Jun 17th 2020

Gut health: does exercise change your microbiome?

by Rachael Rigby and Karen Wright

 

Rachael Rigby is Senior Lecturer in Gastro-Intestinal Health at the Lancaster University.

Karen Wright is Lecturer in Biomedical and Life Sciences at the Lancaster University.

 

The diverse, non-human life forms that live in our guts – known as our microbiome – are crucial to our health. A disrupted balance of these contribute to a range of disorders and diseases, including obesity, diabetes, inflammatory bowel disease. It could even affect our mental health.

It’s well known that the microbes living in our guts are altered through diet. For example, including dietary fibre and dairy products in our diets encourages the growth of beneficial bacteria. But mounting evidence suggests that exercise can also modify the types of bacteria that reside within our guts.

One study found exercise promotes the growth of bacteria which produce the fatty acid, butyrate. Butyrate can promote repair of the gut lining and reduce inflammation, therefore potentially preventing diseases such as inflammatory bowel disease and insulin resistance, which leads to diabetes. Exercise-induced shifts in the gut microbiota can also guard against obesity and improve metabolic function.

Microbiome changes can even be seen following quite modest exercise regimes. One study found that women who performed at least three hours of light exercise – such as a brisk walk or swim – per week had increased levels of Faecalibacterium prausnitzii, Roseburia hominis, and Akkermansia muciniphila compared with sedentary individuals.

F. prausitzii and R. hominis reduce inflammation, while A. muciniphila has been associated with a lean body mass index (BMI) and improved metabolic health. This means that these microbiome changes are likely to be beneficial to overall health.

But it appears that the type of exercise also has different effects on the changes seen in the gut microbiota. Studies of rodents found that being forced to run on a wheel induced different microbiota changes compared to moderate exercise done when the mouse wanted to. There’s some evidence that the same is true in humans.

Athletes also have very different microbiota profiles compared to sedentary people of similar age and sex. Athletes had more diverse microflora, and a higher abundance of the three bacterial species mentioned above.

However, it still remains to be definitively proven that exercise can act independently of diet in making these changes. People who exercise may be more likely to also eat a healthier diet, so separating the two factors apart can be somewhat difficult.

Diet versus exercise

Animal studies, mainly on rodents, can shed some light on this conundrum as their diet is easily controlled. In mice, diet and exercise appear to induce very different changes in the microbiota. Some changes caused by a high fat diet – including an increase in Firmicutes and Proteobacteria, which are linked to type two diabetes and obesity – can be reversed by exercise.

Rodent studies are useful as their diets are easily controlled. Janson George/ Shutterstock

Other studies suggest that exercise-induced changes in the microbiota can be brought about independent of dietary intake – though other studies show dietary changes are required alongside exercise for these to occur. Exercise may even counteract some of the negative effects of a high fat diet, but not all.

Regardless, exercise may still help the good bacteria in our gut, called A. muciniphila, stick to the stomach lining. This better promotes mucus secretion which is important as mucus protects the bacteria from being carried out of the intestine with the digested food.

Studies looking at the immune system have also found that exercise decreases inflammatory signals and promotes a more “regulated” environment, in the gut lining and beyond. This reduces the chances of developing gut diseases. What’s really interesting about A. muciniphila is that it has been found to reverse weight gain from a high fat diet and insulin resistance in mice.

This study also showed that giving mice A.muciniphila also caused an increase in the cannabis-like molecules that our bodies naturally make, termed endocannabinoids. Among other functions in the body, endocannabinoids are involved in controlling gut inflammation and our gut barrier (the front-line molecules that provide a physical immune defence from external attacks).

The endocannabinoid system is also involved with feeding behaviour by controlling brain signals. Specific endocannabinoids are increased when we feel hungry, and released in the gut when we feel full. The endocannabinoid system is overactive in people who are obese.

Different gut bacteria can change the levels of the different components that make up the endocannabinoid system. Researchers used prebiotics to change microbial composition in mice. They saw a decrease of one type of endocannabinoid and a cannabinoid receptor in an obese mouse. They also saw that the prebiotics made bacteria and toxins less able to pass from the mouse’s gut into its bloodstream.

This led to reduced bacterial components found in the blood and reduced fat cell production. A healthy diet improves the diversity and richness of gut bacteria, as does exercise – possibly even through the same few bacterial species mentioned earlier. Although this needs to be tested in humans, the results from these studies show the potential interaction between the microbial population in the gut with diet and exercise to bring about an improved metabolism.

