On first inspection, it seems unlikely that a stomach infection could increase the risk of having a stroke, and so people – including the medical system – don’t associate H pylori and stroke.
Delving deeper, however, the research indicates a possible link between H pylori and stroke.
This blog post summarises the literature on how H pylori and strokes are linked, and why it’s important for you to view H pylori as more than just a “tummy bug”.
Don’t forget that you can get all my information on H pylori and cardiovascular diseases in one place, in my e-book, H Pylori: From Heartburn to Heart Attacks.
I’ve also written extensively on this website how H pylori – especially a specific strain called “CagA” appears to increase the risk of cardiovascular disorders.
These disorders include:
Feel free to explore these articles in the simplest sequence, starting here.
Atherosclerosis is the process by which arteries become progressively narrower due to the accumulation of arterial plaque.
It can occur in the carotid arteries supplying your brain as well as the arteries supplying your heart.
A stroke, or cerebrovascular infarction, is the rapid loss of brain function due to disturbance in your brain’s blood supply.
Affected areas of the brain fail to function, resulting in an:
As with heart disease, conventional risk factors for stroke include old age, high blood pressure, diabetes, high cholesterol and tobacco smoking.
High blood pressure is considered the most important modifiable risk factor of stroke.
As I’ve written elsewhere, research shows that H pylori infection might increase blood pressure, increase insulin resistance, alter cholesterol profiles and more.
Based on these interactions, we can suggest that H pylori may increase stroke risk.
Most doctors would ridicule such a suggestion, but what does the scientific literature reveal?
In a 2006 study, researchers wanted to determine whether H pylori infection, especially the CagA strain, was associated with the occurrence of strokes.
They studied 106 men with a history of strokes and 97 matched control subjects without any vascular diseases.
CagA H pylori strains were detected in 41.5% of the group of men who had a history of strokes, but in only 17.5% of the control group.
The researchers concluded:
“This is the first study assessing the prevalence of active H pylori infection and CagA positive strains in the setting of the general population. Our findings suggest that CagA positive, more cytotoxic strains, of the bacterium are significantly associated to ischemic stroke.”[DiBastiani, R. Prevalence of Virulent Helicobacter Pylori Strains in Patients With Ischemic Cerebrovascular Disease: A Multicenter Study. 2006. Helicobacter. Abstract no: 03.04.]
A further study looked at the relationship between H pylori CagA strains, carotid artery plaque instability and atherosclerotic stroke.
Researchers evaluated 105 patients affected by stroke and 102 controls without evidence of relevant vascular diseases.
The team found that CagA H pylori strains were significantly associated with the presence of carotid plaque irregularity.
Their conclusion was:
“The evidence of a significant association between CagA-positive H pylori strains and the presence of carotid plaque instability suggest their possible causal role in atherosclerotic stroke.” 1
A Japanese team investigated the relationship between H pylori infection and acute ischemic stroke in 62 patients, compared with a control group of 143 age-matched outpatients who did not have heart disease or infection.
Chronic H pylori infection was associated with a higher risk of ischemic stroke due to small artery occlusion, but a lower risk of cardioembolic stroke.
Chronic H pylori infection still showed an overall positive association with strokes after adjusting for major cardiovascular risk factors such as smoking, high blood pressure and cholesterol levels.
In other words, H pylori infection was independently associated with a higher risk of stroke.
The researchers concluded by stating:
“These results suggest that chronic H pylori infection may be a triggering factor that increases the risk of acute ischemic stroke.” 2
In 2010, Elkind et al studied possible associations between various infections and the thickness of carotid artery plaque.
Antibodies to five common infectious microorganisms – Chlamydia pneumoniae, H pylori, Cytomegalovirus, and Herpesvirus 1 and 2 – were measured.
The researchers found that all the individual infections were associated with stroke risk and concluded:
“These results lend support to the notion that past or chronic exposure to common infections, perhaps by exacerbating inflammation, contributes to atherosclerosis.” 3
In a Chinese study, author G. Pan investigated the effect of anti-Helicobacter pylori therapy on inflammation mediators in patients with acute cerebral infarction (stroke).
Patients with acute cerebral infarction (stroke) were tested for H pylori.
The H pylori-positive patients were randomly divided into a treatment group (conventional stroke therapy plus anti-H pylori therapy) and a control group (no treatment for H pylori).
C-reactive protein, triglycerides, and fibrinogen levels were examined before and after the treatment.
Symptoms of acute stroke were observed after six months and one year.
