Association between dietary intake of phosphorus and blood pressure amongst rural adults: Ellisras Longitudinal Study

Abstract

Blood pressure (BP) has been declared a global epidemic, with some studies suggesting that excessive dietary phosphorus (P) may contribute to its rising prevalence. This study aimed to investigate the relationship between BP and dietary intake of P among Ellisras (now known as Lephalale) rural adults in the Limpopo of South Africa. Data on dietary P together with other covariates (vitamins C, B12, A, and E, biotin, polyunsaturated fats, and fibre) were collected using a multiple-pass 24-hour recall method from 732 participants (370 males and 362 females) aged 21−30 years. The average food intake of each participant was recorded for two days. Dietary intake was assessed on two non-consecutive days: one weekday and one weekend day. Three BP measurements were taken from a seated position at five-minute intervals, following standard procedures. Linear regression was used to analyse the association between BP and P. Both females and males had a 0% prevalence of high P intake, with 81.9% of males and 89.7% of females consuming P below the recommended daily allowance (RDA) of 700 mg/d. The prevalence of hypertension was 6% and 17% among the females and males, respectively. There was no significant association between P, systolic BP (B= -0.002, 95% CI: -0.004:0.000, P=0.120) and diastolic BP (B= -0.001, 95% CI: -0.003:0.000, P=0.135) when the model was unadjusted. A low dietary P intake was observed in the study population, with no significant association detected between P intake and BP. Future studies with larger sample sizes and a classification of P according to its dietary sources are recommended.