) cases have been linked to a number of pasture-based raw milk farms and herdshares in states where raw milk sales are legal (34-36). Advances in medical treatment of HUS likely prevented death, although some patients may suffer from permanent kidney damage and other chronic health problems caused by the original E. coli O157 infection.
Myth #9. European researchers recommend raw milk for treatment of child allergies.
This myth originates from large population-based studies of rural farm factors that affect allergic and other conditions in Europe. A correlation between drinking farm milk and reduced childhood allergies has been found in epidemiological studies (37-41). However, the authors admit that causation has not been proven, and it is unclear if farm (unboiled) milk or other farm factors such as being around animals and barns influence the development of allergies in children. The European researchers recommend that raw milk not be used as a “treatment” for childhood allergies due to the risk of pathogens and serious infection.
Myth #10. Pathogens only come from factory farms (“confined feeding animal operations” or CAFOs).
This myth blossomed after publication of a small study in 1998 that showed a possible relationship between grain feeding and E. coli carriage in cattle (42). This lead to a widespread unsubstantiated belief that a grain diet (typical of a feedlot) affects the acidity of the stomach and promotes the growth of E. coli O157:H7. There is still much more research needed to understand how diet affects an animal’s likelihood of shedding pathogens in their feces (43-50). Higher rates of carriage have been found on feedlots where animals are crowded and when high rations of distiller’s grains are fed, but the specific influence of feed remains unclear. Furthermore, pathogens have been found in the guts and feces of cattle and other animals (including free-roaming wildlife) living on pasture with no exposure to grain. See the types of farms linked to recent dairy outbreaks.
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Michele Jay-Russell, DVM, PhD is a researcher at the Western Institute for Food Safety and Security, University of California, Davis. Prior to joining the university, she worked as an epidemiologist with the California Department of Public Health.
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