Effects of a Low Advanced Glycation End Products Diet on Insulin Levels: The Feasibility of a Crossover Comparison Test

Abstract

Background: Advanced glycation end products (AGEs) are associ-ated with diabetes mellitus. Digested food-derived AGEs have been implicated in the pathogenesis of AGE-related disorders, and restrict-ing diet-derived AGEs improves insulin resistance in animal models. The AGE content in foods changes according to cooking method, and it is higher in baked or oven-fried foods than in those prepared by steaming or simmering. Here, we examined the feasibility of crosso-ver comparison tests for determining how different cooking methods (normal diet vs. low-AGE diet) affect insulin levels in non-diabetic Japanese subjects. Methods: Five adult men and women (age, 41 ± 7 years; body mass index (BMI), 21.7 ± 2.6 kg/m 2) were enrolled. The following dietary regimen was used: days 1 -3, control meal; day 4, test meal (normal diet vs. low-AGE diet); day 5, washout day; and day 6, test meal. On days 4 and 6, blood samples were collected before and at 2, 4, and 6 h after meals. Results: Blood levels of N-(carboxymethyl) lysine (CML) increased with dietary intake, but the increase was similar for the normal diet and low-AGE diet groups. Mean plasma glucose, insulin, triglyc-erides (TG), and CML did not differ significantly between the two groups. The area under the curve (AUC) for insulin levels was lower in the low-AGE diet group (d = 0.8). The sample size calculated from the effect size of the insulin AUC change was 22. Conclusions: Twenty-two subjects may be needed to investigate the changes in clinical parameters attributable to cooking method in non-diabetic Japanese subjects.