Prostaglandins, Leukotrienes and Essential Fatty Acids

The relationship between seafood eaten during pregnancy and neurocognition in offspring has been the subject of considerable scientific study for over 25 years. Evaluation of this question led two scientific advisory committees to the Dietary Guidelines for Americans (DGAC), the Food and Agriculture Organization of the United Nations with the World Health Organization (FAO/WHO), Health Canada, the European Food Safety Authority (EFSA), and the U.S. Food and Drug Administration (FDA) to conclude through 2014 that seafood consumed by pregnant women is likely to benefit the neurocognitive development of their children. The evidence they reviewed included between four and ten studies of seafood consumption during pregnancy that reported beneficial associations. In contrast there are now 29 seafood consumption studies available describing over 100,000 mothers-child pairs and 15 studies describing over 25,000 children who ate seafood. A systematic review of these studies using Nutrition Evaluation Systematic Review methodology is warranted to determine whether recent research corroborates, builds on, or significantly alters the previous conclusions. Studies that evaluate the integrated effects of seafood as a complete food more directly and completely evaluate impacts on neurocognition as compared to studies that evaluate individual nutritients or toxicological constituents in isolation. Here we address how the findings could add to our understanding of whether seafood consumed during pregnancy and early childhood affects neurocognition, including whether such effects are clinically meaningful, lasting, related to amounts consumed, and affected by any neurotoxicants that may be present, particularly mercury, which is present at varying levels in essentially all seafood. We provide the history, context and rationale for reexamining these questions in light of currently available data. AAP, American Academy of Pediatrics; AHRQ, Agency for Healthcare Research and Quality; DGA, Dietary Guidelines for Americans; DGAC, Dietary Guidelines Advisory Committee; DHA, docosahexaenoic acid; EFSA, European Food Safety Authority, FAO/WHO, Food and Agriculture Organization/World Health Organization; FDA, U.S Food and Drug Administration; IOM, Institute of Medicine of the National Academy of Sciences; NESR, Nutrition Evaluation Systematic Review; RCTs, randomized controlled trials. https://doi.org/10.1016/j.plefa. 2019.10. 001 Received 26 September 2019; Accepted 10 October 2019 ⁎ Corresponding author. E-mail address: jhibbeln@mail.nih. gov (J.R. Hibbeln). Prostaglandins, Leukotrienes and Essential Fatty Acids 151 (2019) 8–13 0952-3278/ Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/BY/4.0/). T 1. Current developments present a major opportunity The 2020–2025 Dietary Guidelines for Americans (DGA) will address the following two questions: “What is the relationship between seafood consumption during pregnancy and lactation and the neurocognitive development of the infant? What is the relationship between seafood consumption during childhood and adolescence (up to 18 years of age) and neurocognitive development? ” [1] The answers to these questions could have significant public health impacts. The questions are also appropriate because there is considerably more published research available for evaluation since a systematic review of the evidence was conducted for the 2010–2015 DGA [2] and subsequent reviews were conducted by other entities through 2014 [3–7]. The inclusion of term “seafood” in these questions is significant because the 2020–2025 DGA will likely make recommendations for consuming seafood as a whole food in addition to any recommendations it may make about individual nutrients, e.g., fatty acids within seafood. Evaluating seafood consumption is inherently a “net effects” evaluation that implicitly “reflect[s] the sum of benefits and risks from all of the constituents in the fish” [3, p. 8]. As a practical matter, net effects are differences between scores on tests of neurocognition when seafood has been consumed (either by pregnant women or by children) and scores on the same tests when little or no seafood has been consumed. The differences, such as there may be, are measurable in study populations even if the contributions from individual constituents in seafood are not measured or even clearly understood. The sum of risks and benefits, i.e., the net effects from eating seafood under a plausible range of circumstances, essentially answers the two questions about seafood to be addressed by the 2020–2025 DGA. To evaluate these questions, we have conducted two systematic reviews utilizing methodologies detailed by the Dietary Guidelines for Americans Scientific Advisory Committee 2020–2025, USDA's Nutrition Evidence Systematic Review (NESR) team (https://nesr.usda.gov). This process is designed to be rigorous and transparent, such that it can be replicated