**9.3.5 Calcium**

190 Cancer Prevention – From Mechanisms to Translational Benefits

this observation. *H. pylori* could exert negative effect not only on upper parts of

Chronic and extensive IBD is connected with increased cell turnover and elevated risk of developing CRC. The risk for development of CRC in patients with IBD depends on the duration (8-10 years) and the extent of disease (Ekbom et al., 1990). We observed malignant transformation in one patient with ulcer colitis and inflammatory pseudopolyposis with duration more than 10 years. Some big population based studies have found slightly elevated risk of developing CRC in right colon in women 15 years after cholecystectomy (Ekbom et al., 1993). Acromegaly is associated with elevated risk for CRC (Jenkins et al., 1997). We do not have any patient with acromegaly and CRP or CRC. We did not observe association between the patients who have undergone cholecystectomy and the frequency of CRC and CRP. The possible mechanism of this risk factor is associated with the constant free leakage of bile in the gut and with the toxic and carcinogenic effect of secondary bile salts.

**9.3 The mode of action of protective factors for colorectal polyps and cancer** 

bacterial degradation of different alimentary compounds (Kritchevsky, 1995).

Our data confirm that Bulgarian yoghurt (containing *Lactobacilus acidophilus/bulgaricus* and *Streptococcus termophylus)* has a protective effect on large bowel polyp formation. Its use as a prophylactic seems perspective since it is traditionally present in Bulgarian national cuisine.

According to our study the intake of large amounts of fibers is associated with reduced risk for CRP formation, although conflicting data exist. In a large prospective study, approximately 40% reduction of CRC risk in persons with high fiber consumption was reported (Bingham et al., 2003). The protective action of diet fibers is based on their capabilities to accelerate bowel transit time and enlarged volume, which could diminish exposition time of mucosa to food carcinogens and dilute them. Food fibers bind, inactivate and carry out the luminal carcinogens. Food fibers also decrease fecal pH and inhibit

Flavonoids are powerful antioxidants, which are found basically in fruit, vegetables, seeds, nuts, tea and wine (Middleton & Kandaswami, 1993). According to our data consumption of fruit and vegetables is protective factor for CRC and CRP, whereas regular consumption of tea is protective factor for CRP. Flavonoids inhibit cell proliferation and induce apoptosis

In supranutrtional doses selenium has protective effect against development of CRC, cancer of prostate and lung cancer (Schatzkin et al., 1996). Its mode of action is based on its antioxidant, antiproliferative, and proapoptotic properties (Zhu et al., 2000). Selenium is

gastrointestinal tract, but may be also on colorectal mucosa.

**9.2.9 Association with other diseases** 

**9.3.1 Probiotics** 

**9.3.2 Fibers** 

**9.3.3 Flavonoids** 

(Wenzel et al., 2000).

**9.3.4 Selenium** 

Our data show that consumption of milk products has protective effect against developing CRC and CRP. Calcium in milk products bind luminal bile and fat acids in insoluble soaps and inhibits proliferation of colon cells (Bostick et al., 1995). Calcium also enhances cell apoptosis in colon mucosa (Fedirko et al., 2009). Probably, calcium has a modulating role in the western diet, rather than anticarcinogenic properties. Optimal intake of calcium in >50 year old persons is 1200 mg per day (Institute of Medicine, Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D and Fluoride. Food and Nutrition Board, Washington, DC., 1997).
