A complex carbohydrate called pectin may help explain why diets rich in fruits and vegetables can lower cancer risk, according to scientists.

In lab experiments, UK researchers found that particular components of pectin bind to, and possibly inhibit, a protein believed to facilitate the spread of cancer throughout the body.

The findings, published in the FASEB Journal, offer up one more reason to get your fruits and vegetables, according to the investigators. They also support past research suggesting that modified forms of pectin could help battle cancer, the investigators say.

Previous research has shown that modified pectin can kill or prevent the spread of tumor cells in the test tube, explained Patrick Gunning, the lead researcher on the new study. These latest findings point to the mechanism by which pectin may offer cancer protection.

Gunning and his colleagues at the Institute of Food Research in Norwich found that certain sugars in pectin bind to galectin-3, a protein on the surface of tumor cells that helps the cells grow and spread throughout the body.

This binding, in turn, may allow pectin to inhibit galectin-3, and thereby slow or even reverse the spread of cancer cells, Gunning explained.

There are still many questions, however, he said -- one being how the body takes up the particular "bioactive fragments" within pectin.

Pectin is often used as a gelling agent in jams and jellies, but Gunning advised against loading up on the condiments. Research has not shown processed fruit products to be greater cancer fighters than fresh fruit -- and, Gunning pointed out, jams and jellies are typically high in added sugar.

"At present," he said, "given what we know from our study and the others, we feel that the best advice is to eat plenty of fruit and vegetables in the likelihood that it will supply bioactive fragments from the pectins."