The consumption of raw milk has gained considerable popularity in recent years, yet still remains a source of great debate regarding the potential health impacts. The Food and Drug Administration as well as the Centers for Disease Control and Prevention report the well-known risk for contracting foodborne disease from the presence of human pathogens in raw milk. A recent review article goes into great detail about the history of pasteurization, the prevalence of foodborne pathogens in milk and the claims associated with the consumption of raw milk (Lucey 2015). Pasteurization was developed over 100 years ago to reduce the transmission of disease through milk, in particular, tuberculosis. In 1938 it was reported that 25% of all disease outbreaks related to food/water were from milk, compared to less than 1% today and now tuberculosis is not of concern due to the implementation of pasteurization.
Recent surveys have reported the prevalence of pathogens to be as high as 13% for bacteria such as Campylobacter jejuni and Listeria monocytogenes. Considering it takes as little as 5-10 bacterial cells to cause foodborne disease for some pathogens, this prevalence draws great concern. Another important consideration is raw milk can be contaminated with pathogens even when the cow is healthy and the milk appears normal. These pathogens can be in the gland or come from post-harvest contamination, for example, milking equipment. It is not necessarily associated with cleanliness of the farm, whether the cows are on pasture or how often and/or how well the producer cleans the milking equipment. These are simply inherent risks associated with the production of milk.
However, despite the well-known health benefits of pasteurization, some consumers seek the purchase of unpasteurized milk, or raw milk. Consumers of raw milk report they prefer the taste, feel there are added health benefits to consuming the bacteria present in raw milk, and suggest increased nutritional value. Taste preference is an individual consumer decision. Unfortunately we do not have objective measures for taste to evaluate this scientifically, as taste varies so greatly from one person to the next. Consumers report the added health advantages of consuming the beneficial bacteria in milk. Although milk can contain non-harmful bacteria, the risk for pathogenic bacteria is of greater concern for human health. If consumers are interested in consumption of beneficial bacteria for gut health, products containing live cultures including some yogurts should be considered. These products contain strains considered to be highly beneficial for the gut and known to be advantageous.
Another suggested health benefit of the consumption of raw milk is increased nutritional value. However, studies have reported no significant change in the nutritional content of milk following pasteurization (Andersson and Oste, 1995). Minor levels of whey protein denaturation have been shown, but that has no impact on nutritional quality. No change in the concentration of minerals occurs following pasteurization, as these are very heat stable. Pasteurization can cause a very minor loss (<10%) in vitamin B12, but does not change the concentration of riboflavin (B2) or the fat soluble vitamins including A and E (MacDonald et al., 2001). Pasture grazing can greatly influence milk composition, however, this is not necessarily associated with raw milk. There are many pasture grazed animals whose milk goes for conventional or organic sale.
Several large epidemiological studies have shown growing up in a farm environment to have protective effects against the development of asthma and allergies (van Neerven et al., 2012; Braun-Fahrlander and von Mutius, 2010; and Loss et al., 2011). Some suggest this is associated with the early ingestion of raw milk, but no scientific evidence supported this. More recently the studies have pointed to the “hygiene hypothesis” as the reason behind this protective effect. The hygiene hypothesis suggests that the ingestion of low levels of healthy bacteria may help to beneficially regulate the immune system. The development of an individual’s gut microflora begins at an early age and is associated with things like type of milk consumed (breast vs formula), can influence this development which in turn, could impact the development of allergies.
In the end, dairy producers take extreme caution to ensure the milk they sell is of the highest quality with the lowest bacterial load possible. However, raw milk is still not inherently safe to drink, despite these extreme control measures. Foodborne disease from milk can come from the consumption of only a few bacterial cells, from milk that looks and appears normal, from cows that are healthy and from farms that are clean. The beneficial health claims of the consumption of raw milk do not have scientific merit and the risks far outweigh any potential benefit. Pasteurized milk is an excellent, nutritious, and safe product containing many essential nutrients.
Virginia Cooperative Extension materials are available for public use, reprint, or citation without further permission, provided the use includes credit to the author and to Virginia Cooperative Extension, Virginia Tech, and Virginia State University.
Issued in furtherance of Cooperative Extension work, Virginia Polytechnic Institute and State University, Virginia State University, and the U.S. Department of Agriculture cooperating. Edwin J. Jones, Director, Virginia Cooperative Extension, Virginia Tech, Blacksburg; M. Ray McKinnie, Administrator, 1890 Extension Program, Virginia State University, Petersburg.
November 3, 2015