Paging Dr. Frischer: Gut Microbiome

There’s been a lot of discussion lately about our gut’s microbiome. How do our health habits (diet, exercise, smoking, alcohol consumption) affect this microbiome, and why does it matter?

The microbiome is essentially a community of bacteria, fungi, and viruses. Each organ has its own microbiome, but the gut microbiome is the most diverse, because while microbes there perform several functions, our other microbiomes tend to be more specialized. Some of these functions include breaking down fiber and starches, synthesizing vitamins and amino acids (including vitamins B and K), producing short-chain fatty acids that help prevent disease, and maintaining the protective gut lining.

When we eat an apple, some of it is broken down in our stomach and small intestine. The rest of the apple goes to our colon, where bacteria do additional work. As the bacteria break down the apple’s fiber, they produce substances that are beneficial to the cells of the colon and therefore to the body. If we lose these healthy bacteria, there is greater opportunity for disease-causing bacteria to thrive.

A common example of this is Clostridium difficile, a bacterium that can infect the colon. Symptoms of a C. diff infection range from diarrhea to life-threatening colon damage. Risk factors include heavy antibiotic use and hospitalization.

Taking antibiotics does cause our gut microbiome to change for a short time, but it usually returns to its original state. The same thing happens temporarily with other brief changes, like the changes we make to our diet while traveling. Our microbiome is like a rubber band; when stretched a bit, it can bounce back, but if that stretch is too much, it causes disruption.

In addition to gut infections like C. diff, imbalances in the microbiome may be involved in colon cancer, diabetes, depression and other mood disorders, Alzheimer’s disease, Parkinson’s disease, and heart disease. Research to help understand these connections is ongoing.

How can diet and lifestyle help? To nourish a healthy, diverse microbial community in the gut, focus on limiting simple carbohydrates like sugar, salty foods, fatty foods, alcohol, and highly processed foods. Eat a diverse array of fruit, vegetables, and fiber (from nuts, fruits, and vegetables). The more diverse the community, the better your gut will handle “stretching.” Helpful lifestyle habits include drinking plenty of healthy fluids such as water, not smoking cigarettes, and managing stress. You will note that these familiar and common guidelines are helpful to so many systems in our body.

It is not clear precisely what a healthy gut microbiome looks like. We do know that unhealthy diets disrupt the diversity in our gut. Do probiotics help? In general, research supports the use of probiotics which contain microbes which are alive, present in sufficient quantities, and contain at least two different colonies of bacteria.

Our gut microbiome is part of our physiology. If we are thriving, chances are that our microbiome is as well. Sleep, exercise, and psychological well-being all have a meaningful impact. While we may have only limited knowledge of what a healthy microbiome is, it does appear that our gut is vitally relevant to a huge variety of conditions. Stay tuned as research teaches us more.

Dr. Alan Frischer is former chief of staff and former chief of medicine at Downey Regional Medical Center. Write to him in care of this newspaper at 10927 Downey Ave., Suite C, Downey, CA 90241.