What diet helps trimethylaminuria?

November 16, 2025 •

3 min read

Did you know that an estimated 1% of the U.S. population may have a genetic variation affecting how they process choline and other compounds, leading to trimethylaminuria (TMAU)? Managing the symptoms of this rare metabolic disorder often involves a specific dietary approach, and understanding what diet helps trimethylaminuria is key to improving quality of life.

Quick Summary

Managing trimethylaminuria involves a carefully planned diet to restrict choline, carnitine, and TMAO precursors. Reducing intake of high-impact foods can help minimize the associated body odor.

Key Points

Low-Choline Diet: Restricting foods high in choline, like egg yolks, legumes, and organ meats, is the main way to manage TMAU symptoms.
Avoid Marine Seafood: Completely eliminate saltwater fish, crustaceans, and shellfish from your diet due to high levels of the TMA precursor TMAO.
Limit Other Precursors: Reduce your intake of red meat (carnitine) and brassica vegetables (indoles) that can increase TMA production or inhibit its breakdown.
Balance is Key: Do not excessively restrict your diet without guidance from a dietitian, as choline is an essential nutrient and deficiencies can cause other health issues.
Consider Supplements: Short-term use of activated charcoal or copper chlorophyllin can help absorb TMA in the gut, while riboflavin may assist the FMO3 enzyme.
Manage Lifestyle Factors: Reducing stress and avoiding excessive sweating can help control body odor, as these factors can exacerbate symptoms.

Understanding Trimethylaminuria and the Role of Diet

Trimethylaminuria (TMAU), often called "fish odor syndrome," is a metabolic condition where the body cannot properly break down trimethylamine (TMA). TMA is a compound with a strong, unpleasant smell that is produced by gut bacteria from certain dietary precursors, including choline, carnitine, and trimethylamine N-oxide (TMAO). In healthy individuals, the FMO3 enzyme converts TMA into a non-odorous form, which is then excreted. For those with TMAU, a genetic defect or a temporary issue can lead to an excess of TMA being released through sweat, breath, and urine. A low-precursor diet is the primary management strategy to reduce the amount of TMA produced in the gut.

The Low-Choline Diet: The Cornerstone of TMAU Management

Choline is an essential nutrient, but it is also the most significant dietary source of TMA. Therefore, a low-choline diet is the cornerstone of managing TMAU. The goal is not to eliminate choline entirely, which could cause nutritional deficiencies, but to significantly restrict intake under medical supervision. A registered dietitian can help create a balanced meal plan that provides adequate nutrition while minimizing choline consumption. The recommended daily intake of choline for adults is significantly higher than what a person with TMAU can tolerate, highlighting the need for careful management.

High-Choline Foods to Avoid or Limit

Eggs: Egg yolks are particularly high in choline and should generally be avoided.
Seafood and Shellfish: All marine (saltwater) fish, cephalopods, and crustaceans contain high levels of TMAO and must be avoided. Freshwater fish typically contain lower levels.
Organ Meats: Liver, kidney, and other offal are rich sources of choline and carnitine.
Legumes and Beans: Soya beans, peas, and other beans are high in choline.
Brassicas: Vegetables like broccoli, Brussels sprouts, cabbage, and cauliflower contain indoles that may inhibit FMO3 enzyme activity, increasing TMA excretion.
Soy Products: Products made from soybeans, including some tofu and soy milk, can be high in choline. Checking labels and portion sizes is important.
Red Meat: This is a source of carnitine, another TMA precursor. Some individuals may need to restrict their intake.
Lecithin-containing Supplements: Lecithin is a source of choline and is often used as an emulsifier in processed foods and supplements, including some fish oil supplements.

Comparison of Food Choices for a TMAU Diet


Food Group	High Precursor (Avoid/Limit)	Low Precursor (Safer Options)
Protein	Seafood (saltwater), organ meats (liver, kidney), egg yolks, red meat	Freshwater fish, egg whites, vegetarian protein sources (limited legumes), small portions of poultry
Dairy	Milk from wheat-fed cows	Most standard cow's milk, nut or rice milk (check calcium fortification)
Vegetables	Broccoli, cabbage, cauliflower, brussels sprouts	Most other vegetables, including spinach, carrots, and lettuce
Grains	Bran cereals (higher choline)	White bread, rice, oats, pasta
Fats	Fish oil supplements containing lecithin	Standard vegetable oils, margarine

Other Management Strategies

While diet is the primary focus, other interventions can help manage TMAU symptoms:

Acidic Soaps: Washing with slightly acidic soaps and lotions (pH 5.5-6.5) can help remove secreted TMA from the skin, as TMA is an alkaline compound.
Supplements: Short-term use of supplements like activated charcoal or copper chlorophyllin can help sequester TMA in the gut and reduce body odor. Riboflavin (Vitamin B2) may enhance residual FMO3 enzyme activity.
Antibiotics: A short course of antibiotics may be prescribed to reduce TMA-producing gut bacteria, though this is not a long-term solution.
Probiotics: Modulating gut flora with probiotics may help control the bacteria responsible for TMA production.
Stress Reduction: Managing stress is important, as stress can increase sweating and exacerbate body odor.

Conclusion

For individuals with trimethylaminuria, a carefully controlled low-choline diet is the most effective tool for managing symptoms. By limiting dietary precursors like choline, carnitine, and TMAO, and potentially incorporating other strategies like supplements and personal hygiene adjustments, many people can significantly reduce the associated body odor. It is crucial to work closely with a healthcare professional, such as a registered dietitian, to ensure that the diet remains nutritionally complete and balanced. Making informed dietary choices is a powerful way to regain control and improve quality of life with TMAU.

This article is for informational purposes and should not replace professional medical advice. For further reading on dietary choline, visit the USDA database: https://www.ars.usda.gov/ARSUserFiles/80400525/data/choline/choln02.pdf.

Frequently Asked Questions

The primary dietary trigger is choline, a nutrient found in high concentrations in foods like egg yolks, legumes, and organ meats. The TMA is a byproduct of gut bacteria breaking down choline and other precursors.

You should completely avoid saltwater fish and shellfish, which contain high levels of TMAO that is converted to TMA in the gut. Freshwater fish, however, generally have lower levels of TMAO and may be safe to eat in moderation.

Yes, some supplements can help. Activated charcoal and copper chlorophyllin have been used to help sequester TMA in the gut. Riboflavin (Vitamin B2) may also be beneficial by potentially boosting the activity of the FMO3 enzyme.

Some brassica vegetables, including broccoli, cabbage, and Brussels sprouts, contain compounds called indoles that may inhibit the FMO3 enzyme. It is often recommended to limit or avoid these foods, though tolerance can vary among individuals.

Yes, it can be dangerous. Choline is an essential nutrient needed for many bodily functions. A diet that is too restrictive can lead to nutritional deficiencies and health problems. It is crucial to work with a dietitian to ensure your diet remains balanced.

Probiotics may help by rebalancing the gut microbiota. It is the pathogenic or opportunistic bacteria, not the beneficial ones, that convert precursors into TMA. Probiotics might help suppress these TMA-producing microbes.

Good low-choline protein sources include egg whites, most dairy products, freshwater fish, and a variety of vegetarian options like legumes and plant-based proteins, though portion control is important.

A registered dietitian can provide personalized guidance, helping you create a meal plan that restricts triggers while ensuring you still get adequate nutrition. They can help monitor your diet to prevent deficiencies.