If the hype’s to be believed, raw or unpasteurised milk can do everything from boosting your immune system to preventing dairy allergies and improving digestion. But milk is pasteurised (heat treated) for a good reason – to eliminate harmful bacteria as well as extend shelf life.

In the last five years, raw milk sales have increased nearly five times over in the UK. Farmers’ Weekly reports sales rose from 610 thousand litres in 2014 to a whopping 3 million litres in 2018.

It’s been illegal to sell unpasteurised dairy milk in supermarkets or high street shops in England, Wales and Northern Ireland since 1985 and it’s outlawed in Scotland. So is raw milk a superfood or a dangerous food fad?

Lots of us drink milk because we know it’s packed with nutrients. But some vitamins are heat-sensitive, which means the amount could be reduced or eliminated when heated, for instance in pasteurisation. Should we be worried?

A Canadian study concluded the effect of pasteurisation on milk’s nutritional value is minimal (with the exception of vitamin B2), because milk is relatively low in heat-sensitive vitamins.

Some people drink raw milk because they believe it contains beneficial bacteria. Pasteurisation destroys good bacteria as well as bad. A 2015 review found ‘limited’ growth of ‘probiotic bacteria’ (good bacteria) in raw milk. In some dairy products made from pasteurised milk, good bacteria may be developed during fermentation and/or be added.

Studies suggest a link between drinking raw milk and lower rates of asthma and some allergies. The suggestion is raw milk contains proteins and compounds that keep the immune system from over-reacting to allergens.

However, most studies are based on farm families, whose exposure to a diverse range of bacteria and allergens means it’s tricky to pinpoint the reason for their lower allergy rates. Studies often state further research should be carried out to understand this relationship better.

The Food Standards Agency (FSA) advises “raw or unpasteurised milk and cream may contain harmful bacteria that cause food poisoning”. They go on to say infants and small children, the elderly, pregnant women and those with a compromised immune system are among those “particularly vulnerable to food poisoning and should not consume it”. Despite this, children made up almost a third of outbreak patients in 2017.

Raw milk can carry dangerous bacteria such as salmonella, e-coli, listeria and campylobacter.

A 2019 Public Health England review finds raw milk responsible for 26 outbreaks of intestinal infectious disease in England and Wales between 1992 and 2017. These involved 343 people and resulted in 41 hospitalisations. There were no outbreaks between 2003 and 2013, but seven occured between 2014 and 2017.

Pasteurised milk was the cause of 12 outbreaks during the same 25-year timeframe: 10 due to pasteurisation failures and two to post-pasteurisation contamination.

“In terms of food safety, from a microbiological point of view, drinking raw milk is not safe", says Dr Jorge Gutierrez-Merino, a lecturer in food microbiology at the University of Surrey. “Raw milk may contain many different pathogenic microbes, including some deadly bacteria, which could cause fatal infections, mainly in children, the elderly and immunocompromised people", adds Dr Gutierrez-Merino.

A representative of FSA says “a ban of raw cow’s drinking milk was introduced in Scotland in 1983", adding it poses“a high risk to public health ... with 12 potentially associated deaths in Scotland in the early 1980s".

In England, Wales and Northern Ireland, raw milk is sampled and tested four times a year by hygiene inspectors. The farms are inspected twice a year and the herd must be healthy and free from brucellosis and tuberculosis.

If testing detects the presence of harmful bacteria or is ‘inconclusive’, the relevant local authority must be informed and sales of raw drinking milk must cease immediately. The cause of the problem must be identified and corrective action taken. Sales can resume after at least two consecutive tests from different batches of milk proving its safety.

The FSA regularly reviews the regulations concerning raw milk sales. The most recent review in 2018 concluded “the risk from raw dairy milk is not so unacceptable as to justify removing the right of adults to drink it, provided certain controls are met". But they say “improvements are required to ensure better controls and accountability" and to better explain the risk to consumers.

One reason cited for the increase in raw milk sales is an upturn in the number of on-farm vending machines, which make the product more available.

In England, Wales and Northern Ireland, raw dairy milk can only be sold by registered producers directly to customers, such as at the farm via bottles or a vending machine, at farmers’ markets or a farmer’ milk round, or direct online sales. It must be labelled with a health warning.

In Scotland, the sale of raw drinking milk is banned.

There are a number of different types of pasteurisation, but on the whole it is the process of heating a liquid to below the boiling point to destroy micro-organisms. It was developed by Louis Pasteur in 1864 to improve the keeping qualities of wine. It was applied to milk and commercial pasteurisation of milk in the late 1800s.

Intensified milk consumption in the early 20th Century led to increased outbreaks of milkborne diseases, such as tuberculosis, typhoid, scarlet fever and diphtheria. These diseases were subsequently virtually eliminated in humans with the commercial implementation of pasteurisation, in combination with improved management practices on dairy farms.

source: bbc