Cerebral infarction (stroke) readmission rates were also measured in the two groups.
The researchers found that C-reactive protein, triglycerides, and plasma fibrinogen decreased significantly in the H pylori treatment group, while there was no significant change in the control group.
The six-month and one year stroke readmission rates were significantly lower in the H pylori treatment group than those in the control group, indicating a possible benefit of H pylori eradication on preventing stroke reoccurrence.
The authors drew the following conclusion from their data:
“H pylori infection may be a risk factor for cerebral infarction. A positive anti-Helicobacter pylori infection treatment can significantly improve the efficiency of cerebral infarction and reduce the short-term readmission rate.” 4
Another Chinese study investigated the associations of H pylori infection and serum homocysteine levels with acute cerebral infarction.
They found that H pylori seropositivity and CagA status were significantly higher in people who had suffered cerebral infarction compared with healthy control subjects.
They also found that homocysteine levels were higher in patients who tested positive for the CagA H pylori strain.
The team concluded:
“CagA-positive Hp infection may increase the risk of cerebral infarction, which might be associated with the increased serum homocysteine level.” 5
By now, you’ll know I like to present meta-analyses that pull together data from multiple studies. They provide stronger evidence than standalone studies.
In a 2008 paper, researchers pulled together data from ten case-control studies and analysed them for associations between CagA strain H pylori and stroke.
They found that CagA H pylori-infected patients were statistically more susceptible to suffering strokes.
The association was not found in folk infected with non-CagA H pylori.
The researchers concluded:
“These results suggest CagA-bearing strains of H pylori are significantly associated with susceptibility to cerebral infarction (stroke) in Chinese Han and European Caucasians, but that CagA-negative strains are not a definite predisposing factor in either subgroup. The magnitude of this association with cerebral infarction needs to be confirmed by prospective studies and combined studies of H pylori eradication.” 6
In 2012, Wang and colleagues performed another meta-analysis, published in The Journal of Neurology.
This meta-analysis included data from 13 separate studies, with 4,041 subjects.
The authors began their report by stating:
“Chronic infection of H pylori in ischemic stroke incidence has been previously studied in several publications; however, conflicting results have been reported.” 7
The researchers went a step further by examining which of the following diagnostic methods was more effective in predicting stroke risk:
Put simply, the team found that the presence of H pylori in general – as indicated by a positive H pylori IgG test, or a breath test – increased stroke risk.
Positive CagA IgG was the strongest of the three associations.
The study conclusion was as follows:
“This meta-analysis indicated that chronic H pylori infection was significantly associated with an increased risk of IS, especially for non- cardioembolic IS. Compared with anti-H Pylori IgG and the 13C-urea breath test, anti-CagA IgG seemed more effective for prediction of risk of ischemic stroke.” 8
I must point out that I found two studies that did NOT show an association between H pylori and stroke.
This is, indeed, the case with all research focusing on H pylori and cardiovascular diseases and that’s why we can’t draw solid conclusions.
One of the most important factors in study design for assessing the impact of H pylori on cardiovascular health – in fact, ALL elements of health – is the separation of CagA strains from the others.
This was not done in the studies that failed to show any associations between H pylori and stroke.
In future, researchers would be well advised to make sure they separate the influence of H pylori in general from the influence of the H pylori CagA strains.
We have reasonably robust evidence pointing to an association between H pylori – especially the CagA strain – and stroke.
This makes perfect sense because the metabolic changes leading to atherosclerosis – increased blood pressure, inflammation, oxidative stress, and so on – can affect the carotid arteries (brain) as well as the coronary arteries (heart).
I really hope the research community accelerates its investigations into H pylori and cardiovascular disease because you, and everyone else, deserves to know the truth about what causes disease!
Learn how to eat a heart healthy diet AND eradicate H pylori without drugs
By now you probably know I wrote a book detailing how to get rid of H pylori AND many other digestive problems using natural, drug-free protocols.
It’s called The H Pylori Diet and you can grab a copy here if it’s of interest.
It appears that CagA H pylori strains pose the biggest threat when it comes to cardiovascular disease.
You’re able to test whether you have this particular strain at home using a stool test.
I’m biased, but I think this test is really, really important because docs will NOT run tests to identify different strains in general practice.
Strain identification only tends to be done in the research setting.
Do you have a story about H pylori and cardiovascular health you’d love to share?
Or is there anything else on your mind that we can help with?
Let us know by leaving your comment below!