One of the rare inherited metabolic disorders that we work with is TMAU. It is a disorder that doesn’t cause any physical harm, but causes psychological distress. Over that past few years we have had increasing number of people being referred to our service with suspected TMAU. This is mainly due to increased exposure of the disorder on popular TV programs. I though I would give you a little insight into what it is and how it is treated.
Trimethylaminuria (TMAU) or Fish Odour Syndrome is a very distressing rare inherited metabolic disorder that causes the sufferer to smell of a variety of malodours including rotting fish, eggs and rubbish. The smell comes from their sweat, breath and urine. Although only recently discovered in the 1970’s, there has been references to it in history, for examples in Shakespeare’s The Tempest, Trinculo talks about a man who smells of a fish! It has been in the spot light more recently after being highlighted on TV programs such as Embarrassing Bodies, The Food Hospital, The One Show and This Morning.
Often the person themselves cannot smell it, but other people can, resulting in the person staying away from social situations and can become very withdrawn, lonely and depressed as they are worried about what people will say and think about them.
It is caused by the inability of the person to break down a smelly chemical in the body called Trimethylamine (TMA) into the non-odorous form Trimethylamine oxide (TMAO). The TMA builds up in the body and is excreted via urine and sweat producing the smell.
There are various treatments that can be tried to try and reduced the smell. These include restricting foods high in choline (as they are converted to TMA in the gut), the use of acidic (pH 5.5-6.5) soap and body lotions to help neutralise and remove TMA from the skin, using a short course of oral antibiotics to decrease the amount of bad bacteria in the gut that produces TMA and probiotics to change the balance of the gut flora.
Often people have the symptoms for years before getting diagnosed. GP’s have little knowledge of this disorder as it is so rare and it is often the patient that comes up with the diagnosis and then has to persuade the GP to get them tested or to be referred to a specialist centre.
Getting referred to a specialist metabolic service is very important to obtain the correct treatment and management. There is information on the internet, but is often factually incorrect or interpreted the wrong way. Many people try to follow the diet without help from a dietitian, they restrict their diet too much, leaving themselves at risk of nutritional deficiencies and weight loss. Our bodies need a minimum amount of choline per day and below this level it is harmful and liver complications can develop. Getting referred to a specialist dietitian for advice is essential so that they can help the person follow a low choline diet that provides adequate amounts of protein, carbohydrates, fats, vitamins and minerals.
Below gives you an idea of the low choline diet for TMAU suffers.
The main dietary principles are:
1) Foods that are very low in choline and can be eaten freely include bread, pasta, rice, potatoes, non-bran cereals, oats, egg whites, all fruits, most vegetables, olive and sunflower oils, sugar and confectionary.
2) 1-2 portions of meat (non offal) / fresh water fish / beans / pulses per day
3) 2-3 portions of dairy – milk, cheese, yoghurt
4) Foods to be avoided are marine fish and crustaceans (crabs, lobster) as they contain TMA, foods very high in choine – egg yolks and offal, and brassica vegetables (Broccoli, Brussel sprouts, Cauliflower) which are thought to contain a substance that reduces TMA being turned into TMAO.
The above is a guideline, not to replace tailored advice by a specialist dietitian. If you suspect you have TMAU then ask your GP to refer you to a specialist inherited metabolic disorders centre to check the diagnosis is correct before making changes to your diet.
Resources for article
Ellerton C, Chan H, Maritz C. Trimethylaminuria – Fish Odour Syndrome. Complete Nutrition Vol. 10, No.4, August 2010.
Busby M, Fischer L, Da Costa K, Thompson D, Mar M, Zeisel S. Choline- and Betaine- Defined diets for use in clinical research and for the management of Trimethylaminuria. Journal of American Dietetic Association. 2004. Vol 104, 1836-1845.