Mediterranean Style Diet and Kidney Function Loss in Kidney Transplant Recipients.

BACKGROUND AND OBJECTIVES: Despite improvement of short-term graft survival over recent years, long-term graft survival after kidney transplantation has not improved. Studies in the general population suggest the Mediterranean diet benefits kidney function preservation. We investigated whether adherence to the Mediterranean diet is associated with kidney outcomes in kidney transplant recipients. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We included 632 adult kidney transplant recipients with a functioning graft for ≥1 year. Dietary intake was inquired using a 177-item validated food frequency questionnaire. Adherence to the Mediterranean diet was assessed using a nine-point Mediterranean Diet Score. Primary end point of the study was graft failure and secondary end points included kidney function decline (doubling of serum creatinine or graft failure) and graft loss (graft failure or death with a functioning graft). Cox regression analyses were used to prospectively study the associations of the Mediterranean Diet Score with study end points. RESULTS: During median follow-up of 5.4 (interquartile range, 4.9-6.0) years, 76 participants developed graft failure, 119 developed kidney function decline, and 181 developed graft loss. The Mediterranean Diet Score was inversely associated with all study end points (graft failure: hazard ratio [HR], 0.68; 95% confidence interval [95% CI], 0.50 to 0.91; kidney function decline: HR, 0.68; 95% CI, 0.55 to 0.85; and graft loss: HR, 0.74; 95% CI, 0.63 to 0.88 per two-point increase in Mediterranean Diet Score) independent of potential confounders. We identified 24-hour urinary protein excretion and time since transplantation to be an effect modifier, with stronger inverse associations between the Mediterranean Diet Score and kidney outcomes observed in participants with higher urinary protein excretion and participants transplanted more recently. CONCLUSIONS: Adherence to the Mediterranean diet is associated with better kidney function outcomes in kidney transplant recipients.

Effects of 2-year vitamin B12 and folic acid supplementation in hyperhomocysteinemic elderly on arterial stiffness and cardiovascular outcomes within the B-PROOF trial.

INTRODUCTION: Hyperhomocysteinemia is an important cardiovascular risk indicator in the oldest old, and is associated with elevated arterial stiffness in this age group. Since several intervention trials reported a lack of benefit of B-vitamin supplementation on cardiovascular outcomes, we aimed to investigate the effect of B-vitamin supplementation on arterial stiffness and atherosclerosis in hyperhomocysteinemic elderly patients. METHODS: The B-PROOF study is a double-blind, randomized controlled trial, including 2919 elderly aged at least 65 years, with hyperhomocysteinemia (12-50  µmol/l), treated with B-vitamins (500  µg vitamin B12 and 400  µg folic acid) or placebo for 2 years. In a subgroup (n = 569), the effect of B-vitamins on pulse wave velocity (PWV) was investigated as a measurement of arterial stiffness. To measure atherosclerosis, carotid intima-media thickness (IMT) measures had been used. Incidents of cardiovascular and cerebrovascular events were determined via structured questionnaires, and blood pressure was also measured. RESULTS: Compared to placebo, B-vitamin supplementation lowered serum homocysteine by 3.6  µmol/l (P < 0.001). Analysis of covariance showed no effect of supplementation on PWV levels, and this was not different for patients without increased arterial stiffness at baseline. Furthermore, no effect on carotid IMT was observed. DISCUSSION: Vitamin B12 and folic acid supplementation in hyperhomocysteinemic elderly patients have no effect on PWV or carotid IMT. Further research will still be necessary to unravel the effects and pathways of homocysteine-lowering treatment on cardiovascular outcomes.