A maternal dietary pattern characterised by fish and seafood in association with the risk of congenital heart defects in the offspring

Objective To identify maternal dietary patterns related to biomarkers of methylation and to investigate associations between these dietary patterns and the risk of congenital heart defects (CHDs) in the offspring. Design Case-control study. Setting Western part of the Netherlands, 2003-08. Population One hundred and seventy-nine mothers of children with CHD and 231 mothers of children without a congenital malformation. Methods Food intake was obtained by food frequency questionnaires. The reduced rank regression method was used to identify dietary patterns related to the biomarker concentrations of methylation in blood. Main outcome measures Dietary patterns, vitamin B and homocysteine concentrations, biomarkers of methylation (S-adenosylmethionine [SAM] and S-adenosylhomocysteine [SAH]) and the risk of CHD estimated by odds ratios and 95% confidence intervals. Results The one-carbon-poor dietary pattern, comprising a high intake of snacks, sugar-rich products and beverages, was associated with SAH (beta = 0.92, P < 0.001). The one-carbon-rich dietary pattern with high fish and seafood intake was associated with SAM (beta = 0.44, P < 0.001) and inversely with SAH (beta = -0.08, P < 0.001). Strong adherence to this dietary pattern resulted in higher serum (P < 0.05) and red blood cell (P < 0.01) folate and a reduced risk of CHD in offspring: odds ratio, 0.3 (95% confidence interval, 0.2-0.6). Conclusions The one-carbon-rich dietary pattern, characterised by the high intake of fish and seafood, is associated with a reduced risk of CHD. This finding warrants further investigation in a randomised intervention trial.