Metabolomic analysis of plasma metabolites that may mediate effects of rye bread on satiety and weight maintenance in postmenopausal women

The evidence of the beneficial health effects of dietary fiber and whole grain consumption is strong, but the underlying mechanisms are not completely understood. Here, we investigate how the consumption of high-fiber rye bread (RB) or white-wheat bread (WB) modifies the plasma metabolomic profiles in postmenopausal women. The study was a randomized crossover trial consisting of 8-wk intervention periods and an 8-wk washout period. The study included 39 postmenopausal women with elevated serum total cholesterol (5.0–8.5 mmol/L) and BMI 20–33 kg/m². During the intervention periods, the study breads contributed to least 20% of total energy intake. Two analytical platforms for metabolomics were applied. Lipidomic analysis was performed using ultra performance liquid chromatography coupled to electrospray ionization MS and the other metabolites, including sterols, organic acids, and alcohols, were analyzed by 2-dimensional GC coupled to time-of-flight MS. Altogether, 540 metabolites were profiled. Ribitol (P < 0.001), ribonic acid (P < 0.001), and indoleacetic acid (P < 0.001) increased during the RB consumption period. Ribonic acid correlated positively with tryptophan (r = 0.40; P = 0.003), which is a precursor for the biosynthesis of hunger-depressing serotonin. There were no changes in plasma lipidomic profiles during the RB or WB intervention periods. The results suggest that 8-wk consumption of high-fiber rye bread increases metabolites that might mediate positive effects of rye bread on satiety and weight maintenance.