Evaluation of Phosphorus Content Among Plant- and Animal-Based Protein Products: Implications for Dietary Recommendations in Chronic Kidney Disease

Abstract

Kidney function is imperative for human health, especially due to its unique physiologic role in waste regulation. However, approximately 15% of American adults experience diminishing kidney function, which causes substances such as phosphorus (P) to accumulate in the blood, leading to cardiac and skeletal abnormalities. One primary treatment to mitigate elevated serum P levels is to restrict P consumption in the diet. However, this is a largely unsuccessful endeavor due to the ubiquitous nature of P in the food supply, lack of transparency of P content in foods, association of P with protein-rich sources, and economic barriers to acquiring and preparing low P foods. One proposed method for addressing these concerns is transitioning the focus away from P-restricted diets to adopting plant-based eating patterns. However, widespread interest in plant-based eating has generated an emerging industry of ultra-processed plant-based meat alternatives which have unknown health consequences, and it remains unclear whether these products would be beneficial for patients with chronic kidney disease. Therefore, the study described in this thesis sought to investigate the P content of plant- and animal-based protein products through laboratory analysis and exploration of a nutrient database. Laboratory analysis included preparation of food products, freeze drying, ashing, and measurement of mineral content via ICP-OES. Results from this research revealed wide variation in P content and P-to-protein ratios among products in addition to an underestimation of P content of foods in a nutrient database. Further, examining these products illuminated the immense use of phosphorus additives in the food supply and the great discrepancy of cost between plant and animal protein products. The work discussed in this thesis provides foundational knowledge on new-to-market plant protein products, which supplies the groundwork for future research on mineral analysis, bioaccessibility, and bioavailability of food products to ultimately understand the connection between consumption of these foods and the effect on serum P and health outcomes to modify and strengthen dietary recommendations for chronic kidney disease.