"We inherit every one of our genes, but we leave the womb without a single microbe. As we pass through our mother's birth canal, we begin to attract entire colonies of bacteria. By the time a child can crawl, he has been blanketed by an enormous, unseen cloud of microorganisms--a hundred trillion or more. They are bacteria, mostly, but also viruses and fungi (including a variety of yeast), and they come at us from all directions: other people, food, furniture, clothing, cars, buildings, trees, pets, even the air we breathe. They congregate in our digestive systems and our mouths, fill the space between our teeth, cover our skin, and line our throats. We are inhabited by as many as ten thousand bacterial species; those cells outnumber those which we consider our own by ten to one, and weigh, all told, about three pounds--the same as our brain. Together they are referred to as our microbiome--and they play such a crucial role in our lives that scientists like [Martin J.] Blaser have begun to reconsider what it means to be human." - Michael Specter
I recently read a book called The Human Superorganism by Rodney Dietert, PhD. The title is meant to convey an emerging view of the human body which we now know houses trillions of bacterial cells in addition to human cells. Originally it was estimated that we might have as many as ten times the number of bacterial cells as we do human cells. And while that ratio has since been revised, putting it closer to 1:1, that's still pretty significant.
More importantly than the sheer number of bacterial cells is our increasing understanding of how these cells interact with and impact our own, prompting many scientists to view the human body as a complex ecosystem with a multitude of organisms that depend on each other for survival. And as time passes, more and more studies are published in the scientific literature that confirm this notion of interdependence.
Take for example the bugs in our gut which help us digest certain foods, giving us access to nutrients and calories that otherwise would not be available. They also produce metabolites that are critical to normal functioning of the epithelial cells in the small and large intestines. Some even produce vitamins, like vitamin K, that are critical for normal optimal health and function. Our microbiome is even thought to impact our immune cells, which makes sense when you consider that 70% of immune cell activity occurs just below the surface of our gut. And if that weren't enough, there is mounting evidence to suggest that bacterial cells may result in the activation of epigenes, switches on the DNA that determine who does or does not get a certain disease. And whether through gene activation or another mechanism, there is an emerging consensus that the gut microflora and/or its metabolites in particular might contribute to systemic inflammation, be a trigger for auto-immune disorders, and influence the development of diabetes, heart disease, Alzhiemer's, ADHD, food allergies and sensitivities, obesity, and a whole slew of other noncommunicable diseases, including the big “C” cancer.
Of course, there are still many unknowns when it comes to our microbiome and its effect on our health, but there is a growing support for the idea that it does in fact have a significant impact on many body systems as well as our susceptibility to a number of diseases. The likely impact of microbes on our health is in part responsible for the increasing popularity of pre and probiotics, probiotics being the foods, powders, or pills that contain strains of bacteria believed to be necessary for optimal health while prebiotics are the food these bacteria eat.
The term dysbiosis has been created to describe a microbiome that is unhealthy or out of balance.
Unfortunately, what we know when it comes to the microbiome is somewhat overshadowed by what we don't know, and for this reason many of the current recommendations put forth to date have a tenuous basis in science at best, at least for now, and therefore may be completely off the mark. We just don’t know despite claims to the contrary. This is not to say the science and its implications aren't promising, just that we're not quite there yet. Yet given time, addressing the microbiome is likely to play a significant role in not only fighting disease but also in promoting optimal health.
Unknowns aside, it appears that a healthy diet based on nutrient-dense foods including fruits, veggies, nuts, legumes, beans, and seed supports a robust and desirable microbiome, and this may in turn at least partially explain the many benefits already associated with eating a healthy diet. Apparently, we’re not the only ones who are dependent on the foods that we consume to sustain us. Our many resident microbes also depend on us for their nourishment, and it just so happens they (the good ones at least) thrive off the fiber and phytonutrients found in fresh fruits and vegetables. On the other hand, there is some evidence that high protein diets (specifically animal protein), which have become popular thanks to their ability to promote short-term weight loss, do not necessarily support a healthy microbiome in the long-term and thus may be detrimental to it thanks to cancer causing metabolites produced in the large intestine when certain microbes break down undigested proteins. A lot seems to depend on the quality of the protein, plant vs. animal, and grass-fed or wild v.s industrially farm-raised. Regardless, this preliminary finding is consistent with the views of many nutrition experts who are increasingly critical of the very high-protein diets which are currently in vogue.
The dependence of gut microbes on the foods we eat may also explain why supplementing with nutrients is almost always inferior to obtaining those nutrients through real foods since popping a pill that provides nutrients X, Y and Z is not the same as eating foods that have a variety of phytonutrients and fiber, all package and proportioned perfectly thanks to millions of years of evolution.
Finally, exercise, stress management, and adequate sleep also appear to support a thriving and healthy gut microbe population.
In the end, it does appear that we are a complex ecosystem in which an alteration in one area of the system can have a ripple effect, ultimately impacting other areas, usually negatively. Likewise, too much of a good thing can sometimes be as harmful as too little because the ecosystem values balance first and foremost. Consider a vegetable garden in which the ratio of plants to weeds may impact the overall health of the garden. We all know that the best way to keep the weeds at bay are to establish mature plants that are healthy and thriving. Yet if these weeds are not kept in check but instead allowed to multiply, they will almost always leech essential nutrients from the soil, robbing our vegetable plants the nutrition they need to grow properly, often times resulting in a sick or unhealthy plant.
At the present time, probiotics (pills, potions and a handful of fermented foods that contain microorganisms) and prebiotics (food for the microorganisms) do seem promising, unfortunately, there are still too many unknowns to make good recommendations, and so we are left with rough guestimations that may or may not deliver and could possibly even do more harm than good especially when taken outside the guidance of a doctor or other health professional.
Until we have more definitive data, the best way to promote a healthy microbiome is via a diet rich in plant-based foods like colorful fruits and veggies, high-fiber beans and legumes, and healthy fats from nuts and seeds, in addition to participating in regular exercise, managing stress, and getting adequate sleep.