Vitamins

Vitamin A

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Vitamin A, Retinol, Retinoic Acid

  • See also
  1. Vitamin A Deficiency
  2. Carotenoids (Beta Carotene)
  • Physiology
  • Function
  1. General
    1. Vitamin A (Retinol) is derived from ingested retinyl esters or pro-CarotenoidProteins (beta-carotene, alpha-carotene, and beta-cryptoxanthin)
    2. Most of Vitamin A (90%) is stored in the liver as retinyl esters and released as needed
  2. Vision
    1. Cis-Retinal is sythesized from Vitamin A (Retinol)
    2. Cis-Retinal combines with an opsin Protein to form Retinal photoreceptor pigments (rhodopsin in rods, iodopsin in cones)
  3. Epithelial Cell function (skin, mucosa)
    1. Helps maintain skin and mucosa integrity and innate imunity
    2. Roche (2021) Nutrients 13(2):302 +PMID: 33494277 [PubMed]
  4. Bone growth
    1. Promotes Osteoblast activity and inhibits Osteoclast activity
    2. Yee (2021) Molecules 26(6):1757 +PMID: 33801011 [PubMed]
  5. Glycoprotein synthesis
    1. Vitamin A appears to be a Cofactor in Glycoprotein synthesis
  • Pathophysiology
  1. Vitamin A Deficiency
    1. Night blindness
    2. Dry Cornea
    3. Dry Skin
  2. Vitamin A Toxicity or Overdose
    1. Vomiting
    2. Headache
    3. Altered Mental Status
    4. Alopecia
    5. Peeling skin
  • Preparations
  • Sources
  1. Animal products
    1. Liver (beef liver, cod liver oil)
    2. Chicken meat
    3. Egg yolk
    4. Fish oil
  2. Dairy products
    1. Whole milk
    2. Butter
    3. Margarine fortified with Vitamin A
  3. Dark green leafy vegetables
  4. Yellow-orange fruits and vegetables
    1. Apricot
    2. Cantaloupe
    3. Carrots
    4. Oranges
    5. Papayas
    6. Pumpkin
    7. Squash