What This Means
This hospital-based study in China compared 620 children with congenital heart disease (CHD) and their mothers to 620 children without birth defects and their mothers. Mothers answered questions about what they ate and whether they took folic acid around conception. The researchers also tested the children's DNA for variants in two genes, BHMT and BHMT2, which are involved in processing nutrients linked to heart development.
Mothers of children with CHD were more likely to report eating a lot of smoked, barbecued, fried foods and pickled vegetables in early pregnancy. Regular intake of fish and shrimp, eggs, beans and dairy, and taking folic acid around conception, were linked to lower CHD risk. Three BHMT gene variants (rs3733890, rs1316753, rs1915706) were linked to roughly 1.6- to 2.7-fold higher odds of CHD in the children, with similar patterns for atrial and ventricular septal defects. The gene variants also appeared to interact with maternal intake of fish, shrimp and beans, so the diet effect and genetic effect did not simply add up.
This research suggests that both maternal diet and genetic makeup relate to CHD risk. Because this is a case-control study with diet reported by the mothers after the fact, it shows associations rather than proof of cause and effect, and the findings come from a single hospital, so they may not apply everywhere.