Hollman P C, de Vries J H, van Leeuwen S D, Mengelers M J, Katan M B
DLO-State Institute for Quality Control of Agricultural Products (RIKILT-DLO), Agricultural University, Wageningen, Netherlands.
Am J Clin Nutr. 1995 Dec;62(6):1276-82. doi: 10.1093/ajcn/62.6.1276.
Quercetin is a dietary antioxidant that prevents oxidation of low-density lipoproteins in vitro. Intake of quercetin was inversely associated with coronary heart disease mortality in elderly Dutch men. However, the extent of absorption of quercetin in humans is unclear. The aim of this study was to quantify absorption of various forms of quercetin. Nine healthy ileostomy subjects were studied, to avoid losses caused by colonic bacteria. They followed a quercetin-free diet for 12 d; on days 4, 8, and 12 they received a supplement of fried onions at breakfast (rich in quercetin glucosides) equivalent to 89 mg aglycone, pure quercetin rutinoside (the major quercetin compound in tea) equivalent to 100 mg aglycone, or 100 mg pure quercetin aglycone, in random order. Subsequently, participants collected ileostomy effluent and urine for 13 h. In vitro incubations of quercetin or its glycosides with gastrointestinal fluids showed minimal degradation. Absorption of quercetin, defined as oral intake minus ileostomy excretion and corrected for 14% degradation within the ileostomy bag, was 52 +/- 15% for quercetin glucosides from onions, 17 +/- 15% for quercetin rutinoside, and 24 +/- 9% for quercetin aglycone. Mean excretion of quercetin or its conjugates in urine was 0.5% of the amount absorbed; quercetin excretion in urine was negatively correlated with excretion in ileostomy effluent (r = -0.78, n = 27). We conclude that humans absorb appreciable amounts of quercetin and that absorption is enhanced by conjugation with glucose.
槲皮素是一种膳食抗氧化剂，在体外可防止低密度脂蛋白氧化。在荷兰老年男性中，槲皮素的摄入量与冠心病死亡率呈负相关。然而，槲皮素在人体中的吸收程度尚不清楚。本研究的目的是量化各种形式槲皮素的吸收情况。研究了9名健康的回肠造口术受试者，以避免结肠细菌造成的损失。他们遵循不含槲皮素的饮食12天；在第4天、第8天和第12天，他们在早餐时分别随机服用相当于89毫克苷元的炒洋葱补充剂（富含槲皮素糖苷）、相当于100毫克苷元的纯槲皮素芦丁糖苷（茶中主要的槲皮素化合物）或100毫克纯槲皮素苷元。随后，参与者收集13小时的回肠造口术流出物和尿液。槲皮素或其糖苷与胃肠液的体外孵育显示降解极少。槲皮素的吸收定义为口服摄入量减去回肠造口术排泄物，并对回肠造口袋内14%的降解进行校正，来自洋葱的槲皮素糖苷的吸收为52±15%，槲皮素芦丁糖苷为17±15%，槲皮素苷元为24±9%。尿液中槲皮素或其结合物的平均排泄量为吸收量的0.5%；尿液中槲皮素的排泄与回肠造口术流出物中的排泄呈负相关（r = -0.78，n = 27）。我们得出结论，人类可吸收相当数量的槲皮素，并且与葡萄糖结合可增强吸收。
