Plasma metabolite profile of legume consumption and future risk of type 2 diabetes and cardiovascular disease.

BACKGROUND: Legume consumption has been linked to a reduced risk of type 2 diabetes (T2D) and cardiovascular disease (CVD), while the potential association between plasma metabolites associated with legume consumption and the risk of cardiometabolic diseases has never been explored. Therefore, we aimed to identify a metabolite signature of legume consumption, and subsequently investigate its potential association with the incidence of T2D and CVD. METHODS: The current cross-sectional and longitudinal analysis was conducted in 1833 PREDIMED study participants (mean age 67 years, 57.6% women) with available baseline metabolomic data. A subset of these participants with 1-year follow-up metabolomics data (n = 1522) was used for internal validation. Plasma metabolites were assessed through liquid chromatography-tandem mass spectrometry. Cross-sectional associations between 382 different known metabolites and legume consumption were performed using elastic net regression. Associations between the identified metabolite profile and incident T2D and CVD were estimated using multivariable Cox regression models. RESULTS: Specific metabolic signatures of legume consumption were identified, these included amino acids, cortisol, and various classes of lipid metabolites including diacylglycerols, triacylglycerols, plasmalogens, sphingomyelins and other metabolites. Among these identified metabolites, 22 were negatively and 18 were positively associated with legume consumption. After adjustment for recognized risk factors and legume consumption, the identified legume metabolite profile was inversely associated with T2D incidence (hazard ratio (HR) per 1 SD: 0.75, 95% CI 0.61-0.94; p = 0.017), but not with CVD incidence risk (1.01, 95% CI 0.86-1.19; p = 0.817) over the follow-up period. CONCLUSIONS: This study identified a set of 40 metabolites associated with legume consumption and with a reduced risk of T2D development in a Mediterranean population at high risk of cardiovascular disease. TRIAL REGISTRATION: ISRCTN35739639.

Effects of Supplemented Mediterranean Diets on Plasma-Phospholipid Fatty Acid Profiles and Risk of Cardiovascular Disease after 1 Year of Intervention in the PREDIMED Trial.

BACKGROUND: Plasma fatty acids (FAs) have been associated with cardiovascular disease (CVD) risk. Diet and endogenous metabolism influence the FA profile of the plasma phospholipid (PL) fraction. In the PREDIMED trial, we examined 1-year changes in the FA profile of plasma PL according to a nutritional intervention with Mediterranean diets, either supplemented with extra-virgin olive oil (MedDiet + EVOO) or mixed nuts (MedDiet + nuts), in a high cardiovascular risk population. We also analyzed if 1-year changes in PL FAs were associated with subsequent cardiovascular risk. METHODS: We included 779 participants in our case-cohort study: 185 incident cases and 594 participants in the subcohort (including 31 overlapping cases). The end point was the incidence of CVD. We measured the FAs of plasma PL at baseline and after 1 year of intervention. RESULTS: MedDiet + EVOO increased C17:0 and C20:3n9 in linear regression models [ß coefficientperSD : 0.215 (95% CI, 0.032-0.399) and 0.271 (0.107-0.434), respectively] and decreased 16:1n7 and C22:4n6 [ßperSD: -0.239 (95% CI, -0.416 to -0.061) and -0.287 (95% CI, -0.460 to -0.113), respectively] vs the control group. MedDiet + nuts increased C18:3n3 [ßperSD: 0.382 (95% CI, 0.225 - 0.539)], C18:2n6 [ßper SD: 0.250 (95% CI, 0.073 - 0.428)], C18:0 [ßperSD: 0.268 (95% CI, 0.085-0.452)], and C22:0 [ßper SD: 0.216 (95% CI, 0.031-0.402)]; and decreased the sum of six n6 FAs [ßper SD: -0.147 (95% CI, -0.268 to -0.027)] vs the control group. The 1-year increase in C18:2n6 was inversely associated with the subsequent CVD risk (HRperSD: 0.64 (95% CI, 0.44-0.92)). CONCLUSIONS: MedDiet interventions changed n6 FAs and C16:1n7c; other changes were specific for each group: MedDiet + EVOO increased C17:0 and C20:3n9, and MedDiet + Nuts C18:3n3, C18:2n6, C18:0, and C22:0 FAs.

Plasma metabolite profiles associated with the World Cancer Research Fund/American Institute for Cancer Research lifestyle score and future risk of cardiovascular disease and type 2 diabetes.

