who took multivitamins containing folic acid anywhere from one month before through two months after conception than for women who didn't take supplements.
Although there is no direct proof that it was the folic acid in the multivitamins that protected the fetuses against cleft lip and cleft palate, it has been shown previously that folic acid is important in preventing neural-tube defects. The researchers believe the beneficial effects came from folic acid because it is necessary for normal DNA development. The folic acid needs to be present early -- in the first two weeks after conception -- because it is believed that to prevent cleft lip and cleft palate, it acts during the first four to five weeks after conception (3). A recent study which looked at vitamin A supplements found that too much of this vitamin (>10,000 I.U./day) can cause defects of the lip, palate and heart. However, in doses from 4,000 I.U. to 8,000 I.U., vitamin A is thought to be important to having a healthy baby (3).
The evidence for zinc is more direct. A group of 294 wo
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