Doctor’s Tip: Bad gut bacteria cause cardiovascular disease, severe COVID and more |

Doctor’s Tip: Bad gut bacteria cause cardiovascular disease, severe COVID and more

Dr. Greg Feinsinger

The previous column in this series about the gut microbiome was about how good gut bacteria improve health. Today’s column is about how bad gut bacteria cause disease. The information in this column is based on a talk at the recent annual International Plant-Based Nutrition Conference by Kim Williams M.D., past president of the American College of Cardiology.

The gut microbiome is the current hot topic in medicine, with new discoveries being made daily about how the trillions of bacteria in our guts influence our health. “Dysbiosis” is the term for an abnormal, disease-causing gut microbiome. One way that dysbiosis contributes to health problems is that the bad bacteria crowd out the good, so there aren’t enough of the good bacteria around to keep us healthy.

However, bad gut bacteria also directly harm your health, and Dr. Williams cites the following examples:

High blood pressure is a major risk factor for heart attacks, strokes, heart failure and other cardiovascular diseases. Certain gram-negative bacteria such as Klebsiella cause hypertension. Many cardiac risk factors including hypertension are often blamed on genetics. However, the problem is often the genes in our gut microbiome, rather than the genes in our own cells. Dr. Williams foresees a time in the not-so-distant future when instead of giving hypertensives pills that relax walls of blood vessels to lower blood pressure, doctors will prescribe specific bacteria to treat what caused the hypertension in the first place.

Fasting changes the gut microbiome for the better, causing high blood pressure to normalize.

Cholesterol is another cardiovascular risk factor, and some bad gut bacteria contribute to high cholesterol. Conversely, a gene present in some good microbes called ismA changes cholesterol into coprostanol, which doesn’t cause heart disease.

Diabetes is a major risk factor for heart disease. Bad gut bacteria such as Fusobacterium synthesize compounds that contribute to developing type 2 diabetes.

Certain bad gut bacteria contribute to obesity, which is another cardiovascular risk factor.

TMAO is a toxin made by bad gut bacteria when they’re exposed to digested meat, seafood, dairy and eggs. This chemical contributes to heart attacks, strokes, congestive heart failure, hypertension, high cholesterol, type 2 diabetes, obesity, chronic kidney disease and all-cause mortality.

In his talk, Dr. Williams also presented studies showing a connection between bad gut bacteria and severe illness and death caused by COVID-19. First of all, high cholesterol, caused at least in part by dysbiosis, allows COVID-19 to enter cells more easily. Second, dysbiosis causes inflammation, which is the biggest player in severe COVID-19 illness and death. Third, at the beginning of the COVID-19 pandemic, it appeared that people of color were more apt to suffer severe illness and death from COVID-19. This was attributed to race, but that turned out not to be the case. Rather it’s due to risk factors, such as obesity, diabetes, hypertension and heart disease — which are more prevalent in black and brown communities due to economic circumstances, not race. (Being a member of the Association of Black Cardiologists, Dr. Williams has a special interest in this subject).

Dysbiosis causes multiple other health problems as well — too numerous to mention here. An example is cancer. In his book “Eat to Beat Disease,” Dr. William Li says, “Cancer, especially in the organs in the gastrointestinal tract (esophagus, stomach, pancreas, gallbladder, colon and rectum) is associated with microbiome disturbances. When beneficial bacteria are absent, the immune system’s ability to detect and fight cancer cells is disarmed. The wrong bacterial residents interfere with the body’s ability to defend itself.”

Next week’s column will be about steps you can take to develop and maintain a health-promoting microbiome.

Dr. Feinsinger is a retired family physician with special interest in disease prevention and reversal through nutrition. Free services through Center For Prevention and The People’s Clinic include: one-hour consultations, shop-with-a-doc at Carbondale City Market and cooking classes. Call 970-379-5718 for appointment or email

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