Ultra-processed foods and risk of all-cause mortality in renal transplant recipients

Abstract

Background: Renal transplant recipients (RTRs) have a 6-fold higher risk of mortality than age- and sex-matched controls. Whether high consumption of ultra-processed foods is associated with survival in RTRs is unknown.

Objectives: We aimed to study the association between high consumption of ultra-processed foods and all-cause mortality in stable RTRs.

Methods: We conducted a prospective cohort study in adult RTRs with a stable graft. Dietary intake was assessed using a validated 177-item FFQ. Food items were categorized according to the NOVA classification system and the proportion ultra-processed foods comprised of total food weight per day was calculated.

Results: We included 632 stable RTRs (mean ± SD age: 53.0 ± 12.7 y, 57% men). Mean ± SD consumption of ultra-processed foods was 721 ± 341 g/d (28% of total weight of food intake), whereas the intake of unprocessed and minimally processed foods, processed culinary ingredients, and processed foods accounted for 57%, 1%, and 14%, respectively. During median follow-up of 5.4 y [IQR: 4.9-6.0 y], 129 (20%) RTRs died. In Cox regression analyses, ultra-processed foods were associated with all-cause mortality (HR per doubling of percentage of total weight: 2.13; 95% CI: 1.46, 3.10; P < 0.001), independently of potential confounders. This association was independent from the quality of the overall dietary pattern, expressed by the Mediterranean Diet Score (MDS) or Dietary Approaches to Stop Hypertension (DASH) score. When analyzing ultra-processed foods by groups, only sugar-sweetened beverages (HR: 1.21; 95% CI: 1.05, 1.39; P = 0.007), desserts (HR: 1.24; 95% CI: 1.02, 1.49; P = 0.03), and processed meats (HR: 1.87; 95% CI: 1.22, 2.86; P = 0.004) were associated with all-cause mortality.

Conclusions: Consumption of ultra-processed foods, in particular sugar-sweetened beverages, desserts, and processed meats, is associated with a higher risk of all-cause mortality after renal transplantation, independently of low adherence to high-quality dietary patterns, such as the Mediterranean diet and the DASH diet.This trial was registered at clinicaltrials.gov as NCT02811835.

Keywords: NOVA; all-cause mortality; diet; renal transplant recipients; ultra-processed foods.

FIGURE 1

Contribution of food groups to the ultra-processed foods (group 4) according to the NOVA classification.

FIGURE 2

Association of UPFs (percentage of total food weight in g/d) and all-cause mortality in 632 renal transplant recipients. Data were fit by a Cox regression model based on penalized splines and adjusted for age, sex, time between transplantation and baseline, estimated glomerular filtration rate, urinary protein excretion, primary renal disease, donor age, total energy intake, alcohol consumption, smoking status, and physical activity. The black line represents the HR, whereas the gray area represents the 95% CI. The HRs were plotted relative to a value of 1.0 for the median value of UPFs as a reference. A histogram of the distribution of UPFs is plotted in the background. UPF, ultra-processed food.

FIGURE 3

Association of UPFs (percentage of total food weight in g/d) and all-cause mortality in 632 RTRs, plotting RTRs who have a high intake of UPFs and low adherence to the MDS and DASH score against RTRs with a low intake of UPFs and high adherence to the MDS and DASH score (reference). Data were fit by a Cox regression model and adjusted for age, sex, time between transplantation and baseline, estimated glomerular filtration rate, urinary protein excretion, primary renal disease, donor age, total energy intake, alcohol consumption, smoking status, and physical activity. The error bars represent the 95% CI. DASH, Dietary Approaches to Stop Hypertension; MDS, Mediterranean Diet Score; RTR, renal transplant recipient; UPF, ultra-processed food.