The top 9 microbiome myths that I want to set straight

From where you get your first microbes from to how antibiotics affect your gut bacteria, there is a world of misinformation out there.

People ask me questions about the gut microbiome all the time. And the amount of misinformation and myths that are out there never ceases to amaze me.

So, I’ve put together my list of top microbiome myths and why they are wrong. 

1. Your microbiome is inherited at birth

It’s true that you get your first dose of microbes at birth from your mother. And the composition of this will differ whether you’re born naturally or by caesarian section. But this is just the start.

In a paper that I published last year with colleagues, we found that only up to 19% of bacterial strains were likely to be the same as your mother’s by the time you turned 18, and this decreased to 14% by the time you reached 30. 

Your housemates make nearly as much difference to your gut microbiome at this point; we saw that people who live together have around 12% of their bacterial strains in common. 

So, it’s really a combination of your early years and who you decide to spend your time once you’re grown up – plus many other factors including the food you eat, whether you have a pet and how much time you spend in nature – that determine your microbiome as an adult. 

Photo by Stefan Vladimirov

2. There are ten times more microbes in your body than human cells 

This myth is literally plastered all over the media and based on some very crude calculations made in the 70s. 

There are much more accurate estimates now, which put the number of bacteria roughly in the order of trillions to tens of trillions – which is about in the same order of magnitude as the estimate for human cells that stands at 30-40 trillion. 

It’s important to note that these figures are based on an imaginary “standard 100 kg man.” Of course we know that everyone’s microbiome is unique. Therefore, the exact number of microbes in your body will be a little more or a little.