Published: Nov 8, 2013 | Updated: Nov 8, 2013
By Kristina Fiore, Staff Writer, MedPage Today

Full Story:  http://www.medpagetoday.com/MeetingCoverage/ASN/42800

ATLANTA — A Mediterranean-style diet may reduce the risk of kidney disease in healthy patients, researchers reported here.

In a prospective cohort study, patients whose eating habits were closer to the tenets of a Mediterranean diet had about a 50% reduced odds of developing chronic kidney disease (CKD) over 7 years compared with those whose diets didn’t resemble the fruit-and-vegetable-rich, low-saturated-fat diet, according to Minesh Khatri, MD, of Columbia University Medical Center, and colleagues.

The diet may also boost estimated glomerular filtration rate (eGFR), but the numbers weren’t statistically significant, Khatri and colleagues reported during a press briefing at Kidney Week here.

“A Mediterranean diet may protect against development of incident CKD and rapid kidney function decline,” Khatri said, acknowledging, however, that the study’s observational nature precludes it from showing a direct causal relationship.

Currently there are limited therapeutic options for CKD, although dietary modification holds promise in both treatment and prevention, Khatri said.

Studies, however, have focused on protein restriction in patients with pre-existing CKD. These have shown modest benefits — but the question remains as to whether other dietary patterns can impact kidney disease, and if they can prevent development of the condition altogether.

Specifically, researchers are interested in the potential effects of the Mediterranean diet — one high in intake of fruits, vegetables, legumes, cereals, fish, and monounsaturated fats, and low in dairy, meat, and saturated fats, paired with moderate alcohol intake — because of its effects on other cardiovascular conditions. The diet has been linked with better blood pressure, endothelial function, cholesterol, inflammation, and overall cardiovascular risk.

Khatri and colleagues analyzed data from the Northern Manhattan Study (NOMAS), a prospective longitudinal cohort study that had enrolled about 3,300 patients since enrollment began in 1993.

All patients completed a food frequency questionnaire at baseline, and Khatri and colleagues used that to develop a 9-point scoring system that revealed just how closely a patient’s diet was to that of the Mediterranean diet.

A subset of 900 patients in the study had kidney function measured at baseline and again after a mean follow-up of almost 7 years, so the researchers focused on this group.

Khatri noted that the cohort was very diverse, with 65% being Hispanic, 17% black, and 15% white. Their mean age was 64 and their mean baseline eGFR was 83.1 mL/min — indicating this is a group with “relatively well-preserved kidney function, even at this age,” Khatri said.

Over the course of the study, 14% of patients developed incident stage III CKD — and these patients were less likely to have adhered to a Mediterranean diet.

Khatri and colleagues reported that patients with higher Mediterranean diet scores had a significantly lower risk of incident kidney disease compared with those with a lower score, as assessed by various statistical methods:

• Univariate analysis: OR 0.49, 95% CI 0.33 to 0.75
• Demographic analysis: OR 0.49, 95% CI 0.32 to 0.75
• Fully adjusted model: OR 0.50, 95% CI 0.31 to 0.81

The researchers also calculated a 17% reduced odds of CKD for every one-point increase in Mediterranean diet score (P=0.015), as well as a 14% decrease in odds of rapid kidney function decline for every one-point increase in Mediterranean diet score (P=0.009).

Also, they spotted a trend for improved eGFR with better Mediterranean diet scores, but this wasn’t statistically significant, they noted.

Khatri called for larger observational studies and randomized trials to confirm the findings, and to start unraveling possible mechanisms of action.