Trimethylaminuria (TMAU): Understanding Fishy Body Odor Causes & Care

Ian C. Langtree - Writer/Editor for Disabled World (DW)
Published: 2014/03/25 - Updated: 2025/04/19
Publication Type: Informative
Topic: Health and Disability - Publications List

Page Content: Synopsis - Introduction - Main - Insights, Updates

Synopsis: This article provides a clear, practical overview of trimethylaminuria (TMAU), a rare metabolic disorder causing a persistent fish-like body odor due to impaired breakdown of trimethylamine. It explains genetic and secondary causes, dietary triggers, and management strategies while emphasizing the psychosocial challenges faced by individuals - particularly those already navigating disabilities or age-related health concerns - who may struggle with stigma or isolation. By offering actionable advice and validating lived experiences, the piece serves as a valuable resource for understanding symptoms, reducing odor through lifestyle adjustments, and connecting readers to broader support networks - Disabled World (DW).

Introduction

Trimethylaminuria (TMAU) is a rare metabolic disorder also known as fish odor syndrome or fish malodor syndrome. THAU is a rare genetic disorder in which the human body's metabolic processes fail to alter the chemical trimethylamine, symptoms are often present from birth. Trimethylamine is notable for its unpleasant fishy smell. It is the chemical that gives rotten fish a bad smell. When the normal metabolic process fails, trimethylamine accumulates in the body, and its odor is detected in the person's sweat, urine and breath.

Main Content

Trimethylaminuria can affect men, women, and children, from newborns to the elderly in most countries around the world. When an individual tends to give off a strong fishy smelling body odor it can caused by a compound called trimethylamine or TMAU.

TMAU causes a defect in the normal production of the enzyme Flavin containing monooxygenase 3. Trimethylamine builds up in the body of patients with trimethylaminuria. The trimethylamine gets released in the person's sweat, urine, reproductive fluids, and breath, giving off a strong fishy or body odor.

People with trimethylaminuria end up with a build up of trimethylamine, which is then released through their sweat, urine, reproductive fluids, and breath. Many people who suffer from trimethylaminuria, known colloquially as "fish malodor syndrome," also suffer from depression as a result of disruptions trimethylaminuria can cause to social life, relationships, or career.

TMAU is listed as a "rare disease" by the Office of Rare Diseases (ORD) of the National Institutes of Health (NIH). This means that TMAU, or a subtype of TMAU, affects less than 200,000 people in the US population.

The condition seems to be more common in women than men, for unknown reasons. According to the National Human Genome Research Institute, scientists believe that it could be due to the higher levels of female sex hormones such as progesterone and/or estrogen, aggravate symptoms.

Currently, there is no cure and treatment options are limited for TMAU. It is possible for some people with this condition to live relatively normal, healthy lives without the fear of being shunned because of their unpleasant odor. Getting tested is an important first step as a simple urine test will give you the answer; a blood test is available to provide genetic analysis. The prominent enzyme responsible for TMA N-oxygenation is the FMO3 gene.

Ways that may help eliminate the fishy odor include avoiding foods containing trimethylamine and its precursors like:

Eggs
Liver
Peas
Beans
Kidney
Peanuts
Broccoli
Cabbage
Cauliflower
Soy products
Brussel sprouts
Milk from wheat-fed cows,
Lecithin and lecithin-containing fish oil supplements
Seafood (Freshwater fish have lower levels of trimethylamine N-oxide)

Also Try:

Using body soaps with a moderate pH, between 5.5 and 6.5
Avoiding factors that promote sweating, such as exercise, stress, and emotional upsets.
Taking low doses of antibiotics to reduce the amount of bacteria like trimethylamine in the gut
Taking activated charcoal or other supplements to decrease the concentration of free trimethylamine in the urine
Taking riboflavin (vitamin B2) supplements to enhance FMO3 enzyme activity. Recommended intake is 30 to 40mg taken 3 to 5 times per day with food.

TMAU Testing

The only test for trimethylaminuria at this time is a urine test for elevated levels of trimethylamine.

A similar test can be used to identify carriers of this condition - those individuals who carry one copy of a mutated gene but do not have symptoms. In this case, the person would be given a high dose of choline (one of the precursors of trimethylamine) and then have their urine tested for elevated levels of trimethylamine.

Dealing with trimethylamuinuria can be emotionally painful and isolating, but therapy and appropriate medical treatment can prove really helpful in alleviating some of its symptoms and repercussions.

Resources

Journal: Disabled World. Language: English. Author: Monell Chemical Senses Center. Electronic Publication Date: 2017-02-15. Last Revised Date: 2020-05-12. Reference Title: "Potential New Causes for TMAU - A Fishy Smelling Body Odor Disorder", Source: Potential New Causes for TMAU - A Fishy Smelling Body Odor Disorder. Abstract: Study provides new insight into causes of trimethylaminura, a genetically transmitted metabolic disorder that leads to accumulation of a chemical that smells like rotting fish. Retrieved 2020-05-12, from https://www.disabled-world.com/news/research/tmau.php - Reference Category Number: DW#108-12696.

US Foundation - The Trimethylaminuria Foundation is a 501 3 (C) non-profit corporation. The address is P.O. BOX 3361, Grand Central Station, New York, NY, 10163. Telephone: 212-300-4168.

Australian Foundation - A non-profit, charitable foundation with tax free status and tax deductibility against income for donors. 8 Ingram Street, Kensington, NSW 2033, AUSTRALIA Phone: 61-2-9663-0431.

Insights, Analysis, and Developments

Editorial Note: Recognizing and understanding conditions like TMAU is essential to fostering a more inclusive and compassionate society. Resources that demystify rare disorders not only offer crucial support to those directly affected but also raise broader awareness, encouraging patience, respect, and accommodation for visible and invisible health challenges. While trimethylaminuria remains underrecognized, articles like this demystify its complexities, bridging gaps between medical knowledge and daily life. For those affected, such clarity isn't just informative - it's a lifeline, affirming that solutions exist and they're not alone in navigating this invisible burden - Disabled World (DW).

Author Credentials: Ian is an Australian-born writer, editor, and advocate who currently resides in Montreal, Canada. He is the founder and Editor-in-Chief of Disabled World, a leading resource for news and information on disability issues. With a global perspective shaped by years of travel and lived experience, Ian is a committed proponent of the Social Model of Disability-a transformative framework developed by disabled activists in the 1970s that emphasizes dismantling societal barriers rather than focusing solely on individual impairments. His work reflects a deep commitment to disability rights, accessibility, and social inclusion. To learn more about Ian's background, expertise, and accomplishments, visit his full biography.