Bowel cancer is the third most common type of the disease worldwide and the second leading cause of death in Western countries, so it's essential research is done.

It's also been found that 30-50 per cent of bowel cancer in men and 20 per cent in women could be prevented by adopting a healthier diet and exercising more.

The US researchers at Harvard Medical School experimented on mice, finding that those fed a diet high in walnuts displayed tumours containing ten times more omega-3s than the control group.

The mice were fed the equivalent of two servings (around 57g) of walnuts for humans, while the control group had a similar diet but without the walnuts.

"Our research demonstrates that a walnut diet causes significant changes in the expression profile of miRNAs in colorectal cancer tissue," Dr Christos Mantzoros, of Harvard Medical School, said.

The tumour growth rate was also much slower in the mice that were fed walnuts, but it's hard to know yet if humans would react in the same way.

But that's no reason not to grab a handful of walnuts, as they have plenty of health benefits anyway. They're also very good for the heart, thanks to the amino acid l-arginine, and they contain very powerful antioxidants.

Walnuts are also great for those on a diet, as they help you to feel fuller for longer and are a healthy and easy snack to enjoy at home or out and about.

If you need ideas for incorporating walnuts, try adding them to a salad instead of croutons for a healthy crunch. They can also be ground and used instead of breadcrumbs on chicken or fish.