Experimental evidence suggests that
green tea (Camellia sinesis) may reduce the risk of
lung cancer through several hypothesized mechanisms including scavenging oxidative radicals, inhibition of
tumor initiation, and modulation of detoxification
enzymes. However, epidemiologic results have not been consistent as to the relationship between
green tea consumption and lung caner prevention. We employed a population-based case-control study of 122 cases and 122 controls to investigate the effect that
green tea consumption may have on the risk of
lung cancer and whether polymorphisms in 8-oxoguanine-DNA glycosylase (OGG1),
glutathione-S-transferase M1 (GSTM1), and
aldo-keto reductase 1C3 (AKR1C3) modify such an association. Daily
green tea consumption was associated with a non-significant reduction in
lung cancer risk. However, the effect of smoky
coal exposure was higher for non-drinkers (odds ratio (OR)=4.93; 95% confidence interval (95% CI)=1.27-19.13) than for drinkers (OR=1.88; 95% CI=1.01-3.48). Further, among individuals with the OGG1 Cys(326) allele, daily consumption was associated with a 72% reduction (95% CI=0.09-0.94). Among GSTM1 null homozygotes, those who consumed
green tea daily had a non-significant reduction in risk compared with non-consumers.
Green tea consumption had no effect among OGG1 Ser(326) homozygotes or GSTM1 carriers. In addition, AKR1C3 genotype did not modulate the effect of
green tea consumption. The chemopreventive effects of
green tea in this population may be restricted to individuals who are particularly susceptible to oxidative stress and oxidative DNA damage.