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Health effects of excess folic acid and high blood folate during preconception and pregnancy: systematic review
Journal article   Open access   Peer reviewed

Health effects of excess folic acid and high blood folate during preconception and pregnancy: systematic review

Carolyn Ledowsky, Vanessa Scarf, Agata Sobczyńska-Malefora, Tristan Carter, Nathan E. Timbrell and Amie Steel
Reproductive biomedicine online, Vol.First online, pp.1-83
12/09/2025
Appears in  Recent Faculty of Health Publications
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Health effects of excess folic acid use and high blood folateView
Published (Version of record) Open CC BY V4.0

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Abstract

Folate Folic acid Gestational diabetes Maternal health Preconception Pregnancy
Adequate folate is essential to prevent neural tube defects; therefore, supplementation with folic acid is widely recommended for women during preconception and early pregnancy. However, the potential risks associated with excessive intake of folic acid and/or an elevated blood folate concentration are not well recognized. The aim of this review was to evaluate the potential adverse health outcomes associated with excessive intake of folic acid and/or an elevated blood folate concentration during preconception and pregnancy. The review included studies that measured intake of folic acid via dietary sources and supplements, and/or quantified serum/plasma and red blood cell folate concentrations. Excessive intake of folic acid and an elevated blood folate concentration were associated with several adverse outcomes. The most notable association was with gestational diabetes mellitus, where elevated intake of folic acid and a high blood folate concentration were found to increase the risk. Excessive intake of folic acid supplements and a high blood folate concentration were associated with gestational diabetes mellitus, and adverse neurodevelopmental issues in offspring, as well as large-for-gestational-age infants and higher birth weight. Clear definitions of safe upper limits for intake of folic acid and blood folate concentration are needed urgently to prevent potential adverse outcomes.

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