ChemistryCBSE Class 12 · Biomolecules

Vitamins and Their Deficiency Diseases

Updated 15 October 2026 · Fact-checked

Vitamins are organic compounds needed in small amounts in the diet for growth and health. Vitamins A, D, E and K are fat soluble and are stored in the liver and fat tissue. B-group vitamins and vitamin C are water soluble, are lost in urine and must be taken regularly (except B12). Lack of each causes a specific disease.

Fat-soluble vitamins are stored in the body, but water-soluble ones are lost in urine; lacking each vitamin causes its own disease.

Illustration drawn for QuestionBuddy.

Understand Vitamins and Deficiency Diseases

What vitamins are. Vitamins are organic compounds required in small amounts in our diet; their deficiency causes specific diseases. Most vitamins cannot be synthesised in our body, but plants can make almost all of them, so they must come from food. They are named by letters (A, B, C, D, E, K), and the B vitamins are subdivided ( $B_{1}$ , $B_{2}$ , $B_{6}$ , $B_{12}$ ). Excess of vitamins is also harmful, so vitamin pills should not be taken without a doctor's advice.

Classification by solubility.

Fat-soluble vitamins: A, D, E and K. They dissolve in fats and oils but not in water, and are stored in the liver and adipose (fat-storing) tissues.
Water-soluble vitamins: the B group and vitamin C. They are readily excreted in urine and cannot be stored in the body (vitamin $B_{12}$ is the exception), so they must be supplied regularly in the diet.

Vitamins, sources and deficiency diseases (NCERT).

Vitamin A: fish liver oil, carrots, butter and milk. Deficiency: xerophthalmia (hardening of the cornea of the eye) and night blindness.
**Vitamin $B_{1}$ (thiamine): yeast, milk, green vegetables and cereals. Deficiency: beri beri** (loss of appetite, retarded growth).
**Vitamin $B_{2}$ (riboflavin): milk, egg white, liver, kidney. Deficiency: cheilosis** (fissuring at the corners of the mouth and lips), digestive disorders and a burning sensation of the skin.
**Vitamin $B_{6}$ (pyridoxine): yeast, milk, egg yolk, cereals and grams. Deficiency: convulsions**.
**Vitamin $B_{12}$ : meat, fish, egg and curd. Deficiency: pernicious anaemia** (red blood cells deficient in haemoglobin).
Vitamin C (ascorbic acid): citrus fruits, amla and green leafy vegetables. Deficiency: scurvy (bleeding gums).
Vitamin D: exposure to sunlight, fish and egg yolk. Deficiency: rickets (bone deformities in children) and osteomalacia (soft bones and joint pain in adults).
Vitamin E: vegetable oils such as wheat germ oil and sunflower oil. Deficiency: increased fragility of red blood cells and muscular weakness.
Vitamin K: green leafy vegetables. Deficiency: increased blood clotting time.

Using the table. Board questions give a symptom and ask for the vitamin, give a vitamin and ask for the disease, or ask you to classify vitamins by solubility and explain storage. Grouping helps: eye problems (A), nerve and growth problems with B1 and B6, mouth and skin with B2, blood with B12 and K, gums with C, bones with D, and red cell fragility and muscles with E. Vitamin D is unusual because exposure to sunlight is itself listed as a source.

This topic sits inside Biomolecules with enzymes, hormones and nucleic acids; vitamins are not polymers like carbohydrates and proteins, but small molecules with specific roles.

Vitamins and Deficiency Diseases: formulas and key facts

Fat-soluble vitamins: $A, D, E, K$; Stored in liver and adipose tissue.
Water-soluble vitamins: $B group (B_{1}, B_{2}, B_{6}, B_{12}), C$; Excreted in urine; must be taken regularly (except $B_{12}$ , which is stored).
Vitamin → deficiency disease: $A \to xerophthalmia, night blindness; B_{1} \to beri beri; B_{2} \to cheilosis; B_{6} \to convulsions$; From NCERT Table 10.3.
Vitamin → deficiency disease (continued): $B_{12} \to pernicious anaemia; C \to scurvy; D \to rickets, osteomalacia; E \to fragile RBCs, muscular weakness; K \to increased clotting time$; Learn the symptom with the name.
Key sources: $A : carrots, fish liver oil; C : citrus fruits, amla; D : sunlight, fish, egg yolk; K : green leafy vegetables$; One or two sources per vitamin are enough in answers.

