Abstract: SA-OR027

Effect of Dietary Phosphate Intake on Blood Pressure in Healthy Humans

Session Information

Category: Mineral Disease

  • 1201 Mineral Disease: Ca/Mg/PO4

Authors

  • Krapf, Reto, University of Basel, Lucern, Lucerne, Switzerland
  • Bestmann, Lukas, Bioanalytica Labs, Lucerne, Switzerland
  • Scanni, Roberto, Istituto Oncologico Veneto, Padova, Italy
  • Hulter, Henry N., University of California San Francisco, San Rafael, California, United States
Background

Despite strong epidemiologic evidence for CV toxicity of high dietary phosphate (Pi) in humans with normal renal function, controlled Pi intervention effects on systemic human hemodynamics have not been reported. Vitamin D is known to increase intestinal Pi absorption, thereby increasing Pi load. Conversely, vitamin D supply has been associated with better CV outcome.

Methods

Prospective outpatient study with blinded assessment in 20 young healthy humans with normal renal function randomly assigned to high (HP, regular diet, RD, + 1 mmol/kg bw/d of Pi as neutral NaPO4) or to low Pi (LP, RD + lanthanum 750 mg p.o. TID plus 0.7 mmols/kg bw/d NaCl to correct for excess Na intake in HP group) for 11 weeks (w). At end of w6, each subject received 600 000 U of vitamin D3 (i.m.) and continued on HP and LP for another 5w. Recovery visits on RD were performed 2 months after w11. Plasma and 24h urinary assays were performed at BL, w6 and w11. CV endpoints: 24h ABPM. endothelial function (reactive hypoxia index), arterial elasticity (pulse wave velocity). Data are means of 3 consecutive daily measurements/period.

Results

Mean fasting [Pi]p increased significantly by 0.23+0.11 (SEM) mmol/l in HP group as did 24h SBP and DBP, both in comparison to own baseline and to the LP group: + 4.1 (range 2.1-6.1) and 3.2 (1.2-5.2) mmHg, respectively. 24h U Pi was 14.6 ± 1.8, 21.9 ± 2.4 and 41.5 ± 4.1 mmol/24h in LP, RD and HP. Mean 24h pulse rate increased significantly by + 4.0 (2.0-6.0) bpm. Plasma renin/aldosterone concentrations and 24h urinary excretion rates of Na, aldosterone and free cortisol did not differ among the 2 groups. 24h urinary excretion of metanephrin increased significantly (intra- and intergp) in the HP group by + 60 (50-70) ugr/24h. Vitamin D had no effect on the HP-induced increases in BP, pulse rate, metanephrin or renin/aldosterone values and increased U Pi/24h only in the LP group. Serum FGF23, PTH, a-Klotho and urinary Klotho increased significantly in HP vs. LP. Recovery RD visits showed reversal of the elevated 24h ABPM and pulse rates in the HP group. Neither modulation of Pi intake nor vitamin D affected endothelial and arterial function tests significantly.

Conclusion

Increased Pi intake (controlled for sodium intake) significantly increases SBP, DBP and pulse rate in normal humans, an effect explained at least in part by increased sympathoadrenergic activity.

Funding

  • Government Support - Non-U.S.