Novel Fiber Limits Sugar AbsorptionSeptember 2004
Correlating Food Type and Obesity
Mounting evidence points to hyperinsulinemia as being a culprit in today’s obesity epidemic. One way to help reduce excessive insulin is by eating a low-glycemic diet. This means eliminating foods that induce the pancreas to over-secrete insulin. While people seeking to lose body fat know they should avoid sucrose and fructose, too often the craving for sugar (induced by hyperinsulinemia) results in binging on carbohydrate-rich food.
The food industry misleads the public into thinking that high-glycemic foods are healthy. Fruit juices, for instance, are promoted as a concentrated source of nutrients contained in fruit. The downside to juice, however, is that it is a concentrated form of quick-release fructose that can spike serum insulin. Eating whole fruit produces a gradual release of sugar into the blood. Once most fruits are juiced, however, they become catalysts for insulin overload because of their concentration of rapidly absorbable sugar.
Carrots rank high on the glycemic index, but because their glycemic load is very low, there is nothing wrong with eating carrots. Once carrots are juiced, however, the sugar is concentrated into a form that instantly hits the bloodstream and provokes an insulin spike. The moral to this story is to eat lots of fruits and vegetables, but avoid the juice. A look at the calorie content of a glass of fruit or vegetable juice confirms its fat-potentiating effects. For those concerned about obtaining adequate folic acid, vitamin C, alpha carotene, and similar nutrients, these can be obtained by eating whole fruits and vegetables and by taking supplements.
As shown in the sidebar on the previous page, foods that were once considered part of a healthy “low-fat diet” have a high glycemic index and high glycemic load. Ingesting these kinds of foods helps you gain weight, even though you think you are eating right.
The message for those seeking to lose some pounds is to reduce or avoid consumption of foods with a higher glycemic index/load. While this is not the entire solution to the obesity crisis, it is an important component. The problem is that it is difficult to suppress carbohydrate craving. Even when people know they should avoid sucrose-fructose foods, they too often succumb to an insulin-induced addiction and gorge themselves with ice cream, chocolate, and other sugar-laden desserts.
When it comes to the problem of high-glycemic diets, two obstacles must be overcome: cutting the craving for sugar, and changing eating patterns to avoid high-glycemic foods. A partial solution is to impede the rapid absorption of sugars into the bloodstream in order to reduce the accompanying insulin spike. This reduction in postprandial insulin secretion can help induce satiety and somewhat inhibit calorie intake. After six years of intensive research, a supplement is now available that interferes with the rapid absorption of sugar, thus reducing after-meal blood glucose and insulin levels by 23% and 40%, respectively.
The Search for a Better Fiber
The problem until now is that the large quantity of fiber required to produce a meaningful effect has resulted in poor compliance, primarily because of upper and lower gastrointestinal-related discomfort.
In the early 1990s, scientists at the University of Toronto began to investigate a novel class of viscous fibers in order to identify a low-dose blend that would reduce blood glucose, insulin, cholesterol, and LDL levels. Initial studies confirmed the beneficial effects of these soluble fibers. Compared to placebo, those consuming highly viscous fibers before meals showed improvement in glycemic control, blood lipid levels, and blood pressure.35,36 The problem, however, remained—these beneficial effects could be produced only by ingesting large amounts of this fiber.
To overcome this problem, the scientists tested hundreds of different fiber blends with the objective of achieving significant benefits from only a few grams of soluble fiber per meal.
One of the initial findings that motivated the University of Toronto scientists to pursue this research occurred during a study that measured the glycemic-index response to different forms of fiber (or no fiber). In this study, three grams of various fibers were administered prior to a 20-gram glucose challenge. As expected, the glycemic index of the control group receiving no fiber was 100. Those receiving three grams of psyllium and xanthan showed only negligible glycemic index reductions (3% and 6%, respectively). By contrast, test subjects receiving three grams of a novel fiber blend showed a remarkable 39% reduction in their glycemic index. This finding demonstrated that consuming just three grams of this highly viscous fiber before a meal could significantly reduce the number of insulin-spiking carbohydrate calories absorbed.37
Using the Most Viscous Fibers
Four to five grams of glucomannan blended into fluid or mixed with food can slow carbohydrate absorption into the bloodstream and dampen the ensuing insulin spike by up to 50%.39 Controlled clinical studies document that glucomannan can promote satiety and induce modest weight loss.40-43 It has been shown to significantly lower LDL and total cholesterol, improve diabetic control, and correct constipation.29-31,33-38,40-43
The reason glucomannan has fallen by the wayside is that in the 1980s, programs promoting quick weight loss advertised glucomannan as a supplement that could make obese people thin. The FTC stepped in and aggressively attacked those who were making exaggerated fat-loss claims for glucomannan. The subsequent negative reports by the news media caused glucomannan to be viewed by the public as a worthless dietary supplement.
The published scientific studies on glucomannan, however, are quite impressive. Although it does not make fat people thin, a double-blind trial showed that compared to placebo, obese subjects taking one gram of glucomannan before each meal lost 5.5 pounds after only eight weeks.40 The subjects were instructed not to change their eating or exercise patterns. Total cholesterol and LDL also were reduced (by 21.7 and 15.0 mg/dL, respectively) in the glucomannan-supplemented group. No adverse reactions to glucomannan were reported.
Several other published studies confirm that glucomannan modestly reduces weight compared to placebo or diet alone.41-43 Total cholesterol and LDL, along with after-meal insulin and glucose blood levels, are significantly reduced when glucomannan is taken before meals.41-43
With this knowledge of glucomannan as a foundation, University of Toronto scientists led by Vladimir Vuksan, PhD, combined glucomannan with two other viscous fibers (xanthan and alginate) in an exact ratio to increase the viscosity of the original glucomannan material by 2.5-5 times.44 A mulberry concentrate (20:1) was added to enhance the glycemic-control and lipid-lowering effects.48
The primary benefit of this proprietary fiber blend lies in its superior viscosity. This means that it is better able to expand in the gastrointestinal tract to inhibit sugar absorption and bind cholesterol. This enables much smaller quantities to be taken than of other viscous dietary fibers to achieve comparable health benefits. The fiber blend’s trade name is PGX™, which stands for “polyglycoplex.”
Studies Confirm Effectiveness
The second study was performed over a three-week period to better reflect real-life experiences. Study subjects took three grams of the fiber blend three times a day before meals. After three weeks, there was a 23% reduction in postprandial glucose, a 40% reduction in after-meal insulin release, and a 55.9% improvement in whole-body insulin sensitivity scores. In addition, this proprietary fiber blend reduced body fat by 2.8% from baseline by the end of the three-week study period.
As a result of these findings, a large, longer-term clinical study has been initiated to further evaluate this unique fiber blend’s effects on weight loss.