Calcium absorptive consistency

Calcium absorption efficiency was measured two or three times each in 74 premenopausal and 142 postmenopausal women under conditions predicted to alter absorptive performance. A woman's absorptive consistency was evaluated across differing loads, differing intervals, and substances of differing intrinsic absorbability. In all these circumstances there was a statistically significant correlation between a woman's absorption under differing test situations accounting for up to 60% of the variance typically found in cross‐sectional studies. For example, when the same substance but at differing load levels was tested three times over an 8 week period, various coefficients of correlation ranged from + 0.773 to + 0.849 ( P < 0.001). Even over intervals as long as 5 years correlation of absorption fraction within individuals remained significant ( r = +0.487, P < 0.001).