Vitamin B9

  • Also called folate.
  • Function
    • Converted to tetrahydrofolic acid (THF), a coenzyme for 1-carbon transfer/methylation reactions.
    • Important for the synthesis of nitrogenous bases in DNA and RNA.
    • Found in leafy green vegetables. Absorbed in jejunum. Folate from foliage.
    • Small reserve pool stored primarily in the liver.
  • Deficiency
    • Macrocytic, megaloblastic anemia; hypersegmented polymorphonuclear cells (PMNs); glossitis; no neurologic symptoms (as opposed to vitamin B12 deficiency).
    • Labs: ↑ homocysteine, normal methylmalonic acid levels. Seen in alcoholism and pregnancy.
    • Deficiency can be caused by several drugs (eg, phenytoin, sulfonamides, methotrexate) & alcoholism (poor intake, impaired folate absorption, utilization, enterohepatic recycling)
    • Supplemental maternal folic acid at least 1 month prior to conception and during early pregnancy to ↓ risk of neural tube defects. Give vitamin B9 for the 9 months of pregnancy.

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