BALTIMORE--Studies show that supplementing a mother's diet withfolic acid before and during pregnancy can reduce incidences ofneural tube birth defects in children. But researchers at theUniversity of Maryland School of Pharmacy, found poor folic aciddissolution in six prenatal prescription multivitamins theytested, raising questions as to whether or not absorption by thebody is complete.
Stephen Hoag, Ph.D., assistant professor at the UM School ofPharmacy, says tests of nine prenatal prescription multivitaminsfound six products did not release at least 75 percent of theamount of folic acid listed on their labels in one hour, anindustry standard set in 1995.
The report, written by Hoag and co-author Ralph Shangraw, Ph.D.,professor emeritus with the UM School of Pharmacy, and HanuRamachandruni, M.S., a graduate student in the pharmacy school,was published in the July-August issue of the Journal of theAmerican Pharmaceutical Association.
"Typically vitamins, including folic acid, are more readilyabsorbed in the upper gastrointestinal tract, just beyond thestomach," says Hoag. "Not meeting the standard of dissolvingwithin an hour highlights a potential problem with theseproducts. The amount of folic acid available for optimalabsorption in the body could be inadequate."
While dissolution of a substance does not guarantee absorption,the researchers say it is necessary for absorption to occur.Many of the products Hoag tested missed the minimum standard bya wide margin, two released less than 25 percent of the labeledquantity.
Hoag and Shangraw say they will not name the products studiedbecause federal regulations and standards for nutritionalsupplements are changing and some manufacturers have improvedtheir products to insure proper dissolution before this researchwas published. The standards for folic acid dissolution aredeveloped by the United States Pharmacopeial Convention.Nutritional products meeting these standards can label theirproducts USP.
"Folic acid is caught in evolving regulatory policies and isregulated by the FDA as a food, not a drug," says Shangraw."Only products that bear a health claim stating that increasedfolic acid intake before conception and during early pregnancyreduces the risk of having a baby with neural tube defects, arerequired to meet a USP folic acid dissolution standard. Althoughthe products tested contained 1 mg of folic acid, were clearlylabeled prenatal vitamins and sold by prescription only, theytechnically did not have to meet dissolution standards. It seemsreasonable that they should," says Shangraw.
"For drugs it is standard to analyze blood levels to make surethe substance is absorbed. You must substantiate purity, safetyand efficacy with data in a drug application to the FDA. Butbecause nutritional supplements are regulated as a food, thestandards are different," says Hoag.
"Scientifically we know about how drugs are absorbed by thebody, but there has been very little research intobioavailability from vitamin tablets or capsules," saysShangraw.
Hoag and Shangraw say people should not stop taking theirvitamins. "Vitamins should preferably be taken with food andplenty of fluids. Any amount absorbed is beneficial, and no oneis sure what amount of folic acid is needed to reduce neuraltube defects," says Shangraw.
Materials provided by University Of Maryland At Baltimore. Note: Content may be edited for style and length.
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