Erica Sonnenburg Ph.D.

The Good Gut

Microbes Are Holding the Reins to our Health

How our gut microbiota is linked to many aspects of our biology.

Posted Apr 12, 2015

Justin Sonnenburg, Jamie Dant, Jeffrey Gordon, used with permission
Scanning electron micrograph of the human gut symbiont Bacteroides thetaiotaomicron.
Source: Justin Sonnenburg, Jamie Dant, Jeffrey Gordon, used with permission

You are not alone. Your gut is teaming with bacteria that have been linked to everything from autism to obesity and may even be influencing your mood and behavior. Whether this collection of microorganisms, your microbiota, is thriving or suffering has huge implications for your risk of a number of diseases including diabetes, cancer, heart disease, and even mental illness.

Each of us is colonized by a dense collection of microbes that outnumber our own human cells 10 to 1. That’s right, you are more microbe than you are human. In fact if you count up the total amount of genetic material you carry around, only 1% is human in origin, the rest comes from your associated bacteria. Perhaps, a more accurate way to think of yourself is as a super-organism, small part human and large part microbial. These bacteria have been with our species since we evolved millennia ago on the savannahs of Africa. As researchers study this immense collection of bacteria we house, it is becoming more evident each day that they are an integral part of our biology and our health.

Many people think of bacteria as nefarious, evil-doers that should be targeted for elimination with every course of antibiotics and swipe of antibacterial cleaner we use. And based on our use of antibiotics and antibacterial products, it’s clear that our view of microbes is one of - it’s us against them. But groundbreaking research over the past decade is revealing that most bacteria are not only good for us, our body needs them, lots of them.

Most of our associated bacteria live in our large intestine or gut, which houses upwards of 100 trillion bacteria composed of hundreds of different species.  Traditionally these microbes were mainly thought of as free-loaders, eating left-over food in our gut and providing us with a few extra calories in return. But recently there has been a renaissance in the scientific study of these microorganisms thanks in part to the development of cutting-edge DNA sequencing technologies developed for the Human Genome Project. This research is revealing that our gut microbiota is doing so much more than helping us digest food. It is holding the strings of our immune system, dictating our body’s immune response to everything from viruses to peanuts. It is setting the dial on our metabolism, determining whether calories should be burned or stored. It is even communicating with our brain, affecting the perception of the world around us.

Recent studies show that the average American gut microbiota is not as robust as it once was and this deficiency may be at the root of many Western diseases such as obesity, diabetes, asthma, and allergies. People living a lifestyle similar to our hunter-gatherer or early agrarian ancestors have a far more diverse, flourishing ecosystem in their guts compared to the typical Westerner. It appears that our Western lifestyle with its easy access to antibiotics and convenience food diet is contributing to the demise of our microbiota and with it our health.

Biomedical researchers across many disciplines are realizing the amazing potential our “forgotten organ” has to treat and cure disease, improve our health, and prolong our lives. Unlike our human genome, which is determined at conception and fairly fixed, our microbiota is quite malleable in response to changes in our diet, antibiotic use, and exposure to environmental microbes. Whether this internal ecosystem flourishes or suffers is under our control. In this series, I’ll be looking at the different threats to the microbiota and how we can combat them for our own families. We are the stewards of our microbiota and if we take care of these microbes, they will, in turn, take care of us.