NEET PG Medical – 2018 – Question – 29
Fishy odour occurs due to deficiency of this vitamin from diet –
a) Biotin
b) Thiamine
c) Riboflavin
d) Vit. A
Correct Answer – C
Answer: C. Riboflavin
Vitamin B2 or riboflavin deficiency can bring about a fishy odor in the body.
* Fish-odor syndrome, also called trimethylaminuria, is a rare metabolic disorder caused by the absence of enzyne n-oxidase ( A Flavin containing monooxygenase, 3(FMO3). Gene for trimethylamine oxidase has been mapped on chromosome I(Iq23-q25).
* Trimethylamine is normally produced in the intestine from the breakdown of dietary choline and trimethylamine oxide by bacteria.
* Egg yolk and liver are the main sources of choline, and fish is the major source of trimethylamine oxide.
* Trimethylamine is absorbed and oxidized in the liver by trimethylamine oxidase (flavincontaining monooxygenases) to trimethylamine oxide, which is odorless and excreted in the urine. Deficiency of the enzyme results in massive excretion of trimethylamine in urine.
* Consequently, to these patients such foods may taste like rotten fish and import a fishy odor to their salvia, sweat and urine.
Treatment
* Restriction of fish, eggs, liver and other sources of choline (such as nuts and grains) in the diet significantly reduce the odor.
– Treatment with short course of oral
metronidamle, neomycin or lactulose causes temporary reduction in the body odor.
* Riboflavin supplement can be given to enhance residual FMO3 activity.