BACKGROUND: A healthy lifestyle (HL) has been inversely related to type 2 diabetes (T2D) and cardiovascular disease (CVD). However, few studies have identified a metabolite profile associated with HL. The present study aims to identify a metabolite profile of a HL score and assess its association with the incidence of T2D and CVD in individuals at high cardiovascular risk. METHODS: In a subset of 1833 participants (age 55-80y) of the PREDIMED study, we estimated adherence to a HL using a composite score based on the 2018 Word Cancer Research Fund/American Institute for Cancer Research recommendations. Plasma metabolites were analyzed using LC-MS/MS methods at baseline (discovery sample) and 1-year of follow-up (validation sample). Cross-sectional associations between 385 known metabolites and the HL score were assessed using elastic net regression. A 10-cross-validation procedure was used, and correlation coefficients or AUC were assessed between the identified metabolite profiles and the self-reported HL score. We estimated the associations between the identified metabolite profiles and T2D and CVD using multivariable Cox regression models. RESULTS: The metabolite profiles that identified HL as a dichotomous or continuous variable included 24 and 58 metabolites, respectively. These are amino acids or derivatives, lipids, and energy intermediates or xenobiotic compounds. After adjustment for potential confounders, baseline metabolite profiles were associated with a lower risk of T2D (hazard ratio [HR] and 95% confidence interval (CI): 0.54, 0.38-0.77 for dichotomous HL, and 0.22, 0.11-0.43 for continuous HL). Similar results were observed with CVD (HR, 95% CI: 0.59, 0.42-0.83 for dichotomous HF and HR, 95%CI: 0.58, 0.31-1.07 for continuous HL). The reduction in the risk of T2D and CVD was maintained or attenuated, respectively, for the 1-year metabolomic profile. CONCLUSIONS: In an elderly population at high risk of CVD, a set of metabolites was selected as potential metabolites associated with the HL pattern predicting the risk of T2D and, to a lesser extent, CVD. These results support previous findings that some of these metabolites are inversely associated with the risk of T2D and CVD. TRIAL REGISTRATION: The PREDIMED trial was registered at ISRCTN ( http://www.isrctn.com/ , ISRCTN35739639).

Olive oil consumption, plasma metabolites, and risk of type 2 diabetes and cardiovascular disease.

BACKGROUND: Olive oil consumption has been inversely associated with the risk of type 2 diabetes (T2D) and cardiovascular disease (CVD). However, the impact of olive oil consumption on plasma metabolites remains poorly understood. This study aims to identify plasma metabolites related to total and specific types of olive oil consumption, and to assess the prospective associations of the identified multi-metabolite profiles with the risk of T2D and CVD. METHODS: The discovery population included 1837 participants at high cardiovascular risk from the PREvención con DIeta MEDiterránea (PREDIMED) trial with available metabolomics data at baseline. Olive oil consumption was determined through food-frequency questionnaires (FFQ) and adjusted for total energy. A total of 1522 participants also had available metabolomics data at year 1 and were used as the internal validation sample. Plasma metabolomics analyses were performed using LC-MS. Cross-sectional associations between 385 known candidate metabolites and olive oil consumption were assessed using elastic net regression analysis. A 10-cross-validation (CV) procedure was used, and Pearson correlation coefficients were assessed between metabolite-weighted models and FFQ-derived olive oil consumption in each pair of training-validation data sets within the discovery sample. We further estimated the prospective associations of the identified plasma multi-metabolite profile with incident T2D and CVD using multivariable Cox regression models. RESULTS: We identified a metabolomic signature for the consumption of total olive oil (with 74 metabolites), VOO (with 78 metabolites), and COO (with 17 metabolites), including several lipids, acylcarnitines, and amino acids. 10-CV Pearson correlation coefficients between total olive oil consumption derived from FFQs and the multi-metabolite profile were 0.40 (95% CI 0.37, 0.44) and 0.27 (95% CI 0.22, 0.31) for the discovery and validation sample, respectively. We identified several overlapping and distinct metabolites according to the type of olive oil consumed. The baseline metabolite profiles of total and extra virgin olive oil were inversely associated with CVD incidence (HR per 1SD: 0.79; 95% CI 0.67, 0.92 for total olive oil and 0.70; 0.59, 0.83 for extra virgin olive oil) after adjustment for confounders. However, no significant associations were observed between these metabolite profiles and T2D incidence. CONCLUSIONS: This study reveals a panel of plasma metabolites linked to the consumption of total and specific types of olive oil. The metabolite profiles of total olive oil consumption and extra virgin olive oil were associated with a decreased risk of incident CVD in a high cardiovascular-risk Mediterranean population, though no associations were observed with T2D incidence. TRIAL REGISTRATION: The PREDIMED trial was registered at ISRCTN ( http://www.isrctn.com/ , ISRCTN35739639).

Yearly attained adherence to Mediterranean diet and incidence of diabetes in a large randomized trial.

