Vitamins are essential micronutrients required by the body in small quantities, yet their role in maintaining health is enormous. They regulate metabolic reactions, strengthen immunity, support growth, and ensure proper functioning of organs. When the body fails to receive these vitamins in adequate amounts, it leads to vitamin deficiency diseases — a high-yield topic frequently asked in government exams.
This comprehensive guide covers every vitamin, its functions, deficiency disorders, sources, prevention strategies, and exam revision keys.
1. Understanding Vitamins
Vitamins are organic compounds required for:
- Energy metabolism
- Immunity
- Growth and development
- Nervous system functions
- Tissue repair
Classification of Vitamins
Vitamins are broadly divided into:
A. Fat-Soluble Vitamins (A, D, E, K)
- Stored in liver and fatty tissues
- Absorption requires bile
- Deficiency develops slowly
- Risk of toxicity if consumed in excess
B. Water-Soluble Vitamins (B-complex & C)
- Not stored extensively in the body
- Excess amounts excreted through urine
- Deficiency occurs quickly
- Low risk of toxicity
✔️ Read more about: Water-Soluble Vitamins
2. Vitamin-Wise Breakdown of Deficiency Diseases
Below is a detailed, exam-oriented explanation of each vitamin, its functions, deficiency disorders, and food sources.
3. Fat-Soluble Vitamins
3.1 Vitamin A (Retinol)
Functions
- Essential for vision (rhodopsin formation)
- Maintains epithelial tissues
- Boosts immunity
- Helps in bone growth
Deficiency Diseases
- Night Blindness – inability to see in dim light
- Xerophthalmia – dryness of eyes
- Bitot’s Spots – foamy patches on conjunctiva
- Keratomalacia – corneal softening, can lead to blindness
Exam Tip: Vitamin A deficiency is a major cause of preventable childhood blindness.
Food Sources
- Carrots, spinach, pumpkin
- Milk, butter, egg yolk
- Fish liver oil
- Orange and yellow fruits
3.2 Vitamin D (Calciferol)
Functions
- Regulates calcium–phosphorus metabolism
- Essential for bone and teeth health
- Hormone-like action
Deficiency Diseases
- Rickets (children)
- Bow legs
- Bone deformities
- Delayed teething
- Osteomalacia (adults)
- Soft bones
- Bone pain and muscle weakness
Exam Trick:
- Rickets → children
- Osteomalacia → adults
Sources
- Sunlight (most important)
- Egg yolk
- Cod liver oil
- Fortified milk
3.3 Vitamin E (Tocopherol)
Functions
- Powerful antioxidant
- Protects cell membranes
- Supports reproductive health
- Prevents oxidative stress
Deficiency Disorders
- Neuromuscular weakness
- Muscle degeneration
- Hemolytic anemia (in infants)
Sources
- Almonds, peanuts
- Vegetable oils
- Wheat germ
- Green leafy vegetables
3.4 Vitamin K
Functions
- Essential for blood clotting (prothrombin formation)
- Supports bone metabolism
Deficiency Disorders
- Prolonged bleeding
- Hemorrhage
- Internal bleeding (in severe cases)
Exam Pointer
- Newborns are prone to Vitamin K deficiency; hence they receive Vitamin K injections at birth.
Sources
- Spinach, cabbage
- Broccoli
- Gut bacteria synthesis
- Meat and dairy
4. Water-Soluble Vitamins
4.1 Vitamin B1 (Thiamine)
Functions
- Carbohydrate metabolism
- Nerve functioning
- Muscle coordination
Deficiency Diseases
- Beriberi
- Dry Beriberi: nerve degeneration, muscle wasting
- Wet Beriberi: cardiac failure, edema
- Wernicke–Korsakoff Syndrome – seen in alcoholism; memory loss/confusion
Sources
- Whole grains
- Nuts
- Meat
- Legumes
4.2 Vitamin B2 (Riboflavin)
Deficiency Disorders (Ariboflavinosis)
- Cheilosis – cracked lips
- Glossitis – magenta-colored tongue
- Dermatitis
- Photophobia
Sources
- Milk, curd
- Eggs
- Green leafy vegetables
4.3 Vitamin B3 (Niacin)
Deficiency Disease
- Pellagra – characterized by the famous 4 Ds:
- Dermatitis
- Diarrhea
- Dementia
- Death (if untreated)
Sources
- Groundnuts
- Chicken, fish
- Cereals
- Mushrooms
4.4 Vitamin B5 (Pantothenic Acid)
Deficiency
- Extremely rare
- Fatigue
- Irritability
- Numbness
Sources
- Egg yolk
- Whole grains
- Avocado
- Broccoli
4.5 Vitamin B6 (Pyridoxine)
Functions
- Amino acid metabolism
- Hemoglobin synthesis
- Brain health
Deficiency Disorders
- Dermatitis
- Convulsions
- Anemia
- Depression & irritability
Sources
- Fish
- Bananas
- Nuts
- Whole grains
4.6 Vitamin B7 (Biotin)
Deficiency
- Hair loss
- Skin rashes
- Brittle nails
- Neurological issues
Sources
- Egg yolk
- Nuts
- Soybeans
- Whole grains
4.7 Vitamin B9 (Folic Acid)
Deficiency Disorders
- Megaloblastic anemia
- Neural tube defects (NTDs) in fetus
- Spina bifida
- Anencephaly
Important for Exams
Pregnant women require folic acid supplementation to prevent NTDs.
