**9.3.8 Bioactive compounds**

A lot of foods containing bioactive compounds are with protective effect for CRC and CRP according to our data – garlic, tea, fruit, vegetables, onions, grapes, vegetable food, legumes etc. Bioactive compounds include numerous chemical substances, which own anticancer properties (Greenwald, 2002). Some of the most studied bioactive compounds are found in green tea, tomatoes, and different sorts of onions, carrots, lemons and garlic. There are flavonoids and polyphenols in green tea, fruit and vegetables, which possess antioxidant properties. Bioactive compounds d-limonen and perilil alcohol are found in citrus fruit and their impact is associated with the induction of glutathione S-transferase. Red grapes have antioxidant properties, because of the bioactive compound resveratrol. In cereals and in beans are found phytoestrogens, which change the metabolism of steroid hormones. A lot of

Risk and Protective Factors for Development of Colorectal Polyps and Cancer 193

hormones and peptides, like insulin and gastrin, is induced. These hormones and peptides could also promote epithelial hyperploliferation. Apoptosis and cell differentiation are suppressed too, and DNA abnormalities could occur (Fig. 1). Adenomatous, hyperplastic or mixed colorectal polyps are morphological sign of the blended influence of genetic and exogenous factors upon the colorectal epithelium. Occurrence and progression of these polyps are evidence for the readiness of the colorectal epithelium to react in this distinct way under the influence of exogenous risk factors and inherited predisposition. Diet fibers by their volume and fluids dilute large bowel content, shorten the bowel transit time and do not permit a long contact of large bowel content with large bowel wall. As a result of bacterial fermentation of the cereal fibers, short-chain fatty acids are produced, which are very important for the metabolism and proper state of large bowel epithelium and contribute to large bowel integrity (Hague et al., 1995). Changed low pH in the large bowel inhibits dehydroxylation and dehydrogenation of bile acids. Changed low pH in the large bowel plays protective role for occurrence of CRC, because dehydroxylation and

dehydrogenation of bile acids could result in formation of carcinogenic substances.

Fig. 1. Possible mechanisms of influence of diet and lifestyle upon pathogenesis of colorectal

cancer. IFG-1, insulin-like growth factor-1; COX-2, cyclooxygenase-2.

bioactive compounds present in traditional Bulgarian cuisine. Therefore, it is reasonable to keep the tradition of healthy Balkan (Bulgarian) diet from the first half of the 20-th century.
