The effect of dietary carbohydrate modification on metabolic profiles and adipose tissue gene expression in patients with metabolic syndrome

Background: Advanced measurement technologies afford characterization of effects of complex interventions, such as diet intervention studies. Understanding the interrelationships among genes, gene products and diet may lead to the enhanced use of personalized diets to prevent or delay the onset of diseases and optimize and maintain health. Aim: The aim was to study the effect of carbohydrate modification on the serum metabolomic profiles, including lipids, branched chain amino acids and ketoacids and their interaction between clinical measurements in subjects with the metabolic syndrome. We also examined if there is dependencies between serum metabolites and specific gene expression pathways in adipose tissue in order to help understand the physiological importance of different lipids and metabolites. Subjects and methods: Twenty subjects were selected for the lipidomics, ketoacid and microarray analysis of the larger Fungenut study. To be included in the study, the subjects had to be aged 40-70 years, have BMI 26-40 kg/m2 and had to meet the National Cholesterol Education Program criteria for the metabolic syndrome. The subjects were randomly assigned to one of the two groups: oat - wheat bread - potato group and rye bread - pasta group. The subjects replaced their habitually used breads and baked products with test breads during the 12-week test period and preferred either potatoes or pasta as part of warm dishes. Otherwise, the diet was requested to be unchanged. Fasting blood samples and adipose tissue biopsies were taken before and after intervention. The ultra performance liquid chromatography coupled to electrospray ionization mass spectrometry (UPLC/MS) in ESI+ mode was used for lipidomic analyses, gas chromatography (GC FID) method for fatty acids analyses, and UPLC for branched chain amino acid and keto-acid analyses. UPLC/MS data were processed with MZmine software. Pathway analysis of the gene expression data was performed using Gene Set Enrichment Analyses (GSEA). Results and conclusions: The major difference following the intervention as revealed by lipidomic analysis was upregulation of multiple proinflammatory lysophosphatidylcholine species in the oat - wheat bread - potato group while no changes were found in the rye bread – pasta group. The fatty acid analysis revealed an increase in docosahexaenoic acid (DHA 22:6n-3) in the rye bread -pasta group, otherwise the fatty acid changes were not significant. The results suggest that dietary carbohydrate modification causes changes on metabolic profile and it may have a role in proinflammatory processes.