Diet quality, unprocessed plant-based foods, and vascular function in adults with CKD: Secondary analysis of a pilot randomized clinical trial.

Objective: Chronic kidney disease (CKD) is prevalent among Veterans and is strongly associated with cardiovascular disease (CVD) and mortality. Fruit and vegetable intake may help manage CKD and CVD. However, the relationships of dietary intake of kidney-impacting nutrients from plant-based foods with vascular function, oxidation, and inflammation in CKD is uncertain.

Materials and methods: We conducted a post-hoc analysis of the Phosphate Lowering in CKD Trial evaluating the association of unprocessed, plant-based energy and nutrient intake with pulse wave velocity (PWV), flow meditated dilation (FMD), and markers of oxidative stress and inflammation. Participants had stage 3b - 4 CKD and serum phosphorus of 2.8 - 5.5 mg/dL. Linear regression models were adjusted for age, sex, body mass index, blood pressure, diabetes, CVD, and kidney function.

Results: Participants (n = 42) were aged 66 ± 7 years with estimated glomerular filtration rate 36.2 ± 10.1 mL/min/1.73m²; 88% were male. Diets comprised large proportions of animal and processed foods. Higher daily intake of unprocessed plant-based energy, potassium, phosphorus, and protein were each significantly associated with lower PWV in fully adjusted models: -1.11 cm/s (95% CI: -1.98, -0.25 cm/s), -0.49 cm/s (95% CI: -0.86, -0.12 cm/s), -312.4 cm/s (95% CI: -514.5, -110.3 cm/s), and -280.3 cm/s (95% CI: -484.4, -76.2 cm/s), respectively. However, unprocessed, plant-based nutrient intakes were not associated with FMD or markers of oxidation or inflammation.

Conclusion: Despite overall low diet quality, higher consumption of unprocessed, plant-based energy and nutrients was associated with lower arterial stiffness. Future studies are needed to explore these associations in larger cohorts with CKD and the effects of diet quality interventions.