A National fortification program instated in Venezuela in 1993 reduced iron
deficiency and anemia by half in only 1 y. The fortification mixture conta
ined ferrous fumarate, vitamin A and other vitamins. We conducted experimen
ts to characterize ferrous fumarate uptake by Caco-2 cells. Increasing amou
nts of ferrous fumarate, vitamin A, phytate, tannic acid and beta-carotene
were added to incubation mixtures using a range of concentrations that incl
uded the molar ratios used in the Venezuelan fortification program. Cells w
ere incubated for 1 h at 37 degrees C with 37 kBq Fe-59 and the compound to
be evaluated. They were then rinsed, trypsinized and counted to measure up
take. Effects of ascorbic acid, days in culture and use of flasks or insert
s were also evaluated. Optimal conditions for uptake experiments were pH 5.
5, in the presence of ascorbic acid and at 16 d in culture. Use of flasks o
r inserts did not affect uptake. Vitamin A did not significantly increase i
ron uptake under the experimental conditions employed. However, beta-carote
ne (6 mu mol/L) significantly increased iron uptake compared to no beta-car
otene addition (114.9 +/- 6.3 and 47.2 +/- 5.9 pmol/mg cell protein, respec
tively). Moreover, in the presence of phytates or tannic acid, beta-caroten
e generally overcame the inhibitory effects of both compounds depending on
their concentrations. We conclude that beta-carotene improves iron uptake a
nd overcomes the inhibition by potent inhibitors of iron absorption. These
experiments also validated the usefulness of Caco-2 cell model system to ev
aluate iron metabolism.