Dietary carbohydrates and health: do we still need the fibre concept?

• Published in: Clinical nutrition. Supplements 2004, Vol.1 (2), p.5-17
• Main Authors: Cummings, John H., Edmond, Laurie M., Magee, Elizabeth A.
• Format: Article
• Language: English
• Subjects: Carbohydrate; Historical; Non-starch polysaccharides; Oligosaccharides; Resistant starch
• ISSN: 1744-1161; 1878-3368
• DOI: 10.1016/j.clnu.2004.09.003

Dietary fibre, principally the non-starch polysaccharides of the plant cell wall, is an important component of our diet. After more than 30 years of research into the many and varied claims for its benefits, it is now clear that fibre has uniquely significant physical effects in the gut and in addition through fermentation is a major determinant of large bowel function and bowel habit. Its physical properties in the small bowel effect lipid absorption and the glycaemic response. Fibre has some modest effects on appetite. These benefits feed through into a protective role in large bowel cancer, diabetes and coronary heart disease. Equally important, fibre has led us in our thinking about other dietary carbohydrates. Work on fibre was instrumental in the discovery of both resistant starch and the prebiotic oligosaccharides. Resistant starch of itself is not so important as fibre although does provide a substrate for fermentation and may be a good source for butyrate production. However, the discovery of resistant starch led to a revision of our understanding of the digestion of starch in the gut and the important contribution this makes to glycaemic response. The prebiotic oligosaccharides have been the newest and most exciting development in this story. Whilst again they are substrates for fermentation, their effects on bowel habit are negligible but their capacity to alter selectively the composition of the large bowel flora is a novel and highly significant development in our understanding of the intestinal microflora. The clinical benefits of this have yet to be established but will almost inevitably stem from the improvements to colonisation resistance that these changes bring. The dietary carbohydrates, therefore, which include NSP, RS and the oligosaccharides, are a complex group of substances with diverse physiological and health benefits. Instead of considering them to be a single macro nutrient component of the diet, we should, as we do for dietary fat, start to look at their individual contributions to physiology, epidemiology and clinical benefit.