Cyclic and intermittent very low-protein diet can have beneficial effects against advanced diabetic nephropathy in Wistar fatty (fa/fa) rats, an animal model of type 2 diabetes and obesity.

A low-protein diet (LPD), particularly, very low-protein diet (VLPD) is expected for reno-protection in advanced chronic kidney disease, including diabetic nephropathy. We previously also demonstrated that a VLPD clearly improved advanced diabetic nephropathy in a type 2 diabetes and obesity rat. However, clinically, an everyday long-term VLPD contributes to poor adherence, which may be related to controvertial results of an LPD on the suppression for diabetic nephropathy, and has nutritional issues, such as sarcopenia or protein-energy wasting. The aim of this study is to elucidate the reno-protective effect of a cyclic and intermittent VLPD, not an everyday VLPD, against the advanced experimental diabetic nephropathy. Diabetic male Wistar fatty (fa/fa) rats (WFRs) were treated with a standard diet (STD; 23.84% protein) or a cyclic and intermittent VLPD (5.77% protein) consisting of an STD for 3 days and a VLPD for 4 days a week for 20 weeks beginning at 24 weeks of age. A cyclic and intermittent VLPD significantly improved renal hypertrophy, and significantly decreased urinary albumin and liver-type fatty acid binding protein (L-FABP) excretion without changes in body weight or exacerbation of HbA1c levels in diabetic rats. Additionally, diabetes-induced renal injuries including fibrosis, tubular cell damage and inflammation were significantly ameliorated by a cyclic and intermittent VLPD in diabetic rats. Thus, based on our experimental data, a cyclic and intermittent VLPD may be a dietary regimen that is easy to continue and has less risk of malnutrition, compared to an everyday long-term VLPD, against advanced diabetic nephropathy.