BACKGROUND: Several large observational prospective studies have reported a protection by the traditional Mediterranean diet against type 2 diabetes, but none of them used yearly repeated measures of dietary intake. Repeated measurements of dietary intake are able to improve subject classification and to increase the quality of the assessed relationships in nutritional epidemiology. Beyond observational studies, randomized trials provide stronger causal evidence. In the context of a randomized trial of primary cardiovascular prevention, we assessed type 2 diabetes incidence according to yearly repeated measures of compliance with a nutritional intervention based on the traditional Mediterranean diet. METHODS: PREDIMED (''PREvención con DIeta MEDiterránea'') was a Spanish trial including 7447 men and women at high cardiovascular risk. We assessed 3541 participants initially free of diabetes and originally randomized to 1 of 3 diets: low-fat diet (n = 1147, control group), Mediterranean diet supplemented with extra virgin olive (n = 1154) or Mediterranean diet supplemented with mixed nuts (n = 1240). As exposure we used actual adherence to Mediterranean diet (cumulative average), yearly assessed with the Mediterranean Diet Adherence Screener (scoring 0 to 14 points), and repeated up to 8 times (baseline and 7 consecutive follow-up years). This score was categorized into four groups: < 8, 8-< 10, 10- < 12, and 12-14 points. The outcome was new-onset type 2 diabetes. RESULTS: Multivariable-adjusted hazard ratios from time-varying Cox models were 0.80 (95% confidence interval, 0.70-0.92) per + 2 points in Mediterranean Diet Adherence Screener (linear trend p = .001), and 0.46 (0.25-0.83) for the highest (12-14 points) versus the lowest (< 8) adherence. This inverse association was maintained after additionally adjusting for the randomized arm. Age- and sex-adjusted analysis of a validated plasma metabolomic signature of the Mediterranean Diet Adherence Screener (constituted of 67 metabolites) in a subset of 889 participants also supported these results. CONCLUSIONS: Dietary intervention trials should quantify actual dietary adherence throughout the trial period to enhance the benefits and to assist results interpretation. A rapid dietary assessment tool, yearly repeated as a screener, was able to capture a strong inverse linear relationship between Mediterranean diet and type 2 diabetes. Trial registration ISRCTN35739639.

Lipid Profiles and Heart Failure Risk: Results From Two Prospective Studies.

RATIONALE: Altered lipid metabolism has been implicated in heart failure (HF) development, but no prospective studies have examined comprehensive lipidomics data and subsequent risk of HF. OBJECTIVE: We aimed to link single lipid metabolites and lipidomics networks to the risk of developing HF. METHODS AND RESULTS: Discovery analyses were based on 216 targeted lipids in a case-control study (331 incident HF cases and 507 controls, matched by age, sex, and study center), nested within the PREDIMED (Prevención con Dieta Mediterránea) study. Associations of single lipids were examined in conditional logistic regression models. Furthermore, lipidomics networks were linked to HF risk in a multistep workflow, including machine learning-based identification of the HF-related network clusters, and regression-based discovery of the HF-related lipid patterns within these clusters. If available, significant findings were externally validated in a subsample of the EPIC-Potsdam cohort (2414 at-risk participants, including 87 incident HF cases). After confounder-adjustments, 2 lipids were significantly associated with HF risk in both cohorts: CER (ceramide) 16:0 (relative risk [RR] per SD in PREDIMED, 1.28 [95% CI, 1.13-1.47]) and phosphatidylcholine 32_0 (RR per SD in PREDIMED, 1.23 [95% CI, 1.08-1.41]). Additionally, lipid patterns in several network clusters were associated with HF risk in PREDIMED. Adjusted for standard risk factors, an internally cross-validated score based on the significant HF-related lipids that were identified in the network analysis in PREDIMED was associated with a higher HF risk (20 lipids, RR per SD, 2.33 [95% CI, 1.93%-2.81%). Moreover, a lipid score restricted to the externally available lipids was significantly associated with HF incidence in both cohorts (6 lipids, RRs per SD, 1.30 [95% CI, 1.14-1.47] in PREDIMED, and 1.46 [95% CI, 1.17-1.82] in EPIC-Potsdam). CONCLUSIONS: Our study identified and validated 2 lipid metabolites and several lipidomics patterns as potential novel biomarkers of HF risk. Lipid profiling may capture preclinical molecular alterations that predispose for incident HF. Registration: URL: https://www.isrctn.com/ISRCTN35739639; Unique identifier: ISRCTN35739639.

Circulating citric acid cycle metabolites and risk of cardiovascular disease in the PREDIMED study.

BACKGROUND AND AIM: Plasma citric acid cycle (CAC) metabolites might be likely related to cardiovascular disease (CVD). However, studies assessing the longitudinal associations between circulating CAC-related metabolites and CVD risk are lacking. The aim of this study was to evaluate the association of baseline and 1-year levels of plasma CAC-related metabolites with CVD incidence (a composite of myocardial infarction, stroke or cardiovascular death), and their interaction with Mediterranean diet interventions. METHODS AND RESULTS: Case-cohort study from the PREDIMED trial involving participants aged 55-80 years at high cardiovascular risk, allocated to MedDiets or control diet. A subcohort of 791 participants was selected at baseline, and a total of 231 cases were identified after a median follow-up of 4.8 years. Nine plasma CAC-related metabolites (pyruvate, lactate, citrate, aconitate, isocitrate, 2-hydroxyglutarate, fumarate, malate and succinate) were measured using liquid chromatography-tandem mass spectrometry. Weighted Cox multiple regression was used to calculate hazard ratios (HRs). Baseline fasting plasma levels of 3 metabolites were associated with higher CVD risk, with HRs (for each standard deviation, 1-SD) of 1.46 (95%CI:1.20-1.78) for 2-hydroxyglutarate, 1.33 (95%CI:1.12-1.58) for fumarate and 1.47 (95%CI:1.21-1.78) for malate (p of linear trend <0.001 for all). A higher risk of CVD was also found for a 1-SD increment of a combined score of these 3 metabolites (HR = 1.60; 95%CI: 1.32-1.94, p trend <0.001). This result was replicated using plasma measurements after one-year. No interactions were detected with the nutritional intervention. CONCLUSION: Plasma 2-hydroxyglutarate, fumarate and malate levels were prospectively associated with increased cardiovascular risk. CLINICAL TRIAL NUMBER: ISRCTN35739639.

