Association of Intake of Whole Grains with Health Outcomes in the Chronic Renal Insufficiency Cohort Study

Key Points Intake of whole grains was not associated with CKD mineral and bone disorder biomarkers. Intake of whole grains in relation to refined grains was associated with lower risk of cardiovascular disease, kidney failure, and mortality. The restriction of whole grains among people with CKD may be unwarranted. Background Patients with CKD are encouraged to choose refined grains instead of whole grains as part of the low-phosphorus diet for managing CKD-mineral and bone disorders (CKD-MBD). However, there is no direct evidence indicating that limiting whole grains has a beneficial impact on CKD outcomes. Methods This study analyzed Chronic Renal Insufficiency Cohort data in two ways, namely cross-sectional examination of CKD-MBD biomarkers and prospective examination of health outcomes. A total of 4067 (cross-sectional) and 4331 (prospective) participants were included. The primary exposure was reported intake of whole grains (analyzed as servings/d, servings/1,000 kcal, and refined grain servings/whole grain servings). CKD-MBD biomarkers included serum phosphorus, fibroblast growth factor-23, parathyroid hormone, calcitriol, and calcium. Outcomes included cardiovascular events, kidney failure, and all-cause mortality. Results In adjusted models, reported intake of whole grains was associated with higher phosphorus intake and serum phosphorus when assessed crudely (serving/d), but not when analyzed in relation to energy. Higher intake of refined grain relative to whole grains was associated (all models) with higher risk of kidney failure (model 4: 1.01; 95% confidence interval, 1.00 to 1.02; P = 0.01, all-cause mortality (model 4: 1.01; 95% confidence interval, 1.00 to 1.01; P = 0.01), and cardiovascular disease except for the fully adjusted model. Higher dietary density was associated with lower mortality in models adjusted for demographic and clinical factors including kidney function, but not in the fully adjusted model that further adjusted for dietary factors. Conclusions Intake of whole grains was not associated with CKD-MBD biomarkers. Intake of whole grains in relation to refined grains was associated with lower risk of cardiovascular disease, kidney failure, and mortality. The results of this study put into question the long-standing practice of restricting whole grains in patients with CKD.