Diets high in fruits, veggies promote kidney health
Eating high amounts of fruits and vegetables may guard against the development of kidney disease, according to a recent study.
“Our findings suggest that dietary modification may prevent chronic kidney disease (CKD) development in healthy adults and may have potential as a cost-effective risk-lowering strategy,” researchers said.
The study included 9,229 individuals (mean age, 52.0 years; 48.1 percent male) with normal kidney function (mean estimated glomerular filtration rate [eGFR], 93.9 mL/min/1.73 m2) at baseline. All participants completed a food-frequency questionnaire regarding daily consumption of nonfermented and fermented vegetables and fruit.
Kidney function impairment (eGFRs <60mL/min/1.73m2) occurred in 1,741 participants over a mean follow-up of 8.2 years, yielding an incidence rate of 21.9 per 1,000 person-years. The incidence was notably lower among participants with a higher intake of nonfermented vegetables, with rates of 22.8, 22.7 and 20.1 per 1,000 person-years for the lowest, middle and highest intake tertiles, respectively (ptrend<0.001). [Am J Kidney Dis 2019;doi:10.1053/j.ajkd.2019.02.023]
A similar pattern of results was observed for proteinuria, which occurred less frequently in the middle and highest intake tertiles.
In a multivariable cause-specific hazards model, the highest vs lowest intake tertile of nonfermented vegetables reduced the risk of CKD by 14 percent (hazard ratio [HR], 0.86; 95 percent CI, 0.76–0.98) and that of proteinuria by 32 percent (HR, 0.68; 0.59-0.78).
Consumption of fermented vegetables and fruits was not associated with CKD risk. However, the highest vs lowest intake tertiles of either fermented vegetable or fruits reduced the risk of proteinuria by 14 percent and 45 percent, respectively (p<0.001 for both).
During follow-up, there was a notable increase in estimated net endogenous acid production in the lowest intake tertile of nonfermented or fermented vegetables and fruit, whereas it decreased in the highest intake tertile.
“Our findings support those of previous studies that have examined the effect of base-producing foods on kidney function,” researchers said. [Kidney Int 2014;86:1031-1038; Clin J Am Soc Nephrol 2013;8:371-381]
“The primary explanation for the positive association of vegetable and fruit intake with kidney function may be the effects of reducing the acid load… Potential mediators associated with acid loading that may lead to kidney injury include endothelin 1, the renin-angiotensin-aldosterone system, intrarenal ammonium and the complement pathway,” they pointed out.
Additionally, the high amounts of potassium found in vegetables and fruits are also said to positively affect kidney function. This is partly attributed to the blood pressure-lowering effect of potassium. [BMJ 2013;346:f1378]
Taken together, the data highlight the role of eating vegetables with low acid production and high potassium content for preventing CKD development in the general population, researchers said.
The study had several limitations. First, self-reported dietary intake used was vulnerable to measurement error. Also, data for biochemical measures of acid-base status (eg, serum bicarbonate) were lacking.