The effect of diet with different glycemic index on the redox status of duodenums in mice and its underlying mechanism

The mechanisms of some gastrointestinal disease related to high-GI (glycemic index) diet are unknown. Oxidative stress is a well-recognized mechanism in many pathological conditions. Some study reported dietary GI was positively associated with oxidative stress. Whether high-GI diet can induce oxidative stress in digestive tract, whether higher GI diet can induce higher oxidative stress, to explore these two questions, we examined the effect of diet with different GI on redox status of duodenum of mice. In a 2-week study, male Kunming mice were randomized to six groups. Six groups were separately fed using diet with different GI that was obtained by adjusting ratio of cornstarch and glucose. The ratios of cornstarch and glucose in diets for group 1, 2, 3, 4, 5 and 6 were separately as follows: 40%, 0; 30%, 10%; 25%, 15%; 20%, 20%; 10%, 30%; 0%, 40%. The diet for group 4 induced the optional redox status in duodenum compared with other groups. The diet for group 6 induced the complete destruction on redox balance in duodenums of mice. We also detected the underlying mechanism using quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR). We found the expression of Prdx4 was very high in group 4, which might explain why diet for group 4 induced the optional redox status. These findings indicate that (1) higher GI diet inducing higher oxidative stress was not justified; (2) oxidative stress may be the cause of digestive disease induced by high-GI diet.