Higher fruit intake is associated with albuminuria in a nested UK Biobank case control cohort

Introduction: Fruit and vegetable (F&V) consumption is associated with better renal function and lower risk of CKD. These associations may be explained by the protective effects of antioxidant vitamins and phytonutrients, nitric oxide precursors, and other active substances present in F&V. The potential negative consequences of increased fruit intake on renal health however have not been extensively studied. Fruit is an important dietary source of the monosaccharide fructose, high intake of which has been previously associated with dehydration induced renal damage and Mesoamerican nephropathy. This study evaluated associations between F&V consumption and albuminuria in the UK Biobank (UKBB). Methods: A nested case-control design included cases defined by urinary albumin to creatinine ratio (ACR) ≥ 3mg/mmol and controls with ACR < 3mg/mmol, matched for age, gender and ethnicity. Typical daily F&V intake was assessed by touch screen food frequency questionnaire. Associations between fruit, vegetable and F&V intake and ACR were tested using binary logistic regression adjusted for potential confounders age, sex, ethnicity, systolic blood pressure (SBP), diabetes, smoking, blood pressure medication, waist circumference and alcohol consumption. Results: In a sample of 6998 participants (3499 case control pairs), the mean age was 59 years (standard deviation [SD] 8), 53% were female, and 86% were white. SBP was 150 mmHg (SD 22) for cases and 144 mmHg (SD 20) for controls (24% of cases and 16% of controls used BP lowering medication). Twice as many cases (16%) had diabetes compared to controls. In adjusted models, no significant association was found between vegetable intake and ACR. Greater fruit, and combined F&V intake, were significantly associated with ACR ≥ 3mg/mmol (fruit: odds ratio [OR] = 1.03, 95% confidence intervals [CI]: 1.01, 1.05; P = 0.005; Combined F&V intake: OR = 1.02, CI: 1.00, 1.03; P = 0.01). Conclusion: In the UKBB population, vegetable intake alone was not significantly associated with albuminuria. However, increased fruit intake was significantly associated with a greater risk of albuminuria. These findings are consistent with previous associations between fructose intake and renal damage.