The Role of Seafood Consumption in Child Growth and Development

Publication forthcoming

Abstract

Seafood is a source of essential nutrients to support neurocognitive development of children and adolescents, but there are concerns about contaminant exposure. Assessing seafood as a food group, rather than a source of nutrients or contaminants, can inform future dietary guidance. This study aimed to update and assess relationships between seafood consumption during childhood and adolescence and neurocognitive development. Three electronic databases were searched until September 2024 to update a previous search from 2000 to 2019. Articles were included if associations were assessed between seafood intake during childhood and adolescence and neurocognitive development outcomes (cognitive development, social-emotional and behavioral development, movement/physical development, language/communication development, depression, anxiety, attention-deficit/hyperactivity disorder, and autism spectrum disorder). All articles were screened at title, abstract, and full-text levels by 2 independent analysts. Data were extracted by 1 analyst, quality checked by a second analyst, and synthesized narratively by 2 analysts independently, considering direction, magnitude, and statistical significance of results for each outcome; discrepancies were resolved via discussion. Risk of bias was assessed using ROBINS-E and ROB 2.0. Certainty of evidence was assessed with Grading of Recommendations Assessment, Development and Evaluation (GRADE). Eighteen articles from 5 short-term (12–16 wk) RCTs conducted in Northern Europe and 9 prospective cohort studies conducted in various countries were included. The evidence suggested a relationship between higher seafood consumption and improved cognitive development outcomes for children and adolescents aged 0–18 y old (GRADE: low). This conclusion was informed by 5 short-term RCTs in which children aged 10 mo to 15 y were provided fatty fish compared with meat, poultry, or fish oil supplements. These RCTs were largely supported by results from 5 longer-term prospective cohort studies. Evidence was inconsistent for social-emotional and behavioral development outcomes and was lacking for other outcomes. Seafood consumption within current recommended intake amounts consumed mainly as fatty fish likely improves cognitive development outcomes in children and adolescents.

Key Points

This study aimed to describe the scope of the evidence associated with seafood-related toxicant exposure and child outcomes and to identify toxicant-outcome pairs that may have sufficient evidence to conduct a systematic review.

Findings

81 studies were included: 69 studies on exposure during pregnancy and lactation and 14 on exposure during childhood. The number of studies varied by toxicant and exposure population (maternal; child): mercury (n = 49; 7), methylmercury (n = 13; 3), polychlorinated biphenyls (PCBs; n = 11; 1), selenium (n = 11; 1), lead (n = 9; 3), perfluoroalkyl and polyfluoroalkyl substances (n = 8; 2), dichlorodiphenyltrichloroethane (n = 5; 1), arsenic (n = 4; 4), cadmium (n = 4; 4), zinc (n = 3; 2), polybrominated diphenyl ethers (n = 3; 1), dioxin-like compounds (n = 3; 0), iron (n = 2; 1), and magnesium (n = 1; 1). No studies examined polybrominated biphenyls, polycyclic aromatic hydrocarbons, iodine, aldrin, dieldrin, chlordane, chlorpyrifos, or microplastic exposures. Outcomes also varied by exposure population (maternal;child): neurodevelopment (n = 35; 9), child exposure biomarkers (n = 22; 4), growth (n = 17; 1), other adverse events (n = 4; 0), cardiometabolic (n = 3; 2), chronic disease indicators (n = 2; 0), and immune-related (n = 1; 2). Twelve maternal toxicant-outcome pairs had ≥3 studies, including mercury, methylmercury, lead, PCBs, perfluoroalkyl and polyfluoroalkyl substances, and arsenic as exposures and neurodevelopment, child exposure biomarkers, growth, and cardiometabolic as outcomes. For child exposure, only mercury and neurodevelopment had ≥3 studies. In conclusion, this scoping review shows relevant evidence for 14 of the 22 toxicants. Only 12 maternal and 1 child toxicant-outcome pairs, the majority of which examined maternal (methyl)mercury exposure, had ≥3 studies, our cutoff for consideration for systematic review.

