Diet plays an important role in the health of patients with chronic kidney disease, even after transplantation. New research published in the Clinical Journal of the American Society of Nephrology indicates that following the Mediterranean diet may help kidney transplant recipients maintain normal kidney function.
The Mediterranean diet—which focuses on high intake of fish, fruit, vegetables, legumes, nuts, and olive oil together with lower intake of dairy and meat products—has been linked with reduced risks of cardiovascular disease and early death in the general population, and a reduced risk of diabetes after kidney transplantation; however, whether the diet is also associated with kidney function preservation in kidney transplant recipients is unknown.
To investigate, António Gomes-Neto, MD, of the University of Groningen, in the Netherlands, and his colleagues provided a food-related questionnaire to adult kidney transplant recipients from their medical center who had a functioning donor kidney for at least one year. After assessing answers to the questionnaire, which inquired about intake of 177 food items during the last month, the researchers assessed adherence to the Mediterranean diet using a 9-point score.
During an average follow-up of 5.2 years, 119 of the 632 participants in the study experienced kidney function decline (76 of whom developed kidney failure). The Mediterranean Diet Score was inversely associated with kidney function decline and kidney failure. Each 2-point increase in the score was associated with a 29% lower risk of kidney function decline and a 32% lower risk of kidney failure.
“Increasing scientific evidence has demonstrated health benefits of the Mediterranean diet on cardiovascular and kidney health. In this study, we show that kidney transplant recipients with higher adherence to the Mediterranean diet are less likely to experience function loss of their kidney transplant,” Gomes-Neto said. “Moreover, this association was strongest in patients with greater proteinuria and patients transplanted more recently.”
The findings are important because, despite improvements in the survival of transplanted kidneys in the early years after transplantation, loss of kidney function within 10 years still occurs in more than one-third of recipients. Identifying modifiable risk factors may help to improve organ survival. “The observational design of this study precludes us from drawing conclusions of causality, and residual confounding may exist despite adjustments for potential confounders in our analyses,” noted Gomes-Neto.
In addition, no conclusions can be made concerning any potential mechanisms behind the associations seen in the study, but the authors offer several hypotheses, including effects on oxidative stress, inflammation, endothelial dysfunction, dietary acid load, lipid profiles, protein intake, and glycemic index.
Casey Rebholz, PhD, who is an assistant professor of epidemiology at the Johns Hopkins Bloomberg School of Public Health and was not involved with the research, noted that the study is a useful contribution to a growing literature on diet as a modifiable risk factor for kidney disease outcomes.
“These findings align well with the new draft guidelines on nutrition in chronic kidney disease from the Kidney Disease Outcomes Quality Initiative and the Academy of Nutrition and Dietetics, which recommend the Mediterranean diet for chronic kidney disease patients who are not on dialysis,” Rebholz said. “This study provides evidence to support the extension of this recommendation to kidney transplant recipients.”
The article, entitled “Mediterranean Style Diet and Kidney Function Loss in Kidney Transplant Recipients,” will appear online at http://cjasn.asnjournals.org.
