Bioavailability of phosphorus and kidney function in the Jackson Heart Study

• Published in: The American journal of clinical nutrition 2022-08, Vol.116 (2), p.541-550
• Main Authors: Duong, Chi N, Akinlawon, Oladimeji J, Gung, Joseph, Noel, Sabrina E, Bigornia, Sherman, Flanagan, Kaylea, Pourafshar, Shirin, Lin, Pao-Hwa, Davenport, Clemontina A, Pendergast, Jane, Scialla, Julia J, Tucker, Katherine L
• Format: Article
• Language: English
• Subjects: Additives; African Americans; Albumins; Animals; Beef; Beverages; Bioavailability; Biological Availability; Cattle; Creatinine; diet; Epidermal growth factor receptors; Fish; Food additives; Food supply; Glomerular Filtration Rate; Humans; Jackson Heart Study; Kidney; Kidney Diseases; kidney function; Kidneys; Longitudinal Studies; Milk; nutrition; Original Research Communications; Phosphorus; phosphorus intake; Poultry; Risk analysis; Risk factors; Soft drinks
• ISSN: 0002-9165; 1938-3207; 1938-3207
• DOI: 10.1093/ajcn/nqac116

High phosphorus (P) exposure may have negative effects on kidney function. Nutrient databases provide total P, but bioavailability varies by source. We aimed to assess natural, added, and bioavailable P intake, and to relate these to estimated glomerular filtration rate (eGFR) in the Jackson Heart Study (JHS). A total of 3962 African-American participants of the JHS, aged 21–84 y, with urine albumin:creatinine ratio < 30 mg/g, and eGFR ≥ 60 mL · min–1 · 1.73 m–2, and without self-reported kidney disease, were included. Diet was assessed by FFQ. We assigned P in foods as naturally occurring or added, and weighted intake by P bioavailability, based on published literature. Relations between P variables and eGFR were assessed using multivariable regression. Mean ± SE intakes were 1178 ± 6.7 mg and 1168 ± 5.0 mg for total P, 296 ± 2.8 mg and 291 ± 2.1 mg for bioavailable added P, and 444 ± 2.9 mg and 443 ± 2.2 mg for bioavailable natural P, in participants with eGFR = 60–89 and ≥90 mL · min–1 · 1.73 m–2, respectively. Major sources of total P included fish, milk, beef, eggs, cheese, and poultry; and of added P, fish, beef, processed meat, soft drinks, and poultry. After adjustment for confounders, P intakes, including total (β ± SE: –0.32 ± 0.15; P = 0.03), added (β ± SE: –0.73 ± 0.27; P = 0.01), bioavailable total (β ± SE: –0.62 ± 0.23; P = 0.01), and bioavailable added (β ± SE: –0.77 ± 0.29; P = 0.01), were significantly associated with lower eGFR. However, neither total nor bioavailable P from natural sources were associated with eGFR. Added, but not natural, P was negatively associated with kidney function, raising concern about P additives in the food supply. Further studies are needed to improve estimation of dietary P exposure and to clarify the role of added P as a risk factor for kidney disease.