Foods can cause - or resist - cancer.

Some foods can cause cancer, others can prevent it, but no one knows why. "So the bottom line or selecting what you eat is, as usual, variety and moderation," indicates University of Missouri-Columbia food scientist Robert Marshall.

Although a number of food substances are suspected of causing cancer, only one group --aflatoxins--conclusively does so. Aflatoxins are molds that grow on grains or legumes damaged by insects or mishandling. "Aflatoxins appear to cause liver cancer in part of Africa and Asia. But aflatoxins are seldom a problem in the U.S., because they are closely regulated by the Food and Drug Administration."

On the other side of the coin, researchers have found hundreds of substances in fruit and vegetables and other foods that act to suppress the disease. They do so by preventing carcinogen formation and DNA damage and halting the growth of damaged, cancer-producing cells.

"Many substances are suspected of causing human cancer because they have been found to do so in such laboratory animals as rats and mice," Marshall points out. "Whether such substances actually cause cancer in humans remains uncertain." Examples include the nitroso compounds, formed from nitrogen containing organic substances. Scientists found 90% of the 300 nitroso compounds tested produce cancers in...