Understanding What Foods Are High in TMA

October 23, 2025 •

3 min read

Did you know that gut bacteria play a key role in producing Trimethylamine (TMA) from certain foods, which is then converted by the liver into TMAO? This explains why red meat, eggs, and deep-sea fish top the list of what foods are high in TMA precursors and TMAO, which can impact overall health.

Quick Summary

Gut bacteria convert dietary compounds from animal products like red meat, eggs, and dairy into trimethylamine (TMA), which is then processed by the liver. Deep-sea fish also contain naturally high levels of TMAO, a related metabolite, influencing overall levels in the body.

Key Points

Red Meat and Organ Meats: Beef, lamb, and liver are rich in L-carnitine and choline, which gut bacteria convert into TMA.
Eggs and Dairy: Eggs, particularly the yolk, and full-fat dairy products like whole milk and butter are high in choline and lecithin.
Deep-Sea Fish and Shellfish: Unlike other foods, these directly contain high levels of TMAO, which is absorbed bypassing the gut conversion process.
Gut Microbiome is Key: An individual's specific gut bacteria determine how effectively TMA precursors are converted, leading to varied responses to the same foods.
Plant-Based Foods: Fruits, vegetables, whole grains, and legumes are naturally low in TMA precursors and can help lower overall TMA/TMAO levels.
Dietary Moderation: For most people, a balanced diet including both animal and plant foods is manageable, while those with specific health conditions may need to pay closer attention to intake.

The Gut Microbiome and TMA Production

Trimethylamine (TMA) is a metabolite produced by certain gut bacteria when they break down specific compounds found in food. This process is influenced by an individual's unique gut microbiome composition, as some people's bacteria are more efficient at this conversion than others. Once formed, the TMA is absorbed into the bloodstream and sent to the liver, where it is oxidized into trimethylamine N-oxide (TMAO). High TMAO levels have been linked to potential health concerns, including cardiovascular issues, though research is ongoing and complex. Understanding the dietary sources is the first step toward managing TMA and TMAO levels through nutrition.

TMA Precursors: Choline and L-Carnitine

Animal products are the richest dietary sources of TMA precursors, with choline and L-carnitine being the most significant. Choline is a vital nutrient necessary for healthy cellular function, but when consumed in excess, particularly from animal sources, it can fuel TMA production. L-carnitine, an amino acid, is predominantly found in red meat and is another major precursor. The gut bacteria break down these nutrients, releasing TMA as a byproduct.

Choline-Rich Foods: Eggs, especially the yolk, are an extremely rich source of choline. Other sources include beef liver, poultry, fish, dairy products like whole milk and cheese, and some plant-based options like soybeans and cruciferous vegetables, although animal sources generally contribute more significantly to TMA formation.
L-Carnitine-Rich Foods: Red meat, such as beef, pork, and lamb, contains the highest concentration of L-carnitine. Other animal-based sources include game meats and some dairy products.

Seafood: A Direct Source of TMAO

Unlike other animal products that provide precursors for TMA production in the gut, some seafood contains naturally high levels of TMAO. This is because TMAO acts as an osmolyte, helping marine animals, particularly deep-sea species, survive under high hydrostatic pressure. When consumed, this TMAO is directly absorbed into the bloodstream, bypassing the gut bacteria conversion process. Consequently, eating deep-sea fish can result in a significant, though often temporary, spike in circulating TMAO levels.

Dietary Strategies to Influence TMA Levels

For those aiming to manage or reduce their TMA/TMAO levels, diet is a powerful tool. Shifting from an animal-based diet to a more plant-based one can alter the gut microbiome composition, favoring bacterial communities that produce less TMA. Incorporating more whole, plant-based foods rich in fiber and antioxidants can promote a healthier, more diverse gut environment.

Increase Plant-Based Foods: Fruits, vegetables, legumes, and whole grains are low in TMA precursors. Brussels sprouts, in particular, have been shown in some studies to help downregulate the liver enzyme (FMO3) that converts TMA to TMAO.
Modulate Fish Intake: The type of fish consumed matters. Replacing high-TMAO deep-sea fish (like cod and pollock) with shallow-water or farm-raised varieties (such as shrimp or salmon) might help. Tuna is a notable deep-sea fish that is naturally lower in TMAO.
Consider Protein Sources: While animal protein is a primary source of TMA precursors, opting for leaner cuts of meat or replacing some servings with plant-based protein sources like lentils, beans, or tofu can reduce precursor intake.

High vs. Low TMA-Producing Foods


Food Group	High-TMA-Producing Sources	Low-TMA-Producing Sources (Generally)
Meat	Red meat (beef, pork, lamb), organ meats (liver)	Lean poultry (chicken breast), Plant-based proteins (lentils, beans, tofu)
Seafood	Deep-sea fish (cod, Alaska pollock), some shellfish (lobster, snow crab)	Shallow-water fish (farmed salmon, shrimp, trout), tuna
Dairy	Full-fat dairy (whole milk, cream cheese, butter)	Low-fat dairy, fermented dairy (yogurt, kefir)
Eggs	Egg yolks	Egg whites

Conclusion: A Balanced Approach to Diet

Ultimately, the goal is not necessarily to eliminate all TMA-precursor foods, as many are also rich in essential nutrients. Instead, a thoughtful dietary approach that balances nutrient-dense animal products with an abundance of plant-based foods can help manage TMA levels. The gut microbiome's role means that personalized dietary responses can vary, so listening to your body is key. For those with specific health concerns, especially related to cardiovascular disease or kidney function, consulting a healthcare professional for personalized dietary advice is recommended. More research continues to uncover the intricate relationship between diet, the gut microbiome, and overall health, offering new insights into optimizing our nutritional strategies.

Outbound Link: For an in-depth review on the dietary sources of TMAO, see this article published on the National Institutes of Health's website: The dietary source of trimethylamine N-oxide and clinical relevance in chronic kidney disease.

Frequently Asked Questions

TMA (trimethylamine) is a gut metabolite produced by intestinal bacteria from certain dietary compounds. TMAO (trimethylamine N-oxide) is what the body converts TMA into in the liver, or it can be consumed directly from deep-sea fish.

No. While deep-sea fish like cod and pollock have naturally high levels of TMAO to help them survive under pressure, shallow-water fish and certain others like tuna have lower levels.

Yes, adopting a plant-based diet can significantly lower TMAO levels. Studies have shown that people who do not consume red meat or other animal products have a different gut microbiome composition that produces less TMA from precursors like choline and L-carnitine.

To reduce TMA production while still eating meat, you can moderate your intake of red and organ meats, choose leaner cuts, and increase your consumption of fiber-rich plant-based foods, which support beneficial gut bacteria.

For healthy individuals, consuming these foods is typically fine, as they are often nutritious. However, high levels of TMAO are a concern for individuals with cardiovascular or kidney conditions, where a diet lower in TMA precursors may be beneficial.

Yes, taking L-carnitine supplements can increase TMAO levels, especially in individuals with a specific gut microbiome that readily converts it. This is a common finding in studies on this topic.

The gut microbiome is critical because it contains the bacteria responsible for breaking down TMA precursors like choline and L-carnitine into TMA. The specific types and quantity of these bacteria vary among individuals, leading to different metabolic responses.