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

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).