Dietary Phosphorus, Its Sources, and Mortality in Adults on Haemodialysis: The DIET-HD Study

Dietary phosphorus restrictions are usually recommended for people on haemodialysis, although its impact on patient-relevant outcomes is uncertain. We aimed to evaluate the association between total phosphorus intake and its sources with mortality in haemodialysis. Phosphorus intake was ascertained within the DIET-HD study in 8110 adults on haemodialysis. Adjusted Cox regression analyses were conducted to evaluate the association between the total and source-specific phosphorus (plant-, animal-, or processed and other sources) with mortality. During a median 3.8 years of follow-up, there were 2953 deaths, 1160 cardiovascular-related. The median phosphorus intake was 1388 mg/day. Every standard deviation (SD) (896 mg/day) increase in total phosphorus was associated with higher all-cause mortality [hazard ratio (HR), 1.16; 95% confidence intervals (CI), 1.06-1.26] and cardiovascular mortality (HR, 1.18; 95% CI, 1.03-1.36). Every SD (17%) increase in the proportion of phosphorus from plant sources was associated with lower all-cause mortality (HR, 0.95; 95% CI, 0.90-0.99). Every SD (9%) increase in the proportion of phosphorus from the processed and other sources was associated with higher all-cause mortality (HR, 1.06; 95% CI, 1.02-1.10). A higher total phosphorus intake was associated with increased all-cause and cardiovascular death. This association is driven largely by the phosphorus intake from processed food. Plant based phosphorus was associated with lower all-cause mortality.