The Gut Microbiota, a Potential Therapeutic Target for Cardiovascular Disease

Reginold Sivarajan, BSc Microbiology and Immunology
Contributor

---

Source: Heart and Stroke Foundation

Did you know that cardiovascular disease is the second leading cause of death in Canada after cancer? In fact, every 7 minutes, in Canada, someone dies from cardiovascular disease, that’s 206 people dying from heart disease every day (1)!
 
Several factors contribute to cardiovascular disease such as smoking, the amounts of fats and cholesterol in the blood, high blood pressure, the amount of sugar in the blood and blood vessel inflammation (when blood vessels become inflamed, they may become weakened, stretch, and either increase in size or become narrow -- even to the point of closing entirely) (2).
 
These are all factors that you might have heard previously. But have you heard of the very important link between your gut bacteria and heart disease?
 
As described in many of our previous blogs, we greatly benefit from microbial activities in our gut. In fact, bacteria in our gut are essential for the production of vitamins (such as vitamin B and vitamin K), digestion of carbohydrates and production of short chain fatty acids among others. Short chain fatty acids are produced when our gut bacteria ferment the fiber we intake and they play an important role in health and disease. Despite these beneficial effects, studies in the past 10 years have shown that the gut microbiota (bacteria harboring our gut) is associated with several diseases such as obesity, type 2 diabetes and cardiovascular disease among others.
 
As a matter of fact, gut bacteria produce a chemical that increases clotting in the arteries (meaning that it creates a blockage in a blood vessel linked to the heart). Studies show that when this chemical called TMAO (trimethylamine oxide) is added to human platelets, which are tiny blood cells that help your body form clots to stop bleeding, the formation of artery-blocking clots was much faster (4). TMAO is made in the body as a waste product of gut microbes. Furthermore, when researchers increased blood TMAO levels in mice by feeding them a diet rich in choline, which is a TMAO precursor, they found that the animals formed clots faster than those with lower TMAO levels. These results were not seen in mice that lacked gut microbes. When intestinal microbes from mice that produced high levels of TMAO were transplanted into mice with no gut bacteria, the recipients’ clotting risk increased (4). Moreover, TMAO levels were found to be higher in patients with heart failure compared with those without heart failure.
 
As mentioned above, choline is a precursor of TMAO and this can be found in high amounts in foods rich in cholesterol and fats such as:

• Red meat
• Liver
• Egg yolk
• High-fat dairy products

           
Nevertheless, it is still important to take choline nutrients in moderate amount since choline deficiency can cause neurologic impairment. L-carnithine is another common dietary nutrient ingested that produces TMAO (4). In contrast to choline, L-carnithine is not required in our diet since our body is still able to generate it on its own. Studies show that vegetarians and vegans have a reduced capacity to make TMAO compared to omnivores (person that eats food of both plant and animal origin). Basically, this shows that there is a shift in the population of gut bacteria in omnivores that prefer L-carnitine which enhances the potential to produce TMAO (4).
 
Nutrients rich in L-carnitine are:

• Red meat
• pork
• Dairy products such as milk, cheese and ice cream

 
Interestingly, the Dr. Oz show recommended a few years ago to take supplements of L-carnitine claiming that it could increase energy, speed up weight loss and improve athletic performance. After seeing the new research about L-carnitine, he is saying to NOT take these supplements as it has been shown to increase the risk of cardiovascular disease (http://blog.doctoroz.com/dr-oz-blog/why-we-were-wrong-l-carnitine).
 
Now, my recommendation to you is to reduce as much as possible the consumption of red meat as it has been to shown to be very rich in both L-carnitine and choline, which are precursors of TMAO.
 
Finally, results of this study show how much of an impact the gut bacteria has on our overall health. The gut microbiota represents a new target for therapeutic manipulation and targeting for the treatment and prevention of cardiovascular diseases.
 
 References
1.”Facts about Heart Disease." Facts about Heart Disease | The Heart Research Institute - Heart Research Institute. Heart Research Institute, n.d. Web. 25 June 2017.
 
2. "What Causes Heart Disease?" National Heart Lung and Blood Institute. U.S. Department of Health and Human Services, 21 Apr. 2014. Web. 25 June 2017.
 
3. Jonsson, Annika Lindskog, and Fredrik Bâckhed. "Role of Gut Microbiota in Atherosclerosis." Nature Reviews Cardiology 14.2 (2016): 79-87.
 
4. Tang, W.h. Wilson, and Stanley L. Hazen. "The Contributory Role of Gut Microbiota in Cardiovascular Disease." Journal of Clinical Investigation 124.10 (2014): 4204-211.