Pasteurisation kills harmful bacteria
Most milk sold in New Zealand is pasteurised, which means it is heated for a short time. This kills bacteria that can make us sick. Raw (unpasteurised) milk from any animal may be contaminated with illness-causing bacteria such as:
- Shiga toxin-producing E. coli (STEC)
- Campylobacter
- Salmonella
- the bacteria that causes tuberculosis.
Read more about the types of bacteria that can be found in raw milk
These bacteria most commonly cause severe diarrhoea and vomiting. Some have been linked with more serious complications that include:
- miscarriage
- paralysis
- serious kidney problems in children.
Illness caused by drinking raw milk
From the start of 2019 to mid-2023, there have been 10 reported outbreaks of illness associated with people consuming raw milk.
Many people with STEC infections from raw milk need to be hospitalised. Some even develop haemolytic uremic syndrome (HUS), which is life threatening.
Update to the assessment of the microbiological risks associated with the consumption of raw milk [PDF, 1.3 MB]
Raw milk is especially risky for some people
Raw milk is a risky food for anybody who consumes it. But the risk is higher for some people such as:
- young children and babies
- pregnant women
- older people, especially those with underlying health conditions
- people with low immunity.
Find out about food for people with low immunity
Can I get risk-free raw milk?
No – you can't. Harmful bacteria live in the gut of even healthy animals. These bacteria can be present anywhere on a farm. Bacteria can live on clean-looking surfaces and spread from there to the milk.
Careful sanitation practices during raw milk production can reduce health risks but they can't be removed completely. There is no easy way to tell if raw milk is carrying harmful bacteria. It has to be analysed in a laboratory to be sure it is safe.
To reduce your risk of getting sick
If you choose to drink raw milk, we recommend the following to reduce the risk of getting sick:
- Buy it only from a registered raw milk supplier, which must follow strict hygiene practices and sell raw milk directly from the farm gate or by home delivery.
- Keep it chilled while transporting it home from the farm.
- Store raw milk at 4 degrees Celsius or less in your fridge.
- Throw it out if it's been left out of the fridge for 2 or more hours.
- The safest option is to heat raw milk to 70 degrees Celsius and hold it at that temperature for 1 minute. If you don't have a thermometer, heat the milk until it nearly reaches a boil (or scald the milk) before drinking it.
If you're serving raw milk to friends or visitors, make sure you let them know the milk is unpasteurised.
When purchasing raw milk, supply your contact details when asked. You can then be notified if a batch of milk is found to be contaminated with harmful bacteria.
Infographic: Raw unpasteurised milk: What you need to know [PDF, 219 KB]
Video – Reduce your risk of getting sick (3.14)
Transcript - show/hide
We see a woman, Tess, driving a car. She drives down a rural driveway, parks, and turns to the camera.
"Are you someone who chooses to drink raw unpasteurised milk?
"Whether it is a lifestyle or wellbeing choice, or simply you prefer the taste, there are some risks involved."
[Tess gets out of the car and speaks to the camera.]
"Because raw milk has not been pasteurised – that is heat treated to kill harmful bacteria such as Campylobacter, Listeria, and toxic strains of E. coli called STECs – you may get sick from drinking it."
[Tess walks to the boot of the car, opens it, and picks up a chilly bin. She turns and talks to the camera. As she talks cartoon images of a pregnant woman, a young child, and an elderly lady appear on-screen beside her.]
"Pregnant women, young children – especially babies – the elderly, and those with weakened immune systems are at the greatest risk."
[Tess closes the boot of the car and walks off camera.]
[A graphic appears on-screen with the text "Raw Unpasteurised Milk: What you need to know".]
[Tess is in the kitchen and places the chilly bin on the kitchen bench. She speaks to the camera.]
"There are 3 simple steps you can take to reduce the risk of getting sick from the harmful bacteria, and to help protect your friends and family when drinking raw unpasteurised milk."
[On-screen graphic: "Step 1".]
"The first is to keep the milk in the fridge at all times."
[Tess opens the chilly bin and takes out 2 bottles of milk. She then goes to the fridge, opens it, and puts the milk on the lower level of the fridge. While she does this she talks to the camera.]
"The best place is on the lower level of the fridge where it is the coldest. This will reduce the risk of harmful bugs growing in the milk."
[We see a timelapse shot of a bottle of milk left on the kitchen bench. A timer in the upper right corner of the screen counts to 2 hours. Once it has reached 2 hours, Tess picks up the milk and speaks to the camera.]
