Is the future of medicine prescribing 'good' bacteria?

Participants were all male and “strictly matched” based on age, dietary habits, alcohol consumption, smoking status, and blood pressure. Anyone taking antibiotics or who ate yoghurt (a source of “good” live bacteria) were excluded.

Stool samples revealed that several types of bacteria were “significantly enriched” among the monks. In particular, they had much higher levels of Prevotella, which has previously been associated with a reduced risk of major depressive disorder.

Blood sample analysis also showed lower levels of markers linked to increased cardiovascular disease.

The researchers, from Shanghai Jiao Tong University School of Medicine, stressed that this was a small sample and observational study - in other words it doesn't prove cause-and-effect.

READ MORE: A&E delays and excess deaths - what's really going on? 

Nonetheless they hypothesise that the act of meditation itself is altering the diversity and abundance of gut microbiota in a way that could protect against psychosomatic illnesses.

“Collectively, several bacteria enriched in the meditation group [have been] associated with the alleviation of mental illness, suggesting that meditation can influence certain bacteria that may have a role in mental health," said lead researcher, Dr Jinghong Chen

The study adds to a burgeoning body of research which is seeking to unravel clues to everything from obesity to Alzheimer’s by examining the bacteria which flourishes in our digestive system.

Our guts contain around 100 trillion microbes - more than all the cells in a human body - some of which are influenced by our genetics, and some by lifestyle.

In some twin studies, for example, genetically identical siblings have been found to share just 30% of their gut bacteria - helping to explain varying health traits ranging from everything from arthritis to acne.

Meanwhile, children who have been bottle-fed or delivered by Caesarean have also been found to have a lower diversity of gut bacteria and a higher incidence of obesity compared to peers who were exposed early through childbirth and bacteria-rich breast milk.

One very common bacterial species which is carried by around 97 per cent of adults - known as Christensenellaceae - tends to be found in particularly high levels among lean people.

When researchers transplanted Christensenellaceae into the microbiome of mice whose gut make-up was otherwise primed for obesity, they found that the rodents actually lost weight.

This raised the question of whether people could be given probiotics loaded with bacteria tailored to help them slim or to reduce their risk of certain diseases.

READ MORE: The 'life-saving' service set to keep hundreds of people out of hospital every week 

Other studies suggest that diversity of microbes is probably more important for health than the presence of any single type, and that eating a wide variety of foods - especially fibre-rich wholegrains, fruit, vegetables, and pickled or fermented items such as kefir yoghurt, kimchi, sauerkraut or probiotics - was best for boosting bacterial diversity.

Evidence of the link between gut bacteria and brain health is also building, including for diseases such as Parkinson’s and Alzheimer’s.

One research study, published at the end of last year in the journal Nature Communications, concluded that Parkinson’s disease “may start in the gut and spread to the brain”.

Scientists at the University of Surrey and the University of Alabama found that almost 30% of the gut bacteria present in people with Parkinson’s disease differed from those without.

All participants - 490 with a Parkinson’s diagnosis and 234 healthy controls - had been drawn from the US Deep South region.

Analysis of stool samples found that the bacterial species (Bifidobacterium dentium), which is known to cause anaerobic infections such as brain abscesses, were seven times higher in the participants with Parkinson’s, while another bacteria - Roseburia intestinalis - was more than seven times less common.

Roseburia intestinalis is associated with healthy colons, while constipation is a recognised symptom of Parkinson’s.

There is no single known cause of Parkinson’s disease, but worldwide deaths are increasing faster than for any other neurological disease. Diagnoses have more than doubled in the past 25 years.

READ MORE: 'Missed' blood pressure cases leave hundreds facing avoidable heart attacks and strokes 

It is speculated that its onset is probably triggered by a combination of genetic susceptibility and environmental factors, with previous smaller studies pointing to a possible link with gut bacteria - though it remains unclear whether this is really causative.

Dr Ayse Demirkan, co-author of the study, said: “The make-up of the gut bacteria of those with Parkinson’s consists of an over-abundance of pathogens and bacteria that may prompt immune responses among multiple other mechanisms involving various bacterial metabolic pathways, showing us a complex facade of the disorder in the gut.

“However, our current research is not designed to answer whether the bacteria itself is the initial cause of the disease, some may also be a consequence of the disease, or may be even influenced by the genetic makeup of the individual.”

Other research into the so-called “gut-brain axis” suggests that the microbiome could play a role in dementia.

A study published in the journal, Science, this week, found that when scientists at the Washington School of Medicine in St Louis altered the gut bacteria in mice genetically-modified to develop Alzheimer’s, there was a "strong reduction" in brain inflammation and tau pathology - the abnormal protein tangles found in the neurons of Alzheimer's patients.

Antisepsis once revolutionised medicine by revealing that "bad" bacteria was causing deadly infections. Could 21st Century medicine see us prescribing "good" bacteria for better health?