Vegans cannot claim to have a healthier gut than meat-eaters, as research shows people’s daily food choices are more important than whether they eat meat and dairy.
A study looking at 656 vegans, comparing them with more than 1,000 vegetarians and almost 20,000 meat-eaters, found those who have sworn off meat, dairy and eggs do not necessarily have a healthier balance of gut bacteria.
Many vegans may think they have the best gut bugs – the bacteria which live inside us and are affected by our diet, which can prevent dangerous inflammation in the body linked to heart problems, strokes and cancer.
But meat-eaters who do not eat an excessive amount of meat, and who also consume a wide variety of fruit and vegetables, have similar types of ‘good’ bacteria living inside their gut to healthy vegans, the new research found.
Vegans with an unhealthy diet were found to have less beneficial gut bacteria.
This finding was based on a large group of people from the UK, who signed up to the ZOE personal nutrition app and research study and recorded what they ate, before their gut bugs were analysed from stool samples.
The study, involving researchers from King’s College London and published in the journal Nature Microbiology, also found vegans were low on gut bacteria which enter the body when people eat dairy products.
These bugs are so important that they are included in some probiotic drinks to boost people’s gut health.
Pro vegan campaigners have long argued for the benefits of plant-based diets for the millions of microbes in our guts. But experts say this may not be strictly the case.
Professor Nicola Segata, senior author of the study from the University of Trento in Italy, said: ‘Being a vegan or vegetarian, as opposed to a meat-eater, is not as important for your gut bacteria as what you actually eat.
‘When it comes to bacteria living in your gut, this research suggests there is no reason to be vegan or vegetarian and to cut single food types like meat or dairy out of your diet.
‘Meat and dairy, like any foods, are not going to substantially change the balance of bacteria in the gut in a negative way if they are eaten in moderation.
‘Vegans who eat a lot of ultra-processed food can have an unhealthy gut, while meat-eaters with a varied diet including lots of different plants can have a healthy gut.’
However the authors note that in practice vegans and vegetarians do tend to eat more healthily than meat-eaters and have a better balance of gut bacteria.
The study, which analysed the gut bugs of 21,561 people from the UK, US and Italy, found vegans generally have more gut bacteria needed to break down the fibre in fruit and vegetables.
These gut bacteria typically produce short-chain fatty acids, which are linked to lower inflammation in the gut and body, so may reduce the risk of heart attacks and strokes.
Meat-eaters were found unsurprisingly to have gut bugs which help to digest meat, and which have been linked to a greater risk of bowel cancer – seen more often in people who eat too much red and processed meat – and a greater risk of inflammatory bowel diseases like Crohn’s disease and ulcerative colitis.
But vegans had lower levels than vegetarians and meat-eaters of bacteria which enter the body when people eat dairy, called Streptococcus thermophilus and lactic acid bacteria.
These bacteria are important for the immune system and reduce inflammation in the body, which could lessen risk of inflammatory bowel diseases like ulcerative colitis, as well as inflammatory medical conditions like arthritis and heart problems.
The research looked at both the variety of plant foods people ate and quantity, finding this was more linked to the health of gut bacteria than whether they happened to be vegan, vegetarian or an omnivore.
Professor Segata said: ‘From the point of view of gut bacteria, what we can generally recommend is that it is important to eat substantial amounts of as many different plant-based foods as possible, especially those rich in fibre, and that food diversity is important.’
