A study conducted with 170 pregnant women from rural Indonesian villages throughout pregnancy, and 6 months thereafter, assessed blood vitamin A status after supplementation with beta-carotene (vitamin A precursor) and zinc, either alone or in combination.
The women were separated into 4 groups to receive various supplement combinations. All 4 groups received 30 mg of ferrous fumarate (Iron Supplement) and 400 mg of folic acid.
Group 1 also received 4.5 mg of beta-carotene.
Group 2 also received 30 mg of zinc sulfate.
Group 3 also received 4.5 mg of beta-carotene and 30 mg of zinc sulfate.
Group 4 only received the iron and folic acid.
In measuring the vitamin A in the mother's blood and breast milk after 1 and 6 month periods, the researchers concluded, "The findings of this study clearly show that beta-carotene can only improve vitamin A status when zinc is also available."
Because all participants were given iron (ferrous fumerate) which is an oxidant, we can't help but question whether results would have been different if the iron was withheld.
Am. J. Clin. Nutr. 2004;80:1299-307