Konjacmannan, a natural constituent of Amorphophallus konjac (konjac root), is a highly viscous soluble fiber that has been shown to reduce fasting and postprandial glycemia, and cardiovascular risk factors (Vuksan et al., 2000). Intake of foods containing high content of dietary fiber (DF) is emphasized in the recommendations of most diabetes and nutritional associations. It is thought 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 (Liu et al., 2000). 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 (Martinm et al., 2008).