How to solve Vitamins and Deficiency Diseases questions

Vitamin questions are factual but marks are lost through mixing up names. Follow a fixed recall path.

1Classify the vitamin first: fat soluble (A, D, E, K) or water soluble (B group, C).
2Recall its chemical name where NCERT gives one: $B_{1}$ thiamine, $B_{2}$ riboflavin, $B_{6}$ pyridoxine, C ascorbic acid.
3State the deficiency disease and one symptom (e.g. scurvy: bleeding gums).
4Give one or two sources from the NCERT table.
5For 'why' questions on storage, link water solubility to excretion in urine and fat solubility to storage in liver and adipose tissue.
6For symptom-based case studies, match the body system: eyes (A), mouth and skin (B2), nerves (B6), blood (B12, K), gums (C), bones (D), red cells and muscles (E).
7Avoid adding diseases or sources not in the NCERT table; examiners mark against it.

Vitamins and Deficiency Diseases in real life

Each concept, met in an everyday situation. Read the situation, try the problem, then check the solution. The one-line hook is what to remember.

Water-soluble vitamin C must be taken regularly

Suppose a sailor spends several months on a long voyage eating only biscuits, dried meat and grains, with no fresh fruit or vegetables. After some weeks his gums begin to bleed.

Name the disease and the vitamin involved. Explain why he developed it within weeks rather than years, and suggest two foods that would prevent it.

Try it first, then show the solutionSolution

Bleeding gums are a sign of scurvy, caused by deficiency of vitamin C (ascorbic acid).
Vitamin C is water soluble: it is readily excreted in urine and cannot be stored in the body.
Without a regular daily supply, the body's level falls quickly, so symptoms appear within weeks.
Citrus fruits (such as oranges or lemons) and amla, or green leafy vegetables, supply vitamin C.

Answer: Scurvy, from lack of vitamin C; it is water soluble and not stored, so it must be eaten regularly; citrus fruits or amla prevent it.

Memory hook: Water-soluble vitamins wash out daily, so the body needs them daily.

Tricks to remember Vitamins and Deficiency Diseases

Short memory aids. Say each one aloud once, then use it on a question the same day.

'ADEK' is fat
Fat-soluble vitamins spell ADEK; everything else (B, C) is water soluble.
Use it when: Classification questions.
Body map
A for eyes, B1 for appetite (beri beri), B2 for lips, B6 for nerves, B12 for blood, C for gums, D for bones, E for red cells and muscles, K for clotting.
Use it when: Matching symptoms with vitamins.
K is for Koagulation
Vitamin K (from the German 'Koagulation') prevents increased clotting time.
Use it when: Remembering vitamin K's role.

Vitamins and Deficiency Diseases: solved examples

Ordered from board level to HOTS. Try each one before you open the solution.

Example 1: Pernicious anaemia · 1 mark · MCQBoard level

Deficiency of which vitamin causes pernicious anaemia?
(a) Vitamin $B_{1}$ (b) Vitamin $B_{6}$ (c) Vitamin $B_{12}$ (d) Vitamin K

Try it first, then show the solutionSolution

Pernicious anaemia (red blood cells deficient in haemoglobin) is listed against vitamin $B_{12}$ .

Answer: (c) Vitamin $B_{12}$ .

Example 2: Fat or water soluble · 2 marks · Very short answerBoard level

Classify the following vitamins as fat soluble or water soluble: A, $B_{1}$ , C, D, E, K. Why must water-soluble vitamins be supplied regularly in the diet?

Try it first, then show the solutionSolution

Fat soluble: A, D, E, K. Water soluble: $B_{1}$ , C (1 mark).
Water-soluble vitamins are readily excreted in urine and cannot be stored in the body (except $B_{12}$ ), so they must be taken regularly (1 mark).

Answer: Fat soluble: A, D, E, K; water soluble: B1, C. They are excreted, not stored.

Example 3: Vitamin, source and disease · 3 marks · Short answerHarder board level

For each of the vitamins $B_{2}$ , D and E, give one source and the deficiency disease or symptom.

Try it first, then show the solutionSolution

$B_{2}$ (riboflavin): milk, egg white, liver; cheilosis (fissuring at corners of mouth and lips), digestive disorders, burning sensation of skin (1 mark).
D: exposure to sunlight, fish, egg yolk; rickets in children, osteomalacia in adults (1 mark).
E: vegetable oils such as wheat germ oil or sunflower oil; increased fragility of RBCs and muscular weakness (1 mark).

