Correlates of mid-radius bone density among postmenopausal women: a community study

We surveyed mid-radius bone density in a geographically-defined population of 324 women, 55-80 years old from two small, demographically-similar communities whose water supply provided 60 mg/l and 375 mg/l of elemental calcium. Mean community calcium intakes were 964 mg/day and 1329 mg/day respectively. Bone density, measured by photon densitometry, was correlated with physical measurements, medical history, and reported nutritional intake. Mid-radius bone density decreased with age while the following additional factors were independently and positively associated with bone density: humeral muscle area (p = 0.0001), extended estrogen use (p = 0.0004), thiazide use (p = 0.0029), and vitamin D intake (p = 0.0104). Estimated total calcium intake alone did not significantly correlate with bone density; however, mean bone density was significantly greater in persons whose calcium intake was greater than 800 mg/day, consumed concurrently with vitamin D in amounts greater than 400 IU (p = 0.0342), the Recommended Daily Allowance of these two nutrients.