Metabolic signatures associated with diet quality in young adults

BACKGROUND/AIM Poor diet is a known risk factor for many noncommunicable diseases, including cancer and type 2 diabetes. Metabolomics is an emerging exposure assessment method that may improve nutrition assessment and identify biomarkers related to diet and disease. The purpose of this study was to identify metabolites and metabolic pathways associated with diet quality. METHODS We used untargeted metabolomics, determined using liquid chromatography-mass spectroscopy, to evaluate the relationship between metabolic pathways and diet quality in young adults from the Metabolic and Asthma Incidence Research (Meta-AIR) cohort (n=124). Four diet quality indices were evaluated: Dietary Approaches to Stop Hypertension (DASH) score, Healthy Eating Index 2015 (HEI-2015), Mediterranean diet score (MDS), and the Diet Inflammatory Index (DII). Functional pathway analysis was performed with MetaboAnalyst version 5.0, using effect estimates generated from metabolome-wide association studies to identify metabolic pathways with significant (p<0.05) enrichment. Analyses were performed for each diet index separately and adjusted for age, sex, ethnicity, and body mass index. RESULTS MDS, HEI-2015, DASH, and DII were associated with 13, 8, 6, and 5 pathways, respectively. Enriched pathways related to lipid metabolism were associated with DASH (arachidonic acid metabolism, p=0.030), HEI-2015 (carnitine shuttle, p=0.0078), and MDS (de novo fatty acid biosynthesis, p<0.001; fatty acid activation, p<0.001; fatty acid metabolism, p=0.034). These three were additionally significantly associated with vitamin B6 metabolism (DASH: p=0.043, HEI-2015: p=0.0026, MDS: p=0.036) and the metabolism of other vitamins and cofactors. Enriched pathways related to amino acid metabolism were also identified for all four diet indices. CONCLUSIONS Diet quality was associated with biological pathways related to the metabolism of important nutrients, some of which are involved in inflammatory responses. These associations may be used to identify biomarkers indicative of diet quality or describe the metabolic effects of higher quality diets. KEYWORDS Food/nutrition, exposure assessment, biomarkers of exposure, metabolomics