Answer: B2: milk/egg white, cheilosis. D: sunlight/fish, rickets and osteomalacia. E: wheat germ oil, fragile RBCs and muscular weakness.

Example 4: Storage and supply · 3 marks · Short answerHarder board level

(a) Why can vitamin A be stored in the body while vitamin C cannot? (b) Name the one water-soluble vitamin that is stored. (c) Why should vitamin pills not be taken without a doctor's advice?

Try it first, then show the solutionSolution

(a) Vitamin A is fat soluble and is stored in the liver and adipose tissue; vitamin C is water soluble and is readily excreted in urine (1½ marks).
(b) Vitamin $B_{12}$ (½ mark).
(c) An excess of vitamins is also harmful (especially fat-soluble ones, which accumulate in the body) (1 mark).

Answer: (a) Fat-soluble A is stored; water-soluble C is excreted. (b) $B_{12}$ . (c) Excess is harmful.

Example 5: Identify the vitamin from symptoms · 5 marks · Long answerHOTS / competency

Identify the vitamin whose deficiency is most likely in each case, and name one dietary source: (a) a child with bent leg bones; (b) an adult whose blood takes unusually long to clot after a small cut; (c) a person who cannot see well in dim light; (d) a patient with convulsions; (e) a person with cracks at the corners of the mouth.

Try it first, then show the solutionSolution

(a) Vitamin D (rickets); sunlight exposure, fish, egg yolk (1 mark).
(b) Vitamin K (increased clotting time); green leafy vegetables (1 mark).
(c) Vitamin A (night blindness); carrots, fish liver oil, butter, milk (1 mark).
(d) Vitamin $B_{6}$ , pyridoxine (convulsions); yeast, milk, egg yolk, cereals, grams (1 mark).
(e) Vitamin $B_{2}$ , riboflavin (cheilosis); milk, egg white, liver, kidney (1 mark).

Answer: (a) D. (b) K. (c) A. (d) B6. (e) B2.

Where students lose marks in Vitamins and Deficiency Diseases

The slips examiners see most often, and what to write instead.

Mistake: Mixing up B-vitamin diseases
Wrong working
$B_{1}$ deficiency → pernicious anaemia
Right working
$B_{1}$ → beri beri; $B_{12}$ → pernicious anaemia
Do this: Learn B1, B2, B6, B12 as a set with their diseases.
Usually costs: 1 mark.
Mistake: Listing vitamin C as fat soluble
Do this: Only A, D, E, K are fat soluble.
Usually costs: ½ to 1 mark.
Mistake: Forgetting osteomalacia for vitamin D
Do this: Give both: rickets (children) and osteomalacia (adults).
Usually costs: ½ mark.
Mistake: Saying no water-soluble vitamin is stored
Do this: Vitamin $B_{12}$ is the exception: it is stored.
Usually costs: ½ mark.

Exam tips

Reproduce the NCERT table in short form; examiners match answers against it.
Give the chemical name with the letter where NCERT provides one (thiamine, riboflavin, pyridoxine, ascorbic acid).
For deficiency diseases, add the key symptom in brackets (scurvy: bleeding gums).
In classification questions, mention storage sites (liver, adipose tissue) for fat-soluble vitamins.
Read case-study symptoms carefully: 'adult' with soft bones means osteomalacia, 'child' means rickets.

