High Adherence to a Food Guide May Be Associated with Lower Serum C-Peptide Concentrations

A balanced diet has been associated with a lower risk of total and cardiovascular mortality. One intermediate function linking a balanced diet and lower mortality may be optimal insulin secretion. We examined the association between adherence to the Japanese Food Guide Spinning Top (JFGST) and serum C-peptide concentration, an indicator of basal insulin secretion, in a cross-sectional study in a Japanese population, in whom rice (refined grains) is the staple food. A blood sample was collected in November 2012 and a 12-d weighed food record was collected over the subsequent year. A total of 210 healthy residents aged 35-80 y (83 men, 127 women) were included in the analysis. Multiple regression analysis was performed with log-transformed serum C-peptide concentration as dependent variable and total JFGST score or each score by category of dish as independent variable, with adjustment for age and BMI. In both men and women, total JFGST score was inversely associated with serum C-peptide concentration. Slope in the percentage of differences for every 1-point score addition based the regression coefficients was -2.3% (p<0.001) in men and -1.6% (p<0.001) in women. For specified categories of dishes, scores for grain dishes, snacks and alcoholic beverages, and total energy were inversely associated with serum C-peptide concentrations among men. Among women, in contrast, scores for milk and for fruit were inversely associated with serum C-peptide concentrations. A balanced diet consistent with the JFGST was inversely associated with serum C-peptide concentration among middle-aged Japanese.