Acceptability, Adherence, Safety and Experiences of Low Energy Diets in People With Obesity and Chronic Kidney Disease: A Mixed Methods Study.

OBJECTIVES: Obesity is a modifiable risk factor for chronic kidney disease (CKD) progression. Low energy diets (LEDs) have not been adequately studied in people with CKD. This study aimed to explore acceptability, adherence, safety, and experiences of two LED prescriptions in adults living with obesity and CKD. DESIGN AND METHODS: In a mixed-methods study, obese adults with CKD were prescribed two LEDs (∼800 to 1000 kcal/day each), in a randomised order for 2 weeks each. One diet consisted of four meal replacement products daily (Optifast®, Nestlé Health Science) and the other two pre-prepared frozen meals (Lite n' Easy®, Mitchell's Quality Foods). Participants received weekly dietitian support, completed daily adherence checklists (converted to % of provided meals/replacements consumed) and participated in post-intervention semi-structured interviews to capture their experience. RESULTS: Nine participants were included (mean age 46.5 ± 14.3 years, estimated glomerular filtration rate 64 ± 26 mL/min/1.73 m2, 4/9 male). Mean self-reported adherence was 88 ± 11% and mean 4-week weight change was -7.3 ± 5.6 kg. Two participants withdrew at week two. Most frequently reported side effects were hunger and headaches. Adverse events of interest included one episode each of hyperkalaemia and hypoglycaemia. No serious adverse events occurred. Four overarching themes of patient experiences were identified: strategies used to adapt, disruption to the norm, individual preferences, and influences on acceptability. CONCLUSIONS: LEDs were found to be acceptable and safe with high self-reported adherence rates. Future LED trials should include specialist diabetes management, close monitoring for hyperkalaemia and adequate support to assist with managing side effects and dietary and social adjustments.

Relationship Between Dietary Phosphate Intake and Biomarkers of Bone and Mineral Metabolism in Australian Adults With Chronic Kidney Disease.

OBJECTIVE: Higher serum phosphate is associated with increased adverse outcomes including cardiovascular disease. Abnormalities of bone and mineral metabolism in chronic kidney disease (CKD), including higher serum phosphate, are important risk factors for increased cardiovascular disease. Associations between dietary phosphate intake and biochemical and cardiovascular parameters in non-dialysis CKD patients, however, have not been adequately studied. This study aimed to explore associations between phosphate intake and biomarkers of bone and mineral metabolism and intermediate cardiovascular markers in adults with stage 3-4 CKD. DESIGN AND METHODS: One hundred thirty-two participants enrolled in the IMpact of Phosphate Reduction On Vascular End-points in Chronic Kidney Disease trial were invited to participate in this sub-study. At baseline, dietary phosphate intake and its source (animal, plant, or a mixture of animal and plant) were determined using a 7-day self-administered diet food record, and measurements were made of serum and urinary phosphate, serum calcium, parathyroid hormone, fibroblast growth factor-23, and the intermediate cardiovascular markers pulse wave velocity (PWV) and abdominal aortic calcification. The relationships between dietary phosphate intake and these bone metabolism and cardiovascular markers were explored using Pearson's correlation and linear regression. The effect of source of phosphate intake was analyzed using compositional data analysis. RESULTS: Ninety participants (age 64 ± 12 years, 68% male, estimated glomerular filtration rate 26.6 ± 7.6 mL/min/1.73 m2, daily phosphate intake 1,544 ± 347 mg) completed the study. Correlations among dietary phosphate intake and biochemical measures, PWV, and abdominal aortic calcification ranged from r = -0.13 to r = +0.13. Linear regression showed no association between dietary phosphate measurements and biochemical or cardiovascular parameters. Source of phosphate intake was associated with PWV (P = .01), but not with other biomarkers of bone and mineral metabolism. Higher PWV values were associated with higher intake of plant-based relative to animal-based phosphate (1.058 [1.020-1.098], P = .003). CONCLUSION: Levels of total dietary phosphate intake measured by dietary food record show no statistically significant relationship with biochemical markers of bone and mineral metabolism or intermediate cardiovascular markers. Higher PWV levels associated with higher intake of plant-based relative to animal-based phosphate intake were an unexpected finding and further research is needed in this area.

Dietary Phosphate Consumption in Australians With Stages 3b and 4 Chronic Kidney Disease.

OBJECTIVE: Dietary phosphate modification is a common therapy to treat hyperphosphatemia in individuals with chronic kidney disease (CKD). However, current dietary intake and common food sources of phosphate typically consumed by individuals with CKD are not well characterized. This study examined a cohort of CKD patients to determine total dietary intake and common food sources of phosphate, including phosphate additives. DESIGN AND METHODS: Participants with CKD stages 3b and 4 recruited to a substudy of the "IMPROVE-CKD (IMpact of Phosphate Reduction On Vascular End-points in Chronic Kidney Disease) Study" completed a 7-day self-administered diet record at baseline. Diet histories were analyzed and daily phosphate intakes determined using FoodWorks V.9 (Xyris). The proportion of phosphate contributed by each food group was determined using the AUSNUT 2011-2013 Food Classification System. Ingredient lists of packaged food items consumed were reviewed to determine frequency of phosphate-based additives. RESULTS: Ninety participants (mean eGFR 26.5 mL/min/1.73 m2) completed this substudy. Mean phosphate intake of participants was 1544 ± 347 mg/day, with 96% of individuals exceeding the recommended daily intake of phosphate (1000 mg/day). The highest sources of dietary phosphate were milk-based products (25%) and meat and poultry products/dishes (25%). Phosphate-based food additives were identified in 39% (n = 331/845) of packaged foods consumed by participants. CONCLUSION: Dietary phosphate intakes of Australians with CKD are high and come from a variety of sources. Managing dietary phosphate intake requires a patient-centered, tailored approach with an emphasis on maintaining nutritional adequacy and awareness of phosphate additives.