In all, fiber lowers blood glucose by either blocking glucose absorption from the gut and/or increasing the transit time through the gut. The studies mentioned below involve several forms of fiber. Psyllium is a soluble fiber from a shrub-like herb called “Plantago.” Guar gum is a water-soluble fiber that comes from guar seeds, grown mostly in India and Pakistan. Glucommannan, which comes from the konjac plant mostly grown in China, is used as a dietary fiber. Fiber supplements come in tablets, capsules and powder.
A few studies show that fiber has a positive effect on HbA1C in type 2 diabetes. (Recall that this is a form of hemoglobin that reflects the average blood glucose levels over the past 90 days.)
One study involved 17 insulin-dependent type 1 diabetic patients who were randomized to receive either guar gum (five grams daily) or placebo for six weeks. HbA1C in guar-gum-treated patients decreased by 0.6% vs. 0.5% in placebo-treated patients. Fasting blood glucose in guar-gum-treated patients decreased 1.7 millimoles/liter (mmol/L) vs. an increase of 0.3 mmol/L in placebo patients. Total cholesterol in guar-gum-treated patients decreased 1.0 mmol/L vs. a 0.1-mmol/L decrease in the placebo group.
Another study involved 49 type 2 diabetic patients who were assigned to receive 5.1 grams twice a day of psyllium husk fiber or placebo while they continued taking anti-diabetic drugs for eight weeks. Here, psyllium led to a significant drop in fasting blood glucose — 53 milligrams per deciliter (mg/dL) vs. 31 mg/dL by placebo. Also, psyllium-treated patients showed a significant lowering of HbA1C of 1.4% vs. an increase of 1.4% in placebo.
Many studies show fiber having beneficial effects on blood glucose levels.
In one study, 34 men with type 2 diabetes with high cholesterol received 5.1 gram psyllium or placebo for eight weeks. The all-day blood glucose was 11% lower and post-lunch blood glucose was 19% lower in the psyllium group. As compared to the placebo group, total and LDL cholesterol levels were 8.9% and 13% lower, respectively, in the psyllium group.
A total of 14 studies have shown that glucommannan dropped fasting blood glucose by 7.44 mg/dL, body weight by 0.79 kg, total cholesterol by 19.28 mg/dl, LDL cholesterol by 15.99 mg/dL, and triglycerides by 11.08 mg/dL.
The American Diabetes Association recommends that all diabetic patients get 14 grams per 1,000 kilocalories/day of fiber in order to improve their blood sugar control. You should always take your fiber supplement with a full eight-ounce glass of water and drink at least six to eight glasses of water a day. And you should take fiber supplements at least one hour before or two to four hours after taking other medications.
Here are the previous articles in this series: