Vitamin A

Sunflower seeds are unusually rich in B complex vitamins. Sunflower seeds also contain a potent antioxidant team of selenium and vitamin E and are significantly deficient in vitamin A.

Vitamin A is essential for the normal differentiation of epithelial tissue as well as normal reproduction. Yellow and dark green vegetables as well as fruits are good sources of carotenoids, which serve as precursors of vitamin A.

However, egg yolk, butter, cream, and liver and kidneys are good sources of preformed vitamin A.

Vitamin A is necessary for vision, not hearing. The visual pigment rhodopsin is formed from the protein opsin and 11-cis-retinal.

Accutane causes birth defects of the face and brain if taken during the first trimester of pregnancy.

Vitamin A is not synthesized in the skin.

Vitamin D (derivatives of calciferol) can be synthesized in the skin under the influence of sunlight from 7-dehydrocholesterol, an intermediate in cholesterol synthesis. 

C i.e. Liver

A i.e. Retinol, Retinal, and Retinoic acid

C i.e. 11-Cis – Retinalaldehyde

In the dark phase – 11-Cis- retinalQ exists with opsin. In the light phase – 11 trans – retinal exist with opsin.

Visual Cycle

• The photosensitive pigment in the rods is called rhodopsin or visual purple. It has a peak sensitivity to light at 505nm.
• Rhodopsin consists of 11-Cis retinal specifically bound to protein opsin.
• Regeneration of rhodopsin requires isomerization of all trans retinal back to 11-Cis retinal.

Trans retinal after being released from rhodopsin is isomerized to 11-Cis retinal which spontaneously combines with opsin to form rhodopsin thus completing the cycle.

• Similar reactions are responsible for color vision in the cone cells.

Ans. is ‘b’ i.e., Vitamin A

Functions of Vit A

o Vitamin A is essential for –

1.Normal vision

          Retinol is necessory for functioning of retina.

          Regeneration of rhodopsin during dark light is vit A dependent          

          vit A deficiency causes defective dark adaptation.

2. Anti-infective

           Vitamin A is necessary for integrity of epithelial tissues that resist invasion by pathogens.

             Vitamin A has some role in immune response.

Anticancer effect

Beta-carotene has antioxidant property —› by virtue of this action it reduces the incidence of lung, breast, oral, esophageal and bladder cancers.

Skeletal – growth

Vitamin A supports skeletal growth.

Ans. is ‘a’ i.e., Bitot spot; ‘b’ i.e., Xerophthalmia & ‘c’ i.e., Night blindness

o The most characteristic and specific signs of vitamin A deficiency are eye lesions.

o These develop before the age of 2 years.

o The term xerophthalmia comprises all the occular manifestations of vitamin A deficiency.

Xerophthalmia (Dry eye)

o It is a syndrome due to deficiency of vitamin A.

o It has following stages

1.      Night blindness                          Earliest ocular symptom

2.      Conjuctival xerosis                    Earliest ocular sign

3.      Bitot’s spot

4.      Corneal xerosis

Keratomalacia & corneal ulcers

Ans. is ‘c’ i.e., 300 microgram

Daily dose of vitamin in

o Infants                                             300-400 microgram

o Children                                           400-600 microgram

o Adolescents                                      750 microgram

Ans. is ‘b’ i.e., Codliver oil

Amongst the given options, cod liver oil has highest concentration.

Ans. is ‘a’ i.e., 350 g 

Ans. is ‘None’

Vitamin ‘A’ requirment for a Pregnant woman is 800 mg/d.

Ans. is ‘c’ i.e., Sunflower seeds 

Ans. is ‘c’ i.e., 200000 iu 

Ans. is ‘a’ i.e., Fat 

Note : Retinol and carotene are fat, soluble.

Ans. Dose in first trimester of pregnancy is 1 lac IU

Ans. Vitamin A deficiency

Ans. D i.e. Polyneuritis

Ans. B i.e. Green leafy vegetables

Ans. C: 9 months

National programme for prevention of nutritional blindness focuses on

• Promoting consumption of vitamin A rich foods by pregnant and lactating women and by children under 5 years of age.
• Administration of massive doses of vitamin A up to 5 years. First dose of 100,000 IU with measles vaccination at 9 months and subsequent doses of 200,000 IU each, every 6 months up to the age of 5 years should be given.

Ans. D: Vitamin A

Fish liver oil is the richest source of vitamin A, but they are used as nutritional supplements rather than as food sources.

Ans. B: 6 months

National programme for prevention of nutritional blindness focuses on

• Promoting consumption of vitamin A rich foods by pregnant and lactating women and by children under 5 years of age.
• Administration of massive doses of vitamin A up to 5 years. First dose of 100,000 IU with measles vaccination at 9 months and subsequent doses of 200,000 IU each, every 6 months up to the age of 5 years should be given.

Ans. B: 1,00,000 IU

In its severest form, it often result in loss of vision.

Vitamin A deficiency is assessed on the basis of conjuctival xerosis and Bitot’s spot.

Ans. C: Vitamin A

Known as ‘the anti-infective vitamin’, vitamin A plays an essential role in protecting your body from infection. It keeps body surfaces healthy so they can act as barriers to invading micro-organisms.

Skin and membrane alteration partly explain increased sensitivity to infection during vitamin A deficiency. Even marginal deficits may induce modifications of lung membranes.

Vitamin A stimulates and enhances many immune functions including antibody response and the activity of various white blood cells such as T helper cells and phagocytes.

This immune-enhancing function promotes healing of infected tissues and increases resistance to infection.

Ans. B: 1,00,000 IU Orally

Ans. is ‘c’ i.e., 600 mcg

The Image Shows Bitots Spot due to deficiency of Vitamin A