To examine the effects of instant
coffee consumption on
cancer risk, we analyzed the oxidative DNA damage levels and the DNA repair and redox systems in the livers of
coffee-fed mice. Three-week-old male ICR mice were fed with/without 0.1% (w/v) instant
coffee solution. At 2, 4, and 8 mo, the levels of
8-hydroxydeoxyguanosine (8-OH-dG), a major form of oxidative DNA damage, and the expression of mouse
8-OH-dG repair-associated genes and redox system-associated genes, the SOD activity, and the LPO level were analyzed. Simultaneously, half of the mice were fed a low
vitamin (LV) diet (autoclaved diet) to disturb the defense system against oxidative stresses. As a result, the
8-OH-dG level was increased in the livers of LV diet (+ water)-fed mice for 8 mo, in comparison to those of the 0 M control mice and normal diet (+ water)-fed mice. However, no significant differences between
water drinking and
coffee drinking were observed, in terms of the
8-OH-dG level. In addition, the
8-OH-dG repair-associated gene expression, the SOD activity, and the LPO level also showed no significant differences between
water drinking and
coffee drinking in all mouse groups. On the other hand, among the redox system-associated genes, only the expression of GPx1 was changed. These results suggest that instant
coffee consumption has little, if any, effect on the risk of
liver cancer due to oxidative stresses.