Iron bioavailability in prenatal multivitamin supplements with separated and combined iron and calcium.

OBJECTIVE To compare iron absorption of a prenatal multivitamin supplement containing both iron and calcium (HICA) to that of another multivitamin containing a lower iron dose and no calcium (LI). METHODS In a crossover study, serum iron was measured in 12 healthy women administered HICA and LI separately on 2 different occasions. Blood samples were taken at 0, 1, 2, 3, 4, 6, and 8 hours after administration of each supplement. RESULTS The values of the area under the concentration-time curve (AUC) were not significantly different between LI (79.1 +/- 36.0 micro M*h) and HICA (91.4 +/- 50.4 micro M*h) (P =.37). After standardizing the AUC for dose, the relative absorption over the 8-hour time period was significantly higher for LI (2.3 +/-.0 micro M*h/mg) than for HICA (1.5 +/- 0.8 micro M*h/mg) (P =.021). CONCLUSION The absorption of iron from a low-iron-containing supplement was similar to that from a supplement with almost twice the amount of iron, due possibly to the exclusion of calcium in the LI product. Thus, while offering similar amounts of iron, the LI supplement may be better tolerated by women who are sensitive to iron-induced adverse effects.