21: Folate (Chapter 22a)
- Page ID
- 117154
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)The function of folate, in its various co-factor forms, is in mediating one-carbon metabolism, a network of pathways involving the transfer and utilization of single-carbon units, including methylene, forminino, methyl, methenyl, and formyl groups. Folate is thus essential for key biological functions, including the biosynthesis of DNA, serine and glycine metabolism, and methionine synthesis. Folate, in the form of 5‑methyltetrahydrofolate, along with vitamin B12 (as methylcobalamin), is required for the synthesis of methionine from homocysteine, and in turn the generation of S‑adenosylmethionine, a methyl group donor used in numerous reactions, including the methylation of DNA, RNA, proteins, and phospholipids. Clinical deficiency of folate is manifested as megaloblastic anemia, characterized by abnormal cell replication in the hematopoietic system, megaloblasts in the bone marrow and macrocytes in the peripheral blood. The megaloblastic anemia of folate deficiency is identical to that of vitamin B12 deficiency, and specific biomarker testing is essential to provide a differential diagnosis. Folate-related anemia occurs commonly in pregnant and lactating women in low- and middle-income countries. Clinical folate deficiency is less common in high-income countries, but subclinical deficiency is widespread, especially in women of reproductive age and in the presence of certain diseases and drugs. Notably, maternal folate nutrition before and in early pregnancy plays a critical role in fetal development, with conclusive scientific evidence that folic acid supplementation in early pregnancy protects against the occurrence of neural tube defects. Serum and red blood cell (RBC) folate are the biomarkers used to assess folate status, whilst plasma homocysteine provides a functional indictor of status.
- 21.1: Folate (22a.1)
- This page discusses the roles and forms of folate, including its importance in DNA synthesis and potential deficiencies. It highlights the success of folic acid fortification in reducing neural tube defects, with mandatory policies in 85 countries improving population health. Nonetheless, challenges exist in adherence to folic acid recommendations, particularly in Europe.
- 21.2: Biomarkers of folate status (Chapter 22a.2)
- This page highlights the importance of assessing folate status through biomarkers like serum folate, RBC folate, and plasma homocysteine. It discusses the role of various analytical methods in measuring folate, their challenges, and the significance of cutoff values in diagnosing deficiencies and neonatal risks for neural tube defects.
- 21.3: Conclusions (22a.3)
- This page discusses the importance of folate in one-carbon metabolism, influencing amino acid metabolism, DNA synthesis, and methylation. It highlights the need for accurate assessment of folate status via serum and RBC folate concentrations, with serum reflecting recent intake and RBC indicating long-term stores. Plasma homocysteine levels can suggest low folate but are influenced by other factors.