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Vitamin A

  1. Retinol → Vitamin A alcohol
  2. Retinylester → Vitamin A ester
  3. Retinal → Vitamin A aldehyde
  4. Retinoic acid → Vitamin A acid
  5. Retionoic acid is most imp. from of Vit A Q
  6. Vit A from diet ingested as carotene (from plant source) and retinal (from animal sourcs)
    1. (beta- carotene yields highest amount of retinal)
  7. Absorbed Vit A is stored in liver as retinyl palmitate zinc is required for mobilization of retinyl pal imitate to free retinol 

Physiological Role of Vit A

  1. Functioning of retina and vision
    [Scotopsin + 11 – cis retinene]  → Light → Rhodopsin 11-trans retinere
    Dark → Scotopsin
    Vit A is needed for regeneration of rhodopsin Q
  2. Vit A also termed as anti-infective vitamin
    •  Maintaining integrity of epithelial tissue for resisting invasion by patnogens and for functional immne response
  3. Spermatogenesis and integrity of testicular and vaginal epithelium
  4. Antioxidant and scavenger of free radical due to this. Vit A and p. - carotene are said to reduce the incidence of lung, Breast, oral, oesophageal and bladder cancer.

Clinical feature of deficiency

Ocular manifestations
- Defective dark adaptation is the most characteristic early clinical feature, resulting in night blindness. Prolonged def. of Vit A in the diet results in a syndrome of xerophthalmia



 Primary sign

 Secondary sign


 Conjunctival xerosis

 XN Night blindness


 Bator’s spot Q

 XF Fundal Changes


 Corneal xerosis

 XS corneal scarring


 Corneal ulceration (<1/3 of cornea)



 Corneal ulceration (>1/3 of cornea)



Other Feature.

  1. Skin is dry and scaly
  2. Urogenital epithelium Metaplasia lead to infection and calculus
  3. Atrophy of germinal epithelium may interfere with the reproductive functions 

Factors influencing vitamin a status


Diarrhea, worms, other intestinal disorder impair vit A absorption while measles, resp tract infection and other febrile illness the ↑ metabolic demands PEM interferes with absorption storage and utilization of vitamin A.





  1. Every infant should be administrated one dose of 1 lakh units of vitamin A along with measles vaccine-at 9 months followed by four more doses of 2 lakh each at 18,24, 30 and 36 mouth.
  2. A endemic area, children suffering from measles and severe PEM should be adm two doses of oral vit A on two consecutive day
  3. Those with persistent diarrhea and other prolonged febrile conditions are given one dose in each episode keeping at least 1 month interval between the two doses 

Hypervitaminosis A

  1. The sym are nausea, vomiting; drowsiness and bulging of the fontanel. Diplopia, papilledema, cranial nerve palsies and other sym suggestive of brain tumor (pseudotumor cerebri) may also occur.
  2. Chronic hypervitaminosis A affect child has anorexia Pruritus, and lack of wt gain There is also irritability, tenders swelling of the bones, alopecia, hepatomegaly
  3. If given in first 6 weeks of pregnancy, causes craniofacial malformation in fetuses.

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