How plenty of greens can lower the risk of bowel cancer

EATING your greens can help to prevent bowel cancer, scientists say. Leafy green vegetables, or brassicas, have been associated with good health for many years — but the role of chemicals found in them has been little understood.

Experts have now revealed how a substance found in kale, cabbage and broccoli — called indole-3-carbinol or I3C for short — helps prevent gut inflammation.

Mice bred to be susceptible to colon cancer were protected from the disease when fed I3C, researchers at the Francis Crick Institute in London found. The Institute’s Dr Amina Metidji said: ‘When we fed them a diet enriched with I3C, they did not develop inflammation or cancer. When mice whose cancer was developing were switched to the I3C-enriched diet, they ended up with significantly fewer tumours which were also more benign.’

The I3C had its effect on intestinal stem cells, helping them to develop into cells that absorb nutrients or generate protective mucus. Without the I3C, the cells divided uncontrollably, the researchers said, which can lead to bowel cancer.

Study co-author Dr Gitta Stockinger said: ‘Seeing the profound effect of diet on gut inflammation and colon cancer was striking. We often think of colon cancer as promoted by a Western diet rich in fat and poor in vegetable content, and our results suggest a mechanism behind this.

‘These findings are a cause for optimism — while we can’t change the genetic factors that increase our risk of cancer, we can probably mitigate these by adopting a diet with plenty of vegetables.’

The team are now hoping to conduct further experiments in organoids — simplified organs made from human gut biopsies — and eventually human trials.

Professor Tim Key, an epidemiologist who specialises in diet, said: ‘This study suggests it’s not just the fibre contained in vegetables like broccoli and cabbage that help reduce the risk of bowel cancer, but molecules found in these vegetables too. This adds to the evidence that a healthy diet, rich in vegetables, is important.

‘Further studies will help find out if the molecules in these vegetables have the same effect in people.’