High phosphorus intake only slightly affects serum minerals, urinary pyridinium crosslinks and renal function in young women

Objective: Assessment of the physiological effects of a diet rich in phosphorus in young women. Design: Control period I-commercial basic diet containing 1700mg P and 1500mg Ca/day for 4 weeks. Supplementation period-a 6 week high-phosphorus period of 3008 mg P and 1995 mg Ca/day. Control period II-4 weeks washout with basic diet as in period I. Setting: Institute of Nutritional Science, Friedrich Schiller University, Jena. Subjects: Ten healthy women, aged 20-30 y. Interventions: Orange juice and tablets, containing supplements of Ca-5(PO4)(3)OH and NaH2PO4, totalling 1436mg elemental phosphorus per day. Results: There was an increase of 10.7+/-13.7pg/ml in serum PTH, a decrease of 0.6+/-0.6ng/ml in serum osteocalcin, an increase of 73.6+/-136.6 nmol/mmol creatinine in urinary pyridinoline and of 19.3 +/- 36.0 nmol/ mmol creatinine in urinary deoxypyridinoline, and a decrease of 2.6+/-9.3 mg/l in urinary microalbumin. All changes were insignificant. There were no changes in serum levels of Ca, PO4 or Zn, in serum concentration of 1,25-(OH)(2)D-3, and in urinary beta -2-microglobulin excretion. Phosphorus supplementation caused intestinal distress, soft stools or mild diarrhoea. Conclusions: In spite of a high phosphorus supplementation no significant changes in bone-related hormones, pyridinium crosslinks as markers of bone resorption and parameters of renal function in young women were found.