Tag Archives: probiotics

Probiotics are rarely actually useful — and they might sometimes be bad for you

When it comes to probiotics, it’s a bit like “the good, the bad, and the nothing” — they can do some good, they do a whole load of nothing most of the time, and, as a new study has shown — they can also do a bit of bad.

Probiotics are essentially living yeast and bacteria, which are thought to improve various aspects of your health when consumed. However, despite popular belief, the evidence that supports the benefits of probiotics is limited and often restricted to isolated cases.

In order to figure out what really happens when people ingest probiotics, immunologist Eran Elinav of the Weizmann Institute of Science in Israel, directly analyzed people’s microbiomes, after they were fed either a probiotic cocktail or a placebo. Along with colleagues, Elinav and colleagues sampled the microbiomes of volunteers directly, through endoscopies and colonoscopies — most studies were carried through proxies.

For starters, they found that faecal samples are not representative of what goes on in the gut.

“Relying on faecal samples as an indicator of what goes on inside the gut is inaccurate and wrong,” says Elinav.

Then, they found that there are major differences between individuals and probiotics greatly differ in efficiency.

The reasons which caused these differences are not clear, but the study suggests that there’s not enough justification to administer probiotics to everybody because their effect can vary so much.

“This tells us the currently used paradigm of one-size-fits-all probiotic preparation and treatment should be replaced by a tailored therapy which harnesses science and measurement and technology,” said Elinav, adding that “with this tailored approach probiotics have greater chances to benefit health”.

Then, in another study, they administered probiotics to a third group, which had previously been administered antibiotics. This was done to test whether probiotics can help the microbiome recover after a course of antibiotics — a common-held belief.

Researchers found that the probiotics readily colonized the participants’ guts, but they took over so much that the original microbiome had a hard time recovering.

“Once the probiotics had colonised the gut, they completely inhibited the return of the indigenous microbiome which was disrupted during antibiotic treatment,” said Elinav.

This would suggest that the use of probiotics is actually counter-productive in some cases.

Overall, the findings cast a big shadow over probiotics: for once, they only seem to be efficient for some people, and they’re also not always as harmless as most people think.

Journal Reference: CellDOI: 10.1016/j.cell.2018.08.04110.1016/j.cell.2018.08.047

Astronauts on the International Space Station will grow probiotic-rich broccoli

Just because you’re in outer space is no excuse to skip your 5 a day.

Space veggies

Space food is not the most appealing thing in the world. Sure, it’s nutritious and it’s exactly what your body needs for those months away from Earth, but astronauts would still benefit from growing their own vegetables — especially for longer missions to the Moon or Mars.

It’s not the first time astronauts have considered growing vegetables in space — in fact, this has been done before by NASA, and the veggies have actually been eaten. Yes, they were reportedly delicious. Now, NASA wants to expand its range of space veggies, but growing plants in microgravity is not the easiest thing in the world: You need a carefully managed environment, a steady source of light, and even then, we don’t know if all plants will grow properly.

But we’ll learn soon enough.

Astronauts will start growing broccoli from six seeds that were placed aboard the Orbital ATK Cygnus spacecraft that launched this week from Wallops Island, Virginia, as part of a space station cargo resupply mission. Three of the seeds are regular seeds, while the other three were coated with two different species of bacteria, developed at the University of Washington: beneficial bacteria called probiotics.

These probiotics are expected to help the plants grow in the unusual, nutrient-poor environment. The special bacteria belong to a class called endophytes, and are expected to help the plants better develop in micro-gravity.

“It would be ideal if we could grow crops for astronauts at the space station or who are lunar- or Mars-based without needing to ship potting mix or fertilizer,” said Sharon Doty, a UW professor in the School of Environmental and Forest Sciences and a plant microbiologist who isolated and characterized the microbes used in this experiment. “We would like to be able to get plants to grow in what is available with a minimum input.”

Growing veggies on the International Space Station is no easy feat.

Remarkably, the probiotic ensemble was developed by students at Valley Christian High School in San Jose, California, The 11 students carried out ground-based tests which were successful: the probiotic bacteria helped the plants grow bigger and faster than normal. It remains to be seen if the same will happen in space.

“It would be ideal if we could grow crops for astronauts at the space station or who are lunar- or Mars-based without needing to ship potting mix or fertilizer,” said Sharon Doty, a UW professor in the School of Environmental and Forest Sciences and a plant microbiologist who isolated and characterized the microbes used in this experiment. “We would like to be able to get plants to grow in what is available with a minimum input.”

Not just broccoli

The microbes are encapsulated inside a coating that protects the seeds. As the seeds sprout, a camera will monitor them and take photos at regular intervals of time.

While a number of different vegetables have already been grown in space, this is the first time probiotics will be employed for plant growth. After the plants will grow in outer space, they will be brought back to Earth, where Doty and the students will measure their growth and development.

Doty has worked on this project for more than ten years, and so far, results indicate that the probiotics could help plants of all kinds, helping them convert nitrogen from the air into essential nutrients for the plant and reduce the need for synthetic fertilizer.

This work is part of the UW Astrobiology Program. When the program was started 20 years ago, it was the first of its kind.

“This is the first step in what I hope becomes a really long-term research program to develop habitation on Mars and on the moon in a very efficient way using natural symbiosis instead of trying to bring chemical fertilizer to those environments,” Doty concluded.

Probiotics and breastfeeding help fight antibiotic resistance in children, study suggests

A targeted probiotic supplementation, in conjunction with breastfeeding, could help reduce the potential for antibiotic resistance, a new study suggests.

Image credits: Andrés Nieto Porras.

Probiotics (live bacteria and yeasts that are allegedly good for your health and digestive system) remain a controversial topic — their benefits are often oversold and rarely backed up by actual science. But in recent years, studies have shown that, in some specific scenarios, probiotics do offer significant advantages.

