Does increasing fiber improve the health of patients with type 1, type 2 and pre-diabetes?

This study examined if an increase of fiber in the diet improved diabetes-related and other symptoms of health in patients with type 1, type 2 and pre-diabetes. The authors found that high-fiber diets improved blood glucose and cholesterol levels and patients’ survival.

Patients with type 1 (T1D), type 2 (T2D) or pre-diabetes (PD) have high blood glucose levels. HbA1c measures blood glucose levels for the previous three months. Patients also have a higher risk for other diseases, including heart disease. Factors such as increased cholesterol levels and body weight increase the risk of heart disease.

Fiber is a type of carbohydrate that is found in fruit, vegetables, and whole-grain foods. It can be also be given in supplements. Several previous studies have shown that fiber reduces blood glucose levels and improves heart health. It is unclear if this benefit applies to patients with T1D, T2D or PD.

44 previous studies that examined how fiber impacted the health of patients with T1D, T2D or PD were examined collectively. Two studies looked at 8300 patients with T1D or T2D over an average of 8.8 years. The other studies looked at 1789 patients with T1D, T2D or PD for 6 to 12 weeks. 

Over 8.8 years, a high fiber intake reduced the risk of death by 45%. The risk of death due to heart disease was reduced by 39% by a high fiber consumption. There was a 35% lower risk of death in patients who consumed 35g of fibers per day compared to those consuming an average of 19g per day.

A high fiber intake reduced HbA1c by 2 mmol/mol on average. Fasting glucose was reduced in patients who consumed a high fiber diet. A high fiber diet reduced cholesterol and triglycerides (fats in the blood) levels. Bodyweight and waist circumference were also reduced by high-fiber diets, with no change in calorie intake.

The authors concluded that increasing fiber intake up to 35 g per day could improve patient health and reduce their risk of death, including heart disease.

This study was limited by the different designs of the 44 studies included, such as different amounts of fiber given to patients. This study did not distinguish between studies that used diet or supplements to increase patients’ fiber intake. Most studies included were carried out in Europe which may not reflect patients globally.