A Trimethylamine N-oxide (TMAO) blood test measures the level of TMAO in the bloodstream. This test helps assess an individual’s risk for cardiovascular diseases and can guide interventions for managing heart health. It also provides insight into how certain dietary components interact with gut bacteria and influence overall health.
What is TMAO and How it is Formed
TMAO, or Trimethylamine N-oxide, is a compound produced in the body through a multi-step process involving specific dietary components and gut microbes. This process begins when nutrients like choline, L-carnitine, and betaine are consumed. These compounds are found in foods such as red meat, poultry, eggs, and some fish.
Once ingested, these dietary precursors travel to the gut, where specific gut bacteria metabolize them into trimethylamine (TMA). TMA is then absorbed into the bloodstream and transported to the liver.
In the liver, an enzyme called flavin-containing monooxygenase 3 (FMO3) oxidizes TMA into TMAO. The TMAO then circulates throughout the body. The amount of TMAO produced is influenced by diet, the types of gut bacteria present, and the activity of the liver’s FMO3 enzyme.
Why TMAO Matters for Your Health
Elevated TMAO levels have been linked to an increased risk of cardiovascular diseases, including atherosclerosis, heart attack, and stroke. Higher TMAO levels are associated with a greater likelihood of these adverse cardiac events.
TMAO contributes to cardiovascular issues through several mechanisms. It can promote cholesterol accumulation within artery walls, a key step in atherosclerosis, which is the hardening and narrowing of arteries due to plaque buildup. TMAO also influences cholesterol metabolism and can hinder the body’s ability to remove “bad” LDL cholesterol.
Additionally, TMAO can induce inflammation and oxidative stress in the cells lining blood vessels, damaging arterial walls. It also affects platelet function, potentially increasing their reactivity and promoting blood clot formation, which can lead to heart attacks or strokes. These effects highlight TMAO’s role in cardiovascular health.
Understanding the TMAO Blood Test
The TMAO blood test involves a blood draw, similar to many routine lab tests. A healthcare professional collects a small blood sample, usually from a vein in your arm. This sample is typically serum, the liquid portion of the blood after clotting.
Preparation for the test is important for accurate results. Patients should fast overnight, for 8 to 12 hours, before the blood draw. It is also recommended to avoid consuming fish, other seafood, or fish oil supplements for at least 24 hours prior. This is because fish naturally contain TMAO, and recent consumption could temporarily elevate levels, not reflecting the body’s typical production.
Laboratories use methods like Liquid Chromatography/Tandem Mass Spectrometry (LC-MS/MS) for accurate measurement. The results provide a numerical value indicating your current TMAO level, which healthcare providers use to assess cardiovascular risk.
Interpreting Results and Managing Levels
Interpreting TMAO blood test results involves understanding what different concentrations indicate for your health. While reference ranges can vary slightly between laboratories, a level below 6.2 µM (micromoles per liter) is considered optimal and is associated with a lower risk of major adverse cardiovascular events. Levels between 6.2 µM and 9.9 µM may suggest a moderately higher risk, while levels above 9.9 µM are considered elevated and are linked to a significantly increased risk.
If your TMAO levels are elevated, several strategies can help manage or reduce them, primarily focusing on dietary and lifestyle modifications:
Reduce intake of foods rich in TMAO precursors, such as red meat, egg yolks, and full-fat dairy products. Some energy drinks and supplements also contain L-carnitine, which contributes to TMAO formation.
Adopt a plant-based or Mediterranean diet, which emphasizes fruits, vegetables, whole grains, nuts, and olive oil. These diets are lower in TMAO-generating compounds and can favorably impact gut microbiota.
Increase dietary fiber through legumes, whole grains, and vegetables to promote the growth of beneficial gut bacteria that produce less TMAO.
Consider probiotic supplements containing strains like Lactobacillus and Bifidobacterium, which may help rebalance gut microbiota and potentially lower TMAO production.
Engage in regular physical activity, another lifestyle factor that can positively modify gut microbiota composition and contribute to lower TMAO levels.