Sources
- Spinach
- Legumes
- Citrus fruits
4.8 Vitamin B12 (Cobalamin)
Deficiency Disorders
- Pernicious anemia
- Tingling sensation
- Memory loss
- Nerve degeneration
Note for Vegetarians
B12 is mainly in animal foods; vegetarians often require supplements.
Sources
- Meat
- Fish
- Eggs
- Dairy
4.9 Vitamin C (Ascorbic Acid)
Functions
- Collagen synthesis
- Immunity
- Iron absorption
- Antioxidant action
Deficiency Disease
- Scurvy
- Bleeding gums
- Joint pain
- Poor wound healing
- Anemia
Sources
- Citrus fruits
- Amla
- Tomatoes
- Green peppers
5. High-Yield Exam Table: Vitamins & Deficiency Diseases
| Vitamin | Key Function | Deficiency Disease | Identification Trick |
|---|---|---|---|
| A | Vision | Night blindness, xerophthalmia | “A for Augen (German for eyes)” |
| D | Bone health | Rickets, osteomalacia | Sun → D-light (delight) |
| E | Antioxidant | Muscle weakness | E = Energy protector |
| K | Clotting | Hemorrhage | K = Koagulation |
| B1 | Nerve health | Beriberi | 1 word = “Beri” |
| B2 | Skin & mucosa | Cheilosis | Riboflavin → Ribbed lips |
| B3 | Metabolism | Pellagra | 4 D’s |
| B6 | Hemoglobin | Anemia | “6 letters in anemia” |
| B9 | Growth | Megaloblastic anemia | Folic = Fetus |
| B12 | Nerves | Pernicious anemia | 12 → dozen nerves |
| C | Collagen | Scurvy | C = Collagen |
6. Causes of Vitamin Deficiencies
- Poor dietary habits
- Malabsorption disorders
- Chronic alcoholism
- Poverty & limited food availability
- Excessive food processing
- Old age
- Certain medications
7. Symptoms of Vitamin Deficiency (General)
- Fatigue
- Weak immunity
- Skin rashes
- Bone pain
- Vision problems
- Hair fall
- Anemia
- Neurological issues
These symptoms often overlap, making early identification important.
8. Prevention Strategies
- Balanced diet with fruits, vegetables, grains & proteins
- Fortified foods (milk, cereals, oils)
- Supplements when medically necessary
- Government nutrition programs
- Proper cooking methods to preserve vitamins
9. Exam Tips for Quick Revision
- Pellagra = Niacin deficiency = 4 Ds
- Beriberi = Thiamine deficiency → think B1
- Bleeding disorder = Vitamin K deficiency
- Scurvy = Vitamin C deficiency
- Night blindness = Vitamin A deficiency
- Rickets/Osteomalacia = Vitamin D
10. Frequently Asked Questions
Q1. Why are fat-soluble vitamins stored longer?
They dissolve in body fat and accumulate in the liver, unlike water-soluble vitamins which are excreted through urine.
Q2. Can vegetarians become Vitamin B12 deficient?
Yes. B12 mainly comes from animal foods; vegetarians often require fortified foods or supplements.
Q3. Which vitamin deficiency is responsible for neural tube defects?
Vitamin B9 (Folic acid).
Q4. Why do children commonly suffer from Vitamin A deficiency?
Poor diet, infections, and lack of supplementation increase risk.
Conclusion
Vitamin deficiency diseases are preventable yet widespread due to poor nutrition and limited awareness. Understanding the functions, deficiency symptoms, and dietary sources of each vitamin is crucial for both health and competitive exam preparation. The key is a balanced diet, proper supplementation when needed, and regular revision of high-yield points.
