Ever feel like you are alone, on a desert island to fend for yourself. It is never actually true if you count all lifeforms and not just human companionship. Your body is made up of around ten trillion cells, but you harbour a hundred trillion bacteria. For every gene in your genome, there are 100 bacterial ones. Therefore the total number of genes associated with these other creatures exceeds the total number of human genes by a factor of 100 to one. We are mini ecosystems teaming with other organisms. “We are in essence only ten percent human – the rest is pure microbe,” claims Dr Sleator, a Cork Institute of Technology lecturer who has studied human microbial populations.
The human microbiome is the official name for the population of more than 100 trillion bacteria, viruses, fungi and other microbes that live in our gut, mouth, skin and elsewhere in our bodies. These microbial communities have numerous beneficial functions relevant to supporting life. They are needed to digest food, to prevent disease-causing bacteria from invading the body, and to synthesize essential nutrients and vitamins. What we do, in turn, affects them. Everything from the food we eat to the way we’re born influences the species of bacteria that take up residence in our bodies. With the advancement of genomic technologies, the capacity of this “second genome” to influence health can now be harnessed as a function of the whole community rather than as isolated bacterial species. Some scientists are even referring to a human and their inner community as one human-bacteria-super-organism.
Dr. Martin Blaser is the director of NYU’s Human Microbiome Program and their former chairman of medicine. He is an expert on the human microbiome and has written Missing Microbes: How the Overuse of Antibiotics Is Fueling Our Modern Plagues. There are many theories why food allergies, asthma, celiac disease and intestinal disorders like Crohn’s disease have been on the rise in the past couple of decades. Blaser speculates that it may be connected to the overuse of antibiotics as well as modern day birth practices that are killing the healthy strains of bacteria that typically live in the gut.
Martin J. Blaser, MD, in his lab at NYU Langone Medical Center with Xuesong Zhang, PhD. Photo by Carl Glenn
“Since World War II, we’ve seen big rises in a number of diseases: asthma, allergies, food allergies, wheat allergy, juvenile diabetes, obesity. … These are all diseases that have gone up dramatically in the last 50 or 70 years. One of the questions is: Why are they going up? Are they going up for 10 different reasons, or perhaps there is one reason that is fueling all of them.
My theory is that the one reason is the changing microbiome; that we evolved a certain stable situation with our microbiome and with the modern advances of modern life, including modern medical practices, we have been disrupting the microbiome. And there’s evidence for that, especially early in life, and it’s changing how our children develop.”
He suggests there is a choreography going on inside us during the first few years of life that is important for the rest of one’s lifespan. Nature’s great purpose is to evolve to maximize health and create new generations and it is pretty good at it. Modern medical and scientific practices have started to disrupt that great work. One of the main changes is the very process of birth. Inside the body a baby is sterile, protected from the world beyond it’s mother’s womb and what is transferred through the umbilical cord. When the membranes rupture and the water breaks, the baby has to journey from inside the mother’s body to the outside world. And that is the first exposure to the bacteria of the world, the microbes lining the mother’s vagina, the bacteria in the birth canal. As a baby is born those microbes are ingested and and absorbed.
Mammals have been able to transfer the microbiome to their offspring that way for 150 million years. Blaser believes that when children are born by cesarian section, this natural transfer does not happen. “You could project that if they didn’t acquire these organisms or they didn’t acquire them normally or at the normal time, then the foundations might be a little shaky.” More and more epidemiologic studies are trying to determine if there are long-term health consequences of C-section births. As well there is the increased use of antibiotics. It has long been known in the alternative health fields that taking probiotics after antibiotics can help restore the microbes that are lost during the course of medical intervention. According to Blaser there are many types of probiotics available and that although they are currently unregulated and untested, they are generally safe to take and that it is better to take them than not to. “Right now, it’s the Wild West. I’m actually a big believer in probiotics; I think that’s going to be part of the future of medicine, that we’re going to understand the science of the microbiome well enough so that we can look at a sample from a child and say this child is lacking such-and-such an organism and now we’re going to take it off the shelf and we’re going to give it back to that child. … Just as today the kids are lining up for the vaccines, in the future, maybe the kids are going to be drinking certain organisms so that we can replace the ones that they’ve lost.”
If we don’t develop this theory and integrate it into our medical practices, we could lose the microbes we need to function as healthy humans forever.
Based on the article by Fresh Air‘s Terry Gross.