This was an observational study, not a trial, so it cannot prove categorically that calcium or any other food product protects against cancer or makes it more likely.

However, the researchers say the study is “the largest on diet and bowel cancer to date”, which gives them confidence they are on the right track. The findings are also in line with previous studies’ conclusions.

More than 12,000 women in the study developed bowel cancer, and nearly 100 food products and nutrients in their diets were investigated to assess potential links.

Nutrition expert Prof Janet Cade, from the University of Leeds, said the paper “provides important evidence showing that overall diet can influence risk of colorectal cancer”.

Prof Andrew Prentice, from the London School of Hygiene & Tropical Medicine, wonders whether, in the light of the study results, calcium supplements might be protective although he says “the jury is out on this”.

The take-home message for Prof Tom Sanders, from King’s College London, is that “drinking above the safe limits of alcohol intake (more than 14 units per week) increases [the] risk of colorectal cancer in women, but that drinking about half a pint of cows’ milk a day is probably protective”.

Dr Lisa Wilde, from charity Bowel Cancer UK, says someone is diagnosed with bowel cancer “every 12 minutes” and half of all bowel cancers could be prevented with healthier lifestyles.

“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,” she says.