Is your gut microbiome the key to health and happiness?
Research suggests the vast ecosystem of organisms that lives in our digestive systems might be as complex and influential as our genes in everything from mental health to athleticism and obesity. But is ‘poop doping’ really the way ahead?
The gut microbiome weighs more than the brain. Illustration: Andy Goodman/Five Bar Gate
Amy Fleming-Monday 6 November 2017 17.37 GMT
John Cryan was originally trained as a neuroscientist to focus on everything from the neck upwards. But eight years ago, an investigation into irritable bowel syndrome drew his gaze towards the gut. Like people with depression, those with IBS often report having experienced early-life trauma, so in 2009, Cryan and his colleagues set about traumatising rat pups by separating them from their mothers. They found that the microbiome of these animals in adulthood had decreased diversity, he says.
The gut microbiome is a vast ecosystem of organisms such as bacteria, yeasts, fungi, viruses and protozoans that live in our digestive pipes, which collectively weigh up to 2kg (heavier than the average brain). It is increasingly treated by scientists as an organ in its own right. Each gut contains about 100tn bacteria, many of which are vital, breaking down food and toxins, making vitamins and training our immune systems.
Cryan’s study didn’t attract much attention, but a few years later, Japanese scientists bred germ-free animals that grew up to have an elevated stress response. This alerted Cryan and his colleagues that they might be able to target the microbiome to alleviate some of the symptoms of stress, he says.
The hope is that it may one day be possible to diagnose some brain diseases and mental health problems by analysing gut bacteria, and to treat them – or at least augment the effects of drug treatments – with specific bacteria. Cryan and his colleague Ted Dinan call these mood-altering germs “psychobiotics”, and have co-written a book with the American science writer Scott C Anderson called The Psychobiotic Revolution.
The psychobiotics of the title are probiotics that some scientists believe may have a positive effect on the mind. Probiotics are bacteria associated with healthy gut flora – such as the Lactobacillus acidophilusand Bifidobacterium lactis we see advertised in “live” yoghurt. More diverse bacterial cocktails can also be bought as food supplements, but they’re expensive.
Cryan and his team went on to work with germ-free mice. “In these mice, the brains don’t develop properly,” he says. “Their nerve cells don’t talk to each other appropriately, thus implicating the microbiome in a variety of disorders ... We’ve also shown changes in anxiety behaviour, fear behaviour, learning, stress response, the blood-brain barrier. We found a deficit in social behaviour, so for social interactions we have an appropriate repertoire of bacteria in the gut as well.”
Over the past decade, research has suggested the gut microbiome might potentially be as complex and influential as our genes when it comes to our health and happiness. As well as being implicated in mental health issues, it’s also thought the gut microbiome may influence our athleticism, weight, immune function, inflammation, allergies, metabolism and appetite.
The past month alone has seen studies linking the gut microbiome with post-traumatic stress disorder (people with PTSD had lower than normal levels of three types of gut bacteria); fathoming its connection with autoimmune disease; finding that tea alters the gut microbiome in anti-obesogenic ways; showing that “ridiculously healthy” 90-year-olds have the gut microbiome of young adults; and how targeting mosquitos’ gut flora could help beat malaria by increasing the malaria-attacking bacteria in their guts. And last week, two groundbreaking studies provided evidence that gut biodiversity influences whether or not immunotherapy drugs shrink tumours in cancer patients.
One story that caught the public’s imagination during the summer implied that “poop doping” (AKA microbiome enhancement via faecal transplant; what has been delicately described as a “reverse enema”) could become the new blood doping for elite cyclists. Lauren Petersen, a research scientist at the Jackson Laboratory for Genomic Medicine in Connecticut, looked at the stool samples of 35 cyclists, comparing those of elite and amateur cyclists. So sure was she that she would benefit from having some of the bacteria found in the gut microbiome of elite cyclists that she doped herself with the faeces one had donated. An endurance mountain biker herself, she swears (but can’t prove scientifically) that this took her from feeling too weak to train to winning pro cycling races. However, when you consider that one gram of faeces is home to more bacteria than there are humans on Earth – and how little we understand about the vast majority of them, good and bad – this is definitely not recommended.
