A strange world full of organisms lives inside you, but not in the way you think: ScienceAlert

Inside your gut is a whole world made up of mostly harmless microbes that live in the gastrointestinal tract.

Dubbed the gut microbiome, this dazzling collection of bacteria and other microorganisms has garnered a lot of attention – it’s been linked to a variety of health conditions, from autism spectrum disorders and diabetes to depression, Alzheimer’s and movement disorders.

But despite everything researchers have discovered about the gut microbiome, there’s a whole lot we still don’t know — and it seems we have a number of myths to dispel.

registered mail natural microbiology Reviewing the literature, British microbiologists Alan Walker of the University of Aberdeen and Lesley Hoyles of Nottingham Trent University come up with 12 myths and misconceptions about the gut microbiome, partly due to the gut microbiome’s enormous potential for human health.

“Unfortunately, while it’s really exciting, the increased focus on microbiome research has also brought hype and perpetuated certain misconceptions,” write Walker and Hoyles.

“As a result, many unsupported or insufficiently supported statements have become ‘facts’ through constant repetition.”

While some of these myths are relatively trivial, others are more widespread and overall could undermine progress and public confidence in research, Walker and Hoyles argue.

So let’s dive into some of the juicier myths on the list. Watch out for the slime.

First of all, microbiome research is not a new field; It dates back at least to the late 19th century when the first bacterial samples were isolated from the human gut.

Likewise, the mysterious connection between the guts of the body and the mind, the gut-brain axis, has been explored for centuries. Only recently have we understood how this connection works both ways.

Now for some numbers. The total weight of the human microbiota is estimated to be 1 to 2 kilograms (2.2 to 4.4 pounds). However, Walker and Hoyles could not find the original source for this frequently cited number.

Instead, they suggest that the human microbiota is more likely to weigh 500 grams or less. Their revised estimate is based on how much an average human stool weighs (200 grams wet weight), how much of that feces is made up of microorganisms (about half), and the weight of the colon’s contents.

Similarly, some calculations in the 1970s led to the assumption that the human body harbors ten times as many individual microbes as own cells.

Researchers have tried to debunk this myth before, finding that the ratio is probably closer to 1:1. Of course, it’s worth repeating if we see these numbers making the rounds again.

Another commonly reported claim is that babies “inherit” their microbiota from their mothers at birth. While some microorganisms are transmitted directly at birth, research suggests that few species actually stay with us for life.

A mother’s microbiota may give babies a brief health boost, but it’s our diet, antibiotics, genetics, and the environment we’re exposed to that shape our microbiome.

“Every adult has a unique microbiota configuration, even identical twins growing up in the same household,” Walker and Hoyles note.

The remaining misunderstandings are of a more technical nature and concern the laboratory work of busy microbiologists.

But the last question that probably interests us the most is whether changes in a person’s gut microbiome contribute to disease.

It is difficult for researchers to draw clear patterns because “such changes are seldom consistent and the microbiota varies greatly between individuals, both in terms of health and disease,” Walker and Hoyles write.

Age, BMI, and medications, as well as a person’s metabolism and immune system, can also affect the composition of the microbiota, making it very difficult to decipher possible cause and effect in observational studies.

Perspective was published in natural microbiology.

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