Eat blue, red and purple fruit and veg

New research shows that antioxidant compounds called anthocyanins, which give foods like blueberries and aubergines their intense colour, could be the key to cutting colon cancer cell growth

“These foods contain many compounds, and we’re just starting to figure out what they are and which ones provide the best health benefits,” said the study author, Monica Giusti, who is an assistant professor of food science at Ohio State University.

In the university’s studies on human colon cancer cells grown in lab dishes, the researchers tested the anti-cancer effects of anthocyanin-rich extracts from a variety of fruits and vegetable including grapes, radishes, purple corn, chokeberries, bilberries, purple carrots and elderberries – all chosen for their extremely deep colours and high anthocyanin content.

The researchers found that the amount of anthocyanin extract needed to reduce cancer cell growth by 50 per cent varied among the plants. Purple corn extract was the most potent, in that it took the least amount of this extract to cut cell numbers in half, but radish extract proved the least potent, taking nine times as much of this compound to halve cell growth.

Berries

In additional laboratory studies, she and her colleagues found that anthocyanin pigments from radish and black carrots slowed the growth of cancer cells anywhere from 50 to 80 per cent. But pigments from purple corn and chokeberries not only completely stopped the growth of cancer cells, but also killed roughly 20 per cent of the cancer cells while having little effect on healthy cells.

In tests on rats that had colon cancer, those that were fed a daily diet of anthocyanin extracts either from bilberries or chokeberries, reduced signs of colon tumours by 70 and 60 per cent, respectively, compared to rats that did not receive this dietary addition.

Giusti says the results suggest that anthocyanins may protect against certain gastrointestinal cancers.

“Very little anthocyanin is absorbed by the bloodstream,” she said. “But a large proportion travels through the gastrointestinal tract, where those tissues absorb the compound.”

“All fruits and vegetables that are rich in anthocyanins have compounds that can slow down the growth of colon cancer cells, whether in experiments in laboratory dishes or inside the body.”

“It is possible to use natural, anthocyanin-based food colourants instead of synthetic dyes,” she added, “doing so still maintains the wonderful colours of foods while enhancing their health-promoting properties.”

The research was presented yesterday at the annual meeting of the American Chemical Society in Boston.