Probiotics and TMAO: Is There a Connection with Heart Diseases?

Probiotics and TMAO - It may seem like an odd combination but perhaps the connection has to do with prevention of heart diseases.

The combination of TMAO and heart diseases such as myocardial infarctions, (acute versions are called "heart attacks"), atherosclerosis and strokes caused near-hysteria in the news in the last few years. This and other related articles on the website should shed more light on the subject.

For years scientists have known that there is something more than just genetics (which account for less than 20% of cardiovascular disease risk) to cause heart diseases. They speculated that there is a connection between some foods and drinks (among other things) and heart diseases, but they couldn’t pinpoint why and doctors broadly blamed saturated fat and cholesterol.

As with everything else in the human body, the real causes of cardiovascular diseases are more complicated that simply saturated-fat consumption. And yes, even more complicated than cholesterol levels. Now it is even more complicated than both of them combined as the gut and heart diseases may be more closely linked than previously thought. Probiotics and TMAO may possibly be one of the clues.

A molecule known as TMAO is thought to promote atherosclerosis (buildup of plaques in the arteries leading to hardening of the arteries and blockage of blood flow) by changing how cholesterol is used in the artery wall, liver and intestines.



What is TMAO ?

TMAO is an acronym for trimethylamine-N-oxide and it is a combination of a breakdown product (trimethylamine or TMA) in your gastrointestinal (GI) tract of certain compounds that are in many foods, supplements and drinks you may consume and an oxygen atom. It is considered to be one of the gut-derived uremic toxins (GDUT's).

Studies link TMAO to cardiovascular disease, kidney disease, neurological disorders and some cancers.

Where Are Trimethylamines (TMA) Found?

To read more about the food and drink sources of trimethylamines, please see this page.

What Seems to Be the Biggest Source of TMAO?

The amount of TMAO you have is not just based on how much of the foods and drinks you consume that can be converted to TMA. You yourself are involved in the oxidation of the TMA to TMAO and each person has a different genetic capacity for doing this.

You might know people who suffer from  trimethylaminuria (TMAU). Those folks lack a properly functioning gene to make the enzyme FMO3 to do the TMA-to-TMAO conversion, or their bodies are overwhelmed with TMA, resulting in fish-smelling body odor. It has nothing to do with hygiene.

What is the Probiotics and TMAO Connection?

What breaks down the foodstuffs to TMA in the first place? Intestinal bacteria are the biggest culprits in breaking down the foodstuffs to TMA but NOT JUST ANY intestinal bacteria.

The connections between probiotics and TMAO appear to happen because the major bacterial converters of the foods and drinks containing TMA are NOT you probiotic bacteria. They are mostly neutral, pathogenic or opportunistic microbes. Probiotics can help control the populations of microbes like those.

In fact, a June, 2018 study on patients with cardiovascular disease suggested that probiotics and repopulation of the intestinal microbiome may be necessary to dampen the adverse effects of GDUT's like TMAO.

Should You Avoid Foods that Convert to TMAO?

Before you jump on the bandwagon that the foods and drinks that contain TMA or TMAO cause heart diseases, realize that first, research on TMAO and heart diseases, and also on probiotics and TMAO, are still in preliminary stages, and second, that heart disease is more complicated than the media would like you to think.

While reducing your intake of TMA-containing foodstuffs will likely reduce the TMAO produced, it is not the only answer and in some cases can make your health worse, as the page on trimethylaminuria explains.

Probiotics and TMAO: The Incomplete Story

Research published online in February, 2015 pointed to a new risk factor for heart diseases related to the number of plaque segments and severity of calcified plaque burden in HIV patients: TMA. In this study, serum TMAO and choline were not the culprits, which contradicts previous research.

Additionally, the exact way in which TMAO might lead to atherosclerosis is not known. There appears to be a link between GDUT's, including TMAO, and higher carotid artery plaque burden. Additionally, changes in body pathways that affect TMAO generation and atherosclerosis have been observed, and elevated TMAO levels have statistically correlated to an increased risk of having a myocardial infarction, stroke or death.

If either the TMAO-heart disease theory or the TMA-heart disease theory prove to be true or partially true, some of the wild cards in the outcome are the types of microbes you have in your gastrointestinal tract to convert the dietary compounds to TMA, your genetic predisposition to heart disease, your genetic capacity to convert TMA to TMAO, your dietary intakes, some of the factors listed on the trimethylaminuria page, and the relative amounts of probiotics and TMAO you have.

Maybe TMA is the problem, maybe TMAO is, or maybe they both are. Maybe there is much more to this story than we currently know.

At least one major part of the heart disease equation based on the current TMAO/TMA theories is the probiotics and TMAO possibility. To reduce TMAO, tip the balance of microbial effects in your GI tract toward probiotic ones. Not only will this help your prevention of potential TMAO/TMA problems, but it will give you the numerous health benefits that probiotics can provide.

Scientists can investigate whether or not TMA/TMAO causes heart disease and in what capacity. To me, what is important is:

  1. What to do about it now in case it is true or partially true, and
  2. What most likely will not hurt me, yet can provide other benefits


That is a no-brainer to me: probiotics.

For probiotics I look to:

You can learn more about taking and supporting probiotics in Probiotics: How to Use Them to Your Advantage.

To read about the food and drink sources of TMA and to see the latest research on probiotics and TMAO and TMA, please see this page on trimethylaminuria (TMAU).

To read more about what some studies show for TMAO reduction, please see this page.


Return to page on other health conditions.

Return to Homepage.



Thanks for visiting this site! If you've enjoyed reading this page or have found the information to be useful to you, please "like", tweet about it, or share it so others can benefit, too. You can leave comments below via Facebook or Disqus.

Comment with Facebook!

I'd love to hear your opinion about what you just read. Leave me a comment in the box below! Other commenting options follow the Facebook comments.

Comment with Disqus (including as a guest), Twitter or Google accounts:

If you are one of my many readers without a Facebook account, you can still comment.


Disclaimer: Please note: By law, I cannot provide any personalized recommendations for your specific health concern on this site. The information contained in this site is educational in nature and is not intended as diagnosis, treatment, prescription or cure for any physical or mental disease, nor is it intended as a substitute for regular medical care. Consult with your doctor regarding any health or medical concerns you may have.

Subscribe to my monthly newsletter and receive a free copy of "The Quickstart Guide to Probiotics."

To comply with the EU's GDPR data privacy regulation, please subscribe here:


Looking for some quality professional supplements, including probiotics? Check out my online dispensary, as I will be doing reviews of some of these products in the future. Click on the Fullscript picture. (Note: If you were a former Wellevate customer, please switch to Fullscript for a better customer experience. Thanks!)


SiteSell Hosting

Some competitors of SBI (Site Build It) are posting fake negative reviews of SBI. If you are considering creating your own website business, or if you have a brick-and-mortar business but want an online presence, I highly recommend SBI!