Tests on rats showed that plant chemicals in apples called procyanidins helped to prevent changes that can lead to cancer. A number of animals were injected with a substance known to trigger cancer of the bowel. After six weeks, rats fed a mixture of water and apple procyanidins had about half the number of pre-cancerous growths in their colons as those on a regular diet. Other experiments on cells in the laboratory revealed that procyanidins inhibited cancer biomarkers and tumour growth. The chemicals triggered signals that caused apoptosis, a form of programmed cell-death which is an important weapon against cancer. Dr Francis Raul, the study’s leader, from the French National Institute for Health and Medical Research (INSERM) in Strasbourg, said: "For now, our work suggests that eating the whole apple, including the skin, might offer some anti-cancer benefits. "That is certainly something we can comfortably do without further study."