The effects of the soluble fiber konjac glucomannan (GM) on serum cholesterol concentrations were investigated in 63 healthy men in a double-blind crossover, placebo-controlled study. After a 2-wk baseline period, the subjects were given 3.9 g GM or placebo daily for 4 wk. After a washout period of 2 wk, crossover took place, followed by another 4 wk of treatment. The subjects were encouraged not to change their ordinary diets or general lifestyle during the investigation. GM fibers reduced total cholesterol (TC) concentrations by 10% (P < 0.0001), low-density-lipoprotein cholesterol (LDL-C) concentrations by 7.2% (P < 0.007), triglycerides by 23% (P < 0.03), and systolic blood pressure by 2.5% (P < 0.02). High-density-lipoprotein cholesterol (HDL-C) and the ratio of LDL-C to HDL-C did not change significantly. No change in diastolic blood pressure or body weight was observed. No adverse effects were observed. The results of this study show that GM is an effective cholesterol-lowering dietary adjunct.
The aim of the study was to compare the effect of the administration of a mixture of fibres on body weight-loss, satiety, lipid profile and glucose metabolism. We included 200 overweight or obese patients in a parallel, double-blind, placebo-controlled clinical trial, who were randomised to receive, in the context of an energy-restricted diet for a period of 16 weeks, a mixed fibre dose (3 g Plantago ovata husk and 1 g glucomannan) twice (b.i.d. group) or three times daily (t.i.d. group) or placebo. Weight change was the primary efficacy endpoint. Satiety, dietary compliance, lipid profile, glucose tolerance, insulin resistance and high-sensitivity C-reactive protein were secondary endpoints. Weight loss tended to be higher after both doses of fibre (-4.52 (SD 0.56) and -4.60 (SD 0.55) kg) than placebo (-0.79 (SD 0.58) kg); the differences in changes between groups were not statistically significant. Postprandial satiety increased in both fibre groups compared to the placebo. The differences between groups in LDL-cholesterol levels were significant (P = 0.03), with greater reductions in the two fibre-supplemented groups (-0.38 (SD 0.10) and -0.24 (SD 0.09) mmol/l in the b.i.d. and t.i.d. groups v. -0.06 (SD 0.09) mmol/l in placebo group). A similar pattern was observed for changes in total cholesterol:HDL-cholesterol and HDL-cholesterol:LDL-cholesterol ratios. Interventions were well tolerated and had no effects on HDL-cholesterol, glucose and insulinconcentrations, glucose tolerance or high-sensitivity C-reactive protein. In conclusion, a 16-week dietary supplement of soluble fibre in overweight or obese patients was well tolerated, induced satiety and had beneficial effects on some CVD risk factors, the most important of which was a significant decrease in plasma LDL-cholesterol concentrations.
An eight-week double-blind trial was conducted to test purified glucomannan fiber as a food supplement in 20 obese subjects. Glucomannan fiber (from konjac root) or placebo was given in 1-g doses (two 500 mg capsules) with 8 oz water, 1 h prior to each of three meals per d. Subjects were instructed not to change their eating or exercise patterns. Results showed a significant mean weight loss (5.5 lbs) using glucomannan over an eight-week period. Serum cholesterol and low-density lipoprotein cholesterol were significantly reduced (21.7 and 15.0 mg/dl respectively) in theglucomannan treated group. No adverse reactions to glucomannan were reported.
Glucomannan (GM) is differentiated from other soluble fibers by the extraordinarily high viscosity of GM solutions. Administration of 4-5g of GM with meals, blended into fluid or mixed with food, can slow carbohydrate absorption and dampen the postprandial insulin response by up to 50%. Controlled clinical studies document that GM can promote satiety and weight loss, lower LDL cholesterol, improve diabetic control, and correct constipation, with minimal if any side-effects. Rodent studies suggest that GM may have potential for decreasing cancer risk and possibly even slowing the ageing process. Hepatothermic therapy, a technique for achieving rapid loss of body fat by optimizing the liver's capacity for fat oxidation, can only achieve its optimal efficacy if diurnal insulin levels are kept low; ingestion of GM with meals will evidently be of benefit in this regard by moderating postprandial insulin surges.
Viscous soluble dietary fiber has been demonstrated to reduce postprandial glycemia and may promote satiety. PolyGlycopleX (PGX) is a highly viscous polysaccharide manufactured by reacting glucomannan with other soluble polysaccharides using a proprietary process (EnviroSimplex). The resulting polysaccharide (alpha-D-glucurono-alpha-D-manno-beta-D-manno-beta-D-glucan, alpha-L-gulurono-beta-D-mannuronan, beta-D-gluco-beta-D-mannan, alpha-D-glucurono-alpha-D-manno-beta-D-manno-beta-D-gluco, alpha-L-gulurono-beta-D-mannurono, beta-D-gluco-beta-D-mannan) is a novel entity with the highest viscosity and water-holding capacity of currently known fibers.
MATERIALS AND METHODS:
A total of 29 sedentary overweight or obese adults (23 women; six men), ages 20-65 with a body mass index (BMI) range of 25 kg/m(2) to 36 kg/m(2) participated in a clinical weight-loss program. PGX (5 g) was consumed with 500 mL water, 5-10 minutes before each meal, 2-3 times daily for 14 weeks.
Significant reductions were observed (p less than 0.05) in weight (-5.79 +/- 3.55 kg), waist circumference (-12.07 +/- 5.56 cm), and percentage body fat (-2.43 +/- 2.39 percent) compared to baseline values. In addition, subjects employing PGX had a significant reduction of 19.26 percent (n=17; p less than 0.05) and 25.51 percent (n=16; p less than 0.05) in total and LDL plasma cholesterol values, respectively, at the end of the study period.
The consumption of PGX in concert with lifestyle modifications may be a useful strategy for weight loss in overweight and obese individuals.