Zinc supplements may help mothers-to-be reduce the risk for birth defects linked to alcohol use early in pregnancy, Australian researchers report.
The animal study was published in the journal Alcoholism: Clinical & Experimental Research.
"Alcohol's damage to the fetus depends not only on the amount and duration of alcohol exposure, but also on the timing of the exposure relative to the development of the cells and tissues involved," said study co-author Peter Coyle, PhD, an associate professor at the Hanson Institute in Adelaide.
"Earlier work had shown that prenatal alcohol, as well as other toxins, can result in fetal zinc deficiency and developmental malformations) by inducing the zinc-binding protein, metallothionein, in the mother's liver. Since then, our group has confirmed the importance of metallothionein in alcohol-mediated birth defects," he said.
In this study, Dr. Coyle and colleagues injected either saline or a 25% solution of alcohol into pregnant mice on their eighth day of gestation. In mice, the eighth day of gestation is equivalent to weeks three to eight during a human pregnancy. The mice were fed either a regular or zinc-supplemented diet from conception to day 18 of gestation, when some fetuses were assessed for birth defects. The growth of the surviving offspring was monitored for 60 days after birth.
"There were three key findings," Dr. Coyle said.
"One, fetal abnormalities caused by acute alcohol exposure in early pregnancy can be prevented by dietary zinc supplementation. Two, dietary zinc supplementation throughout pregnancy can protect against post-natal death caused by acute alcohol exposure in early pregnancy. Three, dietary zinc supplementation increases the mother's blood zinc to overwhelm the transient drop in zinc caused by alcohol, which we believe prevents the fetal zinc deficiency and subsequent fetal damage."
These findings don't mean that taking zinc makes it safe for women to drink during pregnancy, however.
"We have not determined whether zinc protects against all of the possible negative outcomes from alcohol exposure in pregnancy," Dr. Coyle said. "Nor would we recommend that makers of alcoholic beverages include zinc in their product so that women can drink while pregnant. Indeed, we take the conservative stand of a 'no alcohol policy' during pregnancy."
What the studies do indicate is that dietary zinc supplementation could be as important as folic acid in helping to prevent damage to the fetus during pregnancy, according to Dr. Coyle.