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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."

Gut bacteria in children varies among different Asian countries. The microbiota profiled for the 303 subjects were classified into two main clusters: driven by Prevotella (P-type) or by Bifidobacterium/Bacteroides (BB-type) The majority of children in China, Japan and Taiwan harbored Bifidobacterium/Bacteroides (BB type),whereas those from Indonesia and Khon Kaen in Thailand mainly harbored Prevotella (P-type).Interesting in that even eating different types of rice result in different gut bacteria.From Asian Scientist:

Diet, Location And Your Kid’s Gut Bacteria

An Asia-wide study of the gut microbiota of primary school children has identified differences linked to diet and geographical location

The human intestinal tract hosts a large and diverse community of microorganisms—predominantly bacteria—which plays an important role in the host’s metabolism and ability to combat disease. In a study recently published in Scientific Reports, an international team of researchers led by Associate Professor Lee Yuan-Kun at the National University of Singapore examined fecal samples from 303 primary school children living in urban and rural cities of China, Japan, Taiwan, Thailand, and Indonesia. Unlike infants, children in the 7-11 age bracket have already developed a gut flora similar to that of adults but, unlike adults, they eat predominantly at home so their diets could be tracked more accurately.

The results show a strong correlation between the children’s gut microbiota and their place of residence and diet. The samples from China, Japan and Indonesia diverged the most, with Taiwan and Thailand filling the gaps in between, reflecting not only location but also patterns of human migration and agricultural exchanges. Bacterial communities in the gut vary widely between individuals, but they can be broadly classified into three types, according to the abundance of either Bacteroides, Prevotella, or Ruminococcus bacteria.The researchers found that Asian children display mainly the P-type (abundant in Prevotellaceae) and the BB-type (abundant in Bacteroidaceae and Bifidobacteriaceae), with the abundance of Bifidobacterium being a distinctive feature of the gut flora of Asian children.

P-type (Prevotella) gut communities are normally found in individuals with a high dietary intake of carbohydrates, while a diet rich in proteins and fats will favor a BB-type (Bifidobacterium/Bacteroides) community. Accordingly, the study revealed that Thai children living in Bangkok and eating a diet low in vegetables and fruit displayed a BB-type gut flora, while those living in Khon Kaen and eating a diet high in fruit and vegetables, displayed the P-type.

Not only was the P-type microbiota positively correlated with rice intake across the samples, but differences in contents of digestion-resistant starch across rice cultivars seemed to make a difference. P-type bacteria thrive in an environment rich in digestion-resistant starch, both because resistant starch is a substrate for bacterial fermentation and because it decreases the concentration of secondary bile acids—harmful to P-type bacteria—in the large intestine. After cooking, long grained Indica rice contains 6.6 percent digestion-resistant starch while short grained Japonica rice contains only 0.7 percent. The researchers suggest that the low content of resistant starch in Japonica rice might be the reason why 13 percent of Japanese children who ate a diet predominantly rice-based, still exhibited a BB-type microbiota. Other foodstuff were seen to be associated with P-type gut flora: soybeans (in the form of tempeh, not tofu) because of a high concentration of fiber; eggs, chicken and sweet potatoes because of their high content of vitamin A, which is thought to be beneficial to the growth of Prevotella bacteria.

The article can be found at: Nakayama et al. (2015) Diversity in Gut Bacterial Community of School-Age Children in Asia. 

Of course there is a lung microbiome. From The Scientist:

Breathing Life into Lung Microbiome Research

Although it’s far less populated than the mouth community that helps feed it, researchers increasingly appreciate the role of the lung microbiome in respiratory health.

There’s a constant flow into [the] lungs of aspirated bacteria from the mouth,” he said. But through the action of cilia and the cough reflex, among other things, there’s also an outward flow of microbes, making the lung microbiome a dynamic community.

Like the placenta, urethra, and other sites of the body now known to harbor commensal bacteria, researchers and clinicians once considered the lung to be sterile in the absence of infection. Over the last 10 years, however, evidence has been building that, although it is far less-populated than the mouth or gut, the disease-free lung, too, is populated by a persistent community of bacteria. Shifts in the lung microbiome have been correlated with the development of chronic lung conditions like cystic fibrosis (CF) or chronic obstructive pulmonary disease (COPD), although the relationship between the lung microbiome and disease is complicated.

The surface area of the healthy lung is a dynamic environment. The respiratory organ is constantly bombarded by debris and microbes that make their way from the mouth and nose through the trachea. Ciliated cells on branching bronchioles within the lungs beat rhythmically to move debris and invading microbes, while alveolar macrophages constantly patrol for and destroy unwelcome bugs.

The lung microbiome is about 1,000 times less dense than the oral microbiome and about 1 million to 1 billion times sparser than the microbial community of the gut, said Huffnagle. That is in part because the lung lacks the microbe-friendly mucosal lining found in the mouth and gastrointestinal tract, instead harboring a thin layer of much-less-inviting surfactant to keep the respiratory organs from drying out. ... It appears that the lung microbiome is populated from the oral microbiome, and among this population exists a small subset of bacteria that can survive the unique environment of the lung. The most common bacteria found in healthy lungs are Streptococcus, Prevotella, and Veillonella species.

Segal, who studies small airway disorders with an eye toward early detection of COPD, has found in a series of studies that inflammation of the lungs is often accompanied by a shift in their bacterial makeup. The mechanism behind these changes and consequences of them are still not well understood, however. Other studies have uncovered associations between changes in the lung microbiome and HIV or asthma, but again, causality has been difficult to elucidate.

According to Yvonne Huang  from the University of California San Francisco Medical Center, who is working to characterize lung microbiomes in relation to health and disease progression, “this field is where studies of gut microbiome were 10 to 15 years ago. 

  Human lungs. Credit: Wikipedia