Dietary flavonoid intake and lung cancer--a population-based case-control study.
BACKGROUND
Laboratory studies suggest that flavonoids are antimutagenic and anticarcinogenic. To investigate the associations between commonly consumed flavonoid compounds and lung cancer, the authors conducted a population-based case-control study of 558 lung cancer cases and a group of 837 controls.


METHODS
Dietary intakes of flavonoids were estimated by combining the intake frequency (collected by a food frequency questionnaire), portion size, and food composition data. Unconditional logistic regression analysis was used to estimate odds ratios (ORs) and 95% confidence limits (95% CLs) with an adjustment for potential confounders, including age, sex, race-ethnicity, years of schooling, smoking status, pack-years of tobacco smoking, and daily energy intake.


RESULTS
Lung cancer was associated inversely with the consumption of epicatechin (in 10 mg per day increment: OR, 0.64; 95% CL, 0.46-0.88), catechin (4 mg per day increment: OR, 0.49; 95% CL, 0.35-0.70), quercetin (9 mg per day increment: OR, 0.65; 95% CL, 0.44-0.95), and kaempferol (2 mg per day increment: OR, 0.68; 95% CL, 0.51-0.90) among tobacco smokers. There was little association between lung cancer and the flavonoid compounds mentioned above among nonsmokers. Regardless of smoking status, there was little association with total flavonoids: thearubigins, hesperetin, naringenin, and myricetin. In addition, consumption of vegetables, tea, and wine, all of which are rich sources of flavonoids, was associated inversely with lung cancer among tobacco smokers.


CONCLUSIONS
Certain flavonoid compounds, including epicatechin, catechin, quercetin, and kaempferol, were associated inversely with lung cancer among tobacco smokers, but not among nonsmokers. Further studies of these associations may be warranted.
Cui
Yan
Y
Office of Health Assessment and Epidemiology, Los Angeles County Department of Public Health, Los Angeles, California, USA.
Morgenstern
Hal
H
Greenland
Sander
S
Tashkin
Donald P
DP
Mao
Jenny T
JT
Cai
Lin
L
Cozen
Wendy
W
Mack
Thomas M
TM
Lu
Qing-Yi
QY
Zhang
Zuo-Feng
ZF
D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D004032:Diet; D002149:Energy Intake; D005260:Female; D005419:Flavonoids / Q000008:administration & dosage*; D006801:Humans; D015994:Incidence; D008175:Lung Neoplasms / Q000453:epidemiology* / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D011795:Surveys and Questionnaires; D014481:United States / Q000453:epidemiology
D005419:Flavonoids