A new study has suggested that people with unexplained body odour may not have much control over the problem.
Researchers at the Monell Chemical Senses Centre in Philadelphia found that almost a third of the 353 people who attended the centre for help with their odour problem suffered from a condition known as trimethylaminuria, or TMAU.
TMAU is a genetic disorder which stops a person from metabolising trimethylamine, a chemical linked with certain foods such as eggs, some fish and certain beans. Without it in operation, the person may produce an embarrassing fishy smell.
But you can't rule this disorder out if your bad smell isn't quite of the fishy variety, with one researcher revealing the condition could be present for all with the embarrassing problem.
"Although the scientific and popular literature typically describes TMAU sufferers as smelling fishy, our sensory exams demonstrated this not to be so," researcher George Preti from Monell said in a statement. "The odours are diverse and only after a choline challenge do the most severe cases have a fish-like odour."
So spare a thought for that man on the train who was making you feel ill yesterday he might not be able to help it.