Beneficial effects at viscous dietary fiber from Konjac-Mannan in subjectswith the insulin resistance syndrome - Results of a controlled metabolic trial

OBJECTIVE- Dietary fiber has recently received recognition for reducing the risk of developing diabetes and heart disease. The implication is that it may have therapeutic benefit in prediabetic metabolic conditions. To test t his hypothesis, we investigated the effect of supplementing a high-carbohyd rate diet with fiber from Konjac-mannan (KJM) on metabolic control in subje cts with the insulin resistance syndrome. RESEARCH DESIGN AND METHODS- We screened 278 free-living subjects between t he ages of 45 and 65 years from the Canadian-Maltese Diabetes Study. A tota l of 11 (age 55 +/- 4 years, BMI 28 +/- 1.5 kg/m(2)) were recruited who sat isfied the inclusion criteria: impaired glucose tolerance, reduced HDL chol esterol, elevated serum triglycerides, and moderate hypertension. Alter an 8-week baseline, they were randomly assigned to take either KJM fiber-enric hed test biscuits (0.5 g of glucomannan per 100 kcal of dietary intake or 8 -13 g/day) or wheat bran fiber (WB) control biscuits for two 3-week treatme nt periods separated by a 2-week washout. The diets were isoenergetic, meta bolically controlled, and conformed to National Cholesterol Education Progr am Step 2 guidelines. Serum lipids, glycemic control, and blood pressure we re the outcome measures. RESULTS- Decreases in serum cholesterol (total, 12.4 +/- 3.1%, P < 0.004; L DL, 22 +/- 3.9%, P < 0.002; total/HDL ratio, 15.2 +/- 3.4%, P < 0.003; and LDL/HDL ratio, 22.2 +/- 4.1%, P < 0.002), apolipoprotein (apo) B (15.1 +/- 4.3%, P < 0.0004), apo B/A-1 ratio (13.1 +/- 3.4%, P < 0.0003), and serum f ructosamine (5.2 +/- 1.4%, P < 0.002) were observed during KJM treatment co mpared with WB-control. Easting blood glucose, insulin, triglycerides, HDL cholesterol, and body weight remained unchanged. CONCLUSIONS- A diet rich in high-viscosity KJM improves glycemic control an d lipid profile, suggesting a therapeutic potential in the treatment of the insulin resistance syndrome.