UNC study links low carbohydrate intake to increased risk of birth defects
January 25, 2018
Women who are pregnant or planning to become pregnant may want to avoid diets that reduce or eliminate carbohydrates, as they could increase the risk of having babies with neural tube birth defects, according to a new study from the University of North Carolina at Chapel Hill’s Gillings School of Global Public Health.
The study found that women with low carbohydrate intake are 30 percent more likely to have babies with neural tube defects (NTDs) than are women who do not restrict their carbohydrate intake. NTDs include spina bifida (malformations of the spine and spinal cord) and anencephaly (absence of major portions of the brain and skull), both of which can lead to infant death or lifelong disability.
This is the first study to evaluate the relationship between low carbohydrate intake and having children with NTDs.
“Because avoiding or reducing carbohydrate intake is a relatively common dietary behavior, the findings of this study should encourage additional research on the relationship between low carbohydrate intake and birth defects,” said Tania Desrosiers, PhD, research assistant professor of epidemiology at the UNC Gillings School, who led the study. “For women with low carbohydrate intake, the increased risk of having a baby with an NTD may stem from not consuming sufficient levels of folic acid, since carbohydrate-rich foods such as pasta and bread are fortified with folic acid in the U.S.”
Folic acid is an essential nutrient that minimizes the risk of NTDs. According to a Centers for Disease Control and Prevention (CDC) study of data from the National Health and Nutrition Examination Survey (2007 to 2012), more than 20 percent of women in the U.S. have blood folate concentrations below the recommended level to reduce risk of NTDs. Desrosiers and her study collaborators found that dietary intake of folic acid among women with restricted carbohydrate intake was less than half that of other women.
The CDC recommends that all women who may become pregnant take a daily multivitamin with at least 400 micrograms of folic acid every day before and during pregnancy. However, because almost half of all pregnancies in the U.S. are unplanned, according to a 2016 study published in The New England Journal of Medicine, many women do not initiate folic acid supplementation until later in pregnancy, after an NTD may have occurred, making fortified foods an important source of folic acid for women who may become pregnant.
“Maternal diet before and during early pregnancy plays a significant role in fetal development,” said Desrosiers. “The results of our study reinforce how important it is for women who may become pregnant to talk to their health-care provider about any special diets or eating behaviors they routinely practice.”
The study was published in the journal Birth Defects Research on January 25.
Desrosiers collaborated with Anna Maria Siega-Riz, PhD, a former professor of epidemiology and nutrition at the Gillings School, now associate dean for nursing at the University of Virginia; Robert Meyer, PhD, adjunct professor of maternal and child health at the Gillings School; and Bridget Mosely, MS, of University of Colorado Hospital.
The study analyzed data from the National Birth Defects Prevention Study, which spanned 1998-2011 and included 11,285 pregnant women from Arkansas, California, Georgia, Iowa, Massachusetts, New York, North Carolina, Texas and Utah. Of these women, 1,740 had stillborn infants or terminations with anencephaly or spina bifida, while 9,545 had live-born infants without birth defects. The study was funded by the CDC.
Further investigation needs to be done to replicate these findings in other study populations, as well as to better understand the mechanisms underlying the relationship between carbohydrate intake and NTDs.