In recent years, the interest in consuming raw, unprocessed food products is increasing. An example of this is the consumption of raw milk. In this blog, I will discuss both the safety risks and potential health benefits of raw milk.
Safety of raw milk
The reason milk needs to be at least pasteurised before sale according to European law is safety. All pathogens in milk that are a potential health risk (e.g. Listeria, Salmonella) are killed with such heat treatment. Especially for young children, pregnant women, and elderly, these pathogens can cause severe health problems. Even though the contamination of milk with these pathogens can be minimized, and rapid testing exists, safety can never be fully guaranteed for raw milk.
Nutrients in raw milk
Proponents of consuming raw, unprocessed foods often focus on the retention of nutrients. Indeed, quite a number of nutrients are heat sensitive. The extent of the resulting heat damage depends on the specific nutrient. If we look specifically at milk, protein and B vitamins are the main nutrients of concern. For milk, pasteurisation and UHT sterilisation are the most common heating techniques. Pasteurisation is a rather mild treatment (72°C for 20 seconds) that does not damage nutrients in milk. UHT sterilisation is somewhat more intense, with higher temperatures for very short times (130-150°C for 5-10 seconds). Although small losses of B-vitamins happen, the effect is still rather small. So in the end, heating of milk does not (pasteurisation) or hardly (UHT sterilisation) affect its nutritiousness compared to raw milk.
Health benefits of raw milk
Several studies have been done showing health benefits of raw milk drinking. Especially when it comes to infections, allergy, and asthma in children, there are several studies showing such benefits. Specific immunologically-active milk proteins are very heat sensitive and may underlie this effect. However, the real causal factor(s) underlying the potential health benefits of raw milk consumption are unknown. Also, for ethical reasons, no human intervention trials have been done with raw milk, limiting existing evidence to epidemiological studies, making a cause-effect relation even more difficult to establish.
So, should we drink raw milk to prevent infections, allergies, and asthma? Due to risks associated with raw milk drinking, I do not believe this to be the solution. What I believe should happen is research on better understanding of the causal factor(s) underlying the effects. Then we can use that knowledge to optimize our dairy processing, trying to keep these components intact, while still producing safe dairy products, either using regular heating or non-thermal techniques like UV-C. And for those drinking UHT sterilized milk, switching to fresh pasteurised milk may be beneficial, as more immunologically-active proteins are retained.
Kasper Hettinga, November 2016