We are not alone. Yes, we constantly have companionship with a mass of symbiotic organisms who communicate with our brains and control every aspect of our health. You think me mad or paranoid but it’s true. Deep within our intestinal tract lies over 100 trillion microbes collective known as the gut microbiome. Our understanding of the functions of the gut microbiome has truly revolutionized our approach to wellness and chronic disease.
This may be difficult to fathom, since we’re taught that we need to get rid of germs and maximize our hygiene to optimize our health. In fact, at the first sign of any apparent illness in childhood, we’re doused with antibiotics, though medical science has little idea and virtually no research regarding the long-term consequences of these treatments.
Living deep in your lower intestines is a complex ecosystem of microorganisms—a veritable garden of life. This magnificent orchard is composed of viruses, bacteria, and fungi, all of which collectively constitute what’s called the human gut microbiome. When we care for this garden and nourish our flora, our health flourishes. But when we feed these microorganisms poorly and treat them poorly, the biodiversity of this ecosystem plummets and our health is compromised.
Each of us participates in a larger ecosystem, and our actions influence the health of that ecosystem. If we want our world to be healthy, we have to act in ways that help make it healthy.
But what about the ecosystem inside of you? It’s something few of us think about. Just as our actions influence the ecosystem around us, they influence our ecosystem within. Balance and biodiversity in this ecosystem create health—imbalance and reduced diversity in the ecosystem create illness.
There are many mechanisms by which microbes can protect us from disease or make us sick, help us lose weight or pack on the pounds, and we’ll discuss many of them throughout this series of blogs. Indeed, the most important lesson is that the solution to many of the diseases we face today may never be found if research remains focused on us, the host. We must pay due attention to the host-environment interface—the complex set of relationships that constitute the human-gut microbiome connection.
The average human being has about 100 trillion of these organisms at any given time. Although most are located in your lower intestines, you’re literally bathed and surrounded by microbes. Despite the best hygiene, we carry billions of microbes that hide under fingernails, lounge between teeth, stick to our skin, coat our eyes, hang out in our hair. There are more than 600,000 bacteria living on just 1 square inch of skin. The same holds true at internal passages, your respiratory system, genitourinary system, eustachian (ear) tubes, and much more. Just like in the 1999 sci-fi movie The Matrix, the naked human eye sees only an altered reality. It’s incapable of seeing the trillions of microbes that constantly surround us. How would you feel if you could see every one-celled organism?
The microflora in your gut alone weighs about 3 to 5 pounds. These microbial cells outnumber your own human cells by a factor of 10 to 1, and microbial DNA outnumbers your human DNA by 100 to 1. Take a moment to think about what that means. Inside your body, there are more bacterial cells and DNA than human cells and DNA. Do you think this might have an impact on your health?
While we haven’t yet identified all the strains of human gut microflora, the Human Microbiome Project, a collaboration led by Dr. Jeffrey Gordon of Washington University School of Medicine in St. Louis, made substantial advances in accomplishing this incredible feat. With $173 million in funding from the National Institutes of Health, this project’s mission was to comprehensively characterize the human microbiome and analyze their role in human health and disease.[i],[ii]
So far, they’ve isolated over a 1,000 species across dozens of different phyla—an astounding variety of microbes. There are few ecosystems on the planet that are as complex as the one inside of us. The species density of the human large intestine is nearly equal to that of the Amazon rain forest.
The picture featured to the right is a picture of the Amazon rainforest taken by scientists using laser beam technology about 400,000 times per second! This was taken in Peru — the most biodense region of the rainforest which was mapped in unprecedented detail.
Our relationship with this ecosystem is symbiotic.
We house our flora and provide it with food. In turn, these organisms serve us in a number of ways. They:
Break down complex carbohydrates. Humans lack the enzymes to do this. You wouldn’t be able to properly digest a single fruit or vegetable without your gut microflora.
Produce vitamins and nutrients. You’d otherwise be unable to manufacture these on your own, including vitamin K, vitamin B12, niacin, pyridoxine, and others.[iii]
Produce short-chain fatty acids (SCFAs). We’ll spend a good deal of time on what these are and why they’re important in the future articles, but for now, be aware that they’re involved in regulating immunity, healing, and combating inflammation, and they may protect you against cancer and other diseases.[iv]
Protect against pathogens. Your gut microflora is your first line of defense against foreign invaders.
Help train the immune system. Bacterial genes send signals to your gut’s immune system that control local and systemic inflammation and play a role in determining whether you develop allergies and autoimmune diseases.[v]
Support detoxification. When you metabolize your food, toxic metabolites, including carcinogens, are formed in your liver and carried by your bile into your digestive tract for elimination. Your gut flora degrades these potentially harmful biochemicals so they can be safely eliminated.
Modulate the nervous system. Emerging research shows a connection between your gut microbiota, your digestive system, your nervous system, and your brain that may affect everything from appetite regulation to behavior to mood.[vi]
These are only a few of the important roles your gut microflora play. Over the course of these blogs we will “dig in” and review in more depth their essential role in human health, including their influence on your weight.
To your good health.
Dr. Gerry Mullin
[i] Conlan S, Kong HH, Segre JA. Species-level analysis of DNA sequence data from the NIH Human Microbiome Project. PLoS One. 2012;7(10):e47075.
[ii] Peterson J, Garges S, Giovanni M, McInnes P, Wang L, Schloss JA, et al. The NIH Human Microbiome Project. Genome Res. 2009;19(12):2317-23.
[iii] Leblanc JG, Milani C, de Giori GS, Sesma F, van Sinderen D, Ventura M. Bacteria as vitamin suppliers to their host: a gut microbiota perspective. Curr Opin Biotechnol. 2012.
[iv] Layden BT, Angueira AR, Brodsky M, Durai V, Lowe WL, Jr. Short chain fatty acids and their receptors: new metabolic targets. Transl Res. 2012.
[v] Ivanov, II, Honda K. Intestinal commensal microbes as immune modulators. Cell Host Microbe. 2012;12(4):496-508.
[vi] Rhee SH, Pothoulakis C, Mayer EA. Principles and clinical implications of the brain-gut-enteric microbiota axis. Nat Rev Gastroenterol Hepatol. 2009;6(5):306-14.