Fruit and Vegetable Intake and Mortality in Adults undergoing Maintenance Hemodialysis

Abstract

Background and objectives: Higher fruit and vegetable intake is associated with lower cardiovascular and all-cause mortality in the general population. It is unclear whether this association occurs in patients on hemodialysis, in whom high fruit and vegetable intake is generally discouraged because of a potential risk of hyperkalemia. We aimed to evaluate the association between fruit and vegetable intake and mortality in hemodialysis.

Design, setting, participants, & measurements: Fruit and vegetable intake was ascertained by the Global Allergy and Asthma European Network food frequency questionnaire within the Dietary Intake, Death and Hospitalization in Adults with ESKD Treated with Hemodialysis study, a multinational cohort study of 9757 adults on hemodialysis, of whom 8078 (83%) had analyzable dietary data. Adjusted Cox regression analyses clustered by country were conducted to evaluate the association between tertiles of fruit and vegetable intake with all-cause, cardiovascular, and noncardiovascular mortality. Estimates were calculated as hazard ratios with 95% confidence intervals (95% CIs).

Results: During a median follow up of 2.7 years (18,586 person-years), there were 2082 deaths (954 cardiovascular). The median (interquartile range) number of servings of fruit and vegetables was 8 (4-14) per week; only 4% of the study population consumed at least four servings per day as recommended in the general population. Compared with the lowest tertile of servings per week (0-5.5, median 2), the adjusted hazard ratios for the middle (5.6-10, median 8) and highest (>10, median 17) tertiles were 0.90 (95% CI, 0.81 to 1.00) and 0.80 (95% CI, 0.71 to 0.91) for all-cause mortality, 0.88 (95% CI, 0.76 to 1.02) and 0.77 (95% CI, 0.66 to 0.91) for noncardiovascular mortality and 0.95 (95% CI, 0.81 to 1.11) and 0.84 (95% CI, 0.70 to 1.00) for cardiovascular mortality, respectively.

Conclusions: Fruit and vegetable intake in the hemodialysis population is low and a higher consumption is associated with lower all-cause and noncardiovascular death.

Keywords: Asthma; Cardiovascular Diseases; Diet; ESRD; Epidemiology and outcomes; Fruit; Hyperkalemia; Hypersensitivity; Proportional Hazards Models; Risk; Surveys and Questionnaires; Vegetables; clinical epidemiology; clinical nephrology; hemodialysis; mortality; mortality risk; nutrition; renal dialysis; risk factors; survival.

Graphical abstract

Figure 1.

Flow chart showing the participation process, resulting in the inclusion of 8078 participants in analyses, and all censoring details.

Figure 2.

Median intake of fruit and vegetables (servings per week) by country showing similar, and generally low, intake across all countries.

Figure 3.

Adjusted mortality hazard ratios (HRs) (95% CIs) by tertiles of fruit and vegetable intake (servings per week) showing an association between higher combined intake of fruit and vegetables and lower all-cause mortality largely driven by noncardiovascular causes. HR estimates for one serving per week increase of combined fruit and vegetable intake are 0.99 (95% CI, 0.98 to 1.00; P=0.05), 0.99 (95% CI, 0.98 to 0.99; P=0.001), and 0.99 (95% CI, 0.98 to 0.99; P≤0.001) for cardiovascular, noncardiovascular, and all-cause mortality, respectively. HR estimates for one serving per week increase of fruit intake are 0.99 (95% CI, 0.97 to 1.00; P=0.13), 0.99 (95% CI, 0.97 to 1.00; P=0.03), and 0.99 (95% CI, 0.98 to 1.00; P=0.01) for cardiovascular, noncardiovascular, and all-cause mortality, respectively. HR estimates for one serving per week increase of vegetable intake are 1.00 (95% CI, 0.98 to 1.02; P=0.63), 0.99 (95% CI, 0.97 to 1.00; P=0.12), and 0.99 (95% CI, 0.98 to 1.00; P=0.13) for cardiovascular, noncardiovascular, and all-cause mortality, respectively. All analyses are adjusted for country (random effect), age, sex, smoking (current or former versus never), daily physical activity, myocardial infarction, vascular access type (fistula versus graft/catheter), body mass index (categories according to World Health Organization), albumin (tertiles), Charlson Comorbidity Index score (quartiles), hemoglobin, and energy intake (1000 kcal/d increase). Analyses for fruit are adjusted for vegetables and vice versa. ^aAdditionally adjusted for education (secondary versus none/primary), diabetes, phosphorus, and calcium. ^bAdditionally adjusted for underlying kidney disease and being waitlisted for transplant. ^cAdditionally adjusted for education (secondary versus none/primary), life partner, underlying kidney disease, being waitlisted for transplant, phosphorus, calcium, time on dialysis, and Kt/V.