Christopher Shih, MD FACG

What is Gut Flora?

Regional Gi gastroenterologist lancaster pa specialist doctor shih

Christopher E. Shih M.D., F.A.C.G.

Lately we’ve been hearing a lot about the importance of the gut flora and its impact on both disease and wellness. Each of us carries an estimated 100 trillion microorganisms in our intestines, a number that is roughly ten times higher than the number of human cells in our bodies. Scientific advances over the past few years have demonstrated that the gut flora can profoundly affect everything from digestive disorders to mental health and obesity.

Like all symbiotic relationships, our gut flora serves many important functions, including digesting energy substrates, stimulating the immune system, synthesizing vitamins, and repressing the overgrowth of harmful microorganisms. Clostridium difficile, an example of one such harmful organism, is normally unable to flourish due to competition from beneficial bacteria. When this is disrupted in some way, like with antibiotic use, it can lead to a potentially life-threatening condition called pseudomembranous colitis. There are numerous examples of the important roles that the gut flora plays in immunity: studies have shown that children with severe allergies have different bacterial compositions than children without allergies. And inflammatory bowel disease, which encompasses ulcerative colitis and Crohn’s disease, while relatively prevalent in developed countries, is virtually unreported in third-world nations. The theory is that excessive hygiene and lack of exposure to microorganisms lead to improper immune system development, and eventually to autoimmune responses that result in inflammation.

Clinically, these observations have resulted in a number of important useful developments. Studies have shown a clear benefit of certain probiotic strains in disorders ranging from irritable bowel syndrome to inflammatory bowel disease to the prevention of superinfections like C. difficile. Fecal microbiota transplantation (FMT), which is a way of rapidly and massively altering one’s flora, has emerged in recent years as a promising adjunct to the treatment of refractory C. difficile infection. The theory is that the healthy donor’s stool can replace the diseased host’s stool and thus restore a healthy balance to the gut flora.

This balance may also be important for our brains. There’s no question that our mind has a profound influence on our gut function, and recent evidence suggests that it’s not necessarily a one-way street. Our gut flora composition can actually affect our mental health, well-being, and even appetite. A recent article described how obesity in mice can be influenced by which gut flora they’re fed. When mice without their own native flora were fed bacteria from an obese twin, they got fat. When they were fed bacteria from a non-obese twin, they stayed slim.

These fascinating advances hold tremendous promise for the future of not only digestive disorders, but also a wide range of diseases that importantly includes obesity, which is reaching epidemic proportions. As our understanding of this field continues to grow, we hope to acquire more and more tools to better serve our patients, and to potentially cure their disabling and often deadly diseases.

If you are experiencing any digestive system issues, please contact your primary care physician, or Regional Gi to schedule an appointment with a Gastroenterologist.