Association between serum copper levels and risk of cardiovascular disease: A nested case-control study in the PREDIMED trial.

BACKGROUND AND AIM: Certain trace elements have been associated with increased cardiovascular risk. The aim of this study was to evaluate the association between serum copper (S-Cu) levels and the risk of a first event of cardiovascular disease (CVD) in a population of older adults with high cardiovascular risk. METHODS AND RESULTS: We conducted a case-control study nested within the PREDIMED trial. During a median follow-up of 4.8 years, a total of 207 incident cases diagnosed with CVD were matched for sex, age, and intervention group with 436 controls. Personal interviews, reviews of medical records, and validated questionnaires were used to assess known CVD risk factors. Biological serum samples were collected annually. Inductively coupled plasma mass spectrometry analysis was used to determine S-Cu levels. Adjusted odds ratios were calculated using multivariate conditional logistic regression models. All participants had S-Cu levels within the reference values, 750 µg/L to 1450 µg/L. Among men, but not among women, the mean S-Cu concentration was higher in cases 1014.1 µg/L than in controls 959.3 µg/L; (p = 0.004). In men, the multivariable-adjusted odds ratio for CVD was 2.36 (95% CI 1.07-5.20 for the comparison of the highest vs. the lowest quartile; p for trend = 0.02), in women, it was 0.43 (95% CI 0.11-1.70; p for trend = 0.165). CONCLUSION: In older Spanish men with high cardiovascular risk, a significant association was observed between high S-Cu levels, but still within the reference values, and an increased risk of a first event of CVD. Our findings suggest a sex difference in CVD risk and S-Cu levels. To confirm this relationship and to analyze the differences observed between men and women, further studies are needed.

American Heart Association's life simple 7 and the risk of atrial fibrillation in the PREDIMED study cohort.

BACKGROUND AND AIMS: The American Heart Association proposed 7 ideal cardiovascular health metrics (Life's Simple 7 [LS7]) namely, not smoking, body mass index <25 kg/m2, healthy diet, moderate physical activity ≥150 min/week, total blood cholesterol <200 mg/dL, blood pressure <120/80 mmHg and fasting blood glucose <100 mg/dL. Our objective was to assess the association between these LS7 metrics and the incidence of atrial fibrillation (AF). METHODS AND RESULTS: A total of 6,479 participants of the PREDIMED study were included. We calculated the participants' baseline LS7 index ranging 0-7 points to categorize them according to their adherence to these LS7 health metrics. Multivariable Cox regression models were used to estimate Hazard Ratios (HR) and their 95% Confidence Intervals (95% CI). After a median follow-up of 4.8 years, we identified 250 incident cases of AF. After adjusting for potential confounders, adherence to LS7 index was not associated with the incidence of AF (adjusted HR 0.90 [95% CI: 0.56-1.45] for highest vs. lowest LS7 categories). Body mass index <25 kg/m2 was the only health metric individually associated with a lower risk of AF (HR 0.36 [95% CI: 0.16-0.78]). CONCLUSIONS: In a high cardiovascular risk Spanish population, adherence to American Heart Association's LS7 metrics was not associated with the risk of incident AF. CLINICAL TRIALS NUMBER: ISRCTN35739639.

Circulating Amino Acids and Risk of Peripheral Artery Disease in the PREDIMED Trial.

Effective prevention and risk prediction are important for peripheral artery disease (PAD) due to its poor prognosis and the huge disease burden it produces. Circulating amino acids (AA) and their metabolites may serve as biomarkers of PAD risk, but they have been scarcely investigated. The objective was to prospectively analyze the associations of baseline levels of plasma AA (and their pathways) with subsequent risk of PAD and the potential effect modification by a nutritional intervention with the Mediterranean diet (MedDiet). A matched case-control study was nested in the PREDIMED trial, in which participants were randomized to three arms: MedDiet with tree nut supplementation group, MedDiet with extra-virgin olive oil (EVOO) supplementation group or control group (low-fat diet). One hundred and sixty-seven PAD cases were matched with 250 controls. Plasma AA was measured with liquid chromatography/mass spectrometry at the Broad Institute. Baseline tryptophan, serine and threonine were inversely associated with PAD (ORfor 1 SD increase = 0.78 (0.61-0.99); 0.67 (0.51-0.86) and 0.75 (0.59-0.95), respectively) in a multivariable-adjusted conditional logistic regression model. The kynurenine/tryptophan ratio was directly associated with PAD (ORfor 1 SD increase = 1.50 (1.14-1.98)). The nutritional intervention with the MedDiet+nuts modified the association between threonine and PAD (p-value interaction = 0.018) compared with the control group. However, subjects allocated to the MedDiet+EVOO group were protected against PAD independently of baseline threonine. Plasma tryptophan, kynurenine/tryptophan ratio, serine and threonine might serve as early biomarkers of future PAD in subjects at a high risk of cardiovascular disease. The MedDiet supplemented with EVOO exerted a protective effect, regardless of baseline levels of threonine.

