Tannins, salivary proline-rich proteins and oesophageal cancer.

No single dietary factor or ingested substance has been implicated in the aetiology of oesophageal carcinoma especially in high-risk areas of the world. Although not well defined, there is heavy consumption of tannin-rich foods, particularly sorghum, by populations at high risk for carcinoma. The carcinogenic properties of tannins and extracts of tannin-rich plants have been demonstrated experimentally. It is proposed herein that salivary proline-rich proteins (PRPs) by binding ingested tannins protect the oesophagus from the carcinogenic effects of the latter. It is also possible that genetic variants of PRPs may influence the incidence of oesophageal cancer in different populations.