Dietary carbohydrate modification alters serum metabolic profiles in individuals with the metabolic syndrome☆

Abstract 

Background and aims

Whole-grain cereals and diets with a low glycemic index may protect against the development of type 2 diabetes and heart disease, but the mechanisms are poorly understood. We studied the effect of carbohydrate modification on serum metabolic profiles, including lipids and branched chain amino acids, and dependencies between these and specific gene expression pathways in adipose tissue.

Methods and results

Twenty subjects with metabolic syndrome were selected from the larger FUNGENUT study population, randomized either to a diet high in oat and wheat bread and potato (OWP) or rye bread and pasta (RP). Serum metabolomics analyses were performed using ultra-performance liquid chromatography coupled to electrospray ionization mass spectrometry (UPLC/MS), gas chromatography (GC) and UPLC.

In the OWP group multiple proinflammatory lysophosphatidylcholines increased, while in the RP group docosahexaenoic acid (DHA 22:6n-3) increased and isoleucine decreased. mRNA expression of stress reactions- and adipose tissue differentiation-related genes were up-regulated in adipose tissue in the OWP group. In the RP group, however, pathways related to stress reactions and insulin signaling and energy metabolism were down-regulated. The lipid profiles had the strongest association with the changes in the adipose tissue differentiation pathway when using the elastic net regression model of the lipidomic profiles on selected pathways.

Conclusion

Our results suggest that the dietary carbohydrate modification alters the serum metabolic profile, especially in lysoPC species, and may, thus, contribute to proinflammatory processes which in turn promote adverse changes in insulin and glucose metabolism.

Keywords: Metabolic syndrome, Diet, Metabolomics, Lipidomics

Abbreviations: BCAA, branched chain amino acid, DHA, docosahexaenoic acid, ES, enrichment score, GSEA, gene set enrichment analysis, lysoPC, lysophosphatidylcholine, MS, metabolic syndrome, OWP, oat and wheat bread and potato, RP, rye bread and pasta, T2D, type 2 diabetes mellitus, UPLC, ultra-performance liquid chromatography