ABSTRACT
Diet and its relation to cancer is a fascinating story of discovery, opportunity, blind alleys, and tantalizing clues-but with many gaps.
Colorectal cancer (CRC) occurs far more frequently in Western populations than in other races suggesting genetic differences play a crucial role in determining susceptibility. However, study of disease prevalence in migrants from the East to the West demonstrated the major role of “environment”—for such migrants were found to develop CRC at rates approaching those of the native population. We commonly think of the environment as the physical world around us. In gastrointestinal disease however, the “environment” is the gut lumen with its changing dietary contents, its resident bacteria (a generally stable population) and the interaction between these which
Introduction .................................................................................................................................... 427 Colorectal Cancer-Epidemiology ................................................................................................ 428
Effect of Age and Genes on CRC ......................................................................................... 428 In uence of Diet and Colorectal Cancer Risk ............................................................................... 429
Dietary Fiber ......................................................................................................................... 429 Meat and Fish ....................................................................................................................... 430 Fruits and Vegetables ............................................................................................................ 431 Calcium and Vitamin D ........................................................................................................ 431
Epigenetics-DNA Methylation and Colorectal Cancer ............................................................... 432 Age-Related DNA Methylation ............................................................................................ 432 DNA Methylation and Dietary Factors ................................................................................. 432
Folic Acid .................................................................................................................. 433 Alcohol ................................................................................................................... 433 Selenium ................................................................................................................... 434 Phytoestrogens .......................................................................................................... 434 Green Tea .................................................................................................................. 434
Effects of Dietary Factors on DNA Methylation in the Normal Colon ................................ 434 Colonic Fermentation ........................................................................................................... 435
Gut micro ora ........................................................................................................... 435 Volatile Organic Compounds (VOCs) ...................................................................... 436
Summary Points ............................................................................................................................. 437 References ...................................................................................................................................... 437
leads to the creation of new chemicals (as opposed to those which have been ingested). Such chemicals in turn can affect the DNA of the colonic epithelial cells (colonocytes). As a result the genetic message can be subtly changed.
