Vegetable consumption, flavonoids

Epidemiology behind Fruit and Vegetable Consumption and Cancer Risk with Focus on Flavonoids... 

In the study on colorectal cancer (Table 20.4), a reduced risk was found for increasing intake of anthocyanidins (OR, 0.67 for the highest versus the lowest quintile,p-trend, 0.001), flavonols (OR, 0.64,p-trend < 0.001), flavones (OR, 0.78, p-trend, 0.004), and isoflavones (OR, 0.76, p-trend, 0.001). [Rossi et al., 2006], The estimates did not substantially differ for colon and rectal cancers. After allowance for fruit and vegetable consumption, for dietary fiber, or for micronutrients previously associated to this tumor including vitamin C, the associations with flavonoids did not change by more than 10%. A recent case-control study of 1456 pairs of cases and controls conducted in Sweden confirmed a significant decrease in risk of colorectal cancer for intake of anthocyanidins and flavonols [Theodoratou et al., 2007], but there was no relation for isoflavones and flavones. However, the results on isoflavones and flavones are questionable due to the unusually and generally low intakes of the populations studied. In the Italian population, anthocyanidins were derived mainly from wine, red fruit, and onions, and flavonols from apples or pears, wine, and mixed salads. 

It is important to note that diet is a complex mixture that contain compounds with varying activity. Chemical stimulators of colon cancer growth include bile acids, 1,2-diglycerides and prostaglandins which stem from consumption of fat. In contrast, fruits and vegetables contain substances such as carotenoids, flavonoids and fibre, which may inhibit cancer cell growth, and the risk of colon cancer appears to be mirrored by the ratio of plant sterols to cholesterol in the... 

Other studies have estimated the consumption of fruits or vegetables (rich in flavonoids) and have reported an inverse relationship with some types of cancer but in different extent among men and women (Park and others 2007 McCullough and others 2003 Voorrips and others 2000). 

Cytotox/c/ty There has been some concern raised over cytotoxic and mutagenic in-vitro effects of hypericum, which have been ascribed to the constituent quercetin (Tyler 1994). However, quercetin is a flavonoid that is present in many plants and vegetables, and it is estimated that the average person consumes 50 mg per day. Consumption of hypericum would not significantly add to this (1 mg in commonly used amounts). The German Commission E has concluded that this is not of great concern. 

Cl, 0.37-0.71) for flavanones, 0.62 (95% Cl, 0.43-0.89) for flavonols, and 0.56 (95% Cl, 0.40-0.78) for total flavonoids. No significant association emerged for other classes of flavonoids. The ORs were consistent across strata of age, sex, education, body mass index, tobacco, and alcohol. After allowance for vegetable and fruit consumption, the inverse relations with total flavonoids and flavanones remained significant, whereas that with flavonols became nonsignificant. None of the associations was significant after further allowance for... 

The study on renal cell carcinoma (Table 20.8) showed that flavonols (OR, 0.69, 95% Cl, 0.50-0.95) and flavones (OR, 0.68, 95% Cl, 0.50-0.93) were inversely related to the risk of renal cancer [Bosetti et al., 2007], Allowance for vegetable and fruit consumption only partly explained the inverse relation with flavonoids. No other study systematically investigated the relation between flavonoids and renal cancer risk. 

Epidemiological studies have indicated that high consumption of vegetables and fruits rich in both flavonoids and carotenoids could reduce the risk of various cancers. Common fruits and vegetables contain approximately 40-50 carotenoids, and many of these could be selected as nutraceuticals with diverse functionalities [20]. 

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