Fish Odour Syndrome

If your doctor decides you are afflicted with Fish Odour Syndrome, he might soften the blow by claiming you have a condition called Trimethylaminuria.

The symptoms of Fish Odour Syndrome can be present from birth, but they may not start until later in life, often around puberty. That smell may be constant or may come and go.

The only symptom is that you emit an unpleasant smell, typically of rotting fish – although some might describe it as smelling like other smelly things – that can affect your breath, sweat, urine, and vaginal fluids.

In the Fish Odour Syndrome, the body is unable to turn a strong-smelling chemical called trimethylamine – produced in the gut when bacteria break down certain foods – into a different chemical that doesn't smell. This means trimethylamine builds up in the body and gets into bodily fluids like sweat. That particular sweaty condition is also called Bromhidrosis.

The problem lies in a faulty gene, the FMO3 gene. It provides instructions for making an enzyme that is part of a larger enzyme family called flavin-containing dimethylaniline monooxygenases (FMOs). These enzymes break down compounds that contain nitrogen, sulfur, or phosphorus. The FMO3 enzyme, which is made chiefly in the liver, is responsible for breaking down nitrogen-containing compounds derived from the diet.

Things that can make it worse include sweating, stress, periods and certain foods – such as fish, eggs, and beans.

The Fish Odour Syndrome is probably caused by one or more faulty genes that a person inherits from their parents, but this isn't always the case.

There's currently no cure. Patients are advised to avoid choline-rich foods and take hygienic measures[1].

[1] Kloster, Erichsen: Trimethylaminuria in Tidsskrift for den Norske lægeforening - 2021