Dysfunctional High-Density Lipoproteins Are Associated With a Greater Incidence of Acute Coronary Syndrome in a Population at High Cardiovascular Risk: A Nested Case-Control Study.

BACKGROUND: Studies have failed to establish a clear link between high-density lipoprotein (HDL) cholesterol and cardiovascular disease, leading to the hypothesis that the atheroprotective role of HDL lies in its biological activity rather than in its cholesterol content. However, to date, the association between HDL functional characteristics and acute coronary syndrome has not been investigated comprehensively. METHODS: We conducted a case-control study nested within the PREDIMED (Prevención con Dieta Mediterránea) cohort, originally a randomized trial in which participants followed a Mediterranean or low-fat diet. Incident acute coronary syndrome cases (N=167) were individually matched (1:2) to control patients by sex, age, intervention group, body mass index, and follow-up time. We investigated 2 individual manifestations (myocardial infarction, unstable angina) as secondary outcomes. We measured the following functional characteristics: HDL cholesterol concentration (in plasma); cholesterol efflux capacity; antioxidant ability, measured by the HDL oxidative-inflammatory index; phospholipase A2 activity; and sphingosine-1-phosphate, apolipoproteins A-I and A-IV, serum amyloid A, and complement 3 protein (in apolipoprotein B-depleted plasma). We used conditional logistic regression models adjusted for HDL cholesterol levels and cardiovascular risk factors to estimate odds ratios (ORs) between 1-SD increments in HDL functional characteristics and clinical outcomes. RESULTS: Low values of cholesterol efflux capacity (OR1SD, 0.58; 95% CI, 0.40-0.83) and low levels of sphingosine-1-phosphate (OR1SD, 0.70; 95% CI, 0.52-0.92) and apolipoprotein A-I (OR1SD, 0.58; 95% CI, 0.42-0.79) were associated with higher odds of acute coronary syndrome. Higher HDL oxidative inflammatory index values were marginally linked to acute coronary syndrome risk (OR1SD, 1.27; 95% CI, 0.99-1.63). Low values of cholesterol efflux capacity (OR1SD, 0.33; 95% CI, 0.18-0.61), sphingosine-1-phosphate (OR1SD: 0.60; 95% CI: 0.40-0.89), and apolipoprotein A-I (OR1SD, 0.59; 95% CI, 0.37-0.93) were particularly linked to myocardial infarction, whereas high HDL oxidative-inflammatory index values (OR1SD, 1.53; 95% CI, 1.01-2.33) and low apolipoprotein A-I levels (OR1SD, 0.52; 95% CI, 0.31-0.88) were associated with unstable angina. CONCLUSIONS: Low cholesterol efflux capacity values, pro-oxidant/proinflammatory HDL particles, and low HDL levels of sphingosine-1-phosphate and apolipoprotein A-I were associated with increased odds of acute coronary syndrome and its manifestations in individuals at high cardiovascular risk. CLINICAL TRIAL REGISTRATION: URL: https://www.controlled-trials.com/ISRCTN35739639. Unique identifier: ISRCTN35739639.

Primary Prevention of Cardiovascular Disease with a Mediterranean Diet Supplemented with Extra-Virgin Olive Oil or Nuts.

