葡甘聚糖

葡甘聚糖

葡甘聚糖的功能

葡甘聚糖是水溶性的膳食纤维，从魔芋根提取而来。和其他形式的膳食纤维一样，葡甘聚糖被认为是一种膨化通便药。葡甘聚糖可以帮助大块的干结的大便更易通过结肠，并较轻松的排出。

以前的研究^[1]和近期的双盲实验^{[2 3 4 5]}发现葡甘聚糖治疗便秘有一定的疗效。在便秘的病人中，葡甘聚糖和其他缓泻剂克在12~24小时内帮助大便通过肠道。^[6]以前的研究还利用葡甘聚糖治疗结肠憩室性疾病，大约对三分之一到二分之一的病人有一定的疗效。^[7]

葡甘聚糖可以延缓胃的排空，可以使膳食中的糖阶段性吸收，从而可以降低餐后血糖的水平。^[8]对照试验发现餐中服用葡甘聚糖可以明显降低糖尿病病人的餐后血糖，并且通过食用富含葡甘聚糖的饮食^[9]可以控制糖尿病病人的整体血糖范围。^{[10 11 12]}以前的一项报道认为葡甘聚糖对于怀孕相关性糖尿病也有一定的疗效。^[13]一项双盲实验报道了每天服用8~13克的葡甘聚糖可以有效控制胰岛素抵抗综合征病人的血糖^[14]。在以前的一项试验中，每天餐中加用2.6或5.2克的葡甘聚糖可以预防成人胃术后引起的低血糖症状。^[15]类似的对儿童进行的试验却不能得到稳定的疗效。^[16]

和其他可溶性纤维一样，葡甘聚糖可在肠道中与胆汁酸结合并从大便中将其排出体外，这样可使机体将更多的胆固醇转化成胆汁。^[17]因此可以有效降低血胆固醇和其他血脂。对照试验和双盲实验均发现每天补充数克的葡甘聚糖可以明显降低血液中总胆固醇、低密度脂蛋白和甘油三酯水平，在一些病例中还能升高高密度脂蛋白水平。^{[18 19 20 21]}另一项双盲实验报道了每天服用8~13克的葡甘聚糖可以降低胰岛素抵抗综合征病人的总胆固醇和低密度脂蛋白水平。^[22]

葡甘聚糖可以通过占据胃的空间而使人感觉饱胀而帮助减肥。一项双盲实验报道了成人每天在餐前1小时和水一起服用1克的葡甘聚糖，8周后平均降低5.5磅的体重。^[23]可是，类似的对肥胖儿童进行的试验却发现葡甘聚糖并不比安慰剂更有效的降低体重。^[24]而另一个对照试验发现葡甘聚糖对于肥胖的成人和儿童均有效。^[25]

葡甘聚糖的分布

葡甘聚糖可从魔芋根中提取出来，作为泡腾粉末或丸剂均有效。还没发现其他富含葡甘聚糖的食物。

葡甘聚糖已经被应用于与以下疾病的治疗中。（以下所有信息适用于个体化健康情况）：

哪些人可能会缺乏葡甘聚糖？

因为葡甘聚糖不是必需营养素，所以不会缺乏。

一般需要多少葡甘聚糖？

葡甘聚糖作为缓泻剂有效的剂量是每天3~4克。^{[27 28]}对于降低血胆固醇的有效剂量为每天4~13克。^{[29 30 31]}控制血糖的有效剂量是每100卡路里的饮食服用500~700毫克。^{[32 33]}减肥需要的剂量是每餐1~3克。^{[34 35]}刚开始使用葡甘聚糖和其他膳食纤维时，需要从小剂量开始，然后逐渐加量。推荐每次与至少8盎司的水一起服用。

是否有副作用和药物相互作用？

患有任何食管疾病的人不应服用片剂的纤维补充剂，因为它们会在食管内膨胀并导致梗阻。^[36]以前有报道称在人类试验和动物试验中发现对葡甘聚糖过敏。^[37]

因为肠道细菌会发酵水溶性纤维，所以会产生大量的肠道气体，并导致腹胀和腹部不适。

到目前为止，还不清楚葡甘聚糖与其他药物之间的相互作用关系。

参考文献

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30. Vuksan V, Jenkins DJ, Spadafora P, et al. Konjac-mannan (glucomannan) improves glycemia and other associated risk factors for coronary heart disease in type 2 diabetes. A randomized controlled metabolic trial. Diabetes Care 1999;22:913–9.

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35. Vita PM, Restelli A, Caspani P, Klinger R. Chronic use of glucomannan in the dietary treatment of severe obesity. Minerva Med 1992;83:135–9 [in Italian].

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