Vitamin A – Complete Guide for Competitive Exams

Introduction

Vitamin A is a fat-soluble vitamin essential for vision, immunity, growth, and maintenance of healthy skin and epithelial tissues. Questions on Vitamin A are frequently asked in school exams, TET, DSC, SSC, NTPC, Group exams, and other competitive examinations.

Chemical Nature and Types of Vitamin A

Vitamin A occurs in two major forms:

1. Preformed Vitamin A

• Retinol

• Retinal

• Retinoic acid

• Found in animal sources

• Directly usable by the body

2. Provitamin A

• Carotenoids (mainly Beta-carotene)

• Found in plant sources

• Converted into Vitamin A inside the body

Sources of Vitamin A

Animal Sources

• Liver

• Fish liver oil

• Milk

• Butter

• Egg yolk

Plant Sources

• Carrot

• Spinach

• Green leafy vegetables

• Mango

• Papaya

• Pumpkin

Functions of Vitamin A

1. Helps in vision, especially night vision

2. Essential for formation of rhodopsin pigment

3. Supports growth and development

4. Improves immunity and resistance to infections

5. Maintains healthy skin and epithelial tissues

6. Important for reproductive health

Daily Requirement of Vitamin A

• Infants: ~400 µg/day

• Children: 400–600 µg/day

• Adults: 700–900 µg/day

(Values may slightly vary as per guidelines)

Deficiency Diseases of Vitamin A

Deficiency mainly affects the eyes and immune system.

• Night Blindness (Nyctalopia)

• Xerophthalmia – Dryness of eyes

• Bitot’s spots – White patches on conjunctiva

• Keratomalacia – Softening of cornea

• Frequent infections

Exam Highlight:
👉 Deficiency of Vitamin A causes Night Blindness

Hypervitaminosis A (Excess Intake)

Excess consumption of Vitamin A can lead to:

• Headache

• Nausea

• Dizziness

• Liver damage

• Bone pain

Excess beta-carotene usually does not cause toxicity.

Absorption and Storage

• Absorbed in intestine with the help of bile salts

• Stored mainly in the liver

• Being fat-soluble, it is not easily excreted

Important Exam Points (Quick Revision)

• Vitamin A is fat-soluble

• Known as Anti-infection vitamin

• Stored in liver

• Deficiency causes night blindness

• Beta-carotene is provitamin A

Frequently Asked Questions (FAQ) – Competitive Exams

Q1. Which vitamin is essential for night vision?
Vitamin A

Q2. Deficiency of Vitamin A causes which disease?
Night blindness

Q3. Vitamin A is stored in which organ?
Liver

Q4. Which pigment is formed with the help of Vitamin A?
Rhodopsin

Q5. Vitamin A is soluble in which substance?
Fat

Q6. Bitot’s spots are seen in deficiency of which vitamin?
Vitamin A

Q7. Which vitamin is known as the anti-infection vitamin?
Vitamin A

Q8. Which form of Vitamin A is found in plant foods?
Beta-carotene

Q9. Which disease is NOT caused by Vitamin A deficiency?
Rickets

Q10. Excess intake of Vitamin A causes which condition?
Hypervitaminosis A