Abstract
BackgroundNutritionists advise pregnant women to eat fish to obtain adequate docosahexaenoic acid (DHA), an essential nutrient important for optimal brain development. However, concern exists that this advice will lead to excess intake of methylmercury, a developmental neurotoxicant.ObjectiveConduct a pilot intervention to increase consumption of high-DHA, low-mercury fish in pregnancy.MethodsIn April-October 2010 we recruited 61 women in the greater Boston, MA area at 12–22 weeks gestation who consumed <=2 fish servings/month, and obtained outcome data from 55. We randomized participants to 3 arms: Advice to consume low-mercury/high-DHA fish (n=18); Advice + grocery store gift cards (GC) to purchase fish (n=17); or Control messages (n=20). At baseline and 12-week follow-up we estimated intake of fish, DHA and mercury using a 1-month fish intake food frequency questionnaire, and measured plasma DHA and blood and hair total mercury.ResultsBaseline characteristics and mean (range) intakes of fish [21 (0–125) g/day] and DHA from fish [91 (0–554) mg/d] were similar in all 3 arms. From baseline to follow-up, intake of fish [Advice: 12 g/day (95% CI: -5, 29), Advice+GC: 22 g/day (5, 39)] and DHA [Advice: 70 mg/d (3, 137), Advice+GC: 161 mg/d (93, 229)] increased in both intervention groups, compared with controls. At follow-up, no control women consumed >= 200mg/d of DHA from fish, compared with 33% in the Advice arm (p=0.005) and 53% in the Advice+GC arm (p=0.0002). We did not detect any differences in mercury intake or in biomarker levels of mercury and DHA between groups.ConclusionsAn educational intervention increased consumption of fish and DHA but not mercury. Future studies are needed to determine intervention effects on pregnancy and childhood health outcomes.Trial registrationRegistered on clinicaltrials.gov as NCT01126762
Highlights
In recent years, there has been active interest in reconciling the potential benefits and harms of prenatal fish consumption to provide optimal fish consumption guidance [1]
Maternal age, pre-pregnancy BMI (25.6 [6.1] kg/m2), and other characteristics did not differ among groups at baseline (Table 1), the proportion of women working full-time was somewhat higher in the Advice + Gift Card group (50%) than in the other two groups (35%)
Estimated mean intakes of fish [21 (0–125) g/day], docosahexaenoic acid (DHA) from fish [91 (0–554) mg/d], and mercury from fish [1.4 (0–8.5) mcg/day], were not different across the 3 arms (Table 1), DHA intake from fish was somewhat higher in the Advice group than in the Advice + Gift Card (79 mg/day) and control (63 mg/day) women
Summary
There has been active interest in reconciling the potential benefits and harms of prenatal fish consumption to provide optimal fish consumption guidance [1]. 10% of women of childbearing age in the US have mercury levels higher than the recommended level of 5.8 μg Hg/L in blood or 1.2 μg Hg/g in hair [5,6]. Some experts recommend an even lower threshold of 3.5 μg Hg/L blood to provide maximal protection against harm [7]. Because of the demonstrated neurotoxicity of methylmercury and the particular susceptibility of the developing brain even at low exposure levels [8], the US Food and Drug Administration (FDA) and Environmental Protection Agency (EPA) have issued warnings recommending that pregnant women limit their fish consumption and choose fish species that tend to have lower levels of mercury [9]. Nutritionists advise pregnant women to eat fish to obtain adequate docosahexaenoic acid (DHA), an essential nutrient important for optimal brain development. Concern exists that this advice will lead to excess intake of methylmercury, a developmental neurotoxicant
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