Introduction

The esophageal carcinogens which people frequently encounter, for example nitrosamines in food, drink and tobacco, are at sufficiently high levels of exposure to cause cancer only if the esophageal epithelium is predisposed by additional insults (van Rensburg 1981). Many authors have stressed the multifactorial nature of esophageal cancer, and the likelihood that the disease is the result of a site-specific carcinogen acting on nutritionally predisposed tissue. While alcohol and tobacco are the major secondary risk factors in the West, nutritional status is more important in less affluent communities, especially China, Iran and Africa. A large number of surveys have shown that low consumption of fresh fruit and vegetables is associated with cancers at various sites, including the esophagus. Both epidemiological studies and animal experiments have shown riboflavin deficiency and zinc deficiency to have especially adverse effects on the esophagus. Whether the protective action of fruit and vegetables is due entirely to their vitamin and mineral content, or whether other factors are also involved, has yet to be determined.

Esophageal cancer more than the majority of other cancers is a disease of poor rural areas with inefficient agriculture, or of groups of people elsewhere with the lowest socioeconomic status (Day et al. 1982). The cancer is not the result of one major nutritional deficiency, as with the typical deficiency diseases such as pellagra and scurvy, but is associated with general low nutrition.