Metabolites Associated with Coffee Consumption and Incident Chronic Kidney Disease.

BACKGROUND AND OBJECTIVES: Moderate coffee consumption has been associated with lower risk of CKD; however, the exact biologic mechanisms underlying this association are unknown. Metabolomic profiling may identify metabolic pathways that explain the association between coffee and CKD. The goal of this study was to identify serum metabolites associated with coffee consumption and examine the association between these coffee-associated metabolites and incident CKD. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Using multivariable linear regression, we identified coffee-associated metabolites among 372 serum metabolites available in two subsamples of the Atherosclerosis Risk in Communities study (ARIC; n=3811). Fixed effects meta-analysis was used to pool the results from the two ARIC study subsamples. Associations between coffee and metabolites were replicated in the Bogalusa Heart Study (n=1043). Metabolites with significant associations with coffee in both cohorts were then evaluated for their prospective associations with incident CKD in the ARIC study using Cox proportional hazards regression. RESULTS: In the ARIC study, mean (SD) age was 54 (6) years, 56% were daily coffee drinkers, and 32% drank >2 cups per day. In the Bogalusa Heart Study, mean (SD) age was 48 (5) years, 57% were daily coffee drinkers, and 38% drank >2 cups per day. In a meta-analysis of two subsamples of the ARIC study, 41 metabolites were associated with coffee consumption, of which 20 metabolites replicated in the Bogalusa Heart Study. Three of these 20 coffee-associated metabolites were associated with incident CKD in the ARIC study. CONCLUSIONS: We detected 20 unique serum metabolites associated with coffee consumption in both the ARIC study and the Bogalusa Heart Study, and three of these 20 candidate biomarkers of coffee consumption were associated with incident CKD. One metabolite (glycochenodeoxycholate), a lipid involved in primary bile acid metabolism, may contribute to the favorable kidney health outcomes associated with coffee consumption. Two metabolites (O-methylcatechol sulfate and 3-methyl catechol sulfate), both of which are xenobiotics involved in benzoate metabolism, may represent potential harmful aspects of coffee on kidney health.

Epigenome-wide association meta-analysis of DNA methylation with coffee and tea consumption.

Coffee and tea are extensively consumed beverages worldwide which have received considerable attention regarding health. Intake of these beverages is consistently linked to, among others, reduced risk of diabetes and liver diseases; however, the mechanisms of action remain elusive. Epigenetics is suggested as a mechanism mediating the effects of dietary and lifestyle factors on disease onset. Here we report the results from epigenome-wide association studies (EWAS) on coffee and tea consumption in 15,789 participants of European and African-American ancestries from 15 cohorts. EWAS meta-analysis of coffee consumption reveals 11 CpGs surpassing the epigenome-wide significance threshold (P-value <1.1×10-7), which annotated to the AHRR, F2RL3, FLJ43663, HDAC4, GFI1 and PHGDH genes. Among them, cg14476101 is significantly associated with expression of the PHGDH and risk of fatty liver disease. Knockdown of PHGDH expression in liver cells shows a correlation with expression levels of genes associated with circulating lipids, suggesting a role of PHGDH in hepatic-lipid metabolism. EWAS meta-analysis on tea consumption reveals no significant association, only two CpGs annotated to CACNA1A and PRDM16 genes show suggestive association (P-value <5.0×10-6). These findings indicate that coffee-associated changes in DNA methylation levels may explain the mechanism of action of coffee consumption in conferring risk of diseases.

Dietary phosphorus intake and blood pressure in adults: a systematic review of randomized trials and prospective observational studies.

BACKGROUND: Elevated blood pressure (BP) is a major cause of preventable disease in the United States and around the world. It has been postulated that phosphorus intake may affect BP, with some studies suggesting a direct and others an inverse association. OBJECTIVES: We systematically reviewed the literature on the association of dietary phosphorus with BP in adults and performed a qualitative synthesis. METHODS: We included randomized and nonrandomized behavioral intervention and feeding studies (intervention studies) and prospective observational studies that measured dietary phosphorus intake or urinary phosphorus excretion and BP. We excluded studies of supplements, children, or individuals with major medical conditions. We searched PubMed, Embase, Cochrane Trials, and clinicaltrials.gov on 1 June, 2017 and 22 August, 2018. We assessed studies' risk of bias in their assessment of phosphorus exposure and BP. RESULTS: We reviewed 4759 publications and included 14 intervention studies (2497 participants), 3 prospective observational cohorts (17,795 participants), and 2 ongoing trials. No included intervention studies were designed specifically to achieve a phosphorus contrast. Two studies found a significant positive association of dietary phosphorus with systolic BP, 4 a significant inverse association, and 8 no significant association. Four studies found a significant inverse association with diastolic BP and 10 no significant associations. Two cohorts found lower risk of incident hypertension comparing the highest with the lowest quintiles of phosphorus intake and 1 found no significant difference: HR: 0.86 (95% CI: 0.75, 0.98); HR: 0.83 (95% CI: 0.68, 1.02); and HR: 0.75 (95% CI: 0.45, 1.27), respectively. CONCLUSIONS: We found no consistent association between total dietary phosphorus intake and BP in adults in the published literature nor any randomized trials designed to examine this association. This trial was registered at www.crd.york.ac.uk/prospero/ as CRD42017062489.

Coffee consumption and liver-related hospitalizations and deaths in the ARIC study.

