Frape D L, Jones A M
Pharmaco-LSR, Eye, Suffolk.
Br J Nutr. 1995 May;73(5):733-51. doi: 10.1079/bjn19950077.
We questioned whether a dietary fibre supplement known to lower fasting plasma cholesterol concentrations can also lower the postprandial plasma cholesterol, glucose and insulin concentrations when it is administered just before a meal. Two studies were conducted in healthy middle-aged volunteers of both sexes in whom the fasting plasma total cholesterol concentrations were above normal. In the first study the dietary fibre treatments (2.2 g) were psyllium and a psyllium-citrus pectin mixture to which the subjects (four males, eight females) had no prior exposure. Controls received no supplement. The meals were high-fat breakfasts and lunches. In the second study the dietary fibre (6 g) was from sugar-beet root and the reference control was alpha-cellulose (2 g); the meal was of glucose. The volunteers (eight males, eight females) had prior exposure to the fibre supplements three times daily for 3 weeks. After adjustments for fasting values and changes in haemodilution, the psyllium and psyllium-citrus pectin mixture in the first experiment had no significant effects on the postprandial measurements of plasma glucose, insulin:glucose ratio, total-, LDL- and HDL-cholesterol, and triacylglycerol. By contrast, the sugar-beet fibre in the second study significantly decreased the area under the glucose response curve by 6.9%, the area under the insulin response curve was lower by 9.6%, although not significantly, and the post-glucose meal HDL-cholesterol concentration was significantly (12%) higher. Additionally, the 3-week treatment with sugar-beet fibre significantly lowered the fasting total- and LDL-cholesterol concentrations, by 8.5% and 9.6% respectively. We conclude that low doses of psyllium and citrus pectin at breakfast and lunch have no effects on the postprandial plasma measurements, but that sugar-beet fibre taken daily for 3 weeks affects both fasting and postprandial plasma metabolites favourably in these individuals with mildly increased risk of ischaemic heart disease. Further, we observed that small changes in haemodilution occur after meals, as indicated by plasma albumin concentration and packed cell volume. Underemphasis of the dietary fibre effects may occur when postprandial haemodilution is not taken into account.
我们质疑一种已知能降低空腹血浆胆固醇浓度的膳食纤维补充剂在餐前服用时是否也能降低餐后血浆胆固醇、葡萄糖和胰岛素浓度。对空腹血浆总胆固醇浓度高于正常水平的健康中年男女志愿者进行了两项研究。在第一项研究中，膳食纤维治疗剂量（2.2克）为车前草和车前草 - 柑橘果胶混合物，受试者（4名男性，8名女性）此前未接触过。对照组不接受补充剂。餐食为高脂肪早餐和午餐。在第二项研究中，膳食纤维（6克）来自甜菜根，参考对照为α - 纤维素（2克）；餐食为葡萄糖。志愿者（8名男性，8名女性）此前每天三次接触纤维补充剂，持续3周。在对空腹值和血液稀释变化进行调整后，第一项实验中的车前草和车前草 - 柑橘果胶混合物对餐后血浆葡萄糖、胰岛素：葡萄糖比值、总胆固醇、低密度脂蛋白胆固醇、高密度脂蛋白胆固醇和三酰甘油的测量值没有显著影响。相比之下，第二项研究中的甜菜纤维使葡萄糖反应曲线下面积显著降低了6.9%，胰岛素反应曲线下面积降低了9.6%（虽不显著），且餐后高密度脂蛋白胆固醇浓度显著升高（12%）。此外，3周的甜菜纤维治疗使空腹总胆固醇和低密度脂蛋白胆固醇浓度分别显著降低了8.5%和9.6%。我们得出结论，早餐和午餐时低剂量的车前草和柑橘果胶对餐后血浆测量值没有影响，但在这些缺血性心脏病风险略有增加的个体中，每天服用3周的甜菜纤维对空腹和餐后血浆代谢产物均有有利影响。此外，我们观察到餐后血液稀释会发生微小变化，这可通过血浆白蛋白浓度和红细胞压积来表明。如果不考虑餐后血液稀释，可能会低估膳食纤维的作用。
