Lerer-Metzger M, Rizkalla S W, Luo J, Champ M, Kabir M, Bruzzo F, Bornet F, Slama G
Department of Diabetes, INSERM U341, Paris, France.
Br J Nutr. 1996 May;75(5):723-32. doi: 10.1079/bjn19960176.
The present study aimed to assess the metabolic consequences of the chronic ingestion of two starches giving different postprandial glycaemic responses in normal and diabetic rats. The two starches chosen were mung-bean (Phaseolus aureus) starch (97% pure starch) and wheat starch presented as ground French toast. First, we studied the characteristics of these two starches. In vitro the alpha-amylase (EC 3.2.1.1) digestibilities of these starches were 40 (SE 3) and 62 (SE 4)% respectively at 30 min, whereas the contents of resistant starch were 77 (SE 4) and 22 (SE 4) g/kg respectively. In vivo the mung-bean starch produced lower postprandial glycaemic responses than the wheat starch (areas under the curve were: 91 (SE 28) and 208 (SE 33) mmol.min/l, P < 0.05) in normal rats (n 8). We then submitted twenty-eight normal and twenty-eight diabetic (neonatal streptozotocin on second day of birth) male Sprague-Dawley rats (6 weeks old) to a diet containing 570 g starch/kg as either mung-bean starch or wheat starch (n 14 rats/group). After 5 weeks on the diets food intakes and body weights were identical in each group. Liver and kidney weights were comparable when expressed as relative weight. The mung-bean-starch diet slightly decreased epididymal fat-pad weight (P < 0.14, ANOVA) and led to a marked decrease in adipocyte volume (P < 0.05). Plasma triacylglycerol and phospholipid concentrations were lower after the mung-bean-starch diet than after the wheat-starch diet in both normal and diabetic rats, whereas free fatty acid concentrations were lower only in normal rats. Similarly, non-fasting plasma glucose concentrations decreased (P < 0.05) in normal rats fed on mung-bean starch but not in diabetic ones (P < 0.14). Insulin levels tended to be lower, but not significantly, after mung-bean-starch feeding than after wheat starch. We conclude that the replacement of 570 g wheat starch/kg diet with mung-bean starch for 5 weeks resulted in (1) lowered non-fasting plasma glucose and free fatty acid levels in normal but not in diabetic rats, (2) a reduction in plasma triacylglycerol concentration and adipocyte volume in both normal and diabetic rats. Thus, the type of starch mixed into the diet may have important metabolic consequences in normal and diabetic rats.
本研究旨在评估长期摄入两种在正常大鼠和糖尿病大鼠中产生不同餐后血糖反应的淀粉的代谢后果。所选用的两种淀粉分别是绿豆（Phaseolus aureus）淀粉（97%纯淀粉）和做成法式吐司面包屑形式的小麦淀粉。首先，我们研究了这两种淀粉的特性。体外实验中，30分钟时这些淀粉的α-淀粉酶（EC 3.2.1.1）消化率分别为40（标准误3）%和62（标准误4）%，而抗性淀粉含量分别为77（标准误4）克/千克和22（标准误4）克/千克。在体内实验中，正常大鼠（n = 8）食用绿豆淀粉后产生的餐后血糖反应低于食用小麦淀粉后（曲线下面积分别为：91（标准误28）和208（标准误33）毫摩尔·分钟/升，P < 0.05）。然后，我们将28只正常雄性Sprague-Dawley大鼠和28只糖尿病雄性Sprague-Dawley大鼠（出生第二天注射新生链脲佐菌素，6周龄）分为两组，每组14只，分别给予含570克/千克绿豆淀粉或小麦淀粉的饮食。5周饮食后，每组的食物摄入量和体重相同。以相对重量表示时，肝脏和肾脏重量相当。绿豆淀粉饮食使附睾脂肪垫重量略有降低（P < 0.14，方差分析），并导致脂肪细胞体积显著减小（P < 0.05）。正常大鼠和糖尿病大鼠食用绿豆淀粉饮食后的血浆三酰甘油和磷脂浓度均低于食用小麦淀粉饮食后，而游离脂肪酸浓度仅在正常大鼠中较低。同样，食用绿豆淀粉的正常大鼠非空腹血浆葡萄糖浓度降低（P < 0.05），而糖尿病大鼠则未降低（P < 0.14）。食用绿豆淀粉后胰岛素水平倾向于降低，但不显著低于食用小麦淀粉后。我们得出结论，用绿豆淀粉替代570克/千克饮食中的小麦淀粉5周导致：（1）正常大鼠而非糖尿病大鼠的非空腹血浆葡萄糖和游离脂肪酸水平降低；（2）正常大鼠和糖尿病大鼠的血浆三酰甘油浓度和脂肪细胞体积均减小。因此，饮食中混合的淀粉类型可能对正常大鼠和糖尿病大鼠具有重要的代谢影响。
