What a humbling notion it is to consider the fact that 99% of the DNA contained within the human body is actually DNA that is associated with the bacteria that live within us. When we consider how the human genome has been so aggressively studied as representing the “holy grail” in terms of its role in determining our health destiny, to get our arms around the notion that in fact almost all of the DNA in the human body is actually bacterial certainly changes our perception of who we are and what we are.

And even more compelling is new research that indicates that even that 1% of the DNA in our bodies that we consider our own is itself actually and powerfully influenced by the gut bacteria, our microbiome.

In a new study, published in December 2014, researchers attempted to unravel the finding that changes in the various groups of bacteria contained within the human microbiome have an effect on metabolism. It is known that the ratio of two very large groups of bacterial organisms, the Bacteroidetes group and the Firmicutes group strongly relates to risk of things like obesity, metabolism, insulin sensitivity, and even inflammation. Those individuals with higher levels of Firmicutes organisms, in comparison to the Bacteroidetes group, are more prone to problems in these areas. Moreover, the ratio of Firmicutes to Bacteroidetes is strongly influenced by diet.

What these researchers looked at was the effect of the ratios of these two groups of bacteria in terms of how they influenced human DNA. What they found was really quite remarkable. Higher levels of Firmicute activated human DNA pathways that are associated with detrimental changes in fat metabolism, increased production of fat, and heightened levels of inflammation.

So the end result of this research reveals that not only is most of the DNA in the human body represented by bacteria, but that those bacteria themselves are actually regulating our own DNA! Not only is this humbling information, but it should be looked upon as opening the door to powerful new therapeutic techniques based upon interventions that will alter the ratios of gut bacteria, and therefore change our gene expression in a favorable way. And it’s these concepts that I explore in Brain Maker: The Power of Gut Microbes to Heal and Protect Your Brain–for Life.