ATLANTA – Following a Mediterranean-style diet may reduce the risk of chronic kidney disease, findings from the prospective Northern Manhattan Study suggest.
Among 900 subjects from the large community-based, multiethnic cohort who had requisite data available, 14% developed new chronic kidney disease (CKD) during a mean follow-up of 6.9 years. After adjustment for several potential confounders, including demographics, medication use, laboratory values, and medical history, following a Mediterranean-style diet was associated with a 50% reduction in the risk of incident stage 3 CKD, the primary outcome measure of the study (odds ratio, 0.50), Dr. Minesh Khatri of Columbia University, New York, reported at Kidney Week 2013.
Furthermore, each 1-unit increase in a previously developed 9-point score that measured the degree to which a subject followed a Mediterranean-style diet (the MeDi score) was associated with a 17% reduction in CKD risk (OR, 0.83), Dr. Khatri said.
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Mediterranean diets may reduce the risk of chronic kidney disease, findings from the prospective Northern Manhattan Study suggest.
A MeDi score of 5 or higher also was associated with a 42% reduction in the risk of rapid kidney function decline (OR, 0.58), and each 1-point increase in the score was associated with a 12% reduction in risk (OR, 0.88).
Continuous absolute change in estimated glomerular filtration rate (eGFR) was not significantly affected by the MeDi score, but a higher score was associated with a trend toward improvement.
Study participants were adults who were stroke free and had a mean age of 64 years at baseline. They underwent measurement of serum creatinine at baseline and at follow-up, as well as brain magnetic resonance imaging at follow-up. They also completed a dietary questionnaire at baseline, from which the MeDi score was derived.
Most (65%) were Hispanic, and 59% were women. Mean eGFR was 83.1 mL/min, with a mean annualized decline of 1.1 mL/min.
Incident CKD in this study was defined as a follow-up Modification of Diet in Renal Disease eGFR of less than 60 mL/min among subjects with eGFR greater than 60 mL/min at baseline.
"CKD is highly prevalent. The lifetime risk of stage 3 CKD in the United States may be as high as 59% ... [and] the consequences of CKD are of equal magnitude. CKD increases the risk of morbidity and mortality, especially from cardiovascular disease," Dr. Khatri said. Data show that the worse the kidney function, the greater the cardiovascular disease risk and the greater the likelihood of cardiovascular events, he noted.
The financial toll is also extensive, he said during a press briefing at the conference, which was sponsored by the American Society of Nephrology.
"On top of this, the therapeutic armamentarium for CKD is actually relatively limited. We’ve made tremendous strides in treating traditional risk factors such as diabetes, hypertension, and protein in the urine, but most patients with CKD still have progressive kidney function decline over time. This therefore means we need novel approaches to prevent and ameliorate progression of CKD," he said.
Diet may be one such approach. Some diets have been studied in the context of improving CKD, but most studies have focused on protein restriction – an approach that may be harmful in some patients, such as the frail elderly. Few studies have looked at diet in the context of preventing CKD.
The Mediterranean diet – which generally includes high intake of fruits, vegetables, legumes, cereals, fish, and heart-healthy monounsaturated fats; lower intake of dairy, meats, and saturated fats; as well as moderate alcohol intake, has received a great deal of attention with respect to potential cardiovascular benefits. Studies have shown it has important benefits, including improvements in blood pressure, endothelial function, cholesterol, inflammation, and overall cardiovascular risk, Dr. Khatri said.
In fact, results from the randomized controlled PREDIMED study, published in April, demonstrated a 30% reduction in cardiovascular risk among those following a Mediterranean diet, compared with those following a standard low-fat diet (N. Engl. J. Med. 2013;368:1279-90), he noted.
The current study shows that a Mediterranean-style diet may have similarly beneficial effects for reducing CKD risk, which makes sense given the shared risk factors between CKD and cardiovascular disease, he said.
Larger observational trials and randomized controlled trials are needed to confirm these findings and to elucidate the mechanisms by which a Mediterranean-style diet may protect against kidney disease, he said.
This study was funded by the National Institutes of Health. Dr. Khatri reported having no disclosures.