by qualified professionals [https://nesr.usda. gov/2020dietary-guidelines-advisory-committee-systematic-reviews]. These reviews are reported in our accompanying article entitled: “Relationships between seafood consumption during pregnancy and childhood and neurocognitive development: two systematic reviews. ” These systematic searches and reviews of scientific databases identified 29 studies that examined relationships between seafood consumption during pregnancy and neurocognitive outcomes in over 100,000 children and 15 studies that examined the relationship between seafood consumed by over 25,000 children and their own neurocognitive outcomes. The latter studies make it possible for the first time to address the second 2020–2025 DGA question. 2. Reviews through 2014 In 2007 the Institute of Medicine of the National Academy of Sciences considered both the nutrients in seafood and results from early seafood studies and concluded that “There is evidence.to suggest that there are benefits to the developing infant, such as improved visual acuity, and improved cognitive development” from eating seafood during pregnancy [5]. The evidence cited by the Institute of Medicine included three prospective cohort studies that found beneficial associations between seafood consumption during pregnancy and visual acuity [8], visual recognition memory [9], and early language and communications skills [10]. In 2009 the Government of Canada issued “Prenatal Nutrition Guidelines for Health Professionals – Fish and Omega-3 Fatty Acids,” which recommended that women of childbearing age eat at least five ounces of fish each week based in part on “an association between higher intakes of fish and higher indices of child neurodevelopment” [4]. The Canadian Guidelines cited three prospective cohort studies that reported beneficial associations and also cited the 2007 Institute of Medicine report. The three studies involved visual recognition memory [9], attainment of developmental milestones [11], and improved prosocial behavior, fine motor skills, communication skills, and verbal IQ [12]. In 2010 the scientific advisory committee to the 2010–2015 Dietary Guidelines for Americans (DGAC) concluded that “moderate evidence” indicates at least two servings of seafood per week is associated with improved infant health outcomes including visual acuity and cognitive development [2, p. 239]. Studies cited by the 2010 DGAC included four “methodologically strong” prospective cohort studies that found beneficial associations between seafood consumption during pregnancy and visual recognition memory [9], earlier attainment of developmental milestones [11], improved prosocial behavior, fine motor skills, communication skills, and verbal IQ [12], and improved visual motor ability [13]. Three of the four studies had been cited by the Institute of Medicine or the Government of Canada or both. As an additional matter, the 2010 DGAC excluded results from studies of omega-3 supplements in isolation from its review. It observed that effects attributed to a single nutrient often reflect dietary components acting in synergy. On the basis of the 2010 DGAC's conclusion, the 2010–2015 DGA recommended that pregnant and lactating women eat considerably more seafood than they typically do for “improved infant health outcomes, such as visual and cognitive development” [14, p. 39]. Five years later, the scientific report from the 2015 to 2015 DGAC reiterated the conclusion from 2010 “that moderate evidence supported a positive relationship between maternal dietary intakes of n-3 [omega3 fatty acids] from seafood and improved cognitive ability in infants” [15, p. 206]. Consequently, the 2015–2020 DGA carried over its recommendation from 2010 that pregnant and lactating women eat more seafood and added that some of that seafood should contain higher amounts of omega-3 fatty acids [16, p. 24]. In 2010 the Food and Agriculture Organization of the United Nations together with the World Health Organization (FAO/WHO) convened an “expert consultation” involving scientists from 11 countries on the risks and benefits of seafood consumption [3]. Their review of the evidence included five prospective cohort studies of seafood consumption cited by the 2010 DGAC, the Government of Canada, and the 2007 report by the Institute of Medicine [9–13]. The expert consultation concluded that “maternal fish consumption lowers the risk of suboptimal neurodevelopment in . offspring compared with the offspring of women not eating fish in most countries evaluated” [3]. In addition to this review, the FAO/WHO expert consultation conducted a quantitative assessment of the net effects on childhood IQ from maternal consumption of nearly 100 species and types seafood. The assessment calculated that all these species and types improve IQ through at least 25 ounces of seafood per week (the assessment's “central estimate”). When the expert consultation deemed mercury in the seafood to be