Usually the common phrase “my gut reaction” is considered an expression about one’s intuitive feeling in a particular situation. But this same idiom may be applicable to an emerging medical field: the role the gut’s microorganisms play in health and disease.
Over the last decade scientists have intensified their study of bacteria, viruses and other single-cell critters that reside in a person’s gut and elsewhere within the body. A collection of these diverse microorganisms that inhabit a specific area like the gastrointestinal tract or skin is called either a microbiome or a microbiota.
The microbiome is crucial to normal bodily functions. In addition, an unbalanced microbiome population may be linked to a variety of differing afflictions. The microorganisms’ relationship with broadly based maladies also has implications for potential new treatments.
Modern research of the microbiome of the gut is not entirely unanticipated. Historically, physicians in different eras have been interested in and frequently fixated on the gastrointestinal tract.
Some doctors in the court of the ancient Egyptian rulers bore the title of “guardian of the royal bowel movements.” This name came about because the intestine at that time was considered the main seat of pathology, while the heart was the center of life.
During the Roman Empire and for succeeding generations, physicians believed that the basic composition of sick individuals was an unbalance of the four humors: blood, phlegm, yellow bile and black bile. To establish better health, the humors had to be realigned. One major component that medical practitioners used to achieve this adjustment was strong laxatives to purge the bowel. This harsh treatment persisted for centuries.
The analysis of the influence that the gut’s microorganisms have on normal bodily functions and pathology had to wait until technological advances occurred in the 21st century.
It is now known that there are significantly more microorganisms in the body than human cells. The entire microbiome population may weigh as much as two pounds. While gut microbes have received the most attention, other regions like the skin and vagina are important. Each area has its own distinct group of microscopic organisms.
The microbiome of the gastrointestinal tract is integral to metabolic functions, diet and nutrition. Research into the understanding of its participation in the pathogenesis and treatment of diabetes, obesity, cancer, and inflammatory bowel disease is ongoing.
Investigators have demonstrated that the microbiome has an effect on the body’s immune system. It can produce an interaction with some cancer immunotherapeutic agents. In one instance microbes may make the therapy ineffective, and in another situation microorganisms are necessary for the treatment to work.
Recent preliminary reports highlight two unforeseen conditions in which microbes may play a role. In both cases further analysis is necessary to confirm the findings. In cardiovascular disease, some fecal microorganisms are linked to a specific dietary compound that is associated with increased risk for adverse clinical events. In a separate account, bacteria in the cutaneous microbiome may actually help protect against skin cancer.
A prime example of a human disease that develops as a result of critical changes to the gut’s microbiome is the clostridium difficile infection or CDI. The symptoms range from mild diarrhea to life threatening inflammation of the colon. It is commonly associated with recent antibiotic use.
Recurrent intractable CDI can be effectively treated by a microbiome-based therapy called a fecal transplant. Through a nasogastric tube or colonoscope a non-infected person’s stool is placed into the sick patient’s bowel. This restores healthy bacteria into the ailing colon.
Scientists have only scratched the surface in the importance of the microbiome. My “gut reaction” is that additional research will eventually radically change clinical medicine and lead to novel therapies targeting specific diseases.
Stolz is retired physician and author of the book “Medicine from Cave Dwellers to Millennials.”