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Folic Acid
Folic acid (vitamin B9) is a water-soluble vitamin essential for DNA synthesis, red blood cell formation, and fetal development. It is particularly important during pregnancy to prevent neural tube defects. This article synthesizes information from authoritative sources, including the British National Formulary (BNF), Lippincott Textbook of Pharmacology, Lange Basic & Clinical Pharmacology, Mayo Clinic, and Harvard Medical School, to provide a detailed overview of folic acid.
- Prevents Neural Tube Defects (NTDs):
- Reduces the risk of spina bifida and anencephaly in newborns when taken during pregnancy (Mayo Clinic).
- Supports Red Blood Cell Formation:
- Prevents megaloblastic anemia, characterized by large, immature red blood cells (BNF).
- Cardiovascular Health:
- Lowers homocysteine levels, reducing the risk of heart disease and stroke (Harvard Medical School).
- Cognitive Function:
- May slow cognitive decline in older adults (Lange).
- Cancer Prevention:
- Adequate folate intake is linked to a reduced risk of certain cancers, particularly colorectal cancer (Lippincott).
- Leafy Greens:
- Spinach, kale, and broccoli.
- Legumes:
- Lentils, chickpeas, and black beans.
- Fortified Foods:
- Cereals, bread, and pasta.
- Fruits:
- Oranges, bananas, and avocados.
- Animal Products:
- Liver and eggs.
Deficiency can lead to:
- Megaloblastic Anemia: Fatigue, weakness, and pale skin.
- Neurological Symptoms: Irritability, memory loss, and depression.
- Gastrointestinal Issues: Loss of appetite, weight loss, and diarrhea.
- Pregnancy Complications: Increased risk of neural tube defects (Mayo Clinic).
Risk Factors:
- Poor diet, alcoholism, malabsorption disorders (e.g., celiac disease), and certain medications (e.g., methotrexate).
- Normal: 2.7–17.0 ng/mL (Mayo Clinic).
- Deficiency: <2.0 ng/mL.
- Folic Acid Tablets:
- 400 mcg, 1 mg, 5 mg.
- Prenatal Vitamins:
- Typically contain 400–800 mcg of folic acid.
- Combination Formulas:
Often paired with iron or other B vitamins
- Pregnancy:
- Prevents neural tube defects; recommended dose is 400–800 mcg/day (BNF).
- Megaloblastic Anemia:
- Corrects folate deficiency anemia (Lippincott).
- Cardiovascular Health:
- Reduces homocysteine levels in high-risk individuals (Harvard Medical School).
- Methotrexate Therapy:
- Reduces side effects in patients taking methotrexate for rheumatoid arthritis or cancer (Lange).
Daily Requirements (RDA):
- Adults: 400 mcg/day.
- Pregnancy: 600 mcg/day.
- Lactation: 500 mcg/day.
Deficiency Treatment:
- Adults: 1–5 mg/day orally for 4 months (BNF).
Administration Tips:
- Take with food to enhance absorption.
- Do not exceed recommended doses unless prescribed.
Folic acid is generally safe but may cause:
- Mild: Nausea, bloating, or bitter taste.
- Rare: Allergic reactions (rash, itching).
- Vitamin B12 Deficiency: High folic acid doses can mask B12 deficiency, delaying diagnosis and treatment (Mayo Clinic).
- Pregnancy: Safe and essential for preventing neural tube defects (BNF Category: A).
- Cancer Risk: High doses (>1,000 mcg/day) may promote cancer growth in individuals with pre-existing lesions (Harvard Medical School).
- Methotrexate:
- Folic acid reduces toxicity but may interfere with efficacy in cancer treatment (Lippincott).
- Antiepileptics (e.g., phenytoin):
- Folic acid may reduce drug levels, increasing seizure risk (Lange).
- Sulfasalazine:
Reduces folic acid absorption, requiring supplementation (BNF).
- Folic Acid: Most common form.
- Folinic Acid (Leucovorin): Active form used in chemotherapy rescue.