More recently, researchers have shown runners and cyclists produce more endocannabinoids in their blood, which provides some pain relief and improves mood. However, it’s not known whether these changes are short lived or whether they bring about long-term changes in the gut microbiome.

It is tempting to speculate that exercise can change the composition of the gut microbiome and influence well-being, all through a system that has the ability to have a three-way conversation. It remains to be seen if we can manipulate this through diet and/or specific probiotics – but we should not underestimate how we are shaped by our gut residents both at the metabolic and physical level.

Rachael Rigby, Senior Lecturer in Gastro-Intestinal Health, Lancaster University and Karen Wright, Lecturer in Biomedical and Life Sciences, Lancaster University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Browse articles by author

More Essays

Jan 23rd 2021
EXTRACT: "The ageing global population is the greatest challenge faced by 21st-century healthcare systems. Even COVID-19 is, in a sense, a disease of ageing. The risk of death from the virus roughly doubles for every nine years of life, a pattern that is almost identical to a host of other illnesses. But why are old people vulnerable to so many different things? It turns out that a major hallmark of the ageing process in many mammals is inflammation. By that, I don’t mean intense local response we typically associate with an infected wound, but a low grade, grinding, inflammatory background noise that grows louder the longer we live. This “inflammaging” has been shown to contribute to the development of atherosclerosis (the buildup of fat in arteries), diabetes, high blood pressure , frailty, cancer and cognitive decline."
Jan 20th 2021
EXTRACT: "Anthropos is Greek for human.... The term is used to convey how, for the first time in history, the Earth is being transformed by one species – homo sapiens. ...... The idea of the Anthropocene can seem overwhelming and can generate anxiety and fear. It can be hard to see past notions of imminent apocalypse or technological salvation. Both, in a sense, are equally paralysing – requiring us to do nothing. .. I consider the Anthropocene as an invitation to think differently about human relationships with nature and other species. Evidence suggests this reorientation is already happening and there are grounds for optimism."
Jan 7th 2021
EXTRACT: "During the second world war, Nazi Germany banned all listening to foreign radio stations. Germans who overlooked their duty to ignore foreign broadcasts faced penalties ranging from imprisonment to execution. The British government imposed no comparable ban which would have been incompatible with the principles for which it had gone to war. That’s not to say, though, that it wasn’t alarmed by the popularity of German stations. Most effective among the Nazis broadcasting to the UK was William Joyce. This Irish-American fascist, known in Britain as “Lord Haw-Haw”, won a large audience during the “phoney war” in 1939 and early 1940, with his trademark call sign delivered in his unmistakable accent: 'Jairmany calling, Jairmany calling'. "
Jan 6th 2021
EXTRACTS: "The revelation of Trump’s hour-long recorded call with Brad Raffensperger, Georgia’s Secretary of State, over this past weekend crossed a new line – a line that not only set a high-water mark of moral reprehensibility, but a legal line as well, specifically in his pressuring Raffensperger to 'find the 11,780 votes' that would hand Trump the state and his veiled threat (' it’s going to be very costly…') if Raffensperger failed to comply. ........ Raffensperger – who has been forced to endure intense pressure, intimidation and threats – has proven himself to be a man of integrity and principle."
Jan 6th 2021
EXTRACT: "A final, perhaps more sinister, possibility is that Johnson knows exactly what he is doing. His political style evokes a unique blend of dishevelled buffoon and privileged Etonian. He is someone who likes to bring good news and doesn’t take life too seriously. Making tough, controversial decisions threatens this persona and so hiding in the shadows until his hand is forced helps him to reconcile his identity threat."
Dec 21st 2020
EXTRACT: "The resultant loss of land, the growing impoverishment of its citizens, and the hostile actions of Israeli occupation forces and settlers have forced many Bethlehemites to leave their beloved city and homeland. Given these accumulated violations of human rights and their impact on Christians and Muslims, alike, one might expect Christians in the West to speak out in defense of these residents of the little town they celebrate each year.  That, sadly, is not to be – most especially (and I might add ironically) among powerful Christian conservative groups in the US which, after all, claim to be the defenders of their co-religionists world-wide."
Dec 7th 2020
EXTRACT: "Worldwide, people donate hundreds of billions of dollars to charity. In the United States alone, charitable donations amounted to about $450 billion last year. As 2020 draws to a close, perhaps you or members of your family are considering giving to charity. But there are, literally, millions of charities. Which should you choose?"
Dec 1st 2020
