“Fecal Transplants.” Definitely an attention-grabbing headline, and one that’s been in the news a lot lately. This medical treatment is saving lives, though, and as icky as it sounds, there’s good science behind it. This approach to medicine treats the human microbiome – the extensive microbe community inside each of us.
New science is showing that each of us is really more of a walking ecosystem than the individual we think we are. Understanding this system, learning what it does, and how to use it for health care is a hot field of medical research. The effects of this work are changing medicine and changing the way we think about ourselves as living organisms.
Microbes live just about everywhere in and on the body. Mostly, however, they’re in the gut, i.e., the esophagus, stomach, and intestines. Their numbers are truly humbling, too. In the average person, this microbial community:
- Consists of about 100 trillion microbes
- Represents 90% of the body’s cells
- Carries 99% of the body’s genetic information
- Collectively weighs about two pounds
These organisms interact with the cells of our bodies, each other, and with the environment (what we eat and what we’re exposed to). Although scientists have hardly unraveled all of these interactions, the microbiome is known to have a role in:
- The immune system. Gut microbes may train the immune system to recognize foreign invaders. Depending on internal balances, however, they can harm the body’s immunity
- Managing inflammation. Some bacteria protect the lining of the gut. Conversely, harm to these bacteria can allow chemicals to pass into the bloodstream that induce inflammation
- Obesity and diabetes. One microbe species in the gut regulates a chemical that tell the body when it’s full. Conditions that harm gut bacteria, however, can allow inflammations that lead to obesity and insulin resistance
- Cancer and tumors. Some body conditions can signal gut microbes to secrete chemicals that, in turn, lead to tumors or cancers
- Brain function and mood. Gut microbes are involved in production of some neurotransmitters, including serotonin that’s related to depression
- Infant development. Babies are exposed to a mother’s bacteria in amniotic fluid and during passage through the birth canal. Among other functions, these microbes aid in milk digestion
Things like this get the attention of medical science. It’s no surprise, then, that the condition of a patient’s bacterial community is becoming an essential factor in medical treatment protocols.
Antibiotics have been the standard medical tool for treating disease in modern times: Find the pathogen that causes a disease, kill it, and the disease goes away. The growing rise in antibiotic-resistant disease strains, however, is alarming the medical profession. More than two million people in the US are sickened every year by such resilient strains and at least 23,000 die of them. Clostridium difficile, which kills 14,000 Americans annually, is the biggest threat. This opportunistic organism moves in when the native microbiome has been destroyed by antibiotics. Fecal transplants repair a patient’s compromised microbiome and allow it to fend off C. difficile. In other words, both the patient and their associated microbe community must be treated for effective care.
Although additional medical strategies will almost certainly emerge from microbiome research, the complexity of the underlying phenomena will likely limit the pace of progress. Some thorny questions still need answers, such as:
- What is a “normal” microbiome? Healthy people all over the world appear to have different microbe populations. The connections between environments, cultures, or even genetic traits need a lot of study
- What are the causal actions among microbe species? Does a health problem result from a change to the microbiome or is that change a symptom of an event somewhere? Medical protocols first require reliable cause-effect models.
Regardless of where the research goes, it’s exciting to watch the emergence of fundamentally new perspectives in biology and medicine. Already, however, our knowledge of the microbiome has shown that we can’t look at ourselves the same way we did even a few years ago.
Now, each of us is a living community.