BACKGROUND: Observational cohort studies and a secondary prevention trial have shown inverse associations between adherence to the Mediterranean diet and cardiovascular risk. METHODS: In a multicenter trial in Spain, we assigned 7447 participants (55 to 80 years of age, 57% women) who were at high cardiovascular risk, but with no cardiovascular disease at enrollment, to one of three diets: a Mediterranean diet supplemented with extra-virgin olive oil, a Mediterranean diet supplemented with mixed nuts, or a control diet (advice to reduce dietary fat). Participants received quarterly educational sessions and, depending on group assignment, free provision of extra-virgin olive oil, mixed nuts, or small nonfood gifts. The primary end point was a major cardiovascular event (myocardial infarction, stroke, or death from cardiovascular causes). After a median follow-up of 4.8 years, the trial was stopped on the basis of a prespecified interim analysis. In 2013, we reported the results for the primary end point in the Journal. We subsequently identified protocol deviations, including enrollment of household members without randomization, assignment to a study group without randomization of some participants at 1 of 11 study sites, and apparent inconsistent use of randomization tables at another site. We have withdrawn our previously published report and now report revised effect estimates based on analyses that do not rely exclusively on the assumption that all the participants were randomly assigned. RESULTS: A primary end-point event occurred in 288 participants; there were 96 events in the group assigned to a Mediterranean diet with extra-virgin olive oil (3.8%), 83 in the group assigned to a Mediterranean diet with nuts (3.4%), and 109 in the control group (4.4%). In the intention-to-treat analysis including all the participants and adjusting for baseline characteristics and propensity scores, the hazard ratio was 0.69 (95% confidence interval [CI], 0.53 to 0.91) for a Mediterranean diet with extra-virgin olive oil and 0.72 (95% CI, 0.54 to 0.95) for a Mediterranean diet with nuts, as compared with the control diet. Results were similar after the omission of 1588 participants whose study-group assignments were known or suspected to have departed from the protocol. CONCLUSIONS: In this study involving persons at high cardiovascular risk, the incidence of major cardiovascular events was lower among those assigned to a Mediterranean diet supplemented with extra-virgin olive oil or nuts than among those assigned to a reduced-fat diet. (Funded by Instituto de Salud Carlos III, Spanish Ministry of Health, and others; Current Controlled Trials number, ISRCTN35739639 .).

Plasma Metabolomic Profiles of Glycemic Index, Glycemic Load, and Carbohydrate Quality Index in the PREDIMED Study.

BACKGROUND: The quality of carbohydrate consumed, assessed by the glycemic index (GI), glycemic load (GL), or carbohydrate quality index (CQI), affects the postprandial glycemic and insulinemic responses, which have been implicated in the etiology of several chronic diseases. However, it is unclear whether plasma metabolites involved in different biological pathways could provide functional insights into the role of carbohydrate quality indices in health. OBJECTIVES: We aimed to identify plasma metabolomic profiles associated with dietary GI, GL, and CQI. METHODS: The present study is a cross-sectional analysis of 1833 participants with overweight/obesity (mean age = 67 y) from 2 case-cohort studies nested within the PREDIMED (Prevención con Dieta Mediterránea) trial. Data extracted from validated FFQs were used to estimate the GI, GL, and CQI. Plasma concentrations of 385 metabolites were profiled with LC coupled to MS and associations of these metabolites with those indices were assessed with elastic net regression analyses. RESULTS: A total of 58, 18, and 57 metabolites were selected for GI, GL, and CQI, respectively. Choline, cotinine, γ-butyrobetaine, and 36:3 phosphatidylserine plasmalogen were positively associated with GI and GL, whereas they were negatively associated with CQI. Fructose-glucose-galactose was negatively and positively associated with GI/GL and CQI, respectively. Consistent associations of 21 metabolites with both GI and CQI were found but in opposite directions. Negative associations of kynurenic acid, 22:1 sphingomyelin, and 38:6 phosphatidylethanolamine, as well as positive associations of 32:1 phosphatidylcholine with GI and GL were also observed. Pearson correlation coefficients between GI, GL, and CQI and the metabolomic profiles were 0.30, 0.22, and 0.27, respectively. CONCLUSIONS: The GI, GL, and CQI were associated with specific metabolomic profiles in a Mediterranean population at high cardiovascular disease risk. Our findings may help in understanding the role of dietary carbohydrate indices in the development of cardiometabolic disorders. This trial was registered at isrctn.com as ISRCTN35739639.

High Plasma Glutamate and a Low Glutamine-to-Glutamate Ratio Are Associated with Increased Risk of Heart Failure but Not Atrial Fibrillation in the Prevención con Dieta Mediterránea (PREDIMED) Study.

BACKGROUND: Although the association between glutamate and glutamine in relation to cardiometabolic disorders has been evaluated, the role of these metabolites in the development of atrial fibrillation (AF) and heart failure (HF) remains unknown. OBJECTIVES: We examined associations of glutamate, glutamine, and the glutamine-to-glutamate ratio with AF and HF incidence in a Mediterranean population at high cardiovascular disease (CVD) risk. METHODS: The present study used 2 nested case-control studies within the PREDIMED (Prevención con Dieta Mediterránea) study. During ∼10 y of follow-up, there were 509 AF incident cases matched to 618 controls and 326 HF incident cases matched to 426 controls. Plasma concentrations of glutamate and glutamine were semiquantitatively profiled with LC-tandem MS. ORs were estimated with multivariable conditional logistic regression models. RESULTS: In fully adjusted models, per 1-SD increment, glutamate was associated with a 29% (95% CI: 1.08, 1.54) increased risk of HF and glutamine-to-glutamate ratio with a 20% (95% CI: 0.67, 0.94) decreased risk. Glutamine-to-glutamate ratio was also inversely associated with HF risk (OR per 1-SD increment: 0.80; 95% CI: 0.67, 0.94) when comparing extreme quartiles. Higher glutamate concentrations were associated with a worse cardiometabolic risk profile, whereas a higher glutamine-to-glutamate ratio was associated with a better cardiometabolic risk profile. No associations between the concentrations of these metabolites and AF were observed. CONCLUSIONS: Our findings suggest that high plasma glutamate concentrations possibly resulting from alterations in the glutamate-glutamine cycle may contribute to the development of HF in Mediterranean individuals at high CVD risk.This trial was registered at www.isrctn.com as ISRCTN35739639.