EXTRACT: " The Museum of Modern Art is currently presenting Félix Fénéon: The Anarchist and the Avant-Garde – From Signac to Matisse and Beyond, examining the immense influence of this art critic, editor, publisher, collector and anarchist............A crucial feature of anarchism is the emphasis on the individual as the fundamental building block, the essential point of departure for any human association whatever. The individual was characterized by Grave in 1899 as a social creature who should be “left free to attach himself according to his tendencies, his affinities, free to seek out those with him whom his liberty and aptitudes can agree.” "
Nov 25th 2020
EXTRACT: "As the pandemic raged in April, churchgoers in Ohio defied warnings not to congregate. Some argued that their religion conferred them immunity from COVID-19. In one memorable CNN clip, a woman insisted she would not catch the virus because she was “covered in Jesus’ blood”. "
Nov 18th 2020
EXTRACT: "Here are just a few ways exercise changes the structure of our brain."
Nov 15th 2020
EXTRACT: "Perhaps it is Piller’s discovery that when it comes to war there is no such thing as innocence...."
Nov 4th 2020
EXTRACT: "I imagined America as the land of the free that gave voice to the forgotten. Where race, color, and creed do not matter and human rights are guarded with zeal. Where the ingathering of all cultures and people made it richer and human resources and talent knew no limits or constraints. Where opportunity awaits the able and generosity is extended to the needy. Where everyone is equal before the law and political differences are valued to make America better. Where sacrifices are willingly made to right the wrong morals and fortitude guide its leaders. Where caring about friends and allies is the hallmark of the nation and opposing oppression near and far is the emblem that distinguished America. This is the character of America. This is the soul of America. This is what made America great. The America that gave me a home. The America that fulfilled my dreams."
Oct 15th 2020
EXTRACT: "“The paintings which I propose to do will depict the struggles of a people to create a nation and their attempt to build a democracy” – this is how Jacob Lawrence described his project in 1954. Over sixty-five years later his proposal has, if anything, become only more urgent. Two days after this exhibition closes, Americans will vote in what is arguably the most significant election in a generation, an election that will measure our commitment to preserving that democracy, the struggle for which was Lawrence’s mighty theme."
Oct 15th 2020
EXTRACT: "There are also other ways our life stories can be passed down through generations, besides being inscribed in our DNA...... One 2014 study looked at epigenetic changes in mice. Mice love the sweet smell of cherries, so when a waft reaches their nose, a pleasure zone in the brain lights up, motivating them to scurry around and hunt out the treat.... The researchers decided to pair this smell with a mild electric shock, and the mice quickly learned to freeze in anticipation....... The study found this new memory was transmitted across the generations. The mice’s grandchildren were fearful of cherries, despite not having experienced the electric shocks themselves. The grandfather’s sperm DNA changed its shape, leaving a blueprint of the experience entwined in the genes."
Oct 1st 2020
EXTRACT: "As we Americans face the potential loss of a peaceful transition of power after the election and the possible end of democracy as we know it, we are reminded that discourse matters, that words matter and that the one who quotes poetry is a man who reads—and that matters."
Sep 25th 2020
EXTRACT: "We now know the potentially appalling long-term effects of suffering cruelty from others, including damage to both physical and mental health. The benefits of being compassionate towards oneself, rather than treating oneself cruelly, are also increasingly recognised..... And the idea that we must suffer to grow is questionable. Positive life events, such as falling in love, having children and achieving cherished goals can lead to growth..... Teaching through cruelty invites abuses of power and selfish sadism. Yet Buddhism offers an alternative - wrathful compassion. Here, we act from love to confront others to protect them from their greed, hatred and fear. Life can be cruel, truth can be cruel, but we can choose not to be."
Sep 19th 2020
EXTRACT: "Over his incredible career, David Attenborough has seen more of earth’s natural wonders than almost anyone. To hear him talk, with such clarity, about how bad things are getting is deeply moving. Scientists have recently demonstrated what would be needed to bend the curve on biodiversity loss. As Attenborough says in the final scene, “What happens next, is up to every one of us”. "
Sep 15th 2020
EXTRACTS: "The Anglo-Australian multinational company Rio Tinto – the largest iron ore mining company in the world – demolished two 46,000-year-old Aboriginal rock shelters in May.......The Dampier Archipelago of Western Australia is home to thousands of Aboriginal pictographs, and perhaps the oldest surviving rock art in the world. Indeed, Australia’s Indigenous art represents the longest uninterrupted tradition of art in the world – going back over 50,000 years......Aboriginal people represent the oldest continuous culture in the world...."