To investigate the effect of sodium, protein and calcium in habitual diets on bone resorption.
A cross-sectional study.
A community-based study.
Healthy free-living male (n=342) and female (n=421) volunteers aged 20-79 y recruited for a health and nutrition examination survey conducted by a local government.
Bone resorption was assessed by the measurement of free deoxypyridinoline in 24 h urine. Dietary assessment was by one-day dietary record method. Sodium and urea in 24 h urine were also measured for assessment of sodium and protein intake. The relationships between deoxypyridinoline excretion and the dietary factors were examined using correlation and multiple regression statistics.
In women aged 50-79 y, protein intake was positively associated with deoxypyridinoline excretion (P<0.05); and the urinary deoxypyridinoline/creatinine ratio was positively associated with both the urinary calcium/creatinine ratio (P<0.01) and sodium/creatinine ratio (P<0.05). In the multiple regression model, the association of the deoxypyridinoline/creatinine ratio and sodium/creatinine ratio was still significant (P<0.05) after adjustment for possible confounders, in this sex and age group.
In elderly women, habitual excess sodium in diets may result in bone loss through accelerated bone resorption.