ORLANDO – A low-fat vegan diet reduced symptoms of peripheral neuropathy among patients with type 2 diabetes in the randomized, controlled Dietary Intervention for Chronic Diabetic Neuropathy Pain (DINE) study.
After 20 weeks, 17 patients who were assigned to the vegan diet group were more likely than were 18 control patients to have lost weight, to have reductions in pain scores, and to have neurologic improvements in their foot neuropathy.
The findings demonstrate "the potential of a low-fat vegan diet as a treatment for diabetic neuropathy pain," Anne E. Bunner, Ph.D., reported at the annual meeting of the American Association of Diabetes Educators. Other treatment options for diabetic neuropathy offer pain relief, but do not address the underlying nerve damage.
Support measures are needed to ensure the success of major dietary changes, said Dr. Bunner, associate director for clinical research at the Physicians Committee for Responsible Medicine, Washington, D.C.
The findings confirm those of a prior uncontrolled study (J. Nutr. Med. 1994;4:431-9) in which 81% of patients had pain relief with a low-fat, high-fiber vegan diet, Dr. Bunner said. A review of five studies involving more than 16,000 patients with type 2 diabetes showed that tight blood glucose control reduces the severity of diabetic neuropathy but does not eliminate the associated pain.
Dr. Bunner reported that the mean change scores in the diet group vs. the control group were –7.0 vs. –0.7 for body weight, –2.4 vs. –0.2 for body mass index, –9.1 vs. –0.9 for McGill Pain Questionnaire results, and 0.7 vs. –11.7 for foot conductance.
The diet group also experienced improvements in mean change scores for hemoglobin A1c (–0.8), Quality of Life score (–8.4), and Neuropathy Total Symptoms Score (–3.9), but the changes in these scores were not significantly better than those of the control group (–0.1, –4.7, –2.7, respectively).
The control group experienced greater improvements in pain as measured by a visual analogue scale (mean change scores of –1.2 and –2.1* for the diet and control groups, respectively). The change in the diet group was not statistically significant.
Patients in both groups used vitamin B12 supplements during the course of the study, which could explain the improvements in the control group, Dr. Bunner said. B12 deficiency is associated with diabetic neuropathy, but none of the patients had a B12 deficiency at baseline. It is possible that B12 may have been an active treatment or that the motivation associated with being a study participant was associated with the improvements.
Of note, 4 of 17 patients in the diet group were able to reduce the dosages of lipid-lowering medications; 1 increased the dosage. No one in the control group was able to reduce the dosages of lipid-lowering medications; 3 of 18 increased dosages. Ten of 17 diet group patients reduced the dosages of diabetes medications, and 2 of 18 controls reduced the dosages of diabetes medications.
Mean age of the study subjects was 57 years. Those assigned to the diet group were instructed to consume only plant foods, and to limit intake of oils, nuts, and fatty foods. Fat was limited to 3 g per serving or 20-30 g per day. Patients in the diet group also were advised to include 40 g/day of high-fiber foods, and to consume low–glycemic index foods. No limit was placed on portions.
The diet group participated in weekly classes involving nutrition education, social support, cooking demonstrations, and food product sampling.
Both groups used B12 supplements, and the control group was instructed to make no major dietary changes during the 20-week study.
Thirteen of 17 diet group patients were fully compliant with the vegan diet; 8 of the 13 were compliant with the low-fat instructions at both the 10- and 20-week assessment, and 3 of the 13 were compliant with the low-fat instructions at one of the two assessments. Two were fully compliant with the low-fat guidelines, but not the vegan guidelines, and two were noncompliant with both. One patient did not complete the study.
Dr. Bunner reported having no disclosures.
CORRECTED Aug 8: Improvement in pain in the control group, as measured by a visual analogue scale, was misstated in the original story. That value was –2.1.