Introduction: Chronic kidney disease (CKD) is a major risk factor for cardiovascular disease. Evidence linking dietary intake to CKD is largely focused on management, rather than prevention of CKD. To provide evidence that addresses this gap we analyzed data from CARDIA using objective biomarkers of dietary intake (serum carotenoids and ascorbic acid marking fruit and vegetable intake, tocopherols marking nuts/seeds and oil intake) and serum cystatin C as a measure of kidney filtration.
Hypothesis: Higher levels of serum carotenoids, tocopherols and plasma ascorbic acid are inversely associated with rapid kidney function decline.
Methods: We analyzed data of subjects from the CARDIA study (N=2,210) with blood measures of dietary biomarkers at year 15 (2000-2001, black and white men and women aged 33-45y), concurrent clinical risk factor data, and measures of cystatin-C at years 15 and 20. GFRcys (ml/min/1.73m2) was estimated from the CKD-EPI (CKD Epidemiology Collaboration) equation for calibrated cystatin C at years 15 and 20. Only subjects with GFRcys > 60 ml/min/1.73m2 at year 15 were analyzed. Rapid decline was defined as >15% decline in GFRcys over 5 years (or >3% decline per year). Multivariable logistic regression was used to estimate the Odds Ratio of incident rapid decline over 5 years by quartile of the dietary biomarkers and adjusted for demographic, lifestyle and clinical measures.
Results: From year 15 to 20, 15.3% (339 of 2,210) of subjects experienced rapid kidney function decline. There was a strong inverse association after adjustment (P=0.016) between higher levels of the carotenoid index and incidence of rapid decline, but no association with any other measure. There was no evidence that the associations differed by diabetes or hypertension status.
Conclusions: These results underscore how a nutrient rich, plant based dietary pattern in early middle-age inversely associates with subsequent rapid kidney function decline and provide insight for dietary recommendations related to CKD prevention.