Our Several Trillion Closest Friends
Americans today are germaphobic. We scrub, spray, and anoint ourselves with various antibacterial substances, and take antibiotics for nearly every illness. We believe that most illnesses are caused by germs, so that the more germ free we become, the healthier we’ll be. This mindset is not only misleading, but downright dangerous.
Bacteria, archaea, fungi, single celled eukaryotes and even viruses that live on and inside of us make up the collection of microorganisms known as our microbiome. They live on our skin, in our orifices, and the largest population dwells on the linings of our digestive system. A normal healthy individual houses at least as many microbial cells in and on the body as there are human cells. Our microbiome not only lives peacefully with us, but is vital to our health. Scientists at the National Institute of Health’s Human Microbiome Project, recognizing this vital role, are calling our microbiome “the other human genome.”
For the last couple of decades, the microbiome has become the focus of intense scientific study. The findings have been profound in their implications. The microbiome impacts our health in every conceivable way. It aids in development during the formative years, helping to create a strong immune response. It controls the rate of digestion, so that healthy fruits and vegetables are given more transit time for digestion in the gut. The micobiome plays a key role in digestive function, particularly by breaking down the insoluble fiber that our bodies are incapable of digesting, and supplies our bodies with vitamins, short-chain fatty acids like Butyrate, Propionate and Acetate along with other vital metabolites. These important products circulate throughout the body to maintain healthy bodily function. In fact, our bodies cannot function normally without these products.
Though it is true that infections and some diseases are caused by microscopic invaders, it is also true that our first line of defense against these invaders is the collection of microbes that normally dwells in and on our bodies. They not only compete for the same resources with the unhealthy invaders effectively starving them out, but our microbiome secretes antimicrobials and toxins to kill the invaders.
In addition to directly impacting the proliferation of pathogens, our microbiome is also capable of neutralizing toxins that are excreted from invading pathogens, by creating proteins that bind with the toxins to render them harmless. They can target specific microorganisms in order to wipe out an invader without harming neighboring beneficials. They can even produce
chemical warnings that stimulate our immune system to produce antimicrobial peptides in time to ward off an eminent invasion.
At birth the child is exposed to a living film of protective organisms as it passes through the birth canal. The medical community is now learning that a caesarian birth puts a newborn baby at a distinct disadvantage by losing out on this early inoculation of symbiotic organisms. Such deficiency has been linked to incidence of asthma, allergies and other health conditions in children. In order to make up for this deficiency in exposure some doctors have tried smearing the newborn with a swab of its mother’s vaginal secretions in order to replicate the normal introduction to the mothers fauna.
Nursing the baby rather than feeding formula can also help alleviate the conditions caused by an insufficiently diverse microbiome, since it exposes the infant to the organisms living on the mother’s skin as well as to any organisms that thrive on human breast milk. The mother’s instinctive touching, cuddling and kissing her infant also allows her to share her beneficial organisms. In fact, even having a family dog has been shown to create a more resilient microbiome, so that children who share a home with a dog are less susceptible to asthma and allergies.
As the child continues to grow, and throughout adulthood, the microbiome aids in the development and continued functioning of the immune system. It produces metabolites that stimulate production of immune cells in the bone marrow. It communicates with lymphocytes to establish a system that can distinguish between friend and foe. It even has an impact on gene expression, encouraging the production of anti-inflammatory substances and inducing protective intestinal immune responses. Research in these areas is still in its early stages, but it is becoming quite plain that our microbiome plays a key role in immunity.
Dysbiosis—The Enemy Within
The particular variety and balance of microorganisms in our system is known as our Enterotype. One of the more important goals of the Human Microbiome Project is to understand the difference between the type and diversity of organisms in a healthy person and those who are suffering from various diseases. It is clear that, though there is a diversity in enterotypes of healthy individuals, similar clusters of organisms in populations of people have been identified. In like manner, similarities can be identified between people suffering from the same illnesses. One prominent characteristic in the enterotypes of individuals suffering from various chronic illnesses is a lack of diversity in organisms. Another similarity is the prevalence of Bacteroidetes, which thrive on the digestion of animal based products, and the reduction in number of Firmicutes, which thrive on the fiber found only in plant sources.
Dysbiosis—defined as disruptions in the microbiome characterized by reduction in diversity and dominance by unhealthy organisms—has been linked to many chronic illnesses including diabetes, heart disease, Crohn’s Disease, Irritable Bowel Syndrome, obesity, cancer and even mental disorders such as Alzheimer’s Disease. A multitude of studies have shown that interactions between the immune system and the microbiome play a decisive role in diseases or in their prevention. It has even been suggested that individual characteristics of disbiosis associated with various types of cancer can aid in the diagnosis of difficult to identify cancers.
We Are What We Eat
Dysbiosis has complex causes, but relatively simple solutions. The overuse of antibiotics has been linked to the destruction of a healthy microbiome. The prevalence of preservatives in the standard American diet also plays a role in its destruction. Preservatives and antibiotics were created to kill pathogens that can harm our bodies, but their detrimental effects to our beneficial organisms may cause as much harm as they do good. Antibiotic use should be avoided except in cases of life-threatening infection. We can also limit our exposure to preservatives by avoiding processed foods.
The simplest solution to dysbiosis is a change in diet. What we eat has the greatest influence on the health of our microbiome. As the China Study demonstrated, those who eat a whole food plant based diet—avoiding both animal products and highly processed foods—avoid the diseases most prevalent in affluent societies. Among indigenous populations of rural China heart disease, diabetes, high blood pressure and Alzheimer’s Disease are nonexistent. Cancers common in our society like colon, breast and prostate cancers are rarely seen. The same has been found among other native populations like those in rural Uganda and Tanzania.
Feeding our microbiome sufficient quantities of fiber rich foods is the key to good health. The lack of fiber in animal based foods is just one of its unhealthy aspects, but may be among the most crucial differences. Eschew meat, dairy, eggs and fiber poor refined food products. Eat plenty of fresh fruits and vegetables, legumes, whole grains, nuts and seeds. What is good for the microbiome is also good for us.
In future articles, we’ll explore the role our microbiome plays in Heart Disease, various bowel diseases (like IBD and Crohn’s Disease), Weight Control, and Mental Health (including Alzheimer’s Disease, Autism and depression).