“Bacteria,” “dirty,” “microbes,” these words might conjur up feelings of disgust and images of illness. Recent research is teaching us just the opposite is true.
As we tend to our herbal gardens the soil at our feet is teeming with life, microbia of all sorts. Similarly, the human body harbors up to ten times as many microbial cells as human cells. What are these microbes doing? Can they give us information about the condition of our health? While our human genome records traces of our evolutionary history, our microbial genomes may give us clues to what we have eaten, where we have lived, and who we have been in contact with.
My daughter drew my attention to this subject. As a young toddler she consumed more dirt on our organic farm than I thought humanly possible. At first, like any concerned Mom, I tried to dissuade her. When nothing dire happened, and when she stubbornly persisted I began to wonder if she was craving something she needed. Adopted at birth, she was never breast-fed, except once. I made her a formula from raw goat’s milk and additional nutrients, but the formula was low in iron, something that bottle fed babies often lack. Our soil is very high in iron. Was this driving her craving for dirt? Then, I began to notice that she never got sick – and I mean never! With her first teeth she had one fever for about 3 hours and that was it – until she weaned off her formula…and dirt. I began to wonder if she innately knew something I did not.
Imagine holding a human brain in your hands. It weighs three pounds! Now imagine instead you are holding a teeming pile of microbes. That is the amount of bacteria that colonize your gut! Exactly how “human” are we? With ten times the number of bacterial cells to human cells in our body we might be considered to be 10% human and 90% bug. Take it a step further and compare the number of human genes to microbial genes and we might be considered only .1-1% human. Rob Knight, professor of microbiology at UCSD, teases that maybe we are actually our microbiome’s human, rather than the other way around.
We know that trillions of these microbes reside in and on humans, and in and on the soil at our feet. We receive messages all the time from these little critters that cohabit with us, what and when to eat and when to store energy as fat, to name a few. Bacteria in the gut, and their little bug genes (collectively called the microbiome) are now known to play a key role in immunity, in metabolism and obesity, in inflammatory and auto-immune disorders. What does that mean? It means that understanding our human microbiome, may help us crack the code for the development of diabetes, heart disease, MS, arthritis and even certain cancers. Microbiologists today can predict with 90% accuracy whether a person is obese or lean by looking only at her poop.
Antibiotic resistant genes have been isolated from the bacteria in the human gut. What does this mean for our long term health? Anne M. Estes, PhD, in her recent post Entering the Natural Antibiotic Arms Race gives a lively description of just how antibiotic resistance occurs. Overuse of antibiotics, both in livestock and in human health care, drives antibiotic resistance according to Estes. Constant exposure to antibiotics through the medicines we take and the meat we eat, has encouraged our gut microbes to adapt. If our gut lining, full of immune-protecting bacteria is now full of antibiotic resistant genes, are we vulnerable?
Science now gives credence to the hygiene hypothesis, which declares that we have gone over the deep end with our cleaning habits. Because kids spend most of their times indoors, parents too, they don’t interact with essential microbes in nature. Why is this important? Regular exposure to a variety of bacteria helps the immune system better sort out friend vs. foe. In turn it will be less likely to mount an attack against the benign, such as tree pollen, cat dander, our own thyroid tissue, milk protein. An immune system that has little exercise is like an overly anxious mother bear, ready to strike at anything she perceives might be a danger. An over-reactive immune system means inflammation. Inflammation means joint pain, foggy brain, allergies, autoimmune issues, diabetes and cardiovascular disease. Know anyone with any of those problems?
Exposure to healthy soil, can even boost the diversity of the beneficial bugs in your gut. This, according to Rob Knight and his team, is critical for protection against pathogens and immune balance. So next time your little one is digging in the garden, resist the urge to whip out the antiseptic soap. Let him pull a carrot and nibble it. Better yet, get in there with him, get your hands and feet dirty. And stay that way for a good long time. Even science says you and he will be happier and healthier for it!