MetProc: Separating Measurement Artifacts from True Metabolites in an Untargeted Metabolomics Experiment.

High-throughput metabolomics using liquid chromatography and mass spectrometry (LC/MS) provides a useful method to identify biomarkers of disease and explore biological systems. However, the majority of metabolic features detected from untargeted metabolomics experiments have unknown ion signatures, making it critical that data should be thoroughly quality controlled to avoid analyzing false signals. Here, we present a postalignment method relying on intermittent pooled study samples to separate genuine metabolic features from potential measurement artifacts. We apply the method to lipid metabolite data from the PREDIMED (PREvención con DIeta MEDi-terránea) study to demonstrate clear removal of measurement artifacts. The method is publicly available as the R package MetProc, available on CRAN under the GPL-v2 license.

Changes in arginine are inversely associated with type 2 diabetes: A case-cohort study in the PREDIMED trial.

The associations between arginine-based metabolites and incident type 2 diabetes (T2D) are unknown. We employed a case-cohort design, nested within the PREDIMED trial, to examine six plasma metabolites (arginine, citrulline, ornithine, asymmetric dimethylarginine [ADMA], symmetric dimethylarginine [SDMA] and N-monomethyl-l-arginine [NMMA]) among 892 individuals (251 cases) for associations with incident T2D and insulin resistance. Weighted Cox models with robust variance were used. The 1-year changes in arginine (adjusted hazard ratio [HR] per SD 0.68, 95% confidence interval [CI] 0.49, 0.95; Q4 vs. Q1 0.46, 95% CI 0.21, 1.04; P trend = 0.02) and arginine/ADMA ratio (adjusted HR per SD 0.73, 95% CI 0.51, 1.04; Q4 vs. Q1 0.52, 95% CI 0.22, 1.25; P trend = 0.04) were associated with a lower risk of T2D. Positive changes of citrulline and ornithine, and negative changes in SDMA and arginine/(ornithine + citrulline) were associated with concurrent 1-year changes in homeostatic model assessment of insulin resistance. Individuals in the low-fat-diet group had a higher risk of T2D for 1-year changes in NMMA than individuals in Mediterranean-diet groups (P interaction = 0.02). We conclude that arginine bioavailability is important in T2D pathophysiology.

Longitudinal association of changes in diet with changes in body weight and waist circumference in subjects at high cardiovascular risk: the PREDIMED trial.

BACKGROUND: Consumption of certain foods is associated with long-term weight gains and abdominal fat accumulation in healthy, middle-aged and young, non-obese participants. Whether the same foods might be associated with changes in adiposity in elderly population at high cardiovascular risk is less known. OBJECTIVE: Using yearly repeated measurements of both food habits and adiposity parameters, we aimed to investigate how changes in the consumption of specific foods were associated with concurrent changes in weight or waist circumference (WC) in the PREDIMED trial. DESIGN: We followed-up 7009 participants aged 55-70 years at high cardiovascular risk for a median time of 4.8 years. A validated 137-item semi-quantitative Food Frequency Questionnaire was used for dietary assessment with yearly repeated measurements. We longitudinally assessed associations between yearly changes in food consumption (serving/d) and concurrent changes in weight (kg) or WC (cm). RESULTS: Yearly increments in weight were observed with increased consumption (kg per each additional increase in 1 serving/d) for refined grains (0.32 kg/serving/d), red meat (0.24), potatoes (0.23), alcoholic beverages (0.18), processed meat (0.15), white bread (0.07) and sweets (0.04); whereas inverse associations were detected for increased consumption of low-fat yogurt (- 0.18), and low-fat milk (- 0.06). Annual WC gain (cm per each additional increase in 1 serving/d) occurred with increased consumption of snacks, fast-foods and pre-prepared dishes (0.28), processed meat (0.18), alcoholic beverages (0.13), and sweets (0.08); whereas increased consumption of vegetables (- 0.23), and nuts (- 0.17), were associated with reductions in WC. CONCLUSIONS: In this assessment conducted in high-risk subjects using yearly repeated measurements of food habits and adiposity, some ultra-processed foods, refined carbohydrates (including white bread), potatoes, red meats and alcohol were associated with higher weight and WC gain, whereas increases in consumption of low-fat dairy products and plant foods were associated with less gain in weight and WC. TRIAL REGISTRATION: This study was registered at controlled-trials.com with International Standard Randomized Controlled Trial Number (ISRCTN): 35739639. Registration date: 5 October 2005.

Multiple approaches to associations of physical activity and adherence to the Mediterranean diet with all-cause mortality in older adults: the PREvención con DIeta MEDiterránea study.