Meaning

This scoping review indicates a paucity of research examining seafood toxicants beyond mercury and exposure during childhood. Systematic reviews are required to evaluate the associations for each toxicant-outcome pairs.

Key Points

Beyond its nutritional benefits, seafood is a source of toxicant exposure including polychlorinated biphenyls (PCB). The association of PCB exposure from seafood intake during pregnancy and/or lactation (PL) and child growth outcomes is uncertain. This systematic review investigated the evidence and quantified the association between PCB exposure during PL from seafood intake and child growth outcomes.

Findings

PCB exposure during PL was weakly but significantly associated with lower birthweight [r_p = -0.07; 95% confidence interval (CI): -0.12, -0.02; n = 5], but showed no association with birth length (r_p = -0.04; 95% CI: -0.09, 0.02; n = 4) and head circumference (r_p = -0.03, 95% CI: -0.09, 0.03; n = 3).

Meaning

The evidence suggests minimal to no link between PCB exposure from seafood during PL on child growth outcomes but with low to very low certainty.

Key Points

Despite the essential nutrients, maternal seafood consumption during pregnancy or lactation (PL) is also a potential source of toxins, including lead (Pb). The association between exposure to Pb from seafood during PL on children’s neurodevelopment is uncertain. This systematic review assessed the association of exposure to Pb from seafood during PL on children’s neurodevelopment.

Findings

Four included articles from three prospective cohort studies in Asia examined cognition, motor development, and behavior in children 12-60 months. Only one study reported an analysis between seafood intake and lead concentrations during PL which showed a weak, insignificant association. Pb concentrations were not associated with child cognitive development or behavioral problems, but a weak, negative association with child motor development was reported. The certainty of evidence was very low due to few included studies with some or high risk of bias. Higher seafood intake in this evidence favored positive developmental outcomes from one prospective cohort study, though significance varied.

Meaning

Overall, evidence was not available to address a direct association between Pb exposure from seafood intake during PL and child neurodevelopment. Several other limitations resulted in a very low certainty of overall evidence.

Objective

The objective of this review was to summarize recent and relevant systematic reviews (SRs) that assessed relationships between mercury (Hg) exposure during pregnancy, lactation, and childhood and child outcomes.

Evidence review

Three electronic databases were searched for SRs published between January 2018 to December 2024 about Hg exposure (of any form or source, including seafood), during pregnancy, lactation or childhood and child outcomes including: anthropometrics, neurodevelopment, attention deficit hyperactivity disorder (ADHD), autism spectrum disorder (ASD), exposure biomarkers, cardiometabolic health, immunity, and birth outcomes. All articles were screened at title/abstract and full-text levels by two independent reviewers. A MeaSurement Tool to Assess systematic Reviews (AMSTAR) 2 critical appraisal tool was used to assess the methodological quality of the included SRs.

Findings

Twenty-nine SRs of observational studies were identified that assessed Hg during pregnancy (n = 19) and/or childhood (n = 17). During pregnancy, results from the SRs suggested that higher Hg may be associated with higher risk of birth defects, pre-term birth, ADHD, ASD, and low birth weight, length, and head circumference. Results varied for neurodevelopment outcomes in the child, likely due to co-exposure with seafood during pregnancy, variation in response by sex of the child, and etiological differences among developmental domains. During childhood, SRs suggested that higher Hg may be associated with higher risk of ADHD and adverse neurodevelopment, growth, and body composition outcomes. Also, Hg concentrations were higher in children with ASD than those without in case-control studies but longitudinal data were lacking. Evidence on methylmercury exposure from seafood during pregnancy and childhood was limited and inconclusive.

Conclusion and relevance

Mercury exposure during pregnancy and childhood is recognized as a major public health concern. However, more research is needed that specifically examines methylmercury from seafood to better inform future dietary recommendations.