Yacon supplementation reduces serum free fatty acids and tumor necrosis factor alpha concentrations in patients with type 2 diabetes

Abstract

Yacon is a perennial plant originating from South America that forms >20 large subterranean tubers weighing from 100 to 500 g. These tubers have become popular in Japan and contain beta-1, 2-oligofructans as the main saccharides. Preliminary work in animals revealed yacon feeding ameliorates diabetes by reducing blood glucose. We therefore examined whether yacon feeding modulates glucose metabolism in patients with type 2 diabetes. We conducted a single-center, open-label, randomized controlled trial to investigate the effect of yacon on patients with type 2 diabetes. Fifty-eight patients with type 2 diabetes were selected from the medical outpatients department. There had been no changes in their diet or medications during the 3 months before the study commenced. After ethical clearance, written informed consent was obtained. Patients were randomly assigned to two groups: group 1 received an intake level of 100 g yacon/day, and group 2 received an intake level of 100 g aroid/day (control). Fasting glucose, insulin, glycated albumin, and adiponectin concentrations at baseline did not differ significantly between groups; after 5 months, concentrations did not change significantly in either group. Interestingly, after 5 months of yacon consumption, tumor necrosis factor alpha (TNF-α) and free fatty acid (FFA) concentrations decreased significantly by 10.3 % and 9.8 % (p < 0.01), respectively; neither changed significantly in the aroid group. In conclusion, the results suggest longer-term yacon supplementation may improve insulin resistance by reducing FFA and TNF-α in patients with type 2 diabetes.