PURPOSE: Although evidence indicates that both physical activity and adherence to the Mediterranean diet (MedDiet) reduce the risk of all-cause mortality, a little is known about optimal intensities of physical activity and their combined effect with MedDiet in older adults. We assessed the separate and combined associations of leisure-time physical activity (LTPA) and MedDiet adherence with all-cause mortality. METHODS: We prospectively studied 7356 older adults (67 ± 6.2 years) at high vascular risk from the PREvención con DIeta MEDiterránea study. At baseline and yearly thereafter, adherence to the MedDiet and LTPA were measured using validated questionnaires. RESULTS: After 6.8 years of follow-up, we documented 498 deaths. Adherence to the MedDiet and total, light, and moderate-to-vigorous LTPA were inversely associated with all-cause mortality (p < 0.01 for all) in multiple adjusted Cox regression models. The adjusted hazard of all-cause mortality was 73% lower (hazard ratio 0.27, 95% confidence interval 0.19-0.38, p < 0.001) for the combined category of highest adherence to the MedDiet (3rd tertile) and highest total LTPA (3rd tertile) compared to lowest adherence to the MedDiet (1st tertile) and lowest total LTPA (1st tertile). Reductions in mortality risk did not meaningfully differ between total, light intensity, and moderate-to-vigorous LTPA. CONCLUSIONS: We found that higher levels of LTPA, regardless of intensity (total, light and moderate-to-vigorous), and greater adherence to the MedDiet were associated separately and jointly with lower all-cause mortality. The finding that light LTPA was inversely associated with mortality is relevant because this level of intensity is a feasible option for older adults.

Dairy products intake and the risk of incident cataracts surgery in an elderly Mediterranean population: results from the PREDIMED study.

PROPOSAL: The aim of this study was to examine the association between the consumption of total and specific types of dairy products and the risk of incident cataracts in an elderly Mediterranean population at high cardiovascular risk. METHODS: We prospectively analyzed 5860 subjects from the PREvención con DIeta MEDiterránea (PREDIMED) Study. The time to cataract surgery was calculated as the time between recruitment and the date of the surgery, last visit of the follow-up, date of death, or until the end of the study. Dairy products intake was assessed using validated food frequency questionnaires. We used Cox proportional hazard regression to assess the risk of cataract surgery according to average dietary energy-adjusted total dairy products, milk, yogurt and cheese consumption. RESULTS: We documented a total of 768 new cataract events after a median of 5.6 years of follow-up. Subjects in the second [hazard ratio (HR) 0.62; 95% CI 0.52, 0.74] and third tertile (HR: 0.71; 95% CI 0.60, 0.85) of skimmed yogurt intake had a significantly lower risk of cataracts after adjusting for potential confounders. No significant associations were observed for total dairy products, whole and skimmed milk, whole yogurt and cheese consumption. CONCLUSION: The intake of skimmed yogurt was associated with a reduced risk of cataracts in an elderly Mediterranean population with high cardiovascular risk. No significant associations were observed for other type of dairy product. CLINICAL TRIAL REGISTRATION: International Standard Randomized Controlled Trial Number (ISRCTN): 35739639. Registration date: 5 October 2005.

High plasma glutamate and low glutamine-to-glutamate ratio are associated with type 2 diabetes: Case-cohort study within the PREDIMED trial.

BACKGROUND AND AIMS: Glutamate, glutamine are involved in energy metabolism, and have been related to cardiometabolic disorders. However, their roles in the development of type-2 diabetes (T2D) remain unclear. The aim of this study was to examine the effects of Mediterranean diet on associations between glutamine, glutamate, glutamine-to-glutamate ratio, and risk of new-onset T2D in a Spanish population at high risk for cardiovascular disease (CVD). METHODS AND RESULTS: The present study was built within the PREDIMED trial using a case-cohort design including 892 participants with 251 incident T2D cases and 641 non-cases. Participants (mean age 66.3 years; female 62.8%) were non diabetic and at high risk for CVD at baseline. Plasma levels of glutamine and glutamate were measured at baseline and after 1-year of intervention. Higher glutamate levels at baseline were associated with increased risk of T2D with a hazard ratio (HR) of 2.78 (95% CI, 1.43-5.41, P for trend = 0.0002). In contrast, baseline levels of glutamine (HR: 0.64, 95% CI, 0.36-1.12; P for trend = 0.04) and glutamine-to-glutamate ratio (HR: 0.31, 95% CI, 0.16-0.57; P for trend = 0.0001) were inversely associated with T2D risk when comparing extreme quartiles. The two Mediterranean diets (MedDiet + EVOO and MedDiet + mixed nuts) did not alter levels of glutamine and glutamate after intervention for 1 year. However, MedDiet mitigated the positive association between higher baseline plasma glutamate and T2D risk (P for interaction = 0.01). CONCLUSION: Higher levels of glutamate and lower levels of glutamine were associated with increased risk of T2D in a Spanish population at high risk for CVD. Mediterranean diet might mitigate the association between the imbalance of glutamine and glutamate and T2D risk. This trial is registered at http://www.controlled-trials.com, ISRCTN35739639.