J. de Vogel: Green vegetables and colon cancer: the mechanism of a protective effect by chlorophyll.

One of the important environmental determinants of the risk of colon cancer is the composition of the diet. Regular consumption of high amounts of red meat increases colon cancer risk. In contrast, consumption of green vegetables decreases the risk of colon cancer. This thesis provides a molecular mechanism of how these two dietary components might modulate colon cancer risk.

Feeding rats heme (the iron carrier in red meat) resulted in damage to the colonocytes and increased proliferation, which are considered as important risk markers for colon cancer. Mixing this diet with spinach or chlorophyll prevented the heme-induced damage to the colonocytes. In humans we demonstrated that increasing the molar ratio of heme over chlorophyll is associated with an increased risk of colon cancer in men.

Our results indicate that chlorophyll and heme bind in the intestinal contents of the rat and thus prevent the heme-induced damage to the colonocytes. This offers a molecular explanation for the protective effect of green leafy vegetables on colon carcinogenesis.