The compounds which give certain fruit and vegetables their dark colour may contain powerful cancer fighting properties, US research suggests.
Chokeberries are not commercially grown in the UK...
Studies on rats and human cells found anthocyanins - which colour red, purple and blue fruits - notably slowed the growth of colon cancer cells.
The more exotic the plant the better: purplecorn and bilberry were found to be much more potent than the radish.
The research was presented at a meeting of the American Chemical Society.
In some experiments, the researchers from Ohio State University saw cancer growth not just slowed, but as many as 20% of the cells killed.
For instance, anthocyanin pigments obtained from black carrots and radishes slowed the growth of cancer cells by between 50 to 80%.
But compounds from chokeberries for instance killed up to a fifth of existing cells, without impacting upon healthy ones.
Working it out
The researchers say their findings bring the scientific community closer to understanding what it is that gives fruit and vegetables their much touted cancer-fighting properties.
But blueberries, which may contain similar compounds, are readily available
"These foods contain many compounds, and we're just starting to figure out what they are and which ones provide the most health benefits," said Monica Giusti, the lead author of the study.
She suggested that the results from this particular study suggested that anthocyanin may be of particular use in fighting gastrointestinal cancers.
Very little of the substance is absorbed by the bloodstream, but it may be absorbed in the gastrointestinal tract as it passes through, she said.
However, the researchers stopped short of recommending one particular fruit and vegetable over another, stressing that more research was needed into how these compounds worked.
Henry Scowcroft, senior information officer at Cancer Research UK, said: "Although at an early stage, this research helps us understand exactly how the substances in fruit and veg protect us from bowel cancer.
"Isolating these substances - and tweaking them so that they're even more potent - could allow scientists to develop new drugs to treat the disease.
"In the future, it could lead to the development of drugs that help prevent bowel cancer in people at high risk."