Effects of Replacing High Protein Foods in People With Chronic Kidney Disease

This study will be a single-blind crossover, human-feeding study comparing 3 weeks of a lacto-ovo vegetarian diet to the same diet with 20% of the protein replaced by red meat. There will be a 2-week baseline period and a 5-week washout period where participants will consume their typical, self-selected diet. Once eligible, the participant will be randomized to a diet order. The investigators will recruit up to 15 participants. Descriptive statistics (means and standard deviations) will be used to summarize the characteristics of the study population. In general, data will be analyzed using linear mixed-effect models to account for the potential correlation among measurements from the same participant. A power analysis of this pilot study will be conducted based on the estimated interparticipant and intraparticipant variabilities to estimate the required number of participants to detect a certain size of difference with a certain power for a full study.

Inclusion criteria

• Age 40-70 years
• Male or postmenopausal female
• Stage 3 CKD (eGFR between 30-59ml/min/1.73m^2 by the CKD-EPI equation (without race correction)).
• If eGFR is greater than or equal to 45ml/min/1.73m^2 then albuminuria must be greater than 300mg/g creatinine by spot urine.
• Willing to consume controlled diet for duration of the study
• Willing to collect fecal samples at home

Exclusion criteria

• Hemoglobin A1c greater than 7% within previous six months
• Treatment with metformin or insulin within previous three months
• Blood pressure greater than 150/100 mmHg from chart of home on at least two occasions in prior month (can be inclusive of screening visit)
• Change in cardiovascular and/or hypertension medication in the last 30 days
• History of major gastrointestinal disease (e.g. inflammatory bowel disease, uncontrolled irritable bowel syndrome, C. difficile chronic infection, celiac disease, diverticulitis, stomach or duodenal ulcers)
• Known HIV disease
• Hospitalization in the last two months
• Significant recent unintentional weight loss (5% of weight over past three months)
• Cancer or received cancer treatment in the last year (except basal cell carcinoma)
• Prior bariatric surgery (i.e. gastric bypass, sleeve gastrectomy) or restrictive bariatric surgery (i.e. adjustable gastric band)
• Treatment with immunosuppressive medications in the past six months or more than one week of treatment with prednisone greater than 10mg per day in the past three months (or equivalent steroid dose of non-prednisone steroids)
• Recent antibiotic use defined as a single course of antibiotics within the past three months or two or more courses within the past six months
• Known food allergy that would influence the ability to consume the study diets
• History of hyperkalemia defined as greater than 5.5mmol/L on at least two occasions
• Other medical conditions or concerns at the discretion of the investigators