In this Biome Bite, Dr James McIlroy 3 myths and misconceptions about the gut microbiome.
Timecodes:
00:00:00 Intro
00:00:56 Weight of the microbiome
00:04:39 We’re more microbial than human
00:07:00 Microbiota is inherited from our mothers
 What we're talking about today on this Biome Bite is microbiome myths and misconceptions. We're going to cover 3.
There's this lovely article written by Professor Alan Walker, who's been on the podcast, highly recommend you watch and listen to that episode, and Professor Leslie Hoyles and it's in Nature Microbiology, so really nice high-impact scientific journal, and they go through a lot of the things which you hear within this space, be it in social media, be it in when you're speaking to someone who's just generally taking an interest in the microbiome, even in scientific papers, this still comes up, even though it's been refuted and proven to be untrue.
Arming Our Listeners With Facts About the Microbiome
So we're going to arm you as the listeners to Inside Matters with this knowledge so that you can truly start to become an expert and you've got your finger on the pulse of the field. And if you hear it, you go, I heard on inside matters. That's not true.  So the first one is the human microbiota weighs one to two kg.

You hear this a lot, several kilograms, almost like a weight plate at the gym. Wow, that's a lot.  Now although it's mentioned many times in literature, although you hear people talking about it, people say it weighs as much as a grapefruit.  And what the professors do in their papers, they explain that. The majority of the microorganisms reside within the colon,  i. e. the large intestine. And if you've listened to the previous Biome Bites episode, we walk through the digestive tract, the gut, what the gut is, what the digestive system is, how it all links together and how the microbiota fits into all of that. 

And in that episode, if you've not listened to it, what we say is that the vast majority of the microbiota, i.e. the microorganisms, particularly bacteria that reside within the body live in the large intestine.  And what's interesting is when you take a stool sample, or we can just use the other word, a poo the microorganisms typically account for roughly 50% of the weight of the faecal solid mass. 

This has been published, but also we've done a lot of stool collection and stool analysis in EnteroBiotix. In fact, we may collect more stool regularly and analyze stool in a more in-depth manner than anyone else in the world at the moment.  So we know a fair bit about it.
How Heavy is the Microbiome?
The size, shape, mass, and composition of stool can vary within an individual and also differ among various people. According to the paper, an average human stool typically weighs less than 200 grams when wet. However, in our experience, we have observed significant variations, which makes it a likely accurate statement.
And when you're running a donor program like EnteroBiotix, you actually want to target people who donate larger amounts, but also who have a good ratio of microorganisms versus solids. And that's driven by fibre and fibre content.  Now, they say a really interesting paper in patients or people, unfortunately, who have had a sudden death.
The human microbiota, particularly the gut microbiota, plays a crucial role in maintaining our health. The weight of these microorganisms has been the subject of many studies, and recent findings suggest that the total weight is likely to be less than previously thought. In sudden death cases, post-mortem assessments of the total colonic contents have shown a range between 83 to 421 grams. This data challenges earlier estimates that placed the weight of the human microbiota in the range of one to two kilograms.
Researchers concluded that barring unusual instances of severe constipation, where an individual's colon is compacted with a large amount of faecal matter, the total weight of the gut microbiota is more likely