Vitamin A

Report
I C R O N U T R I E N T
Vitamin A
Ashwini Kalantri
Vitamins
• Essential Nutrients
• Types
– Fat soluble – A, D, E, K
– Water soluble – B group, C
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Vitamin A
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•
•
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Per-formed vitamin – Retinol
Pro-vitamin – β-carotene
1IU = 0.3µg retinol (0.55µg of retinol palmitate)
Retinol Equivalent (RE)
– 1µg retinol = 1 RE
– 1µg β–carotene = 0.167 RE
– 1RE = 3.333 IU of Vitamin A
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Functions
• Normal Vision
– Retinal pigmentation  vision in low light
• Integrity and function of glandular and epithelial
tissue of Respiratory System, Urinary Tract, Skin
and Eyes
• Skeletal Growth
• Anti-infective
• Protective against some epithelial cancers
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Sources
• Animal Foods: liver, eggs, butter, cheese, milk,
fish, meat
• Plant Foods: green leafy vegetables – spinach.
Yellow and green fruits – papaya, mango,
pumpkin. Roots – carrots.
• Fortified Foods: vanaspati, margarine, milk.
Liver stores Vitamin A as retinol palmitate.
Reserves for 6-9 months
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Deficiency
Xerophthalmia
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•
•
•
•
•
•
•
XN
X1A
X1B
X2
X3A
X3B
XS
XF
Night blindness
Conjunctival xerosis
Bitot spot
Corneal xerosis
Corneal ulceration, less than 1/3
Corneal ulceration, more than 1/3
Corneal scar
Xerophthalmic fundus
Singh, K. "Modified classification of xerophthalmia." Indian Journal of Ophthalmology 39.3 (1991): 105.
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Deficiency
Extra-ocular
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•
•
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Folicular Hyperkeratosis
Anorexia
Growth retardation
Mortality and morbidity due to respiratory
and intestinal infections.
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Prevention
• Improvement of diet
• Reducing the severity of the contributory
factors
– PEM, respiratory tract infection, diarrhea,
measles.
• 6 monthly massive dose administration
– 1,00,000 IU (6 months – 1 year)
– 2,00,000 IU (1 year – 6 years)
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Treatment
• Urgent treatment
• Early stages of Xerophthalmia  Massive
dose of Vitamin A (2,00,000 IU) orally.
Repeat after 4 weeks.
• All children with corneal ulcers
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Assessment
• Population surveys - clinical and biochemical
• Per-school children (6 months – 6 years)
Criteria
Night blindness
Bitot’s spots
Corneal xerosis/corneal
ulceration/keratomalacia
Corneal Ulcer
Serum retinol (less than 10 µg/dl)
WHO TRS 672
Prevalence in population at risk
(6 Months – 6 Years)
> 1%
> 0.5%
> 0.01%
> 0.05%
> 5%
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Recommended Dietary Allowance
Group
Adults
Man
Women
Pregnancy
Lactation
Infants
0 – 6 months
6 – 12 months
Children
1 – 6 years
7 – 9 years
Adolescents
10 – 17 years
Retinol (µg)
β – carotene (µg)
600
600
800
950
4800
4800
6400
7600
350
350
2800
400
600
3200
4800
600
4800
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ICMR. “Nutrient requirement and recommended dietary allowances for Indians, A report of the expert group of the ICMR” 2010
Toxicity
• Retinol
– Nausea, vomiting, anorexia and sleep disorders
– Skin desquamation, enlarged liver, papillar
odema
• Carotene
– Colour skin and plasma, not dangerous
• Teratogenic effects of massive dose of
vitamin A
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