Question:
A fishy body odour can occur due to dietary deficiency of which vitamin?
A fishy body odour can occur due to dietary deficiency of which vitamin?
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FMO3 needs a flavin cofactor that comes from this B vitamin.
Updated On: Jun 24, 2026
- Biotin
- Thiamine
- Riboflavin
- Vitamin A
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The Correct Option is C
Solution and Explanation
Step 1: The enzyme that normally clears odourous trimethylamine (TMA) is flavin-containing monooxygenase 3 (FMO3), and like all flavin enzymes it depends on flavin cofactors (FAD/FMN).
Step 2: These flavin cofactors are derived from riboflavin (vitamin B2). When riboflavin is deficient, FMO3 activity falls, TMA accumulates, and a fishy odour appears. So the answer is riboflavin.
Step 3: This links a dietary cause (low riboflavin) to the same fishy-odour mechanism seen in genetic trimethylaminuria.
Step 4: The other vitamins are not involved in this pathway: biotin is a carboxylation cofactor, thiamine works in decarboxylation reactions, and vitamin A is for vision and epithelial health, none of which controls TMA oxidation.
Step 2: These flavin cofactors are derived from riboflavin (vitamin B2). When riboflavin is deficient, FMO3 activity falls, TMA accumulates, and a fishy odour appears. So the answer is riboflavin.
Step 3: This links a dietary cause (low riboflavin) to the same fishy-odour mechanism seen in genetic trimethylaminuria.
Step 4: The other vitamins are not involved in this pathway: biotin is a carboxylation cofactor, thiamine works in decarboxylation reactions, and vitamin A is for vision and epithelial health, none of which controls TMA oxidation.
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