Japanese tradition calls glucomannan “the broom of the intestines.” Many Japanese food products use glucomannan as a gel or thickener. A type of Japanese noodle made primarily from glucomannan is often advertised as a low-calorie appetite suppressant.
Glucomannan molecules are water-soluble. This means glucomannan dissolves in water. Another important property of glucomannan is its high viscosity. This high viscosity means glucomannan resists flow. These two properties led to the study of glucomannan as an appetite suppressant, constipation treatment, and for other uses.
Glucomannan is also available as a flour or powder. Sometimes it is used as a food additive to emulsify or thicken.
Glucomannan is primarily used as a dietary fiber. As a dietary fiber, glucomannan absorbs water in the digestive organs. This action increases the digestion rates either to treat constipation or to suppress appetite.
Patients taking 1 gram of glucomannan a day lost weight over an eight-week period without changing their diet or exercise habits. In a separate study, patients with chronic constipation showed significant improvements after using glucomannan.
A combination of glucomannan, xanthan, and sodium alginate demonstrated effectiveness as an appetite suppressant. In this study, adolescents who took this dietary fiber combination ate fewer calories compared to other groups.
Sometimes glucomannan is used as a treatment for diabetes or controlling blood sugar. When glucomannan expands in the digestive tract, it slows sugar and cholesterol absorption. A slower absorption rate means better blood sugar and cholesterol control.
Several studies have examined glucomannan’s effects on cholesterol.
In one study, adult men took 3.9 grams of glucommanan daily for four weeks. At the end of the trial, they showed improvement in several health markers. These included total cholesterol, triglycerides, low-density lipoproteins, and systolic blood pressure.
In another study, researchers found glucomannan was both safe and effective for children with excess cholesterol.
Glucomannan is considered safe in powdered or flour form. These glucomannan types are most commonly found in food.
Most people experience no adverse side effects from glucomannan capsules. However, some reports say solid glucomannan tablets cause blockages in the throat or intestines. This may be due to glucomannan’s rapid expansion rate.
Drinking at least 8 ounces of water with every 1 gram of glucomannan significantly decreases this risk.
The Canadian government issued a warning in 2010 advising the public to take any glucomannan products with at least 8 ounces of water. The primary concern cited was choking.
People with diabetes, especially those taking oral diabetes medications, need to monitor their blood sugar closely while using glucomannan.
Glucomannan alters absorption rates of oral medications. Take any glucomannan at least one hour before dosages of oral medications.
Treating constipation with glucomannan requires 3 to 4 grams per day.
Effective doses for lowering cholesterol are between 4 and 13 grams a day.
For treating a combination of type 2 diabetes and high cholesterol, the recommended glucomannan dosage is between 3.6 and 10.6 grams per day.
For weight loss, studies indicate dosages of 1 to 5 grams daily are effective.
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