Vitamin A

Ashwini Kalantri

M I C R O N U T R I E N T S

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Vitamins• Essential Nutrients• Types– Fat soluble – A, D, E, K–Water soluble – B group, C

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Vitamin A• 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• XN Night blindness• X1A Conjunctival xerosis• X1B Bitot spot• X2 Corneal xerosis• X3A Corneal ulceration, less than 1/3• X3B Corneal ulceration, more than 1/3• XS Corneal scar• XF Xerophthalmic fundus

Singh, K. "Modified classification of xerophthalmia." Indian Journal of Ophthalmology 39.3 (1991): 105.

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Deficiency

Extra-ocular• 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 Prevalence in population at

risk(6 Months – 6 Years)

Night blindness > 1%

Bitot’s spots > 0.5%

Corneal xerosis/corneal ulceration/keratomalacia > 0.01%

Corneal Ulcer > 0.05%

Serum retinol (less than 10 µg/dl) > 5%WHO TRS 672

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Recommended Dietary Allowance Group Retinol (µg) β – carotene

(µg)Adults

Man 600 4800Women 600 4800Pregnancy 800 6400Lactation 950 7600

Infants

0 – 6 months 350 -6 – 12 months 350 2800

Children

1 – 6 years 400 32007 – 9 years 600 4800

Adolescents

10 – 17 years 600 4800ICMR. “Nutrient requirement and recommended dietary allowances for Indians, A report of the expert group of the ICMR” 2010

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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