Can milk and dairy products cause cancer?
- There is no good evidence that milk and dairy cause cancer
- Eating and drinking these products can reduce the risk of bowel cancer
- Some studies suggest that eating large amounts of dairy could be linked to an increased risk of prostate cancer – but more research is needed
How do milk and dairy products decrease bowel cancer risk?
There is good evidence that eating and drinking dairy products decreases the risk of bowel cancer.
Milk and other dairy products contain calcium, which is important for strong bones. High calcium content is thought to be one way dairy products could decrease bowel cancer risk.
What about other cancer types?
There is no strong evidence linking dairy products to any other types of cancer. Some studies suggest there’s a link between eating and drinking large amounts of dairy and increased prostate cancer risk - but evidence for this is limited. We need further research to find out more about the potential link between dairy products and prostate cancer risk.
How much dairy should I eat or drink?
Milk and dairy are good sources of calcium and protein. Having some dairy or dairy alternatives is recommended in the NHS Eatwell Guide, as part of a healthy, balanced diet.
Not everyone can eat dairy and some people choose not to. Dairy alternatives such as calcium-fortified soya versions of milk, cheese and yoghurt, are also good sources of calcium. Try to have low-sugar and reduced-fat versions of dairy or dairy-alternatives.
Fish with bones, nuts and green, leafy vegetables are also sources of calcium.
Government guidelines recommend that adults aged 19 to 64 have 700mg of calcium a day. For more information on recommended calcium intake and dairy portion sizes, see the British Dietetic Association calcium fact sheet.
Should I be worried about casein and hormones in milk?
Casein is the main protein in milk. There is no strong evidence to show this causes cancer in humans.
Although dairy products contain hormones, this is very small compared to the amount produced naturally by the body. There is no strong evidence to show that hormones in milk could go on to cause cancer.
In some countries, a hormone called bovine somatotrophin (BST) is used to speed up or increase the production of milk or meat. In the UK and the rest of Europe, farmers are banned from using this hormone. But this ban is on animal welfare grounds, not because there is any proven effect on human health.
The Food Standards Agency regulates the content of dairy products, including milk. This set of standards makes sure these products are safe to eat and drink.
We regularly review and evaluate newly published research into the causes of cancer in order to shape our health information. And there are key things we look out for to evaluate any new study.
What type of study is it?
Was the study looking at cells in a dish, animals or people? Studies in animals and cells can help scientists understand the basics of cancer but they cannot replicate how things will work in humans.
So, we focus more on studies in people as they can show with much more certainty how something affects the risk of developing cancer in humans. The best studies also account for other factors that could affect someone’s cancer risk, such as whether they smoke or drink.
How many people were in the study, and how long were they followed for? Studies involving only a handful of people aren’t likely to be as reliable, because results are more likely to happen by chance. And studies that only follow people for a short timeframe can miss any potential long-term effects. Therefore, we mainly look at studies that follow hundreds or usually thousands of people for a long time because they give results we can be surer of.
Who carried out the study and where is it published?
It’s important to see if a study was published in a scientific journal and was carried out by scientists that work for a university or known institute. This is because before researchers can publish their findings in a journal, other experts who were not involved in the study will check it is accurate.
How does the study fit in with previous evidence?
Some studies show conflicting results, but we evaluate any new study within the context of all the available research and give more weight to the most rigorous scientific studies.
How to spot fake news about cancer?
Sometimes news outlets can over-inflate stories about cancer, whether it’s a new treatment, or news on what could lower or increase your risk of developing the disease. You can use the same questions we discussed above to judge a study and news story yourself. For more tips on how to spot fake news visit our blog here.
World Cancer Research Fund/American Institute for Cancer Research. Continuous Update Project Expert Report 2018. Diet, nutrition, physical activity and colorectal cancer. https://www.wcrf.org/sites/default/files/Colorectal-cancer-report.pdf
NHS. The Eatwell Guide. 2020. https://www.nhs.uk/live-well/eat-well/the-eatwell-guide/
Public Health England. Government recommendations for energy and nutrients for males and females aged 1–18 years and 19+ years. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/618167/government_dietary_recommendations.pdf
Food Standards Agency. Farming and Animal Feed. https://www.food.gov.uk/business-guidance/farming-animal-feed