A high dietary fiber (DF) intake is emphasized in the recommendations of most diabetes and nutritional associations. It is accepted that viscous and gel-forming properties of soluble DF inhibit macronutrient absorption, reduce postprandial glucose response, and beneficially influence certain blood lipids. Colonic fermentation of naturally available high fiber foods can also be mainly attributed to soluble DF, whereas no difference between soluble and insoluble DF consumption on the regulation of body weight has been observed. However, in prospective cohort studies, it is primarily insoluble cereal DF and whole grains, and not soluble DF, that is consistently associated with reduced diabetes risk, suggesting that further, unknown mechanisms are likely to be involved. Recent research indicates that DF consumption contributes to a number of unexpected metabolic effects independent from changes in body weight, which include improvement of insulin sensitivity, modulation of the secretion of certain gut hormones, and effects on various metabolic and inflammatory markers that are associated with the metabolic syndrome. In this review, we briefly summarize novel findings from recent interventions and prospective cohort studies. We discuss concepts and potential mechanisms that might contribute to the further understanding of the involved processes.

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Metabolic Effects of Dietary Fiber Consumption and Prevention of Diabetes

DIETARY FIBER AND BODY-WEIGHT REGULATION: Observations and Mechanisms

Guar gum as a promising starting material for diverse applications: A review.

Dietary Fiber Supplements: Effects in Obesity and Metabolic Syndrome and Relationship to Gastrointestinal Functions

Postprandial glucose, insulin, and incretin responses to grain products in healthy subjects

Fourteen patients with non-insulin-dependent diabetes (NIDDM) attended the study centre on 4 mornings separated by at least 3 days, to receive in random order 75 g carbohydrate breakfast meals of control or guar breads with jam and butter. Guar gum flours of low, medium, and high molecular weight (MW) were incorporated into wheat bread rolls to provide 7.6 g guar per meal. Venous blood samples were taken via an indwelling cannula in a forearm vein at fasting and at eight postprandial times and then analysed for blood glucose, plasma insulin, C-peptide, and gastric inhibitory polypeptide (GIP). Guar gum bread significantly reduced the postprandial rise in blood glucose, plasma insulin, and, except for bread containing low MW guar gum, plasma GIP levels compared to the control. Thus, the partial depolymerization of guar gum does not diminish its physiological activity. No reductions in postprandial plasma C-peptide levels were seen after any of the guar bread meals. This suggests that guar gum attenuates the insulin concentration in peripheral venous blood in patients with NIDDM by increasing the hepatic extraction of insulin.

L.M. Morgan

Papers

Effect of partially depolymerized guar gum on acute metabolic variables in patients with non-insulin-dependent diabetes