Can Your Gut Health Affect Blood Pressure?

Can Your Gut Health Affect Blood Pressure?

The American College of Cardiology has released new guidelines for defining hypertension or high blood pressure.  There are news sources like CNN[1] and the Wall Street Journal[2] that are claiming that the affected American population that will now be defined as hypertensive will go up from 72.2 million to 103.3 million covering roughly half of the adult, male, U.S. population and a third of adult, women.  I’m not sure where they are getting their data as they do not cite a specific source, but just refer to it as “the report.”  I cannot find anything out there with this data as a primary source, but it is safe to say that there will be a rise in diagnoses and an increase in prescriptions for diuretics and ACE inhibitors.

Reducing Sodium

The new guidelines also outline treatment options and recommend reduced sodium intake for people at risk.  The authors claim that a “diet low in sodium, saturated fat, and total fat and increase in fruits, vegetables, and grains may decrease SBP by approximately 11 mm Hg,”[3] Perhaps it is accurate, or maybe it is just another factoid floating around the medical community.

For sodium intake alone, probably the best study out there comes from the medical department at the University of Toronto.  The authors conducted a meta-study looking at fifty-six randomized, controlled trials.[4]  They concluded that for people with hypertension (under the old guidelines), they saw an average drop of 3.7 mm Hg (2.35-5.05 mm Hg) for systolic, and 0.9 mm Hg (-0.13 to 1.85 mm Hg) for diastolic.  For people without hypertension, they found a drop of 1.0 mm Hg (0.51-1.56 mm Hg) for systolic, and 0.1 mm Hg (-0.32 to 0.51 mm Hg) for diastolic, but the P value in the normative trial was significantly higher.

What does this mean?  The kidneys do a good job of regulating the sodium to potassium ratio that affects fluid retention and blood pressure.  If you have high blood pressure, you are going to see a greater benefit in reducing sodium intake than if you are pre-hypertensive, but not by a significant amount.  For example, if you are 135/80, your doctor, under the new guidelines will tell you that you have high blood pressure.  If you try a low sodium diet to try and lower your blood pressure, you might be able to get down to 132/80, but that still puts you in the hypertensive range.  If you come in with 155/100 and you try a low sodium diet, you might be able to get down to 151/99 by reducing sodium alone.

If the initial strategy for reducing blood pressure is to reduce dietary sodium, I don’t think that it is going to be very successful and unless we find another solution, we are going to see a lot more prescriptions filled within the coming months.

So, if it isn’t sodium that is causing high blood pressure, then what is it?  Could it be your gut?  There are some studies that have been published this year that shows the interplay between the microbiome, or the bacteria and fungi that live in our gut and blood pressure[5] and prod us to look deeper.[6]  In this article, we are going to look at some of these relationships and continue to educate the public about the necessity of gut health.

Chronic Inflammation

When people have high blood pressure, their doctor might choose to prescribe them an ACE inhibitor.  ACE stands for angiotensin-converting-enzyme, which is a protein that makes a hormone called angiotensin which regulates vasoconstriction, or the narrowing of blood vessels.  An ACE inhibitor stops the enzyme from being created and less angiotensin will be produced.  This will relax the blood vessels and lower blood pressure.  It is an effective treatment, but it is hard on the kidneys, liver, and has some unpleasant side effects.  This is why most doctors try other treatments first before prescribing an ACE inhibitor.

There is a relationship between the hormone angiotensin and the inflammatory cytokine, interleukin 6 (IL-6).[7]  In studies, not only do we find increased IL-6 values leading to an increase in angiotensin-II hormones, we also see a reduction in the kidneys for excreting dietary sodium.[8]  This means that people with chronic inflammation are far more likely to have issues with blood pressure.

Studies also show that people with SIBO (an overgrowth of bacteria in the small intestines) have a higher concentration of IL-6.[9]  Clinically, people with SIBO—especially methane dominant SIBO, have a negative feedback loop where the bacteria are upregulating IL-6 causing high blood pressure, and the high blood pressure slows down motility causing constipation which exacerbates the SIBO.[10]  This cycle can have a big impact on your blood pressure, and how many general practitioners would even think to ask a patient about their motility when assessing treatment for high blood pressure?  How many of them even know about SIBO?

Increase in Gastric Pressure

An overgrowth of bacteria in the gut often leads to an increase in gastric pressure.  It’s not just their biomass that takes up space in the gut, the pressure comes from the waste products that they expel.  When you eat, bacteria also feed on the food before, during, and after digestion.  The bacteria metabolize nutrients in the food for energy and release gas.  The gas builds up leading to bloating and the pressure starts to build against the sphincters.  The vagus nerve signals the sphincters to tighten to hold in the pressure during digestion.  This leads to an increase in blood pressure.

TH1 Dominance

Opportunistic infections, like H. Pylori, have an impact on the immune system.  This is particularly noticeable in upper gut infections (the link between oral health and cardiovascular disease has been well documented.)[11]  Similar to the example of SIBO and IL-6, these pathogenic organisms trigger T-helper cells and their related cytokines to fight the infection.  A side effect of this is an increase in blood pressure.[12]

Conclusion

Having good blood pressure is vitally important to living a long and healthy life.  Reducing dietary sodium seems to be synonymous with lowering blood pressure in the medical community, but digestive health is much more so.  When we take a look at the biological process that shows how blood pressure is raised and lowered, we see the body’s immune system at work, and what is the biggest influence on the body’s immune system?  The gut!  The gut is the body’s window into the outside environment and it makes systemic changes based on what is going on in the gastrointestinal tract.  If you are working with a doctor to lower your blood pressure, consider talking to her about healing your gut to see if you can avoid medications and live a long and happy life.

Do you have blood pressure issues?  Was it gut related?  We would love to hear your story in the Fix Your Gut forums!

References

[1] http://www.cnn.com/2017/11/13/health/new-blood-pressure-guidelines/index.html

[2] https://www.wsj.com/articles/nearly-half-of-u-s-adults-have-high-blood-pressure-under-new-guidelines-1510611138

[3] http://www.acc.org/latest-in-cardiology/ten-points-to-remember/2017/11/09/11/41/2017-guideline-for-high-blood-pressure-in-adults

[4] https://jamanetwork.com/journals/jama/article-abstract/402918

[5] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5474689/

[6] https://www.ncbi.nlm.nih.gov/pubmed/27798455

[7] http://www.sciencedirect.com/science/article/pii/S0006291X00923647

[8] https://www.ncbi.nlm.nih.gov/pubmed/21716327

[9] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4917718/

[10] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3099351/

[11] http://journals.sagepub.com/doi/abs/10.1177/00220345960750090301

[12] https://www.ncbi.nlm.nih.gov/pubmed/20038749

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