Calcium absorption from three salts and CaSO₄-fortified bread in premenopausal women

Two studies were conducted to measure calcium absorption from calcium sulfate fortified bread and three salts (calcium lactate, calcium carbonate, and calcium sulfate) in healthy premenopausal women using a crossover design. In study I, calcium fractional absorption levels from the three salts labeled with a stable isotope, ⁴⁴Ca, were not significantly different (0.039-0.47) as determined by the fecal recovery method. In a second study, absorption of ⁴⁵Ca from CaSO₄-fortified labeled bread or labeled milk was measured in serum exactly 5 h postingestion. Fractional calcium absorption was slightly but significantly greater from fortified bread than from milk (mean within subject difference = 0.0675 ± 0.016). Calcium sulfate is a bioavailable fortificant for white bread that compares favorably with milk and two other salts.