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Trial registered on ANZCTR

Registration number

ACTRN12619000442101

Ethics application status

Approved

Date submitted

11/03/2019

Date registered

18/03/2019

Date last updated

15/12/2022

Date data sharing statement initially provided

18/03/2019

Type of registration

Prospectively registered

Titles & IDs

Public title

SYMBIOTiC Study – SYMptom, microBIOme and dieT in Chronic Kidney Disease

Scientific title

A randomised, cross-over, pilot trial investigating the effects of a novel renal dietary intervention (rich in plant foods, utilising a whole food dietary approach) designed to improve diet quality, symptom burden, the gastrointestinal microbiome and other health outcomes including biochemical markers in adults with moderate to severe chronic kidney disease.

Secondary ID [1]

Nil known

Universal Trial Number (UTN)

U1111-1227-1769

Trial acronym

SYMBIOTiC Study – SYMptom, microBIOme and dieT in Chronic Kidney Disease

Linked study record

Nil

Health condition

Health condition(s) or problem(s) studied:

Chronic Kidney Disease

Symptom burden

Quality of life

Uraemic syndrome

Condition category

Condition code

Renal and Urogenital

Kidney disease

Diet and Nutrition

Other diet and nutrition disorders

Intervention/exposure

Study type

Interventional

Description of intervention(s) / exposure

This research will intentionally recruit people with moderate to severe, pre-dialysis chronic kidney disease (stage 3-4, eGFR 15-59mL/1.73m2) or anyone deemed suitable by the medical team (Nephrologists).

The use of a crossover trial requires fewer subjects, allows subjects to be their own controls and accounts for inter-individual variability in responses, thereby providing for a stronger study design.

Participants will be randomly allocated to either the 'intervention treatment' or 'control treatment' for the first study arm (see below in the comparator/control treatment for more information regarding the control diet). Dietary education will be based on the Evidence Based Practice Guidelines for the Nutritional Management of Chronic Kidney Disease relevant for the disease stage. For instance, education counselling for both groups will control for adequate protein and energy as well as co-morbidities that contribute to the progression of the disease (i.e. blood glucose control in diabetes, fluid and sodium control in hypertension, lipid and weight control based on the priorities relevant to the individual).

When allocated to the intervention treatment, participants will receive diet counselling and an individualised prescription for achieving at least 30 different plant foods over a 7 day (week) period as well as written information sheets designed specifically for this study. This prescription is based on new evidence and inspired by the recent findings from the American Gut Project, which is one of the largest studies to date to investigate reported habitual diets and the gut microbiome (although not specific to people with CKD). Results from this study indicated that individuals who consumed more than 30 different plant types per week, had greater gut microbiota biodiversity and reduced abundance of antibiotic resistance genes in their microbiome compared to those that consumed less than 10 plant foods per week.

Participants will first be asked to select 30 different plant foods to focus on during the first week. Following this, participants will be given an ideal day example that reflects their typical eating pattern (breakfast, lunch, dinner and snacks) but provides the number of food servings they need to consume in order to adhere to the dietary guidelines (i.e. 5 vegetable serves, two servings of fruits, 1 serve of dairy food etc.). Participants will be encouraged to swap out different plant foods from the day example using the 30 different plant foods they had individually selected to ensure they consume these foods over the week. In addition, participants will also be given a one A4 page swap-list of different plant foods and suggested serving size they can alternate over the 6 weeks to encourage variety and ensure they don't get tired of eating the same foods. Depending on the individual, specific daily targets maybe suggested to achieve the overarching goal of consuming 30 different plant foods over the week. For instance, participants may be prescribed to consume 4 different plant foods each weekday for 5 days of the week, and 5 different plant foods on weekends or at least two days over the week. A weekly checklist system for the participant to ‘tick’ or 'cross off' if they have or haven’t completed their overall targets (30 or more) for plant food consumption.

Participants will be asked to bring this check list to clinic visits/ dietetic consultations as a means to assess compliance, but also provide an opportunity for the participant and dietitian to discuss additional strategies.

Adherence to a stable diet will be monitored using 24hr food recalls at weeks 3 and 13 for both groups (the intervention and control).

Intervention code [1]

Lifestyle

Intervention code [2]

Treatment: Other

Comparator / control treatment

When allocated to the control treatment, participants will receive diet counselling and an individualised prescription for achieving less than 15 different plant foods over a 7 day (week) period as well as written information sheets designed specifically for this study (similar to that provided in the intervention arm).

Similar to the intervention treatment, participants will asked to highlight/ select 10-15 different plant foods to focus on during the first week of the control treatment arm. Following this, participants will be given an ideal day example that reflects their typical eating pattern structured as breakfast, lunch, dinner and snacks, but still provides the number of food servings they need to consume in order to adhere to the dietary guidelines (i.e. 5 vegetable serves, two servings of fruits, 1 serve of dairy foods or alternatives etc.). Participants will be encouraged to swap out different plant foods from the day example with the 10-15 different plant foods they had individually selected for that week. In addition, participants will also be given a one A4 page swap-list of different plant foods and suggested serving size they can alternate over the 6 weeks to encourage variety and ensure they don't get tired of eating the same foods. It will be explained to participants that the type of plant foods may differ from one week to the next; However, for that particular week period (7 days) they are asked to limit different plant foods to the suggested target of 10-15. Same as the intervention group, a weekly checklist system for the participant to ‘tick’ if they have or haven’t completed their overall targets (less than 15) for plant food consumption.

Participants who receive the intervention first, will receive a 4 week wash-out period where they can resume their 'usual' (habitual) diet. Then, participants will be encouraged to adhere to the targets of the control treatment as much as possible for the next 6 weeks in order to see if there is a change.

Control group

Active

Outcomes

Primary outcome [1]

Change in urine concentrations of at least 1 of 2 uraemic toxins (Indoxyl Sulfate and p-Cresyl Sulfate)

Timepoint [1]