Whole Grains and Phosphorus in Chronic Kidney Disease
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Authors
Winkelman, Dillon
Issue Date
2024
Type
Dissertation
Language
Keywords
Alternative Title
Abstract
Chronic kidney disease (CKD) is one of the leading causes of death in the United States and impacts around 15% of the population. The development and progression of CKD introduces the risk of developing CKD-mineral and bone disorder (CKD-MBD), which has been attributed to excess dietary phosphorus intake. As a result, this has led to people with CKD being advised to restrict whole grains and consume refined grains, which are lower in phosphorus. However, whole grains are generally recognized as being healthier, and there is no direct evidence linking whole grains to kidney decline or CKD-MBD. This dissertation will address three research questions: 1) to what extent does restricting whole grains lower phosphorus exposure in people with CKD; 2) what are the effects of whole grain consumption on CKD-MBD and mortality; and 3) what are the perspectives of people with CKD regarding whole grains in their diet. Study 1 (Chapter 2). The contribution of whole grains to phosphorus exposure and CKD-MBD was explored and analyzed through a narrative review. After evaluating known determinants of phosphorus exposure from grain products, three model diets were created based on the reported grain intake of the general U.S. population, and adjusting for the likely contribution of phosphate additives, as well as differences in phosphorus bioavailability: standard grain diet, 100% refined grain diet, and mixed (50/50 whole and refined grain) diet. This analysis found that the additional phosphorus exposure from a mixed grain pattern (231 mg/day) compared to the 100% refined grain (127 mg/day) was unlikely to be enough to raise serum phosphorus levels in most people with CKD and could be meaningfully mitigated by avoiding phosphate additives in processed grain products. Study 2 (Chapter 3). The association of whole grains with CKD-MBD and mortality in people with CKD was analyzed in the Chronic Renal Insufficiency Cohort (CRIC) study. The cross-sectional analysis found no strong association between whole grains and CKD-MBD biomarkers. Although, the prospective analysis found that whole grains in relation to refined grains and overall energy intake were associated with a lower risk of cardiovascular disease (CVD) and mortality. Study 3 (Chapter 4). Reported intakes of whole grains and participants perspectives regarding grain consumption were assessed in a cross-sectional study of patients undergoing hemodialysis treatment in Northern Nevada. The majority of participants did not report dietitians as the most reliable source of information and although most participants stated they had some form of confidence about grain recommendations, their opinions differed, with most stating people with CKD should consume less grains than the general population. However, some participants stated that people with CKD should consume whole grains. Conclusions. The results of this dissertation do not support the current practice of restricting whole grains and support a link between how the lack of agreement about grain recommendations may lead to confusion among people with CKD.