Recent British research involving more than half a million women suggests that upping your daily milk intake by as little as one glass could reduce your chances of developing bowel cancer, writes oncologist Justin Stebbing in The Conversation.
The study was carried out by Oxford University and Cancer Research UK.
Stebbing writes:
There are nearly 45 000 cases of bowel cancer every year in the UK, making it the nation’s fourth most common cancer – and third worldwide – but many of these are preventable.
According to Cancer Research UK data, 54% of all bowel cancers could be prevented by having a healthier lifestyle. Smoking, lack of exercise, alcohol, eating processed meat and poor diet are all significant factors in the development of the disease.
As an oncologist, I advise my patients about how diet and lifestyle can influence health, including the risk of developing cancer. But this research, which is one of the largest studies into diet and disease so far, has shed new light on how easy, cheap diet changes can help everyone to reduce their cancer risk.
For example, as well as drinking an extra glass of milk per day, reducing consumption of alcohol and red and processed meat could also help protect against cancer. The study found that drinking an additional 20g of alcohol a day, equivalent to a large glass of wine, increased bowel cancer risk by 15%.
Consuming more than 30g of red and processed meat daily was linked to an 8% increase in bowel cancer risk.
Researchers took a novel, two-pronged approach to examine the association between milk consumption and bowel cancer risk. First, they analysed genetic data from more than 542 000 women and focused on variants – tiny changes in DNA – associated with lactase persistence, the ability to digest lactose in adulthood.
Second, the team collected detailed dietary information from participants, including their daily milk intake. By combining these two data sets, the researchers were able to better estimate the causal effect of milk consumption on bowel cancer risk.
Striking results
The analysis revealed that participants who consumed an additional 244g of milk per day, roughly equivalent to one large glass containing 300mg of calcium, had a 17% lower risk of developing bowel cancer. This reduction in risk applied to various types of milk, including whole, semi-skimmed and skimmed.
The researchers also found that the protective effect of milk consumption was independent of other dietary factors and lifestyle habits. This suggests that the benefits of milk in reducing bowel cancer risk are not because milk replaces unhealthy food choices or is consumed as part of an overall healthier lifestyle.
The reasons why milk consumption may reduce bowel cancer risk are not fully understood, but the researchers propose several potential explanations. First, milk is a rich source of calcium, which has been linked previously to a reduced risk of bowel cancer.
Calcium may help protect against cancer by binding to potentially harmful substances in the gut and promoting the death of abnormal cells.
Next, many milk products are fortified with vitamin D, which has been shown to have anti-cancer properties and may help regulate cell growth and division. Also, the lactose in milk can promote the growth of beneficial gut bacteria that produce butyrate, a short-chain fatty acid with anti-inflammatory and anti-cancer effects.
Finally, milk contains conjugated linoleic acid, a fatty acid found in meat and dairy products, which, according to a 2021 lab study, could also have anti-cancer properties.
Crucially, milk consumption may not be suitable or beneficial for everyone. Those with lactose intolerance, milk allergies, or other dietary restrictions should consult healthcare professionals before making significant changes to their dairy intake.
Overall, this ground-breaking research provides compelling evidence for the potential role of milk consumption in reducing bowel cancer risk. The finding that a relatively modest increase in daily milk consumption could lead to a significant reduction in bowel cancer risk is particularly encouraging.
It suggests that small, achievable changes in diet could have meaningful impacts on public health.
As we continue to unravel the complex relationships between diet and disease, studies like this one provide valuable insights that can inform both individual health choices and broader public health strategies. The potential for a simple dietary change to have such a significant impact on cancer risk underscores the importance of continued research in this field and highlights the power of nutrition in shaping our health.
Justin Stebbing – Professor of Biomedical Sciences, Anglia Ruskin University, Cambridge, UK.
Study details
Diet-wide analyses for risk of colorectal cancer: prospective study of 12,251 incident cases among 542 778 women in the UK
Keren Papier, Kathryn Bradbury, Angela Balkwill et al.
Published in Nature Communications on 8 January 2025
Abstract
Uncertainty remains regarding the role of diet in colorectal cancer development. We examined associations of 97 dietary factors with colorectal cancer risk in 542,778 Million Women Study participants (12,251 incident cases over 16.6 years), and conducted a targeted genetic analysis in the ColoRectal Transdisciplinary Study, Colon Cancer Family Registry, and Genetics and Epidemiology of Colorectal Cancer Consortium (GECCO). Alcohol (relative risk per 20 g/day=1.15, 95% confidence interval 1.09-1.20) and calcium (per 300 mg/day=0.83, 0.77–0.89) intakes had the strongest associations, followed by six dairy-related factors associated with calcium. We showed a positive association with red and processed meat intake and weaker inverse associations with breakfast cereal, fruit, wholegrains, carbohydrates, fibre, total sugars, folate, and vitamin C. Genetically predicted milk consumption was inversely associated with risk of colorectal, colon, and rectal cancers. We conclude that dairy products help protect against colorectal cancer, and that this is driven largely or wholly by calcium.
See more from MedicalBrief archives:
Meat, eggs, milk healthier than plant-based foods – UN agency review
Regular milk consumption not associated with increased cholesterol
Vitamin D could boost survival in bowel cancer patients
Cancer mortality may drop by 12% with daily vitamin D – Germany study