One glass of milk a day could help prevent bowel cancer - study

One glass of milk a day could help prevent bowel cancer - study

Sources such as milk, yoghurt, vegetables, and even calcium in tea and coffee were found beneficial.

A new study suggests that drinking a glass of milk daily could lower the risk of bowel cancer, the third most common cancer globally, by up to 20 per cent. With cases rising, particularly among young adults, researchers are stressing milk's protective nutrients as a potential preventive measure.

Bowel cancer means cancer that starts in the large bowel (colon) and the back passage (rectum). It is also known as colorectal cancer.

Published in Nature Communications, the study analysed dietary habits and cancer risk in 542,778 women over nearly 17 years as part of the Million Women Study.

During this period, 12,251 participants developed bowel cancer, making it one of the largest investigations into diet and disease. Researchers found that an additional 300mg of calcium daily—equivalent to a 240ml glass of milk or two pots of yoghurt was associated with a 17% reduction in bowel cancer risk.

The findings revealed that calcium from both dairy and non-dairy sources offered similar protective effects, highlighting the mineral itself as the key factor.

Sources such as milk, yoghurt, vegetables, and even calcium in tea and coffee were found beneficial. However, the study did not explore the effects of calcium supplements, and evidence for cheese and ice cream was inconclusive, possibly due to lower consumption of these foods among participants.

Researchers suggest that calcium protects against bowel cancer by binding with bile acids and free fatty acids in the colon, reducing their ability to cause cancer. Animal studies also indicate that higher calcium intake helps preserve the structural integrity of the bowel.

While calcium showed clear benefits, the study confirmed the detrimental effects of alcohol and processed meat. Drinking 20g of alcohol daily—roughly a medium glass of wine or a pint of beer—was linked to a 15% increase in bowel cancer risk. Similarly, consuming an additional 30g of red or processed meat per day raised the risk by 8%.

Implications for prevention

Dr. Keren Papier, the study's lead researcher, described it as the most comprehensive investigation into diet and bowel cancer to date. "This research highlights calcium’s protective role in reducing bowel cancer risk," she stated.

Sophia Lowes, Senior Health Information Manager at Cancer Research UK, which funded the study, added: “Bowel cancer is one of the most common cancers in the UK, making prevention critical. Maintaining a balanced diet, avoiding smoking, and reducing alcohol and red or processed meat intake are key steps. Dairy products, including milk, can form part of a diet that reduces bowel cancer risk.”

The World Health Organisation notes that Globally, bowel cancer accounts for nearly 2 million cases and 1 million deaths annually, with diagnoses projected to rise to 3.2 million by 2040.

Alarmingly, the disease is increasing among younger people for reasons that remain unclear. Despite this concerning trend, more than half of bowel cancer cases are considered preventable through lifestyle and dietary changes.

Strategies such as increasing fibre intake, staying physically active, reducing alcohol consumption, and eating less processed meat can significantly lower the risk. This latest research provides strong evidence that calcium, particularly from milk, may play a key role in reducing the burden of this devastating disease.

Several factors contribute to the development of colorectal cancer. Lifestyle choices play a significant role, with diets high in red and processed meats, low fibre intake, excessive alcohol consumption, and smoking increasing the risk. Physical inactivity and obesity further elevate the likelihood of developing the disease.

Genetics and age are additional contributors. While colorectal cancer can occur at any age, the risk increases significantly after the age of 50. Family history of the disease or inherited syndromes such as Lynch syndrome or familial adenomatous polyposis (FAP) can also predispose individuals to this cancer.

Environmental factors, such as prolonged exposure to harmful chemicals or radiation, and chronic conditions like inflammatory bowel disease (IBD), including Crohn’s disease and ulcerative colitis, are known to heighten the risk.

Emerging research highlights rising cases among younger populations, often linked to changes in diet, sedentary lifestyles, and possibly undetected genetic predispositions. Addressing these causes through preventive measures, such as maintaining a balanced diet, staying active, and participating in regular screenings, is critical to reducing the global burden of colorectal cancer.

Calcium is believed to play a protective role in the following ways:

Binding to harmful compounds in the colon: Calcium binds to bile acids and free fatty acids in the colon. These compounds, when present in high concentrations, can irritate the bowel lining and promote the growth of cancer cells. By neutralising them, calcium reduces their cancer-causing potential.

Strengthening the structural integrity of the bowel: Experimental studies, including research on animals, suggest that calcium helps maintain the structure of the bowel lining, which may prevent damage that could lead to cancer development.

Reducing cell proliferation in the colon: Calcium can influence cellular processes in the colon, helping to regulate cell division and prevent the uncontrolled growth of cells that could form tumours.

Anti-inflammatory effects: Milk also contains other nutrients, such as vitamin D, which work synergistically with calcium to reduce inflammation and promote a healthy gut environment. Chronic inflammation in the colon is a known risk factor for bowel cancer.

Improving gut health: Milk is sometimes fortified with probiotics, which can support gut health by balancing the microbiome. A healthy gut microbiome is linked to a lower risk of colorectal cancer.

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