Gut problems often go hand in hand with cardiovascular disease.  There are links between GERD, IBD, Celiac disease, and H. pylori infection with cardiovascular complications including cornary artery disease and cardiac arrythmia.

Furthermore, a link was recently established between small intestinal bacterial overgrowth(SIBO) and coronary artery disease.  This is a pretty strong link and people with SIBO should take notice: more than twice the number of people with SIBO had coronary artery disease than those without it(80.2% vs 38.8%) and they were far more likely to have multiple coronary arteries blocked(2 blocked: 83%vs 17% and 3+blocked: 80% vs 20%).

While I think this relationship is bi-directional where CVD feeds in to SIBO and vice versa, I believe it’s far more likely that SIBO and CVD are both a marker for a more sinister problem that’s likely driving both: atherosclerotic plaque driven organ ischemia.

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Small vessel disease: It’s not only in the heart

Since cardiovascular disease is the biggest killer in the Western World and that often presents suddenly as a heart attack, much of our focus has been on how it affects the heart.  Unfortunately, the heart isn’t the only thing you need to worry about in reference to cardiovascular disease because all organs are supplied with small blood vessels that can become blocked.  This happens either through narrowing from plaque accumulation or a plaque rupture that blocks a smaller vessel.

Fortunately, when this happens, we can form new blood vessels called collateral vessels that help bring blood to the affected area.  However, our ability to do this is limited and when this process happens over and over in the heart, we eventually need to surgically add collateral vessels in a process known as a bypass.

While the focus has been on the heart, other tissues can be impacted as well.  The same process plays out in the brain in a stroke, in the kidneys as renal vascular disease, and in the penis as erectile dysfunction.  In fact, erectile dysfunction has been suggested to be predictive of heart attack; men with erectile dysfunction have twice the risk of having a heart attack within 3.8 years than those without it.

It’s probably no mistake that Viagra, everyone’s favorite boner pill, was initially used to treat hypertension.  It opens up the blood vessels in the penis allowing it to get the blood it needs to erect.  Interestingly enough, it does the same thing by protecting against liver damage during intestinal ischemia in rats.  In other words, it reopens blood flow when it’s blocked.

So what to take from this?  Small vessel disease is small vessel disease.  If the small vessels serving your heart or brain are crudded up with plaque, chances are that most of your small vessels are crudded up with plaque.  Since the brain and heart are highly sensitive to oxygen deprivation, they’ll fail first and their failure is more likely to be fatal.

But the gut also consumes a lot of energy, and it’s gradual failure due to ischemia won’t kill you, it’ll just make you miserable.

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Evidence that SIBO is driven by small vessel disease

If what we’re looking at in SIBO is driven by small vessel disease instead of some bi-directional link between the gut and heart, people with SIBO would be more likely to have problems in other areas served by smaller vessels.  Additionally, you would expect to see some evidence of hypertension, as blockages in smaller vessels typically indicate partial blockages in bigger vessels ad the sum of that increases blood pressure.

In a study published in 2018, a strong link was established between SIBO and all of these markers.  As with the study mentioned above, coronary artery disease and the number of vessels involved were worse in people with SIBO as established by glucose hydrogen/methane breath test.  In fact, people with SIBO were more than 7x more likely to have coronary artery disease than those without it, independent of other risk factors.

But the case gets even stronger.  They also found that people with SIBO were:

• Almost 50% more likely to be on ACE inhibiting drugs for hypertension
• More than twice as likely to have chronic kidney disease
• Almost twice as likely to have diabetes mellitus.

It’s probably important to point out that many of the complications in diabetes are caused by restricted blood flow to various organs and tissues due to small vessel disease.  That’s why they become dependent on dialysis and eventually begin losing their extremities.

So if small vessel disease is small vessel disease and the gut gets its blood supply from small vessels, it’s quite likely that these problems are related because they’re essentially due to blood flow restriction to the target organ.  Of course, you may initially form collateral vessels that can offset the problem, but you are certainly limited in your ability to do that.

What would expect to see in a gut with poor blood supply?  Possibly poor enzyme and mucus secretion and certainly poor motility.  So what about that?

SIBO is basically a condition that is, in almost all cases, caused by poor gut motility (failure of the MMC to clean out your small intestine between meals). You cannot get SIBO unless you have a motility problem.

-Steve Kirsch in summing up his interview with Dr. Mark Pimentel

It wouldn’t surprise me in the least bit if other gut problems, particularly IBS since it’s often associated with SIBO, are caused by this same problem.  And this is not to say that the only cause of SIBO is cardiovascular disease.  It’s likely a constellation of problems that all intersect.

It shouldn’t be lost on anyone that most likely every adult over 30 years of age and even some children have some level of plaque accumulation in their blood vessel wall.  Atherosclerosis starts in the teens, even in otherwise healthy individuals.

Conclusion

A small but growing amount of evidence indicates that SIBO may be driven by vascular disease in the gut.  Small vessel disease is slow and progressive, but the sudden nature of heart attacks gives us the impression that it’s a sudden process.

It would be foolish to believe that the gut would go completely unaffected by small vessel disease.  In fact, it’s an energy intensive organ to maintain, so on the contrary, it makes perfect sense that it would be affected.  I don’t believe this would be a sudden process: there would be a progressive decline in to dysfunction that may ultimately manifest itself as SIBO due to poor motility.

Is this reversible?  I don’t know, but I think it’s clear that your best bet is to do everything you can to boost motility by optimizing circadian rhythms, being physically active, reducing inflammation, and avoiding hypertension and hyperlgycemia.  Consuming foods that increase nitric oxide such as beets, dark chocolate, nuts, and leafy greens coupled with these behaviors will also improve blood pressure by dilating the vessels that supply the gut.