Johnston Kelly L, Clifford Michael N, Morgan Linda M
Centre for Nutrition and Food Safety, School of Biomedical and Molecular Sciences, University of Surrey, Guildford, United Kingdom.
Am J Clin Nutr. 2003 Oct;78(4):728-33. doi: 10.1093/ajcn/78.4.728.
Accumulating evidence suggests that certain dietary polyphenols have biological effects in the small intestine that alter the pattern of glucose uptake. Their effects, however, on glucose tolerance in humans are unknown.
The objective was to investigate whether chlorogenic acids in coffee modulate glucose uptake and gastrointestinal hormone and insulin secretion in humans.
In a 3-way, randomized, crossover study, 9 healthy fasted volunteers consumed 25 g glucose in either 400 mL water (control) or 400 mL caffeinated or decaffeinated coffee (equivalent to 2.5 mmol chlorogenic acid/L). Blood samples were taken frequently over the following 3 h.
Glucose and insulin concentrations tended to be higher in the first 30 min after caffeinated coffee consumption than after consumption of decaffeinated coffee or the control (P < 0.05 for total and incremental area under the curve for glucose and insulin). Glucose-dependent insulinotropic polypeptide secretion decreased throughout the experimental period (P < 0.005), and glucagon-like peptide 1 secretion increased 0-120 min postprandially (P < 0.01) after decaffeinated coffee consumption compared with the control. Glucose and insulin profiles were consistent with the known metabolic effects of caffeine. However, the gastrointestinal hormone profiles were consistent with delayed intestinal glucose absorption.
Differences in plasma glucose, insulin, and gastrointestinal hormone profiles further confirm the potent biological action of caffeine and suggest that chlorogenic acid might have an antagonistic effect on glucose transport. Therefore, a novel function of some dietary phenols in humans may be to attenuate intestinal glucose absorption rates and shift the site of glucose absorption to more distal parts of the intestine.
越来越多的证据表明，某些膳食多酚在小肠中具有生物学效应，可改变葡萄糖摄取模式。然而，它们对人类葡萄糖耐量的影响尚不清楚。
研究咖啡中的绿原酸是否能调节人体的葡萄糖摄取、胃肠激素及胰岛素分泌。
在一项三因素随机交叉研究中，9名健康的空腹志愿者分别饮用400毫升水（对照组）、400毫升含咖啡因咖啡或400毫升脱咖啡因咖啡（相当于2.5毫摩尔绿原酸/升），并摄入25克葡萄糖。在随后的3小时内频繁采集血样。
饮用含咖啡因咖啡后最初30分钟内的葡萄糖和胰岛素浓度，往往高于饮用脱咖啡因咖啡或对照组后（葡萄糖和胰岛素曲线下总面积及增量面积的P<0.05）。整个实验期间，葡萄糖依赖性促胰岛素多肽分泌减少（P<0.005），与对照组相比，饮用脱咖啡因咖啡后，餐后0至120分钟内胰高血糖素样肽1分泌增加（P<0.01）。葡萄糖和胰岛素曲线与咖啡因已知的代谢效应一致。然而，胃肠激素曲线与肠道葡萄糖吸收延迟一致。
血浆葡萄糖、胰岛素和胃肠激素曲线的差异进一步证实了咖啡因的强大生物学作用，并表明绿原酸可能对葡萄糖转运有拮抗作用。因此，某些膳食酚类在人体中的新功能可能是降低肠道葡萄糖吸收率，并将葡萄糖吸收部位转移至肠道更远端。
