Background. Dietary fats are an important source of energy, essential fatty acids, and fat-soluble vitamins, and, as part of a nutritious diet, support optimal physical growth and cognitive development during fetal development, infancy, and childhood. To support possible updates and expansion the 2005 U.S.-Canadian Dietary Reference Intakes (DRIs), this systematic review was designed to identify and summarize the evidence on the relationships between consumption of omega-6 and/or omega-3 (n-6 and n-3) polyunsaturated fatty acids (PUFAs) during pregnancy and risk of preterm birth (Key Question 1), and between intake during pregnancy and/or lactation and infant and child growth and development (Key Question 2), and between intake of total fat (Key Question 3) or n-6 and/or n-3 PUFA (Key Question 4) by children between birth through 18 years of age and growth and developmental outcomes. Methods. A medical research librarian designed and conducted a search of Ovid MEDLINE®, CINAHL, and Cochrane CENTRAL from 1990 through October 2024. Researchers manually reviewed reference lists and responses to a Federal Register Notice request for information. Dual, independent review of abstracts and full-text articles was conducted using a priority specified inclusion and exclusion criteria. Established methods were used in dual, independent assessment of risk of bias. Data were synthesized quantitatively using meta-analyses when possible; randomized controlled trials (RCTs) and nonrandomized studies (NRS) not included in the meta-analyses were summarized qualitatively in tables and text. For each set of analyses with sufficient data, we assessed the strength of evidence (SOE) using set criteria and applicability of findings to a generally healthy population from the United States and Canada. Results. Searches identified 8,717 abstracts. Eighty-four studies in 124 publications were included across the four Key Questions. Of all the publications, 105 described RCTs and 19 described NRS; over half were rated high risk of bias (53%), followed by moderate risk of bias 30%) and low risk of bias ratings (17%). The population was generally healthy, with no diet- or nutrition-related conditions requiring supplementation with PUFA or total fat or unusual dietary patterns. In the 84 parent or standalone studies, the majority (70%) assessed the effects of dietary supplementation on outcomes, followed by diet only (26%), and then a combination of dietary and supplement intake (4%). Interventional exposure duration was generally less than 6 months, and only 4 studies followed offspring into early adolescence (up to 13 years). Overall, across all comparisons, additional PUFA or total fat intake in healthy populations resulted in similar growth and developmental outcomes versus no additional intake or different amounts. Studies reported no significant difference in infant weight with PUFA supplementation verses no supplementation during pregnancy (SOE: moderate), and no difference in risk of preterm birth <37 weeks (SOE: Low), or weight or head circumference with PUFA supplements during pregnancy and lactation (SOE: Low). There was insufficient or no evidence linking most developmental outcomes and to total fat intake. Of the 28 studies reporting differences in any outcome, exposure was primarily during pregnancy or infancy, from birth to 6 months of age, and was associated with growth outcomes, although differences were small and heterogeneity was high.Conclusions. There were few findings of differences across polyunsaturated fatty acid supplementation or dietary intake of fatty acids and growth and developmental outcomes in ahealthy population during pregnancy and childhood. The largest body of evidence consisted of RCTs with moderate or high risk of bias evaluating polyunsaturated fatty acid supplementation during pregnancy or infancy and growth outcomes in the first year of life. Of outcomes with sufficient evidence, heterogeneity in study design, exposures and comparators, and outcomes resulted in the strength of evidence being rated mostly as low. Additional PUFA and total fat intake in healthy populations, at the amounts that have been studied, may not confer demonstrable advantages, but the consistent finding of no difference suggests no harm. Additional research in older children and adolescents, studies with longer exposure durations, and populations who have diet- or nutrition-related conditions that may benefit from PUFA or total fat supplementation is needed to inform future DRIs.
Agency for Healthcare Research and Quality (AHRQ), HHS., 2025, Published date to be confirmed. 2024-26783.pdf