It is known that increased dietary intake of fruits and vegetables is associated with reduced risk of cancer. The authors studied the relationship between dietary quercitin intake and the risk of cancer. Quercitin (a flavonoid) is found in fruits (apples and grapes) and vegetables (onions and broccoli).
The authors used information from the Environment and Genetics in Lung Cancer Etiology (EAGLE) study for this study of quercitin use and cancer risk in Italy. Those people who were in the highest quintile (1/5) of fruit and vegetable intake had a reduced lung cancer risk by 30% when compared to those in the lowest quintile of intake. This association was especially strong for the heaviest cigarette smokers. This association was especially strong for people with adenocarcinoma.
The finding of this study was that the dietary intake of quercitin was inversely associated with lung cancer risk. Those in the highest quintile of quercetin had a 53% reduced risk of lung cancer compared to those in the lowest quintile of quercetin consumption. These results were especially significant for heavy smokers (over 20 cigarettes per day).
DNA/RNA studies show that quercetin rich diets alter the genes for enzymes which detoxify cigarette carcinogens. This could be one way that quercetin reduces lung cancer. Plants of the Rosaceae family are rich in quercetin. This plant family reduces the risk of lung cancer. Quercetin is found in onions and red wine, not white.
Isothiocyanates from cruciferous vegetables are other chemicals which reduce lung cancer risk.
CONCLUSION: Dietary quercetin reduces the risk of lung cancer, especially in heavy smokers.
NOTE: Rosaceae family includes pears, apples, plums and almonds. High levels of quercitin are found in cabbage (green), spinach, garlic, white grapefruit, cranberries, kale, pears.
Read about the ability of quercetin to reverse multi-drug resistance (multidrug resistance.)
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