To validate a phosphate food frequency questionnaire using dietary recalls and test for reproducibility in people with end stage kidney failure on dialysis.

In an initial dietetic consultation participants will complete the phosphate specific FFQ survey (this consists of 31 foods that are high sources of dietary phosphorous ranked in order of frequency from never to 2 or more times per day) and a 24 hour multi pass recall which will be verified by the renal dietitian in an interview-administered methodology. This will confirm the reported number of serves, portion sizes and take-aways as well as brand names of regular packaged foods in the survey. Participants will also via interview with the dietitian complete a further two 24-hour multi pass recalls so that there is one that covers a dialysis day, a non-dialysis weekday and a non-dialysis weekend day. Where possible participants will be encouraged to take photographs of packaged meals to confirm exact brand and type. All information will be collected on paper, scanned in by the renal dietitian and sent to the principal investigator for data entry and analysis. In total the patient will have 3 interviews ( 1 x 60 mins and 2 x 30 mins) with the dietitian (via Telehealth or face to face if patient prefers) over a period of 2 weeks. The same participants will be invited to opt-in to a sub-study to also provide weighted 24-hour food records, reflecting a dialysis and non-dialysis day in the following week. Those that opt in for the sub study will be given verbal and written instructions on how to accurately measure foods and how to complete the food record and will be provided with scales, measuring cups, spoons, and food recording sheets. The patient will have 1 extra interview lasting 30 minutes with the patient to explain the procedure. The sub study will begin 1 week after the patient has completed the interviews for the main observational study.