The more I practice medicine, the more appreciation I have for science and the promise it brings for understanding the complexities and connectedness of the human body. We’re finding that many systems in the body such as the gastrointestinal system, cardiovascular system, endocrine system, musculoskeletal system, and others are interconnected and work in concert with one another.
In the last decade or so, we’ve witnessed an explosion of research surfacing about the gut microbiome and how it can influence other systems in the body. Since my father, Dr. Stephen Sinatra, specializes in integrative cardiology, I am fascinated with any research that connects gut health with cardiovascular health. How can it be that the health of the gut can influence the health of the heart and blood vessels?
I think we can all agree that diet certainly has an effect on the cardiovascular system. We know from many studies that those populations who eat foods similar to a Mediterranean diet have superior heart health. We also know that eating foods loaded with sugar, processed foods, and bad fats (trans fats, oxidized fats, etc.) can increase your risk of diabetes, obesity, and cardiovascular disease. Is it the foods themselves, or the health of the gut microbiome, that leads to these health outcomes? I think the answer is both.
Why the Right Balance of Gut Flora Matters
I’ve written a lot before about how gut dysbiosis, an imbalance in gut flora, can cause issues not only along your gastrointestinal track like bloating, heartburn, abdominal discomfort, gas production, diarrhea and constipation, but also systemically in the body like joint pain, brain fog, depression, or even insomnia. If you fix the underlying problem, like dysbiosis, many of these systemic symptoms will fade away and health will be restored over time.
In regard to cardiovascular health, studies show that an imbalance in gut flora, or dysbiosis, has been linked to certain cardiovascular pathologies including:
- Hypertension
- Heart failure
- Kidney disease
- Atherosclerosis
- Obesity
- Type II Diabetes
In fact, in a 2018 study in the Journal Digestive Diseases and Sciences, researchers followed patients who had SIBO (small intestinal bacterial overgrowth), a form of dysbiosis, and looked at the development of coronary artery disease. They found that having SIBO correlated with the following results:
- Higher frequency of CAD (coronary artery disease)
- Higher frequency of diabetes
- Higher frequency of chronic kidney disease
- Higher use of ACE inhibitors (a medication used to treat blood pressure)
- Higher use of statins (a class of medication used to treat high cholesterol)
Another study showed that having SIBO lead to an increase in arterial stiffness. We know that SIBO can affect the absorption of certain vitamins like Vitamin K2, and we also know that SIBO can lead to systemic inflammation.
Without going into too much detail about these results, we can conclude that having SIBO may increase the risk for certain pathologies like CAD. This is more evidence that anyone with heart disease should make sure gut health is in good shape.
Probiotics and Cholesterol
Many studies have shown mixed results looking at the effect of probiotics on lowering cholesterol and other lipid markers. In many of the studies I read, yogurt or fermented milk was mainly used as the source of probiotic. Some studies showed a modest cholesterol lowering effect, while others no significant effect.
Fortunately, in 2018, a huge meta-analysis was completed, which analyzed 32 randomized control trials (RCTs). Researchers looked at the association of probiotic supplementation on cholesterol markers. They found that probiotic supplementation did, in fact, significantly lower total serum cholesterol and that probiotics in pill form had a greater cholesterol-lowering effect than fermented milk products.
I think that that this meta-analysis is a very important study for physicians, including cardiologists, to read as it shows that taking a probiotic can lower total cholesterol. Yes, the cholesterol-lowering effect is relatively small compared to medication, but at least it’s a good place to start with minimal risk.
Instead of immediately reaching for the prescription pad, which surely will include a statin medication, I wish physicians would first educate patients about the importance of healthy foods and probiotics. Including these in the diet may help reduce cholesterol levels and lead to more improved cardiovascular health outcomes.
The Importance of Fiber for Heart Health
When you consume fiber, there are flora in your gut that feed on it to produce short chain fatty acids. These short chain fatty acids can have the following effects on the cardiovascular system:
- Improve blood sugar and weight in diabetics
- Help regulate blood pressure
- Help decrease inflammation
- Modulate the immune system
If SCFAs are good for the cardiovascular system, does this mean that you immediately load up on fiber supplements? No, I don’t think so. To me these findings suggest that choosing a diet rich in fruits and vegetables over the long term is a good idea if you want to improve your cardiovascular health.
If you introduce too much fiber too quickly into your diet, you may experience gas and bloating, which can be very uncomfortable. I suggest slowly introducing the following fiber rich prebiotic foods into your diet:
- Onions
- Garlic
- Artichokes
- Leeks
- Asparagus
- Cabbage
In summary, I am so excited to learn more about research linking gut health to cardiovascular health. For years we’ve been aware of the classic cardiovascular risk factors like obesity, diabetes, smoking, hypertension, and dyslipidemia. Now we know that certain GI conditions like dysbiosis may also be a risk factor, or that probiotics and fiber containing foods can be protective in the fight against heart disease.
Resources:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5390330/
https://www.health.harvard.edu/heart-health/why-the-mediterranean-diet-is-so-good-for-your-heart
https://www.nejm.org/doi/full/10.1056/NEJMoa1800389
https://www.health.harvard.edu/heart-health/healthy-gut-healthy-heart
https://www.ahajournals.org/doi/full/10.1161/hypertensionaha.114.03469
https://www.ncbi.nlm.nih.gov/pubmed/29110161
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5323449/pdf/WJG-23-1241.pdf
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4413085/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5805418/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6244749/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5517538/
https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.118.036652
