Oxford University study reveals a host of dietary changes which could help tackle rising bowel cancer cases among the young
Scientists believe calcium could be key to preventing bowel cancer after a study found people drinking a glass of milk a day are less likely to develop the disease.
A huge 17-year study of over half a million women showed 12,251 women developed bowel cancer. An extra 300mg of calcium per day – equivalent to a large 240ml glass of milk or a couple of pots of yoghurt – led to a 17% decrease in the risk of bowel cancer. But the study showed 20g of alcohol a day – around a medium glass of wine or a pint of beer – increases the risk of bowel cancer by 15%. Red meat raised the risk of bowel cancer, with 30g more per day linked to an 8% increase in risk.
Lead researcher Dr Keren Papier, said: “This is the most comprehensive single study ever conducted into the relationship between diet and bowel cancer, and it highlights the protective role of calcium in the development of this disease.”
Bowel cancer, which causes common symptoms and so is hard to diagnose, now kills almost 17,000 Brits each year and is increasing in the under 50s. Studies are ongoing to work out why more younger people are developing bowel cancer, but experts believe poor diet, more ultra-processed foods, obesity and a lack of exercise are playing a role.
One in 20 women and one in 17 men in the UK will be diagnosed with bowel cancer in their lifetime. It is the third most common cancer in the UK and is the same type that killed TV presenter Dame Deborah James at age 40 in 2022.
Early onset bowel cancer in those aged 25 to 49 is increasing globally, but England is among the countries with the biggest rise, averaging a 3.6% increase every year.
The research, published in the journal Nature Communications, looked at 97 dietary factors and their impact on bowel cancer risk among 542,778 women taking part in the Million Women Study. The Oxford team said it is the strongest evidence yet that calcium protects against the deadly disease.
People got the protective benefit from extra calcium even if they previously consumed no calcium at all, and got extra benefit from adding more calcium to their usual intake. The study found that calcium had a similar effect on cancer risk from both dairy and non-dairy sources – suggesting it was calcium itself that was the main factor responsible for cutting risk.
The researchers said calcium from milk – including in tea and coffee – yoghurt, vegetables and other sources all counted, but the link for cheese and ice-cream was not made clear in the study. They suggested there was no obvious reason why cheese and ice-cream would not count – it may just be that people in the study did not consume much of either.
Sophia Lowes, senior health information manager at Cancer Research UK, which funded the study, said: “Bowel cancer is one of the most common cancers affecting people in the UK, which is why it’s so vital that we know how to prevent it. Maintaining a healthy, balanced diet, alongside keeping a healthy weight and stopping smoking, is one of the best ways to lower your risk of bowel cancer. This includes cutting down on alcohol and red and processed meat, and eating lots of fruit, vegetables and wholegrains.
“Dairy products like milk can also be part of a diet which reduces bowel cancer risk. We look forward to further research, including into the effects of specific ingredients like calcium, to ensure fewer people are impacted by this devastating disease.”
The researchers suggested the protective role of calcium may relate to its ability to bind to bile acids and free fatty acids in part of the bowel, cutting their effects in driving cancer. Experimental work in rats has also shown that having higher levels of dietary calcium could help protect the structure of the bowel, they suggested.
Dr Lisa Wilde, director of research and external affairs at Bowel Cancer UK, said: “Every 12 minutes someone in the UK is diagnosed with bowel cancer, making it the fourth most common cancer in the country. This study shows that drinking dairy milk can help reduce your bowel cancer risk. However, it is the calcium in milk that is important. If you don’t drink dairy milk there are other ways you can get calcium, for example from broccoli or tofu, and still reduce your bowel cancer risk.
“Other changes you can make to help reduce your risk of developing bowel cancer include eating plenty of fibre from wholegrains, pulses, fruits, and vegetables, avoiding processed meat and limiting red meat, being a healthy body weight, taking part in regular physical activity, stopping smoking, and cutting down on alcohol. Making lifestyle changes can be a challenge, but we believe it’s worth the effort.”
Previous research shows more than half of bowel cancer cases are preventable, with 13% caused by eating processed meat and 11% caused by overweight and obesity. One alcohol unit is the equivalent of 8g of alcohol.
Dr Helen Croker, assistant director of research and policy at the World Cancer Research Fund, said: “This new research reinforces how important diet is when considering cancer risk, especially given low public awareness surrounding factors such as alcohol consumption.”
