Is raw milk healthier than pasteurised milk?

Pasteurisation kills disease-causing bacteria in milk. That is scientifically well established and represents the most important practical difference between raw and pasteurised milk. Raw milk can contain bacteria such as Salmonella, Listeria and Campylobacter that cause serious illness, even in healthy people.

Pasteurisation does measurably reduce the levels of vitamins B1, B2, C and folate in milk. However, for most of those vitamins, milk contributes so little to begin with that the loss barely affects your daily intake. Vitamin B2 (riboflavin) is the exception: milk is an important source of it, so the loss after pasteurisation is genuinely relevant there. Interestingly, vitamin A actually increases after pasteurisation.

Raw milk has been linked to a lower risk of allergies in six studies. Whether raw milk is the true explanation for this is unclear, however: people who drink raw milk often also live on a farm, and all those other farm-related factors could just as plausibly be the protective element. This is therefore an association, not a proven causal relationship. The quality of the evidence is low.

Claims that raw milk helps with lactose intolerance or reduces cancer risk have barely been studied. There is one study on the former and two on the latter, none of which demonstrated a measurable effect. No conclusions can be drawn from this at all.