Dietary Fiber Intake (Supplemental or Dietary Pattern Rich in Fiber) and Diabetic Kidney Disease: A Systematic Review of Clinical Trials

Fiber intake is associated with better glycemic control being an important non-pharmacological treatment for diabetes (DM). We hypothesize that a dietary fiber intake can bring benefits to diabetic kidney disease (DKD), improving renal outcomes. This systematic review aimed to evaluate the effect of dietary fiber (supplemental or dietary pattern rich in fiber) on DKD. We searched six databases to identify clinical trials that reported fiber intake and renal outcomes (albuminuria, proteinuria, estimated glomerular filtration rate (eGFR) dialysis) in patients with DM. From 1814 studies, 48 papers were fully evaluated. In the end, seven trials (161 patients, aged 58.3 years, 49% females) were included. The studies were organized into three categories (vegetarian, Dietary Approaches to Stop Hypertension (DASH) diet, and fiber supplement), two evaluated supplements and five dietary patterns. Vegetarian diet reduced albuminuria in three trials, two in patients with type 1 DM and one in patients with type 2 DM; and one study demonstrated a change in the eGFR in type 1 DM. The individual quality of the studies was low/uncertain. A vegetarian dietary pattern may have a beneficial effect on these renal outcomes. However, the individual effect of the intake of fiber on DKD not was possible to be evaluated.