Vitamins

Vitamin C

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Vitamin C, Ascorbic Acid

  • See Also
  1. Vitamin C Deficiency (Scurvy)
  • Preparations
  • Dietary Sources
  1. Citrus fruits
    1. Orange Juice (8 ounces contains 100 mg)
    2. Lemons
    3. Grapefruit
  2. Dark-green leafy vegetables
    1. Asparagus
    2. Broccoli
  3. Tomatoes
  • Dosing (Ascorbic Acid per day)
  1. Recommended Daily Allowance: 200 mg/day
  2. Minimum (Scurvy prevention)
    1. Formula fed infants: 35 mg/day
    2. Lactating mothers: 100 mg/day
    3. Other children and adults: 45-60 mg/day
  • Mechanism
  1. Key role of Vitamin C is in keeping iron reduced in hydroxylase enzymes
  2. Essential Cofactor for hydroxylation of procollagen Amino Acids: Proline, Lysine
    1. Proline and Lysine are converted to hydroxyproline and hydroxylysine via hydroxylase and Vitamin C
    2. Collagen's triple helix structure in connective tissue is reliant on procollagen hydroxylation
    3. When procollagen pathway is dysfunctional, Scurvy results (pupura, Petechiae, Gingival Bleeding)
  3. Tyrosine, as well as Phenylalanine, are converted to homogenistic acid via enzyme with Vitamin C
  4. Contributes to hair disulfide bond formation
  5. Cofactor in Norepinephrine biosynthesis (from Dopamine)
    1. Adrenal Gland has among the highest Vitamin C concentrations in the body
  6. Cofactor in carnitine biosythesis
  7. Oxidative promotion of iron absorption
  8. Has both antioxidant and pro-Oxidant effects
  • Effects
  1. Potential benefits of high intake
    1. Reduced risk of Senile Cataract
    2. Reduced risk of Cancer
    3. Reduced risk of Coronary Artery Disease
    4. Higher HDL Cholesterol concentrations
  2. Disproved Myths: non-benefits
    1. Does NOT prevent Upper Respiratory Infections
      1. Studied with short term studies
  • Adverse Effects
  • High doses of Vitamin C (>1 gram)
  1. Poorly absorbed
  2. Diarrhea
  3. Increased urinary oxylate excretion
    1. Nephrolithiasis risk
  • References
  1. Behrman (2000) Nelson Pediatrics, p. 182-4
  2. Rendon et al. (2017) Crit Dec Emerg Med 31(6): 15-21