Fish Odour Syndrome - Types, Causes, Symptoms, Treatments

Fish Odour Syndrome: How Trimethylamine Builds Up in the Body

Trimethylaminuria (TMAU), commonly known as fish odour syndrome, is a rare but distressing condition that disrupts the daily life of affected individuals by causing a strong, unpleasant body odour. Read on to learn about the causes and factors contributing to fish odour syndrome.

Role of Trimethylamine in Fish Odour Syndrome

Trimethylamine (TMA) is a foul-smelling compound produced in the gut when bacteria break down nutrients like choline, lecithin, and carnitine that are commonly found in fish, eggs, beans, milk, and liver. Normally, an enzyme converts TMA into an odourless substance.

However, in individuals with trimethylaminuria (TMAU), this conversion is impaired. As a result, TMA builds up in the body and is released through sweat, urine, and breath, causing a strong, fish-like odour characteristic of the condition.

Role of the FMO3 Gene in Trimethylaminuria

The FMO3 gene provides instructions for producing the enzyme flavin-containing monooxygenase 3, which breaks down trimethylamine (TMA) into an odourless compound. Mutations in the FMO3 gene impair this process in individuals with trimethylaminuria (TMAU).

As a result, TMA accumulates in the body and is released through sweat, urine, or breath, causing the characteristic fishy body odour associated with the condition.

Types of Fish Odour Syndrome

Read below to understand the two types of fish odour syndrome in detail:

• Primary Trimethylaminuria: Primary trimethylaminuria is the most common form of this syndrome. It gets inherited in an autosomal recessive pattern. When a person inherits faulty copies of the FMO3 gene from both of their parents, they develop this disorder. The mutations thereby stop the body from processing trimethylamine effectively.
• Secondary Trimethylaminuria: In some cases, individuals can also develop symptoms without any inherited mutations. It occurs due to underlying health conditions, such as kidney or liver disease. There are medications and supplements which trigger temporary symptoms.
   

Symptoms of Fish Odour Syndrome

While it is not physically harmful, the effects can heavily disrupt daily life. Here are a few common symptoms of the condition:

• Noticeable Body Odour: The primary symptom of TMAU is a strong and fishy body odour. A combination of different factors, such as diet, stress and hormonal changes, influences the intensity of odour.
• Hormonal Triggers and Fluctuations: Women often report stronger symptoms of this syndrome during menstruation, puberty or while using oral contraceptives. It is likely due to fluctuations in progesterone and oestrogen that affect how the body processes TMAU.
• Emotional and Social Impact: Individuals with this condition, at times, suffer from psychological symptoms. These include anxiety, embarrassment, social isolation and low self-esteem. The fear of giving out unpleasant odours leads to an avoidance of public spaces and affects personal relationships.
   

Diagnosis of Fish Odour Syndrome

An accurate diagnosis is essential for effective symptom management. Here are a few ways to diagnose fish odour syndrome:

• Urine Testing: It is the most common method, which measures the levels of trimethylamine and its oxidised form (TMAO).
• Genetic Testing: A DNA test helps confirm mutations in the FMO3 gene linked to primary TMAU.
• Clinical Evaluation: Doctors may assess medical history, symptoms, and diet to diagnose fish odour syndrome. A referral to a genetic specialist is needed for an accurate diagnosis and tailored treatment planning.

Treatment and Management of Fish Odour Syndrome

Management of fish odour syndrome involves a combination of lifestyle changes and medical interventions. Below are a few ways to treat and manage the condition:

• Dietary Management: Avoid having foods that are high in choline, such as fish, eggs, legumes and certain types of meat. A low-choline diet can reduce odour.
• Medical Support: Doctors can prescribe short courses of antibiotics to lower gut bacteria that produce trimethylamine. Supplements like activated charcoal or copper chlorophyllin may also help.
• Personal Hygiene and Lifestyle: Frequent washing with acidic soaps, wearing breathable clothes and changing garments daily can help manage external odour. Getting mental support is also vital, as psychological effects can be very severe.
   

Fish Odour Syndrome is a challenging but manageable condition and can deeply affect one's emotional and social well-being. With timely diagnosis, lifestyle changes, and medical support, individuals can effectively manage symptoms and improve their quality of life.

What Triggers the Smell?

Several factors contribute to fish odour syndrome, making it quite a hassle in daily life. A few such factors are:

• Diet: The diet of a person plays a great role in triggering this syndrome. Foods rich in choline (and its source lecithin), carnitine and trimethylamine N-oxide (TMAO) make the odour even stronger. These include eggs, dairy products, soy, tofu, liver, and fish. One can reduce the smell caused by this syndrome by avoiding these foods.
• Hormonal Changes: Women may notice strong odour during puberty, pregnancy and menstruation. The hormones of a person may affect how well the enzyme works, triggering the smell.
• Stress and Exercise: Engaging in strenuous physical activity increases sweating. It intensifies body odour. Furthermore, hot weather leads to sweating and triggers symptoms of fish odour syndrome.

How to Manage Fish Odour Syndrome?

An effective management of the condition focuses on reducing TMA production and minimising its release through the body. Here are a few ways to manage it:

• Controlling Diet: Managing diet is the most effective way to reduce symptoms. Avoid foods that are high in carnitine, choline, and lecithin, which can lower the production of trimethylamine in the gut.

A dietician can help create a balanced meal plan that meets nutritional needs while limiting trigger foods like offal, eggs, legumes and certain fish.

• Using Odour Control Products: Using pH-balanced soaps, antibacterial body washes, and aluminium-based deodorants can help to minimise external odour.

Regular washing when you sweat can help remove TMA from the skin over time. For better results, one should make it a habit of changing and washing clothes frequently.

• Keeping Gut Bacteria in Check: Maintaining gut bacteria balance is essential, as certain microbes produce trimethylamine (TMA), a compound linked to health issues. Low-dose antibiotics may reduce TMA production but must be used cautiously to prevent resistance and side effects.

Supporting gut health with regular monitoring and probiotics can help sustain a healthier, more stable microbial environment.

• Getting Emotional Support: Living with TMAU can lead to stress, anxiety and low self-esteem. Cognitive behavioural therapy, counselling, and support groups, both online and offline, can provide valuable emotional support and help individuals manage their feelings and connect with others facing similar challenges.

While the condition of fish odour syndrome is not dangerous, it can affect the quality of life. With a proper diagnosis and support, people with TMAU can effectively manage their symptoms to live a more comfortable life.