What is TMAU?
Trimethylaminuria (TMAU) often referred to as ‘fish odour syndrome’ was first detected in 1970 by a group of doctors in Colorado who tested a child who was said at times to have a ‘fishy odor’.
Primary TMAU (also known as genetic TMAU) is caused by a defect of the FMO3 enzyme that should turn the (smelly) Trimethylamine (TMA) into the odourless TMA-oxide.
Secondary TMAU is not genetic and the main cause is due to an overgrowth of bacteria in the gut that produce TMA.
Symptoms are caused by a build up of the smelly TMA which is the excreted via the urine, sweat, breath and reproductive fluids leading to the characteristic fishy odour.
There are no physical symptoms associated with TMAU other than an unpleasant odour, however social and psychological symptoms are common due to the nature of the condition. Many people with TMAU seem to suffer intermittent or transient odour symptoms
Where does TMA come from?
A genetic inability to convert TMA into TMAO will lead to a build up of TMA and the characteristic odour.
Secondary TMAU is formed in the gut by the action of bacteria on certain foods that primarily contain choline and carnitine; for example eggs, certain legumes, fish and organ-meats. It can also be naturally found in certain seafood as TMA-oxide, which is broken down in the gut to TMA.
Symptoms of TMAU
In small quantities a build up of TMA can cause halitosis (bad breath) a fishy or garbage like odour but a greater build up of TMA can cause a smell of rotting fish as well as being sulphurous.
Symptoms can be present from birth, but most people seem to develop symptoms around puberty and through the teens however it TMAU can develop much later in life.
In women symptoms can be more severe just before and during menstruation, after taking oral contraceptives and around the time of menopause
What is being measured?
Free Trimethylamine (TMA) – odourous
TMA – oxide – non-odourous
Genetic TMAU is suspected if the TMA/TMAO ratio is above 0.21
Urine sample – Please see instructions that come with the test kit. Return postage costs are not included in the test fee.
Trying to provoke the odour for the sample is suggested. This is most commonly done by eating a high choline diet for a day or two before you complete the test.
See below and the instruction sheet for more advice.
Age range this test is suitable for
Adults and children
Children must be able to supply a sample of urine that is free from nappy fibres and stool samples.
Before taking the test
Please stop all current supplements for a 3 or 4 days before completing the test.
Many people restrict their diets in an attempt to control and reduce odour but this may affect an initial diagnosis as levels of TMA may be reduced to normal or give a normal TMA/TMAO ratio (less than 0.21).
It is necessary for diagnostic clarity that the sample is collected when odour is at it’s maximum. This may mean increasing dietary intake of choline (eg. pulses, eggs, liver), and carnitine (red meat) a few days before you take the test. Dietary ‘loading’ is possibly most effective when a simple high choline meal of 2 eggs and 400g baked beans the evening before completing the test.
Please avoid cruciferous vegetables – cabbage, broccoli, cauliflower and Brussel sprouts before completing the test. Indoles in these vegatables naturally inhibit the FMO3 enzyme which would skew the result.
Equally if you are worried about odour at certain times, such as around menstruation, it is important to collect urine at that time.
Please note: Not all causes of malodour are ruled out by this test. Malodour can be caused by other volatiles such as hydrogen sulphide, methanethiol, cysteamine and dimethyl sulphide. Unfortunately we cannot test for these at this time.
Please note: results can take up to 6-8 weeks as they are ran in batches and enough samples need to be collected before a batch is ran. The test is carried out at Sheffield Children’s Hospital
You will need to be responsible for returning the test kit and this should be by overnight courier. The package return is a a small jiffy bag measuring 25cm x 19cm x 5 cm weighting no more than 100g but delivery must be overnight (arriving within 24 hours of collection) for monday, tuesday or wednesday only
MEBO-Biolab TMAU Test Program
A five pound donation will be made to MEBO Research https://www.meboblog.com to support their continued work in the area of TMAU. For current events, please see MEBO’s blog, www.meboblog.com