This two-year follow up, single-center, open-label, feasibility study will recruit outpatients from the Renal Medicine Clinic at Changi General Hospital. Eligible patients with Stage 3 or 4 CKD will be assigned preferencebased to either a plant-based diet intervention (intake of at least 50% protein from plant sources) with regular dietitian counselling and follow up, or a control group receiving dietitian counselling for general CKD dietary advice without information on percentage of plant-based foods. Six monthly assessments will include estimated glomerular filtration rate (eGFR), serum potassium, nutritional markers, and other relevant biochemical parameters. Quality of life and dietary adherence will be evaluated through questionnaires and food frequency records. This study will evaluate primarily, the feasibility of a plant-based diet in the Singaporean context. Secondarily it will evaluate its safety in terms of incidence of hyperkalaemia, and benefit in terms of improvement in acidosis.
Other exploratory outcomes will include (1) preliminary efficacy of plant-based diets on CKD progression (measured by eGFR decline); (2) risk of nutritional deficiencies such as vitamin D, B12 and iron; and (3) impact on other biochemical parameters of CKD.
Age 21-79 (Only adults who can give consent will be recruited. Older adults aged 80 are not included to reduce the risk of confounding due to age-related frailty, sarcopenia and multimorbidity. Additionally, older adults may have different nutritional needs and energy requirements)
CKD stage 3-4 (baseline eGFR 15-60ml/min/1.72m2 for the past 6 months)
Willingness to see a dietitian and follow either a standard CKD diet or a predominantly plant-based CKD diet
On maximum tolerated dose of ACE-inhibitors (Angiotensin converting enzyme inhibitors) or ARB (Aldosterone receptor blocker) as determined by Renal Physician in charge
Transplant patients (who will tend to have more variable trajectories, immunosuppression related challenges etc which may make this study less feasible)
Pregnant or lactating patients (who have different nutritional requirements than the standard CKD patients)
Patients who were on any special diet for at least 1 month prior to recruitment (inclusive of
long-term vegans or vegetarians) - excluded because they already have stable dietary habits
Parallel
Predominantly Plant-Based CKD Diet
Other interventionSubjects in the intervention group will receive personalised dietary advice \& educational materials from a renal dietitian for retarding CKD progression (low salt, moderate protein) with additional focus on including more non-/minimally processed plant-based foods. Food recommended would be those easily obtained
Standard CKD Diet
Other interventionSubjects in the control arm will receive advice from a renal dietician for general healthy eating for retarding CKD progression (low salt, low-moderate protein intake). No specific advice on percentage of protein intake contributed to by plant-based protein will be given.
Adherence to diet - based on Good vs Moderate vs Poor Adherence
Percentage adherence will be assessed independently by the dietician and investigator seeing the patient, then averaged. * Where there is a \>10% difference in assessment between dietician and investigator, the results will be discussed, and a combined decision will be made on adherence level * \>75% adherence - "Good Adherence" * 50-75% - "Moderate Adherence" * \<50% - "Poor Adherence"
Acceptability of Diet
Acceptability of diet via Diet, palatability and appetite questionnaire. In the absence of a validated cut-off score, acceptability will be assessed based on the proportion of positive versus negative responses to each item in the Diet, Palatability, and Appetite Questionnaire. A higher porportion of positive responses suggests a more accepatable diet. \>50% positive responses will indicate an acceptable diet while \< 50% of positive responses will indicate an unacceptable diet.
Serum Potassium level in mmol/L
Potassium will be measured in mmol/L. Hyperkalaemia will be defined as serum potassium level \> 5.3 mmol/L
Serum Bicarbonate Level (mmol/L)
Absolute serum bicarbonate level (mmol/L) will be measured. Metabolic acidosis will be defined as serum bicarbonate level \< 20 mmol/L.
Estimated GFR (ml/min/1.73m2) decline
Change in Estimated GFR (ml/min/1.73m2) over 1 year will be calculated
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