Amy Fleming-Monday 6 November 2017 17.37 GMTJohn Cryan was originally trained as a neuroscientist to focus on everything from the neck upwards. But eight years ago, an investigation into irritable bowel syndrome drew his gaze towards the gut. Like people with depression, those with IBS often report having experienced early-life trauma, so in 2009, Cryan and his colleagues set about traumatising rat pups by separating them from their mothers. They found that the microbiome of these animals in adulthood had decreased diversity, he says.The gut microbiome is a vast ecosystem of organisms such as bacteria, yeasts, fungi, viruses and protozoans that live in our digestive pipes, which collectively weigh up to 2kg (heavier than the average brain). It is increasingly treated by scientists as an organ in its own right. Each gut contains about 100tn bacteria, many of which are vital, breaking down food and toxins, making vitamins and training our immune systems.
Cryan’s study didn’t attract much attention, but a few years later, Japanese scientists bred germ-free animals that grew up to have an elevated stress response. This alerted Cryan and his colleagues that they might be able to target the microbiome to alleviate some of the symptoms of stress, he says.
The hope is that it may one day be possible to diagnose some brain diseases and mental health problems by analysing gut bacteria, and to treat them – or at least augment the effects of drug treatments – with specific bacteria. Cryan and his colleague Ted Dinan call these mood-altering germs “psychobiotics”, and have co-written a book with the American science writer Scott C Anderson called The Psychobiotic Revolution.
The psychobiotics of the title are probiotics that some scientists believe may have a positive effect on the mind. Probiotics are bacteria associated with healthy gut flora – such as the Lactobacillus acidophilusand Bifidobacterium lactis we see advertised in “live” yoghurt. More diverse bacterial cocktails can also be bought as food supplements, but they’re expensive.
Cryan and his team went on to work with germ-free mice. “In these mice, the brains don’t develop properly,” he says. “Their nerve cells don’t talk to each other appropriately, thus implicating the microbiome in a variety of disorders ... We’ve also shown changes in anxiety behaviour, fear behaviour, learning, stress response, the blood-brain barrier. We found a deficit in social behaviour, so for social interactions we have an appropriate repertoire of bacteria in the gut as well.”
Over the past decade, research has suggested the gut microbiome might potentially be as complex and influential as our genes when it comes to our health and happiness. As well as being implicated in mental health issues, it’s also thought the gut microbiome may influence our athleticism, weight, immune function, inflammation, allergies, metabolism and appetite.
The past month alone has seen studies linking the gut microbiome with post-traumatic stress disorder (people with PTSD had lower than normal levels of three types of gut bacteria); fathoming its connection with autoimmune disease; finding that tea alters the gut microbiome in anti-obesogenic ways; showing that “ridiculously healthy” 90-year-olds have the gut microbiome of young adults; and how targeting mosquitos’ gut flora could help beat malaria by increasing the malaria-attacking bacteria in their guts. And last week, two groundbreaking studies provided evidence that gut biodiversity influences whether or not immunotherapy drugs shrink tumours in cancer patients.
One story that caught the public’s imagination during the summer implied that “poop doping” (AKA microbiome enhancement via faecal transplant; what has been delicately described as a “reverse enema”) could become the new blood doping for elite cyclists. Lauren Petersen, a research scientist at the Jackson Laboratory for Genomic Medicine in Connecticut, looked at the stool samples of 35 cyclists, comparing those of elite and amateur cyclists. So sure was she that she would benefit from having some of the bacteria found in the gut microbiome of elite cyclists that she doped herself with the faeces one had donated. An endurance mountain biker herself, she swears (but can’t prove scientifically) that this took her from feeling too weak to train to winning pro cycling races. However, when you consider that one gram of faeces is home to more bacteria than there are humans on Earth – and how little we understand about the vast majority of them, good and bad – this is definitely not recommended.
