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

Vitamin A

Ashwini Kalantri

Vitamins

• Essential Nutrients • Types – Fat soluble – A, D, E, K – Water soluble – B group, C 2

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 3

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 4

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 5

Deficiency

Xerophthalmia

• 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.

6

Deficiency

Extra-ocular

• Folicular Hyperkeratosis • Anorexia • Growth retardation • Mortality and morbidity due to respiratory and intestinal infections.

7

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) 8

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 9

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% 10

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)

600 600 800 950 350 350 400 600 600

β – carotene (µg)

4800 4800 6400 7600 2800 3200 4800 4800

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 12