The Mediterranean diet, plasma metabolome, and cardiovascular disease risk

Abstract

Aims: To investigate whether metabolic signature composed of multiple plasma metabolites can be used to characterize adherence and metabolic response to the Mediterranean diet and whether such a metabolic signature is associated with cardiovascular disease (CVD) risk.

Methods and results: Our primary study cohort included 1859 participants from the Spanish PREDIMED trial, and validation cohorts included 6868 participants from the US Nurses' Health Studies I and II, and Health Professionals Follow-up Study (NHS/HPFS). Adherence to the Mediterranean diet was assessed using a validated Mediterranean Diet Adherence Screener (MEDAS), and plasma metabolome was profiled by liquid chromatography-tandem mass spectrometry. We observed substantial metabolomic variation with respect to Mediterranean diet adherence, with nearly one-third of the assayed metabolites significantly associated with MEDAS (false discovery rate < 0.05). Using elastic net regularized regressions, we identified a metabolic signature, comprised of 67 metabolites, robustly correlated with Mediterranean diet adherence in both PREDIMED and NHS/HPFS (r = 0.28-0.37 between the signature and MEDAS; P = 3 × 10-35 to 4 × 10-118). In multivariable Cox regressions, the metabolic signature showed a significant inverse association with CVD incidence after adjusting for known risk factors (PREDIMED: hazard ratio [HR] per standard deviation increment in the signature = 0.71, P < 0.001; NHS/HPFS: HR = 0.85, P = 0.001), and the association persisted after further adjustment for MEDAS scores (PREDIMED: HR = 0.73, P = 0.004; NHS/HPFS: HR = 0.85, P = 0.004). Further genome-wide association analysis revealed that the metabolic signature was significantly associated with genetic loci involved in fatty acids and amino acids metabolism. Mendelian randomization analyses showed that the genetically inferred metabolic signature was significantly associated with risk of coronary heart disease (CHD) and stroke (odds ratios per SD increment in the genetically inferred metabolic signature = 0.92 for CHD and 0.91 for stroke; P < 0.001).

Conclusions: We identified a metabolic signature that robustly reflects adherence and metabolic response to a Mediterranean diet, and predicts future CVD risk independent of traditional risk factors, in Spanish and US cohorts.

Keywords: Cardiovascular disease; Dietary metabolic response; Mediterranean diet; Mendelian randomization analysis; Metabolomics; Risk prediction.

Figure 1

Flowchart of study cohorts. For PREDIMED study, * indicates the total number of participants with complete diet and metabolomics data at baseline, and ^# is the number of participants with repeated measurements at year-1 visit. CVD NCC, the nested case-cohort study for incident cardiovascular disease.

Figure 2

The metabolic signature for adherence to the Mediterranean diet: flow chart for analytic approach and validation. (A) The training and testing procedures of a metabolic signature for the Mediterranean diet adherence screener (MEDAS). (B) The metabolic signature was trained using PREDIMED baseline measurements and tested with PREDIMED year-1 (interval validation) and the NHS/HPFS baseline measurements (external validation). The correlations between MEDAS and the 67-metabolite signature in the two validation sets are shown in (C) and (D). In the training set, in order to include the training dataset in association analyses, we used the leave-one-out-cross validation (LOOCV) approach to acquire an unbiased metabolic signature score; and the correlation between MEDAS and the LOOCV-derived score is presented in (B).

Figure 3

Associations of the 67 metabolites constituting the metabolic signature with MEDAS components, total MEDAS score, and subsequent cardiovascular disease risk. Data were based on measurements at PREDIMED baseline (replications were provided in the supplementary material). Presented from left to right are the metabolites’ coefficients (weights) in the signature, and associations with each food component, MEDAS, and subsequent cardiovascular disease risk. Coefficients for associations with food items and MEDAS indicate the SD changes in metabolites per dietary score increment. Coefficients for cardiovascular disease risk indicate ln (hazard ratio) of cardiovascular disease risk per SD increment in metabolites. Colours denote the association directions (red-positive and blue-inverse) and magnitudes (the darker the colour, the stronger the magnitude); asterisks represent association significance (*P < 0.05 and **P < Bonferroni corrected 0.05; for associations with total MEDAS score and cardiovascular disease risk, we Bonferroni corrected for 67 metabolites; for associations with each of the food items, we Bonferroni corrected for 67 metabolites × 14 food items). CVD, cardiovascular disease; MEDAS, the Mediterranean Diet Adherence Screener.

Figure 4

Mendelian Randomization analyses of the metabolic signature with risk of coronary heart disease and stroke. In mode-based estimate of Hartwig (MBE) Mendelian randomization analyses, 58 genetic variants associated with the metabolic signature at P < 1 × 10⁻⁶ were used as the instrument variable. CHD, coronary heart disease; CVD, cardiovascular disease; MR, Mendelian randomization; OR, odds ratio; CI, confidence interval.

Take home figure

Integrating clinical, metabolomic, and genetic data from one Spanish and three US prospective cohorts, this study identified and validated a metabolic signature that robustly reflects adherence and metabolic response to a Mediterranean diet and predicts future cardiovascular disease risk independent of traditional risk factors. CHD, coronary heart disease; CI, confidence interval; CVD, cardiovascular disease; HR, hazards ratio; M, metabolites; MEDAS, a 14-item Mediterranean Diet Adherence Screener; Medi-Diet, Mediterranean diet; OR, odds ratio.