The impact of refined food processing on the kidney-preclinical evaluation

Abstract Background Purified diets combine refined ingredients that convey a precise nutritional load. At a preclinical level, these formulas are used to dissect the impact of each nutrient on a given phenotype, from excess [e.g. High Fat (HF) diet] to deficiency [e.g. Low Fat (LF) diet; a nutrient-matched control]. Yet, processing strategies deteriorate the health potential of cereal-based diets as reported in a panoply of diseased conditions. Herein, we aim to disclose the impact of refined ingredients in the kidney. Methods Twenty-four male Wistar rats were divided in three groups (n = 8) for 24 weeks: Control group (8.57 Kcal/fat), HF group (45% Kcal/fat) and the LF group (13% Kcal/fat). In vivo glycemic/insulinemic/lipidic profiles were assessed. Renal parameters evaluated were serum/urinary measures of uric acid/albumin/creatinine/glucose. Periodic Acid-Shiff and Gomori’s green trichrome staining were used to gauge kidney histology. Renal KIM-1/NLRP3 relative gene expression (RT-PCR) was also evaluated. Values are means ± S.E.M (ANOVA/post-hoc tests). This work was approved by the ORBEA of iCBR-FMUC (9/2018). Results HF-fed animals displayed a phenotype aligned with a prediabetic condition: glucose intolerance, postprandial hyperinsulinemia, hepatic/renal lipidosis, mild renal dysfunction and initial histological lesions. Surprisingly, LF-fed animals also displayed glucose intolerance and postprandial hyperinsulinemia paralleling an exacerbated renal injury phenotype: LF-fed animals displayed a decrease in creatinine clearance along with glycosuria (P < 0.05). Histological/gene expression markers collectively indicate kidney damage. Conclusions Our findings allude for prominent renal impairments arising from LF feeding. These results claim for a cautious selection of ‘control’ diets when kidney diseases are foreseen.