The randomised trial, published in Journal of Functional Foods, evaluated the effects of ethanol extracts of Citrus junos Tanaka peel (YE) on glucose control in subjects with impaired fasting glucose – finding that YE may be effective for controlling fasting blood glucose levels and could serve as a useful supplement for people with pre-diabetes.
Led by Jin-Taek Hwang from the Korea Food Research Institute and Korea University of Science & Technology, the team noted that currently the treatment of diabetes relies on drugs that can cause severe side effects, and that the identification of effective approaches to improve blood glucose levels without side effects is needed.
“Many investigators have proposed the use of plant extracts as a most promising source of novel treatments for the prevention of diabetes, based on the results of both in vivo studies and clinical trials,” the team wrote.
They noted that yuja, also known as yuzu, is a yellow-coloured citrus fruit grown in Korea, Japan, and China. In Korea, yuja has traditionally been used in the treatment of the common cold, and has also been traditionally linked to the prevention of certain diseases.
“Citrus junos Tanaka peel may be an effective and safe treatment option for lowering blood glucose levels in individuals with impaired fasting glucose. Furthermore, YE may serve as a functional food in subjects with pre-diabetes,” the authors wrote.
The double-blind, crossover, placebo-controlled study, randomly assigned participants in receive either YE or a control for eight weeks before switching groups for a further eight weeks.
Measures of fasting plasma glucose (FPG), postprandial glucose (PPG), and fasting plasma insulin (FPI) concentrations; homeostatic model assessment-insulin resistance (HOMA-IR) were taken before and after the eight-week trial, furthermore at 12 weeks, and again after an eight week crossover (week 20).
“Upon completion of the 20 weeks of the clinical trial, changes in lifestyle, eating patterns, and pill compliance were assessed,” noted the team.
After 8 weeks of intervention, the YE group showed significantly lower FPG levels, FPI, and HOMA-IR compared to the placebo group, said Hwang and colleagues – who noted that PPG and c-peptide were also slightly reduced in the YE groups.
“Although we had previously reported the anti-diabetic effect of YE both in cell culture and animal models, this is the first time that the effect of YE has been reported in humans,” the team said. “Our data demonstrated that IFG, fasting insulin, and HOMA-IR showed significantly greater improvement after YE supplementation compared to supplementation with placebo.”
Source: Journal of Functional Foods
Volume 18, Part A, Pages 532–537, doi: 10.1016/j.jff.2015.08.019
“A randomized, double-blind, placebo-controlled clinical trial to investigate the anti-diabetic effect of Citrus junos Tanaka peel”
Authors: Jin-Taek Hwang, et al