Does psyllium fiber benefit patients with diabetes?

This review analysis looked at whether psyllium fiber supplements benefit patients with type 2 diabetes (T2D). It found that psyllium improves LDL cholesterol and blood sugar control for patients with T2D.

Diabetes is a metabolic condition in which the body cannot reduce high levels of glucose (sugar) in the blood. Glucose enters the body from starchy and sugary foods. Carbohydrates (CH) which are absorbed quickly will cause a high, sudden spike in blood glucose. Because fat and protein are absorbed more slowly, eating these other nutrients at the same time as CH slows down the release of glucose into the bloodstream.

Fiber also slows down the absorption of digestible CH. Fiber is a type of CH that cannot be absorbed or digested by humans. Soluble fiber can dissolve in water. Oatmeal is an example of a food high in soluble fiber, and it is what makes the oats stick together after cooking. Soluble fiber can absorb some fat and cause it to pass out of the body without being digested. Additionally, soluble fiber supports healthy gut bacteria, which are also known as the microbiome.

Fiber from the psyllium plant is sold as a powdered supplement to be taken daily dissolved in water. It is unclear whether psyllium fiber supplements benefit patients with T2D.

This review included 8 studies of 395 adult patients with T2D. 205 patients had been randomly selected to receive psyllium fiber supplements. The other 190 received a placebo (an inactive substance). Patients were followed for between 8 and 20 weeks depending on the study.

Six studies of 315 patients looked at levels of triglycerides (fat) in the blood. The combined results found that psyllium significantly reduced triglyceride levels (reduction of 19.18 mg/dl). There was a trend toward lower total cholesterol levels (reduction of 8.02 mg/dl). Additionally, levels of LDL (“bad”) cholesterol were significantly lower in the psyllium group (reduction of 8.96 mg/dl).

Blood sugar control was assessed in six studies with 124 patients taking psyllium and 112 taking placebo. The psyllium group had significantly lowered blood glucose levels after not eating for at least eight hours (reduction of 31.71 ml/dl). Glycated hemoglobin (HbA1c) is an indication of blood glucose control over the previous two to three months. Patients in the psyllium group had significantly improved HbA1c (reduction of 0.91%). Psyllium did not affect body weight.

There were no side effects of psyllium at the dose used (average of 9 g/day).

This review found that psyllium fiber supplements improved triglyceride, LDL cholesterol, and blood glucose control for patients with T2D.

The authors evaluated the 8 studies for bias. While they found low levels of bias overall, not all studies prevented patients and researchers from knowing which group was taking active supplements (double-blinding).