High fiber diet and diabetic kidney disease

The aim of this study was to investigate the effect of fiber in the diet on diabetic kidney disease. The main outcome of the study was that a vegetarian dietary pattern may have a beneficial effect on kidney function.

Diet and lifestyle changes are a major part of treatment for both type 1 (T1D) and type 2 diabetes (T2D). Patients with diabetes have a higher risk of heart disease. It is known that high fiber in the diet is associated with better blood sugar control and decreased risk of heart disease. The American Diabetes Association recommends that patients consume at least 14g fiber for each 1000 kcals every day.

There are many different diet patterns that are associated with high fiber. These include the DASH diet and a vegetarian diet. The Dietary Approaches to Stop Hypertension (DASH) diet was developed in 1997. It consists of 8 components: high intake of fruit, vegetables, whole-grains, low-fat dairy foods, legumes and nuts and a low intake of salt, sweetened drinks, red and processed meat. A vegetarian diet includes fruit, vegetables, nuts, whole grains, and dairy products but not meat or seafood. Diabetic kidney disease is a common complication of diabetes. The effect of dietary fiber on diabetic kidney disease is not known.

This study evaluated 7 individual trials including 161 patients in total. These studies examined the effect of either DASH diet, a vegetarian diet or a diet with fiber supplementation.  

In 3 of the trials, the vegetarian diet reduced the amount of protein in the urine (a marker of diabetic kidney disease) in patients with type 1 and type 2 diabetes. In one study the vegetarian diet also improved the rate at which the kidney filters the blood (a marker of kidney function). There was no change in protein in the urine in patients who were on the DASH diet.

The authors concluded that a vegetarian diet may have beneficial effects on diabetic kidney disease. 

Each of these studies involved a very small number of patients (8-49) and were only treated with a specific diet for a very short length of time (4-12 weeks). The individual quality of the studies was low/uncertain. Further studies are needed to evaluate the effect of dietary fiber on diabetic kidney disease.