BACKGROUND/OBJECTIVES: Coffee consumption has been found to be associated with reduced risk of chronic conditions such as liver disease. However, less is known about the association between coffee and liver-related hospitalizations and deaths. SUBJECTS/METHODS: We conducted a prospective analysis on 14,208 participants aged 45-64 years from the Atherosclerosis Risk in Communities (ARIC) study. Coffee consumption (cups/day) was assessed using food frequency questionnaires at visit 1 (1987-89) and visit 3 (1993-95). Liver-related hospitalizations were defined as a hospitalization with any International Classification of Diseases, Ninth Revision (ICD-9) code related to liver disease identified through cohort surveillance. Liver-related death was defined as any death with a liver disease ICD-9 code listed anywhere on the death certificate form. RESULTS: There were 833 incident cases of liver-related hospitalizations over a median follow-up of 24 years and 152 liver-related deaths over a median follow-up of 25 years. Participants who were in the highest category of coffee consumption (≥ 3 cups/day) were more likely to be men, whites, current smokers, and current alcohol drinkers. In our fully adjusted model, consuming ≥ 3 cups/day of coffee was significantly associated with a reduced risk of liver-related hospitalizations compared with never drinkers (hazard ratio: 0.79, 95% CI: 0.63-0.99). There were no significant associations between coffee consumption and liver-related deaths after adjusting for covariates. CONCLUSIONS: Coffee drinkers may be at lower risk for liver-related hospitalizations. This supports current evidence that low and moderate levels of coffee may be protective to the liver.

Coffee Consumption and Incident Kidney Disease: Results From the Atherosclerosis Risk in Communities (ARIC) Study.

BACKGROUND: Moderate coffee consumption has been suggested to be associated with lower risk for chronic conditions such as diabetes, a major precursor to chronic kidney disease (CKD). However, the association between coffee and CKD has not been fully established. STUDY DESIGN: Prospective cohort study. SETTING & PARTICIPANTS: 14,209 participants aged 45 to 64 years from the Atherosclerosis Risk in Communities (ARIC) Study. PREDICTORS: Coffee consumption (cups per day) was assessed at visits 1 (1987-1989) and 3 (1993-1995) using food frequency questionnaires. OUTCOMES: Incident CKD defined as estimated glomerular filtration rate < 60mL/min/1.73m2 accompanied by ≥25% estimated glomerular filtration rate decline, CKD-related hospitalization or death, or end-stage renal disease. RESULTS: There were 3,845 cases of incident CKD over a median of 24 years of follow-up. Men, whites, current smokers, and participants without comorbid conditions were more likely to consume higher amounts of coffee per day. After adjustment for demographic, clinical, and dietary factors, higher categories of coffee consumption were associated with lower risk for incident CKD compared with those who never consumed coffee (HR for <1 cup per day, 0.90 [95% CI, 0.82-0.99]; 1-<2 cups per day, 0.90 [95% CI, 0.82-0.99]; 2-<3 cups per day, 0.87 [95% CI, 0.77-0.97]; and ≥3 cups per day, 0.84 [95% CI, 0.75-0.94]). In continuous analysis, for each additional cup of coffee consumed per day, risk for incident CKD was lower by 3% (HR, 0.97; 95% CI, 0.95-0.99; P<0.001). LIMITATIONS: Self-reported coffee consumption and observational design. CONCLUSIONS: Participants who drank higher amounts of coffee had lower risk for incident CKD after adjusting for covariates. Coffee consumers may not be at adverse risk for kidney disease.

Potato Consumption Does Not Increase Blood Pressure or Incident Hypertension in 2 Cohorts of Spanish Adults.

Background: Potatoes have a high glycemic load but also antioxidants, vitamins, and minerals. It is unclear what mechanisms are involved in relation to their effect on blood pressure (BP) and hypertension.Objectives: This study aimed to assess the association between potato consumption, BP changes, and the risk of hypertension in 2 Spanish populations.Methods: Separate analyses were performed in PREDIMED (PREvención con DIeta MEDiterránea), a multicenter nutrition intervention trial of adults aged 55-80 y, and the SUN (Seguimiento Universidad de Navarra) project, a prospective cohort made up of university graduates and educated adults with ages (means ± SDs) of 42.7 ± 13.3 y for men and 35.1 ± 10.7 y for women. In PREDIMED, generalized estimating equations adjusted for lifestyle and dietary characteristics were used to assess changes in BP across quintiles of total potato consumption during a 4-y follow-up. Controlled BP values (systolic BP <140 mm Hg and diastolic BP <90 mm Hg) during follow-up were also assessed. For SUN, multivariate-adjusted HRs for incident hypertension during a mean 6.7-y follow-up were calculated.Results: In PREDIMED, the total potato intake was 81.9 ± 40.6 g/d. No overall differences in systolic or diastolic BP changes were detected based on consumption of potatoes. For total potatoes, the mean difference in change between quintile 5 (highest intake) and quintile 1 (lowest intake) in systolic BP after multivariate adjustment was -0.90 mm Hg (95% CI: -2.56, 0.76 mm Hg; P-trend = 0.1) and for diastolic BP was -0.02 mm Hg (95% CI: -0.93, 0.89 mm Hg; P-trend = 0.8). In SUN, the total potato consumption was 52.7 ± 33.6 g/d, and no significant association between potato consumption and hypertension incidence was observed in the fully adjusted HR for total potato consumption (quintile 5 compared with quintile 1: 0.98; 95% CI: 0.80, 1.19; P-trend = 0.8).Conclusions: Potato consumption is not associated with changes over 4 y in blood pressure among older adults in Spain or with the risk of hypertension among Spanish adults. This trial was registered at www.controlled-trials.com as ISRCTN35739639.