Question:easy
Casal's necklace is seen in the deficiency of:
Casal's necklace is seen in the deficiency of:
Show Hint
Think of the photosensitive dermatitis of the 4 D disease.
Updated On: Jun 23, 2026
- Vitamin A
- Niacin
- Iron
- Vitamin B12
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The Correct Option is B
Solution and Explanation
Mnemonic-led: Casal's necklace equals pellagra equals the 4 Ds, and pellagra is caused by deficiency of Niacin (vitamin B3) plus its precursor tryptophan. The necklace itself is the photosensitive hyperpigmented dermatitis that rings the neck where sunlight strikes, so the answer is niacin.
Eliminate fast. Vitamin A loss gives ocular signs, night blindness, Bitot spots and xerophthalmia, not a neck rash. Iron loss gives microcytic hypochromic anaemia with spoon nails. Vitamin B12 loss gives megaloblastic anaemia with neurological deficits. Only niacin deficiency produces the dermatitis, diarrhoea and dementia triad with Casal's necklace, more often in women because estrogen metabolites inhibit tryptophan conversion.
Ref: DM Vasudevan, Textbook of Biochemistry, 6th edition, pg 395.
Eliminate fast. Vitamin A loss gives ocular signs, night blindness, Bitot spots and xerophthalmia, not a neck rash. Iron loss gives microcytic hypochromic anaemia with spoon nails. Vitamin B12 loss gives megaloblastic anaemia with neurological deficits. Only niacin deficiency produces the dermatitis, diarrhoea and dementia triad with Casal's necklace, more often in women because estrogen metabolites inhibit tryptophan conversion.
Ref: DM Vasudevan, Textbook of Biochemistry, 6th edition, pg 395.
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