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Previous studies have indicated a link between maternal intake of multivitamin supplements containing folate and decreased occurrence of cleft lip and/or cleft palate, and studies in animals have shown positive direct results. However, most studies in humans are more ambiguous. It is difficult to distinguish the effects of a specific nutrient, which are generally entwined with the effects of other nutrients, and many previous studies display design flaws (ie, lack of randomized sampling, insufficient sample size to have statistical significance, and inconsistent results).
Studies in Norway and California have reported a weak correlation in mothers who reported taking no supplements before becoming pregnant and then started taking supplements (Norway) or who ate fortified cereal (California) during the first 3 months of pregnancy. However, other studies show no change in orofacial cleft prevalence before and after the introduction of cereal fortification (Canada, Texas) or with/without use of supplements (2 large multistate US studies).
A new study in the Cleft Palate–Cranofacial Journal reports that the link between periconceptional folate intake and cleft palate or cleft lip may be weaker than previously thought. In a population-based, statistically comprehensive study of almost 500 infants in the United Kingdom, Little, et al used multiple measures of folate status and detailed assessments of confounding factors and found no correlation between prevalence of orofacial cleft and dietary or supplemental folic acid. A slight correlation was found between the presence of folic acid antagonists and increased orofacial cleft incidence.
Smoking and alcohol intake, use of medications, maternal age, medical history, reproductive history, and family history of clefts did not show any confounding effects. It is possible that other factors correlating to dietary folic acid may play a role in orofacial cleft incidence, but this study found that higher folate intake did not prevent or reduce the occurrence of cleft palate or cleft lip. Cleft lip and cleft palate are the most frequently occurring birth defects in the United States, affecting nearly 7,000 children yearly, or one in every 600 newborns. (Source: American Cleft Palate-Craniofacial Association, July 2008)
