Intestinal calcium absorption and serum vitamin D metabolites in normal subjects and osteoporotic patients: effect of age and dietary calcium.

Intestinal calcium absorption assessed by a double-isotope method, decreased significantly with aging in 94 normal subjects (r = -0.22, P < 0.025). In 52 untreated patients with postmenopausal osteoporosis, calcium absorption was significantly lower than normal when either age or habitual calcium in... View More