Skip to content

The following is a nice article about a recently published study finding a link between some bacteria commonly found in the mouth and inflammatory bowel diseases (IBD). The researchers found that some strains of oral bacteria are also found in the gut of people with inflammatory bowel diseases.

They theorize that these bacteria make it down to the gut when saliva is swallowed - and for susceptible people this may trigger inflammatory disease. They did a number of experiments to determine that the antibiotic-resistant, inflammation causing species of Klebsiella pneumoniae and Klebsiella aeromobilis could be triggering IBD. These bacteria are able to replace normal colon microbes after antibiotic therapy.

However, it must be noted that other studies also find other microbial differences among those with IBD and healthy people - e.g. low or absent levels of Faecalibacterium prausnitzii, and even fungal and viral differences. From Harvard Magazine:

Gut Health May Begin in the Mouth

Chronic gastrointestinal problems may begin with what is in a patient’s mouth. In a study published Thursday in Science, an international team of researchers—including one from Harvard—reported on strains of oral bacteria that, when swallowed in the 1.5 liters of saliva that people ingest every day, can lodge in the gut and trigger inflammatory bowel conditions like Crohn’s disease and ulcerative colitis.

“For some time now, we’ve noticed that when we look at the microbiome of patients with inflammatory bowel disease, or IBD, we’ve found microbes there that normally reside in the oral cavity,” says study co-author Ramnik Xavier, chief of gastroenterology at Massachusetts General Hospital (MGH)....

Simultaneously, “There’s always been this other search, asking, ‘Are there pathobionts?’”—in other words, microbes that live innocuously in one part of the body but can turn pathogenic when moved to another. “For some time we have been looking for pathobiont organisms for Crohn’s and colitis.”

The researchers believe they have found them: two strains of Klebsiella bacteria, microbes commonly found in the mouth. ....the researchers pinpointed a strain of Klebsiella pneumoniae as the trigger for the immune response. A subsequent experiment using samples from two ulcerative colitis patients turned up another inflammation-causing strain, of Klebsiella aeromobilis

Checking databases of thousands of IBD patients at MGH and the Hospital of the University of Pennsylvania, Xavier and others found that people with inflammatory bowel conditions had significantly more Klebsiella bacteria in their gut microbiome than healthy patients did. Most likely, he explains, oral bacteria, including Klebsiella, traffics through everyone’s gut in the saliva we swallow. Usually it passes through harmlessly; but in people with a genetic susceptibility to IBD that alters the gut microbiome, the Klebsiella has a chance to take hold in the intestine and proliferate, inducing an immune response that causes the disease. 

And there is another twist: Klebsiella bacteria are often extremely resistant to multiple antibiotics. That explains, Xavier says, “why antibiotics have limited value in treating patients with Crohn’s disease and ulcerative colitis....  “Because we also showed in a 2014 paper that patients who took antibiotics—and this has been seen in the old clinical data accumulated before the microbiome was even examined in IBD—that patients who took antibiotics early in the disease had more complicated outcomes.” 

Klebsiella  pneumoniae Credit: Wikipedia

 Interesting idea - that perhaps our community of gut microbes being out of whack (dysbiosis) leads to hypertension. This study was done in both humans and mice - with an analysis of bacteria in both hypertensive individuals and pre-hypertensives, and also healthy individuals (the controls). Then the microbes from 2 hypertensive individuals were transplanted into mice (fecal microbiota transplants). And lo and behold - the mice became hypertensive with an alteration of their gut microbes. This is amazing!

The study showed that transplanting microbes from hypertensives to non-hypertensives caused an elevation in blood pressure in the formerly healthy group. This shows the direct influence of gut microbes on blood pressure. The bacteria found in both the pre-hypertensives and hypertensives (especially an overgrowth of Prevotella and Klebsiella bacteria) are those linked to inflammation. And what kind of diet is linked to that bacteria? A high fat diet. Yes, the Western diet with lots of fat and highly processed foods.

The researchers talked about other research also showing Prevotella being associated not only with hypertension, but also other diseases (e.g., periodontal diseases and rheumatoid arthritis). On the other hand, Faecalibacterium, Oscillibacter, Roseburia, Bifidobacterium, Coprococcus, and Butyrivibrio, which were "enriched" in healthy controls, were lower in pre-hypertensive and hypertensive persons. In the past I have posted about a "special" bacteria that is even called  a "keystone" gut bacteria - Faecalibacterium prausnitziithat is linked to health and is low or absent in the gut in a number of diseases ((here and here). It is not available in a supplement at this time (because it dies within a few minutes upon exposure to oxygen), but diet influences it. A high animal meat, high animal fat, high sugar, highly processed foods, and low fiber diet (the typical Western diet) lowers F. prausnitzii numbers, while a high-fiber, low meat diet increases F. prausnitzii numbers.

What you can do: Feed the beneficial gut microbes by increasing the amount of fruits, vegetables, whole grains, seeds, nuts that you eat. And cut back on the greasy, high fat processed and fast foods.

The following excerpt is misleading - for example, it ignores the first part of the actual study which looked at the gut bacteria of pre-hypertensives, hypertensive, and healthy people. Then gut bacteria from hypertensive people were transplanted into healthy mice, and gut bacteria from healthy people were transplanted into hypertensive mice. Also, it wasn't rats, but mice used in the study. It goes to show why it's important to look at original studies - not just believe articles out there blindly. [See original study.] From Science Daily: Unhealthy gut microbes a cause of hypertension, researchers find

Researchers have found that the microorganisms residing in the intestines (microbiota) play a role in the development of high blood pressure in rats mice....Scientists studied two sets of rats mice, one group with high blood pressure ("hypertensive") and one with normal blood pressure ("normal").... All animals were then given antibiotics for 10 days to reduce their natural microbiota. After the course of antibiotics, the researchers transplanted hypertensive microbiota to normal blood pressure rats mice and normal microbiota to the hypertensive group. 

The researchers found that the group treated with hypertensive microbiota developed elevated blood pressure. A more surprising result is that the rats mice treated with normal microbiota did not have a significant drop in blood pressure, although readings did decrease slightly. This finding is "further evidence for the continued study of the microbiota in the development of hypertension in humans and supports a potential role for probiotics as treatment for hypertension," wrote the researchers. "Studies showing that supplementing the diet with probiotics (beneficial microorganisms found in the gut) can have modest effects on blood pressure, especially in hypertensive models."

NOTE that the actual study said in its CONCLUSIONS:  "Taken together, we have described clearly the disordered profiles of gut microbiota and microbial products in human patients with pre-hypertension and hypertension, established the relationship between gut dysbiosis and hypertension, and provided important evidence for the novel role of gut microbiota dysbiosis as a key factor for blood pressure changes. Our findings point towards a new strategy aimed at preventing the development of hypertension and reducing cardiovascular risks through restoring the homeostasis of gut microbiota, by improving diet and lifestyle or early intervening with drugs or probiotics."