"You should throw out your raw milk if it has been left out on the bench for more than 2 hours."
[On-screen graphic: "Step 2".]
[Tess is at the kitchen bench. She is pouring milk into a saucepan. She speaks to camera.]
"The second is, before drinking it, heat the milk until it just starts to boil…"
[Tess puts the saucepan on the stove and heats the milk. We see it start to boil.]
"…or, if you have a thermometer, heat it to 70 degrees Celsius for 1 minute before drinking it."
[Tess puts a thermometer in the milk. It measures 70 degrees Celsius. A sped-up timer on the side of the screen measures 60 seconds. Tess takes the milk off the stove.]
"Doing this will greatly reduce the number of potentially harmful bacteria present in the milk."
[On-screen graphic: "Step 3".]
[Tess takes some milk from the lower level of the fridge and checks its use-by date.]
"And the third, of course: make sure you drink your milk by its use-by date."
[Tess pours the milk into 3 glasses.]
"Also, if you offer raw unpasteurised milk to friends or visitors, make sure you let them know what the risks are."
[On-screen graphic: "New rules to make things safer".]
[Tess is doing the dishes. She talks to the camera.]
"New safety rules have been introduced to help farmers and suppliers manage the risks associated with raw unpasteurised milk.
"From 1 November 2016, you will only be able to get it at the farm gate and from home deliveries. There will no longer be collection points.
"If you buy at the farm make sure you provide your contact details. This way you can be contacted if milk testing identifies any problems."
[We see 2 bottles of milk being put in a chilly bin.]
"Make sure you keep your milk chilled while transporting it home.
"Once you get it home, follow the 3 simple steps to help ensure you don’t get sick."
[We see milk being placed on the lower level of a fridge, with on-screen text matching the spoken text.]
"Step 1: Store your milk in the coldest part of your fridge (the lower level)."
[We see milk being heated, with on-screen text matching the spoken text.]
"Step 2: Before drinking it, heat your milk until just boiling or, if you have a thermometer…"
[We see milk being heated using a thermometer, with on-screen text matching the spoken text.]
"…heat it to 70 degrees Celsius for 1 minute."
[Tess speaking to the camera with matching on-screen text.]
"Step 3: Drink it before its use-by date."
[Tess speaking to the camera.]
"To find out more about who how to stay safe, the new rules, or even who is registered to sell raw unpasteurised milk, please visit the Ministry for Primary Industries website."
[On screen graphic: www.mpi.govt.nz/rawmilk ]
[End of transcript]
Raw-milk cheeses can also have risk
Bacteria found in raw-milk cheeses comes from the raw milk itself. The process of making cheese can kill some bacteria. This depends on the type of cheese. Safer raw-milk cheeses are low-moisture or hard cheeses like parmesan or gruyere. The cheesemaking process may not kill bacteria in soft cheeses like camembert, brie, feta, or fresh cheeses, so these could have a food safety risk.
An assessment of available information on raw milk cheeses and human disease 2000–2010 [PDF, 327 KB]
Other sources of bacteria can come from the cheesemaking environment including equipment and personnel, or cross contamination between finished products and raw materials. Both pasteurised and raw-milk cheeses can be contaminated this way.
You can tell if a cheese is made from raw milk if the label says "raw" or "unpasteurised". If unsure, ask shop staff, or if you are at a restaurant, ask the waiting staff.
Pregnant women are most at risk from the bacteria Listeria monocytogenes and should avoid eating raw-milk cheeses.
Evaluation of the microbial safety of raw milk cheeses [PDF, 1.2 MB]
Risk profile update: Listeria monocytogenes in cheese [PDF, 1.4 MB]
Keeping and handling raw-milk cheese
If you choose to buy and serve raw-milk cheese, take care how you store and handle it.
- Buy your cheese from a reputable supplier.
- Keep the cheese wrapped in your fridge and separate from other ready-to-eat foods.
- Make sure your fridge is between 2 degrees Celsius and 4 degrees Celsius.
- Use separate knives and chopping boards for the cheese.
- Discard the cheese on its use-by date.
- Don't leave it at room temperature for more than 2 hours.
Scientific evidence doesn't support raw milk health claims
There is no substantial scientific evidence to suggest raw milk offers any health benefits over pasteurised milk.
An assessment of the effects of pasteurisation on claimed nutrition and health benefits of raw milk [PDF, 340 KB]
Who to contact
If you have questions about raw milk, email info@mpi.govt.nz
