Patients with chronic kidney disease (CKD) have several complications that are linked to oxidative stress and inflammation, and among the most recently studied is the alteration of the intestinal microbiota. Considering this scenario, bioactive compounds have been considered as a therapeutic alternative in the modulation of intestinal microbiota as well as transcription factors such as nuclear-kappa factor B (NF-κB) and factor 2 nuclear factor-related erythroid 2 Nrf2), involved with oxidative stress and inflammation. Among several foods, cranberry is a fruit rich in flavonoids and other polyphenols, which has antioxidant, anti-inflammatory and immunoregulatory actions and may be an adjuvant treatment for CKD complications. However, clinical evidence evaluating the effects of cranberry is limited and there are no studies specifically involving patients with CKD. Thus, the present randomized crossover double-blind crossover with placebo-controlled washout period will aim to evaluate the effects of cranberry supplementation on the modulation of the intestinal microbiota and expression of transcription factors as well as cytokine levels inflammatory effects of CKD patients.

This is a longitudinal study with a randomized crossover design, double-blind, placebo-controlled, and with washout period. Thirty non-dialysis patients of both genders, aged between 18 and 60 years and with CKD stage3-4 (glomerular filtration rate < 59 mL/min/1.73 m2) will be included in the study. Pregnant patients, smokers and those under use of antibiotics in the last 3 months, or in use antithrombotic, pre-, pro- or synbiotic supplements, antioxidant supplements or habitual cranberry intake will be excluded. In addition, those with autoimmune and infectious diseases, cancer, liver diseases and HIV will also not be included in the study. The patients that fulfill the eligible criteria and sign the ethical informed consent will be randomized to either Group A (Cranberry) or Group B (Placebo). During 12 weeks, patients allocated in group A will receive capsules containing cranberry extract (Vaccinium macrocarpon to 25% anthocyanosides 160mg, equivalent to 40mg anthocyanosides), once daily (lunch), totaling 500mg / day and those allocated in the group B will receive a placebo (500mg of corn starch). After the supplementation period, a 12-week washout will be performed for subsequent crossover of the supplement. The randomization will be computed in the ratio of 1: 1, with block size of 15 (Cranberry group and Control), to receive cranberry or placebo. This project was approved by the Ethics Committee of the Faculty of Medicine-UFF, n. 2.653.752.

Inclusion Criteria:

• Clinical diagnosis of Chronic Kidney Disease in conservative treatment
• Aged 18 years or older
• Must be able to swallow tablets

Exclusion Criteria:

• Patients pregnant
• Smokers
• Using antibiotics in the last 3 months
• Using antioxidant supplements in the last 3 months
• Usual intake of cranberry fruit or extract
• Clinical diagnosis of infectious diseases
• Clinical diagnosis of Cancer
• Clinical diagnosis of AIDS