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gut bacteria


A new study, published in the journal Cell, suggests Parkinson’s disease may be caused by bacteria living in the gut.

Scientists say the findings could eventually lead to new ways of treating the brain disorder, such as drugs to kill gut bugs or probiotics.

In Parkinson’s disease the brain is progressively damaged, leading to patients experiencing a tremor and difficulty moving.

Californian researchers used mice genetically programmed to develop Parkinson’s disease as they produced very high levels of the protein alpha-synuclein, which is associated with damage in the brains of Parkinson’s patients.

Experts found that only those animals with bacteria in their stomachs developed symptoms. Sterile mice remained healthy.

Parkinson's disease is the second most common neurodegenerative disorder and the most common movement disorder

Parkinson’s disease is the second most common neurodegenerative disorder and the most common movement disorder

Further tests showed transplanting bacteria from Parkinson’s patients to mice led to more symptoms than bacteria taken from healthy people.

Dr. Timothy Sampson, one of the researchers at the California Institute of Technology, said: “This was the <<eureka>> moment, the mice were genetically identical, the only difference was the presence or absence of gut microbiota.

“Now we were quite confident that gut bacteria regulate, and are even required for, the symptoms of Parkinson’s disease.”

Researchers believe the bacteria are releasing chemicals that over-activate parts of the brain, leading to damage.

The bacteria can break down fiber into short-chain fatty acids. It is thought an imbalance in these chemicals triggers the immune cells in the brain to cause damage.

Dr. Sarkis Mazmanian said: “We have discovered for the first time a biological link between the gut microbiome and Parkinson’s disease.

“More generally, this research reveals that a neurodegenerative disease may have its origins in the gut and not only in the brain as had been previously thought.

“The discovery that changes in the microbiome may be involved in Parkinson’s disease is a paradigm shift and opens entirely new possibilities for treating patients.”

Parkinson’s disease is currently incurable.

The findings need to be confirmed in humans, but the researchers hope that drugs that work in the digestive system or even probiotics may become new therapies for the disease.

The trillions of bacteria that live in the gut are hugely important to health, so wiping them out completely is not an option.


According to a recent study, bacteria living deep inside the digestive system seem to alter how cancer drugs work.

Immunotherapies – which harness the body’s own defenses to fight tumors – can clear even terminal cancer in a small proportion of patients.

However, a small study by the University of Texas found those harboring a more diverse community of gut bugs are more likely to benefit.

Image source Wikipedia

Image source Wikipedia

The human body is home to trillions of micro-organisms – estimates suggest our own tissues are so heavily outnumbered that our bodies are just 10% human.

A growing wealth of studies shows these microbes can influence our immune systems and have been implicated in auto-immune diseases and allergies.

Immunotherapies are one of the most exciting breakthroughs in treating cancer. They work by taking the brakes off the immune system to help it to attack tumors more easily.

The research group compared the gut bacteria in 23 patients who responded to the therapy and 11 who did not.

The study, presented at the National Cancer Research Institute’s Cancer Conference in Liverpool, found Ruminococcus bacteria in much higher levels in those that responded to treatment.

It suggests that it may be possible to boost the effectiveness of immunotherapy by altering the balance of bacteria in the gut.

Procedures such as a trans-poo-sion – a transplant of fecal matter containing beneficial bacteria – are already used as a treatment for some diseases.

It is not yet clear if the differences in bacteria are the cause of the better response.

People with diets containing more fruit and vegetables tend to have a richer set of gut bugs, so it is possible that it is those with a healthier lifestyle that respond better to therapy.


People who are taking antibiotics may benefit from taking probiotics at the same time, a review of evidence shows.

Scientists at the organization Cochrane Collaboration say taking the supplements could prevent diarrhoea – a common side-effect of many antibiotics.

They looked specifically at cases of diarrhoea caused by the potentially dangerous Clostridium difficile bug.

Experts say probiotics could be a “pre-emptive strike” to ensure a healthy balance of bacteria in the gut.

Antibiotics can disturb the ecosystem of organisms normally present in the digestive system, allowing bacteria such as C. difficile to overwhelm the gut.

And people infected with the bug can suffer from diarrhoea, an inflamed and painful bowel or even death.

People who are taking antibiotics may benefit from taking probiotics at the same time

People who are taking antibiotics may benefit from taking probiotics at the same time

Researchers worldwide have been investigating whether probiotics – cocktails of micro-organisms – can keep gut bacteria in check by competing with more harmful bugs.

Scientists from the independent Cochrane Collaboration looked at data from 23 trials involving 4,213 patients who were on antibiotic treatment for a variety of reasons.

The researchers found 2% of patients given probiotics developed C. difficile-associated diarrhoea compared with 6% of patients who were taking placebos.

The authors suggest probiotics could be particularly useful when there are outbreaks of C. difficile.

Dr. Bradley Johnston, part of the Cochrane team, said: “Implementing the appropriate dose and strains of probiotics in hospitals could provide cost savings and improve quality of life.”

And the review showed that people taking probiotics had fewer unwanted side-effects than those on placebos, including stomach cramps, nausea and taste disturbances.

The authors say more work needs to be done to to pinpoint exactly which types of probiotics work best.

And though probiotics were seen to prevent diarrhoea associated with the bug, they note they did not prevent infections with C. difficile.

They suggest this property needs further investigation to help them understand more about how probiotics work.


Researchers have found that a certain type of bacteria that live in the gut have been used to reverse obesity and Type-2 diabetes in animal studies.

Research, published in Proceedings of the National Academy of Sciences, showed that a broth containing a single species of bacteria could dramatically alter the health of obese mice.

It is thought to change the gut lining and the way food is absorbed.

Similar tests now need to take place in people to see if the same bacteria can be used to shed the pounds.

The human body is teeming with bacteria – the tiny organisms outnumber human cells in the body 10 to one.

And there is growing evidence that this collection of bacteria or “microbiome” affects health.

Studies have shown differences between the types and numbers of bacteria in the guts of lean and obese people.

Researchers have found that a certain type of bacteria that live in the gut have been used to reverse obesity and Type-2 diabetes in animal studies

Researchers have found that a certain type of bacteria that live in the gut have been used to reverse obesity and Type-2 diabetes in animal studies

Meanwhile gastric bypass operations have been shown to change the balance of bacteria in the gut.

Researchers at the Catholic University of Louvain, in Belgium, worked with a single species of bacteria Akkermansia muciniphila. It normally makes up 3-5% of gut bacteria, but its levels fall in obesity.

Mice on a high fat diet – which led them to put on two to three times more fat than normal, lean, mice – were fed the bacteria.

The mice remained bigger than their lean cousins, but had lost around half of their extra weight despite no other changes to their diet.

They also had lower levels of insulin resistance, a key symptom of Type-2 diabetes.

Prof. Patrice Cani, from the Catholic University of Louvain, said: “Of course it is an improvement, we did not completely reverse the obesity, but it is a very strong decrease in the fat mass.

“It is the first demonstration that there is a direct link between one specific species and improving metabolism.”

Adding the bacteria increased the thickness of the gut’s mucus barrier, which stops some material passing from the gut to the blood. It also changed the chemical signals coming from the digestive system – which led to changes in the way fat was processed elsewhere in the body.

Similar results were achieved by adding a type of fiber to diets which led to an increase in the levels of Akkermansia muciniphila.

Prof. Patrice Cani said it was “surprising” that just one species, out of the thousands in the gut, could have such an effect.

He said this was a “first step” towards “eventually using these bacteria as prevention or treatment of obesity and Type-2 diabetes” and that some form of bacteria-based therapy would be used “in the near future”.