A wide array of substances derived from the diet have been found to stimulate the development, growth and spread of tumours in experimental animals, and to transform normal cells into malignant ones. These are regarded as suspected human carcinogens. So,many dietary constituents can increase the risk of developing cancer, but there is also accumulating evi- dence from population as well as laboratory studies to support an inverse relationship between regular con- sumption of fruit and vegetables and the risk of specific cancers. Several organizations — such as the WHO, the American Cancer Society, the American Institute of Cancer Research (AICR) and the National Cancer Institute (NCI) — have established dietary guidelines to help people.
