Bijlani R L
Prog Food Nutr Sci. 1985;9(3-4):343-93.
Technological advances have reduced and refined man's plant food intake and consequently brought about an unprecedented decline in his consumption of dietary fibre (DF). The emergence of certain diseases selectively in regions which have been affected the most by this dietary change has led to an enhanced awareness of the functions of DF. DF is a heterogeneous group of substances which resist digestion by the endogenous enzymes of the human gut, although they are fermented to a substantial extent by the bacterial flora of the large intestine. Chemically, DF essentially consists of nonstarch polysaccharides and lignin, and its major constituents are cellulose, hemicelluose, lignin and pectin. The physiological effects of DF are attributable largely to its physicochemical properties. DF primarily affects gastrointestinal (GI) function; its effects are observable at all stages from ingestion through defaecation. It restricts caloric intake, shows gastric and small intestinal transit, and affects the activity of digestive enzymes and release of GI hormones. Its overall impact is to reduce apparent digestibility of nutrients marginally but consistently. In the large intestine, DF accelerates transit, supports bacterial growth and serves to hold water. As a result, the faecal weight and water content increase, and the transit time generally becomes shorter. Secondary to its GI effects, DF attenuates postprandial glycaemia and has long term effects on glucose tolerance and lipoprotein metabolism. These effects have important implications in the aetiopathogenesis of constipation and its sequelae including diverticulosis, cholesterol gallstones, colorectal cancer, obesity, diabetes mellitus and atherosclerosis. DF has traditionally been used therapeutically for constipation; now its use in diabetes is also well established. Our appreciation of the role of DF in human nutrition has undergone a major change in the last two decades. From a redundant constituent of plant foods, it has now moved to the position of an essential nutrient, the deficiency of which seems to have serious consequences.
技术进步减少并细化了人类对植物性食物的摄入量，从而导致膳食纤维（DF）的摄入量出现前所未有的下降。在受这种饮食变化影响最大的地区，某些疾病的选择性出现，使人们对DF的功能有了更强的认识。DF是一类异质性物质，它们能抵抗人类肠道内源性酶的消化，尽管它们在很大程度上会被大肠菌群发酵。从化学角度来看，DF主要由非淀粉多糖和木质素组成，其主要成分是纤维素、半纤维素、木质素和果胶。DF的生理作用很大程度上归因于其物理化学性质。DF主要影响胃肠（GI）功能；从摄入到排便的各个阶段都能观察到其作用。它限制热量摄入，减缓胃和小肠的蠕动，并影响消化酶的活性和胃肠激素的释放。其总体影响是使营养素的表观消化率略有但持续下降。在大肠中，DF加速蠕动，支持细菌生长并有助于保持水分。结果，粪便重量和含水量增加，转运时间通常会缩短。继发于其对胃肠的影响，DF可减轻餐后血糖，并对葡萄糖耐量和脂蛋白代谢产生长期影响。这些影响在便秘及其后遗症（包括憩室病、胆固醇性胆结石、结直肠癌、肥胖症、糖尿病和动脉粥样硬化）的发病机制中具有重要意义。传统上，DF一直用于治疗便秘；现在其在糖尿病治疗中的应用也已得到充分证实。在过去二十年中，我们对DF在人类营养中作用的认识发生了重大变化。从植物性食物中的多余成分，它现在已成为一种必需营养素，缺乏它似乎会产生严重后果。
