Background: A high purified protein intake has been shown to induce urinary calcium loss. However, these findings could not be reproduced with a high-protein meat diet. Also, most studies have been carried out in young subjects and the applicability of their results to the elderly population on a mixed vegetable:animal diet remains unclear.
Objectives: To study whether a mixed vegetable:animal high-protein intake increases urinary calcium loss in elderly volunteers, as has been shown for younger subjects on a purified high-protein intake.
Methods: Eight male volunteers, with ages ranging from 66 to 88 years, recruited from the University Hospital Geriatric Medicine Outpatients Clinic, were studied. 24-hour urinary calcium, phosphorus, and creatinine were measured during a period of usual protein intake (approximately 0.6 g/kg/day) and during 7 days of vegetable:animal (1:1) high-protein intake (2 g/kg/day). Calcium and phosphorus intake were adjusted to be kept constant (1 g/day of each) during the whole study.
Results: Mean calcium urinary levels did not change significantly during the study (1.89 and 1.83 mmol/24 h during the usual and high-protein diet, respectively). Urinary phosphorus and creatinine levels also remained stable throughout the entire study.
Conclusions: This study has not detected any increased calcium urinary excretion in male elderly volunteers submitted to the mixed vegetable:animal high-protein diet. Therefore, it does not support the suggestion that a high-protein intake is a risk factor for urinary calcium loss in elderly men.