Efficacy of Plant-protein Diets in Patients With Chronic Kidney Disease

• Plant-protein Diets (Other): Participants will consume meals with 70% plant-based protein three times a day. Participants will be prohibited to have meals other than experimental diets and to drink milk and soy milk.
• Control Diets (Other): Participants will consume meals with 50% plant-based protein three times a day. Participants will be prohibited to have meals other than experimental diets and to drink milk and soy milk.

Primary outcomes

• Change in serum levels of indoxyl sulfate, p-Cresyl sulfate and trimethylamine N-Oxide [4 weeks after starting intervention]

Secondary outcomes

• Change in eGFR [4 weeks after starting intervention]
• Change in urinary protein creatinine ratio [4 weeks after starting intervention]
• Change in serum bicarbonete levels [4 weeks after starting intervention]
• Change in urinary citrate to creatinine ratio [4 weeks after starting intervention]: The measurement of this outcome was abandoned because of the end of sales for its measuring reagent (F-kit citrate; JK International, Tokyo, Japan) in Japan on December 23, 2022. This decision had been made before we initiatited the recruitement of study participants.
• Change in blood pressure [4 weeks after starting intervention]
• Change in serum levels of calcium, phosphate, intact parathyroid hormone and intact fibroblast growth factor 23 [4 weeks after starting intervention]
• Change in serum levels of acetic acid, propionic acid and butyric acid [4 weeks after starting intervention]
• Diversity and composition of the gut microbiota [4 weeks after starting intervention]
• Change in muscle mass [4 weeks after starting intervention]
• Dietary adherence [4 weeks after starting intervention]: How many times participants have the study diet during the study period.
• The number of oral medications including antihypertensive drugs, diuretics, potassium tablets, potassium binders, phosphate binders, calcium tablets, active vitamin D3 analogs and sodium bicarbonate [4 weeks after starting intervention]

Sex: All, ages: 20 Years to any

Inclusion Criteria:

1. patients with chronic kidney disease who were referred to the Outpatient Department of Nephrology at Osaka University Hospital
2. eGFR < 20 mL/min/1.73 m2
3. taking anigiotensin-converting enzyme inhibitors or angiotensin Ⅱ receptor blockers or angiotensin receptor neprilysin inhibitor
4. K < 5.5 mEq/L

Exclusion Criteria:

1. Being planned to intitate renal replacement therapies within 3 months
2. Having inflammatory bowel diseases
3. History of gastrointestinal tract surgery
4. Taking antibiotics within 1 month before the entry
5. Taking or being planned to start warfarin
6. Having dietary allergies
7. Having difficulty in oral intake
8. During pregnancy or breastfeeding
9. Unsuitable for participant in the trial by an attending physician