Practice questions on Vitamins and Deficiency Diseases

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

Q1 · 1 mark · MCQBoard level
Which of the following is a fat-soluble vitamin?
(a) Vitamin C (b) Vitamin $B_{1}$ (c) Vitamin K (d) Vitamin $B_{6}$
Hint
ADEK.
Answer
(c) Vitamin K.
Q2 · 2 marks · Very short answerBoard level
Name the deficiency diseases caused by the lack of (a) vitamin A and (b) vitamin D.
Hint
Eyes and bones.
Answer
(a) Xerophthalmia (hardening of the cornea) and night blindness. (b) Rickets in children and osteomalacia in adults.
Q3 · 2 marks · Very short answerHarder board level
Give one source and the deficiency disease of (a) thiamine and (b) ascorbic acid.
Hint
Thiamine is B1; ascorbic acid is C.
Answer
(a) Thiamine ( $B_{1}$ ): yeast, milk, green vegetables, cereals; beri beri. (b) Ascorbic acid (C): citrus fruits, amla, green leafy vegetables; scurvy (bleeding gums).
Q4 · 1 mark · Assertion-reasonHarder board level
Assertion (A): A person who eats a balanced diet but almost never goes out in daylight may still develop vitamin D deficiency.
Reason (R): Exposure to sunlight is one of the sources of vitamin D.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Hint
Check the sources of vitamin D in the NCERT table.
Answer
(a). Sunlight is a source of vitamin D, so too little exposure can cause deficiency (rickets or osteomalacia).
Q5 · 2 marks · Very short answerHarder board level
What are the deficiency symptoms of vitamin E? Name two of its sources.
Hint
Vegetable oils.
Answer
Increased fragility of red blood cells and muscular weakness. Sources: wheat germ oil, sunflower oil (vegetable oils).
Q6 · 3 marks · Short answerHarder board level
Where are fat-soluble vitamins stored in the body? Why is taking very large doses of them more risky than taking large doses of water-soluble vitamins?
Hint
Storage vs excretion.
Answer
In the liver and adipose (fat) tissue. Because they are stored, excess fat-soluble vitamins accumulate and can be harmful; excess water-soluble vitamins (except $B_{12}$ ) are largely excreted in urine. NCERT notes that excess vitamins are harmful, so pills should be taken only on medical advice.
Q7 · 3 marks · Short answerHOTS / competency
Suppose a person follows a strict diet with no meat, fish, eggs or dairy products for many years and develops anaemia in which red blood cells lack haemoglobin. Which vitamin is most likely deficient? Explain using its sources, and say why the problem may take a long time to appear.
Hint
Its NCERT sources are all animal foods.
Answer
Vitamin $B_{12}$ ; its deficiency causes pernicious anaemia. Its NCERT sources are meat, fish, egg and curd, all excluded from this diet. Unlike other water-soluble vitamins, $B_{12}$ is stored in the body, so the stores last a long time before deficiency appears.
Q8 · 4 marks · Case-basedHOTS / competency
Read and answer.
Suppose a school health camp records these findings: student P has bleeding gums; student Q has poor vision in dim light; student R has bones that are soft and painful (an adult teacher); student S has a cut that keeps bleeding much longer than normal.
(a) Name the deficiency disease (or condition) and the vitamin for P and Q. (1 mark)
(b) Name the disease and vitamin for R, and the related disease in children. (1 mark)
(c) Which vitamin is lacking in S? Give a source. (1 mark)
(d) Which of these four vitamins must be taken most regularly, and why? (1 mark)
Hint
Only one of the four is water soluble.
Answer
(a) P: scurvy, vitamin C. Q: night blindness, vitamin A. (b) Osteomalacia, vitamin D; rickets in children. (c) Vitamin K; green leafy vegetables. (d) Vitamin C: it is water soluble, excreted in urine and not stored, unlike A, D and K.

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

1.Which vitamins are fat soluble?Show answer
A, D, E and K.
2.Deficiency disease of vitamin C?Show answer
Scurvy (bleeding gums).
3.Chemical name of vitamin $B_{6}$ ?Show answer
Pyridoxine.
4.Deficiency of vitamin K causes?Show answer
Increased blood clotting time.
5.Which water-soluble vitamin can be stored?Show answer
Vitamin $B_{12}$ .
6.Deficiency disease of vitamin $B_{1}$ ?Show answer
Beri beri.

Vitamins and Deficiency Diseases: frequently asked questions

What are vitamins in Class 12 Chemistry?

Organic compounds needed in small amounts in the diet to perform specific biological functions; their deficiency causes particular diseases.

Why must vitamin C be taken daily?

It is water soluble, so it is readily excreted in urine and cannot be stored in the body.

Which vitamins are stored in the body?

The fat-soluble vitamins A, D, E and K (in the liver and adipose tissue), and vitamin B_{12}.

What disease does vitamin D deficiency cause?

Rickets (bone deformities) in children and osteomalacia (soft bones and joint pain) in adults.

Can taking too many vitamins be harmful?

Yes. Excess vitamins, especially fat-soluble ones that accumulate, can be harmful, so supplements should be taken only on medical advice.