A rat model for determining the postprandial response to foods

Investigating the hypoglycaemic potential of processed apple and acarbose combination in vitro, ex vivo, and in vivo: the role of quercetin-3-glucoside in steering α-glucosidase inhibition

This study investigated the interaction between apple juice (AJ) and acarbose (A) in modulating glycaemic responses, with the aim of validating in vivo results previously observed in vitro. When administered to rats, AJ alone reduced the glycemic curve, but the combination of AJ with increasing doses of A resulted in higher glycemic responses, suggesting an antagonistic interaction in α-glucosidase inhibition. To explore this mechanism, quercetin-3-glucoside (Q-3-G), a major phenolic compound in AJ, was tested for α-glucosidase inhibition in vitro. Q-3-G and A together showed reduced inhibitory efficacy compared to either compound alone, consistent with in vivo findings. Ex vivo studies in Caco-2 cells further supported this antagonism. Sucrose hydrolysis experiments showed that low concentrations of Q-3-G increased residual sucrose when combined with moderate concentrations of A, but higher concentrations of Q-3-G favoured sucrose hydrolysis regardless of A levels. The results highlight the antagonistic interaction between Q-3-G and A in inhibiting α-glucosidase and emphasise the need to combine in vitro, ex vivo and in vivo studies to evaluate food-drug interactions. This comprehensive approach is essential before advocating the use of functional foods alongside pharmacological therapies.

Determining the Glycaemic Index of Standard and High-Sugar Rodent Diets in C57BL/6 Mice

The glycaemic index (GI) is a useful tool to compare the glycaemic responses of foods. Numerous studies report the favorable effects of low GI diets on long term metabolic health compared with high GI diets. However, it has not been possible to link these effects to the GI itself because of other components such as macronutrients and dietary fibre, which are known to affect GI. This study aimed to create and evaluate isocaloric diets differing in GI independent of macronutrient and fibre content. The GIs of eight diets differing in carbohydrate source were evaluated in mice; cooked cornstarch (CC), raw cornstarch (RC), chow, maltodextrin, glucose, sucrose, isomaltulose, and fructose. A glucose control was also tested. The GIs of all eight diets were different from the GI of the glucose control (GI: 100; p < 0.0001). The GIs of the glucose (mean ± SEM: 52 ± 3), maltodextrin (52 ± 6), CC (50 ± 4), RC (50 ± 6), and chow (44 ± 4) diets were similar, while the GIs of the sucrose (31 ± 4), isomaltulose (24 ± 5), and fructose (18 ± 2) diets were lower than all other diets (p < 0.05). This is the first trial to report GI testing in vivo in mice, resulting in three main findings: chow is relatively high GI, the glucose availability of raw and cooked cornstarch is similar, and the GI of different sugar diets occur in the same rank order as in humans.