Associations of socioeconomic status and processed food intake with serum phosphorus concentration in community-living adults: the Multi-Ethnic Study of Atherosclerosis (MESA)

Objective: Higher serum phosphorus concentrations are associated with cardiovascular disease events and mortality. Low socioeconomic status is linked with higher serum phosphorus concentration, but the reasons are unclear. Poor individuals disproportionately consume inexpensive processed foods commonly enriched with phosphorus-based food preservatives. Accordingly, we hypothesized that excess intake of these foods accounts for a relationship between lower socioeconomic status and higher serum phosphorus concentration.

Design: Cross-sectional analysis.

Setting and participants: We examined a random cohort of 2,664 participants with available phosphorus measurements in the Multi-Ethnic Study of Atherosclerosis, a community-based sample of individuals free of clinically apparent cardiovascular disease from across the United States.

Predictor variables: Socioeconomic status, the intake of foods commonly enriched with phosphorus-based food additives (processed meats, sodas), and frequency of fast-food consumption.

Outcomes: Fasting morning serum phosphorus concentrations.

Results: In unadjusted analyses, lower income and lower educational achievement categories were associated with modestly higher serum phosphorus concentration (by 0.02 to 0.10 mg/dL, P < .05 for all). These associations were attenuated in models adjusted for demographic and clinical factors, almost entirely due to adjustment for female gender. In multivariable-adjusted analyses, there were no statistically significant associations of processed meat intake or frequency of fast-food consumption with serum phosphorus. In contrast, each serving per day higher soda intake was associated with 0.02 mg/dL lower serum phosphorus concentration (95% confidence interval, -0.04, -0.01).

Conclusions: Greater intake of foods commonly enriched with phosphorus additives was not associated with higher serum phosphorus concentration in a community-living sample with largely preserved kidney function. These results suggest that excess intake of processed and fast foods may not impact fasting serum phosphorus concentrations among individuals without kidney disease.