Milk and dairy products are important components of a healthy diet. However, if raw milk (unpasteurised) is consumed this can cause illness due to potential contamination with harmful bacteria.

Toi Te Ora Public Health encourages people to consume milk that has been heat treated (pasteurised).

What is raw milk?

Raw milk is taken directly from an animal such as a cow, goat, or sheep, and does not undergo any heat treatment (e.g. pasteurisation) to kill bacteria that may be present.

All milk sold in New Zealand (except for raw milk sales at the farm gate) is made safe by being pasteurised or heat treated to kill harmful bacteria. This does not adversely affect the health benefits of milk.

How does milk get contaminated?

Disease-causing bacteria can pass into milk directly from the animal's infected udder or milk can be contaminated from the dairy farm environment during milking, e.g. from dirty udders and teats, and by cross-contamination when a batch includes raw milk from more than one animal. No matter how carefully the animals are milked there is always a risk of contamination with harmful bacteria.

What are the risks?

Consuming raw milk is risky for everyone.  Recent international studies have shown that raw milk was 150 times more likely than pasteurised milk to cause illness.  Raw milk may contain harmful bacteria such as Listeria, E.Coli, Cryptosporidium, Campylobacter, Salmonella and Yersinia. These bacteria can cause serious illnesses. You cannot tell if raw milk is contaminated by its taste, sight or smell.

It is never advisable for anyone to drink raw milk but some people are at particular risk of becoming sick or having a more severe illness – including the elderly, pregnant women, babies and young children.

Benefits of pasteurised milk

  • Pasteurising milk does not cause lactose intolerance and allergic reactions. However, both raw milk and pasteurized milk can cause allergic reactions in people sensitive to milk proteins.
  • Pasteurisation does not reduce milk's nutritional value.
  • Pasteurisation does not mean that it is safe to leave milk out of the refrigerator for extended time, particularly after it has been opened.
  • Pasteurisation does kill harmful bacteria.
  • Pasteurisation does save lives.

Further information

From the Ministry for Primary Industries: