Healthy diets are good for the kidneys

Dietary modifications may be a low-cost, simple intervention to reduce the burden of chronic kidney disease (CKD). To test this hypothesis, Andrew Smyth, MD (National University of Ireland Galway) and his colleagues analyzed questionnaires completed by 544,635 participants of the National Institutes of Health-AARP Diet and Health Study that assessed diet quality, as well as sodium and potassium intake.

A higher-quality diet, as measured using 3 different scoring systems for dietary qualities known to reduce the risk of cardiovascular disease, was associated with a 16% to 23% reduced risk of needing dialysis or dying from kidney problems. Higher-quality diets included those high in fruits, vegetables, and unsaturated fats. The researchers also found that high sodium intake (average of 4.7g g/day) was linked with an increased risk of needing dialysis or dying from kidney problems, but no significant benefit was seen for low sodium intake (average 2.0 g/day) compared with moderate intake. In contrast, high potassium intake was associated with a reduced future risk.

"Our findings extend the known benefits of healthy eating and show that the consumption of a healthy diet may protect from future major renal endpoints," said Dr. Smyth. "As dietary modification is a low-cost, simple intervention, it offers the potential to significantly reduce the burden from chronic kidney disease, while also protecting from cardiovascular disease."

In another study, Meg Jardine, MBBS, PhD (The George Institute for International Health, in Australia) and her colleagues found that reducing salt intake reduces albuminuria, or excess protein in the urine, which is a hallmark of kidney dysfunction. For the study, 120 rural villages in China were randomized to no intervention or an 18-month sodium reduction program, including education and access to a reduced-sodium salt substitute with added potassium.

Individuals in villages that received the sodium reduction intervention had a 33% decreased likelihood of having albuminuria compared with individuals in the control villages.

"The fundamental question now is whether dietary salt reduction will also protect against progressive kidney damage," said Dr. Jardine. "If it does, community dietary interventions would present a new method for improving kidney health with efficient uptake and relatively low cost, which would supplement current pharmaceutical-based approaches."