Maternal seafood consumption in pregnancy and neurodevelopmental outcomes in childhood (ALSPAC study): an observational cohort study
Hibbeln J ., et al., Lancet, 369: 578-585 (2007).
Laboratory of Membrane Biophysics and Biochemistry, US National Institute on Alcohol Abuse and Alcoholism, US National
The ALSPAC study (Avon Longitudinal Study of Parents and Children) was designed to assess for relationships between dietary patterns during and after pregnancy (including maternal seafood consumption in pregnancy) and subsequent health parameters of the children including neurodevelopmental outcomes and other parameters. The study included 11,875 pregnant women living in Bristol , UK , who completed a food frequency questionnaire which assessed their consumption of seafood (source of omega-3 fatty acids as DHA/EPA) at 32 weeks of gestation. The developmental, behavioural, and cognitive outcomes of the children from age 6 months to 8 years of age were assessed after separating seafood consumption amongst the women into three groups categorized as none, some ( 1-340 g/week), and >340 g/week of fish / seafood consumption.
Maternal seafood consumption during pregnancy of less than 340 grams per week was associated with an increased risk for their children being in the lowest quartile (bottom 25%) for verbal intelligence quotient (IQ). It is noted that 3 fish servings per week is the equivalent of 340-350 grams of fish/seafood per week in this study. In addition, a low maternal seafood intake was also associated with an increased risk of suboptimum outcomes for social behaviour, fine motor, communication, and social development scores. The lower intakes of seafood during pregnancy were associated with higher the risk for suboptimal developmental outcomes in the children. The authors also reported that the lower the fish intake, the more likely the children were to perform poorly in various assessment parameters. Those children of mothers who were found to have consumed no fish were more likely to have poor communication skills at 6 months (30% higher risk of suboptimal outcome), more likely to have poor fine motor coordination at age 42 months, more likely to have poor social behaviour at age 7 (44% risk), and more likely to have a relatively low verbal IQ at age 8 (48% risk) when compared with children of women who the highest intakes of fish (> 340 g/week).
The authors also reported that advice to restrict seafood consumption (source of omega-3 fatty acids) during pregnancy could be potentially detrimental and concluded from their results that the overall benefits to the health and well being of the children were greater than the risk of harm from exposure to trace contaminants via three servings of fish per week (approximately 340-350 g/ week).
Direct assessments of intakes of omega-3 fatty acids (as DHA + EPA) amongst pregnant women from our lab (Denomme at al., J Nutr., 135:206-211 (2005)) in Ontario (Canada) have indicated that the average intakes of DHA and EPA were approximately 85 mg and 35 mg, respectively, per day for a summed intake of these omega-3 fatty acids, mainly from fish/ seafood, of approximately 120 mg/day or 0.9- 1.0 g/week. In the present study on pregnant women living in the UK and surrounding areas, the average seafood intake per week was 235 grams or 0.9 g/week based on the types of seafood consumed and the estimated levels of DHA + EPA present therein. Interestingly, only 23% of the pregnant women were consuming > 340 grams per week of fish (associated with superior outcomes in the measured neurodevelopmental parameters in the children). This latter intake (> 3 fish servings per week) would be expected to provide at least 1.6 grams of DHA/EPA (omega-3) per week or a daily average intake of approximately 220 mg.
The present results support the encouragement of higher intakes of fish/ seafood during pregnancy when currently consumed in North America, the UK , and numerous other countries. The 1999 workshop in Bethesda, Maryland at the National Institutes of Health (supported by ISFFAL- International Society for the Study of Fatty Acids and Lipids) recommended a minimal intake of 300mg of DHA per day during pregnancy and lactation to support the supply of DHA to the baby during pregnancy and lactation in the recognition of the physiological essentiality of DHA for optimal brain/ neuronal functioning. Selected servings of fatty fish containing DHA omega-3 fatty acids 3-4 times per week can readily provide intakes of omega-3 fatty acids to meet the latter recommendations of 300 mg of DHA per day. A recent Canadian (Dr. E. Dewailly and colleagues in Quebec) study indicated, for example, that 3 servings of salmon (wild or farmed) or rainbow trout (wild or farmed) could provide such target intakes of DHA during pregnancy and lactation without exposure to levels of contaminants reaching cut- off safety levels set by the World Health Organization, the Environmental Protection Agency (US), or Health Canada. Nonetheless, discrimination in terms of the type of fish consumed during pregnancy needs to be communicated to the public such that the small minority of fish sources which may be problematic with respect to contaminants (eg., methyl mercury, others) may be avoided.