EFFECT OF CALCIUM SUPPLEMENTATION ON DAILY NONHEME-IRON ABSORPTION AND LONG-TERM IRON STATUS

The short-term effect of calcium supplements (1200 mg Ca/d) on daily n onheme-iron absorption was measured in 14 healthy adult volunteers by using stable isotope extrinsic labeling and fecal monitoring technique s. Mean (+/- SEM) non heme-iron absorption from a low-calcium (<320 mg /d), moderately high-iron (15 mg/d) diet was 15.8 +/- 2.1%, but in the presence of calcium (400 mg/meal) as calcium carbonate, absorption fe ll significantly to 4.7 +/- 1.4% (P < 0.001). The long-term effect of consuming calcium supplements with meals (1200 mg Ca/d) on body iron ( functional and storage iron) was investigated in 11 iron-replete adult s over a 6-mo period. An unsupplemented control group (n = 13) was als o monitored to correct for any seasonal changes in the biochemical mea surements, There were no changes in any of the hematologic indexes, in cluding hemoglobin, hematocrit, zinc protoporphyrin, and plasma ferrit in resulting from the calcium supplementation. The results clearly sho w that long-term supplementation with calcium did not reduce plasma fe rritin concentrations in iron-replete adults consuming a Western-style diet containing moderate to high amounts of calcium in most meals.