In a new study, researchers found that breastfed infants who were given a specific probiotic strain of B. infantis had, on average, 87.5% less antibiotic resistance genes in their gut microbiome compared to infants who were breastfed without that probiotics.

Antibiotic resistance is not something many people think about while raising their children, but perhaps we should start paying more attention to it: recently, the World Health Organisation announced antibiotic resistance as one of the biggest threats to global health, and this is definitely a growing concern for the younger generations. Having a simple way to reduce antibiotic resistance could make a big difference in the long run.

[panel style=”panel-default” title=”Antibiotic resistance” footer=””]Because many members of the public take antibiotics when they are not required to, many pathogens have started developing an immunity to common treatments — even the strong treatments. This has become a great concern, especially as some infections have started going beyond the limit of what we can currently treat.

Misuse of antibiotics in both humans and animals is accentuating this problem, and researchers are looking for ways to combat it.[/panel]

Dr. Giorgio Casaburi, lead author of the research, comments:

“These results demonstrate that targeted bacterial supplementation is capable of remodelling the ecology of the infant gut microbiome and therefore reduce antibiotic gene reservoirs in children. We found that supplementation with the infant gut symbiont significantly diminished both the abundance and diversity of antibiotic resistance genes”.

Casaburi and his colleagues administered the probiotic supplement for 21 days. They chose a probiotic uniquely adapted to thrive in the infant’s gastrointestinal system. The probiotic bacteria colonize the infant’s gut. Without it, the gut is colonized by other bacteria which enable the evolution, persistence and dissemination of antibiotic resistance genes.

While this is a fairly small trial, it still showcases an important potential for dealing with antibiotic resistance in a safe way that doesn’t have any unwanted side effects.

“The supplementation offers a novel approach towards providing an alternative, safe and non-invasive method to decrease the number of genes that resist antibiotics in infants” added Dr Casaburi. “This is the first demonstration of significant remodelling of the infant gut microbiome. This modulation could help to reduce the burden and diversity of antibiotic resistance genes in current and future generations”.

The results have not yet been peer-reviewed and will be presented at European Society for Paediatric Gastroenterology Hepatology and Nutrition.

New evidence suggests that probiotics are good for the liver

Following previous evidence that probiotics really do help the gut, a new study suggests that they might also help the liver.

Probiotics are basically bacterial populations that play a beneficial role in our gut. While most of the hype around probiotics is not supported by evidence, they do show some promise. Recent research has backed up some of the claims around probiotics, and the topic has gained significant attention in recent years, especially as we’ve learned that bacteria in our gut affect much more than just our intestines.

“Probiotics have been studied most intensely in the context of the gastrointestinal tract,” said Bejan Saeedi, a doctoral candidate at Emory University who conducted new research on the matter.

“This study provides evidence that the effects of probiotics extend beyond the gastrointestinal tract. What makes this study unique is that it suggests a discreet molecular mechanism by which these effects are elicited.”

He and his colleagues focused their research on the probiotic Lactobacillus rhamnosus GG (known as LGG), a common probiotic species found in many over-the-counter supplements. They gave mice food rich in these probiotics for two weeks, and then they recorded their response to a high dose of acetaminophen (the active ingredient in Tylenol), a drug known to send the liver into overcharge.

Taking too much acetaminophen is one of the leading causes of liver damage. Researchers found that mice who received a dose of probiotics were less likely to suffer from an acetaminophen overdose.

“Administration of the probiotic LGG to mice improves the antioxidant response of the liver, protecting it from oxidative damage produced by drugs such as acetaminophen,” explained Saeedi.

Since the liver is essentially a hub for toxin removal from the body and also plays a role in transforming food into energy, it makes sense that it is affected by the gut bacteria population — especially as it’s “downstream” from the gut.

The team traced this protective effect to a protein called Nrf2, which regulates the expression of genes involved in fighting free radicals. Taking too much acetaminophen creates oxidative stress and free radicals inside the liver (though there are other processes which can have a similar effect).

Previous mice studies have also shown that LGG can protect against alcoholic liver disease and non-alcoholic fatty liver disease. Of course, mice studies don’t always translate to humans, and Saeedi is now in the process of looking for human volunteers for trials.

While there seems to be growing evidence that probiotics are good for the body, it’s important not to fall into the trap of exaggerating potential benefits. Much is being said and advertised about probiotics, and not everything can pass the scrutiny of science.

The study will be presented at the Experimental Biology conference. Results have not yet been peer-reviewed.

Taking fish oil and probiotics during pregnancy may reduce food allergies

Taking a fish oil capsule daily during pregnancy and the first few months of breastfeeding can reduce your baby’s risk of egg allergy by 30%, a new study has found.

Via Pixabay/PublicDomainPictures

Researchers from the department of medicine at Imperial College London say that omega-3, a polyunsaturated fatty acid found in fish oil, has positive, anti-inflammatory effects.

According to a 2014 study, the lifetime self-reported prevalence of common food allergies in Europe ranged from 0.1 to 6.0%. In the UK, one in 20 children suffers from food allergies, such as nut, egg, milk or wheat allergies. Food allergies are caused by chaotic functioning of the immune system, that overreacts to some types of foods. Common symptoms of food allergies include rashes, swelling, vomiting, and wheezing.

For the study we’re discussing today, the team looked at data collected from 19 trials of fish oil supplements taken during pregnancy, involving a total of 15,000 participants. They report that the reduction in allergy risk equated to 31 fewer cases of egg allergy per 1,000 children. Afterward, they also analyzed the effect of probiotic supplements taken during pregnancy and discovered a 22% reduction in the risk of eczema development in children up to the age of three.

“Our research suggests probiotic and fish oil supplements may reduce a child’s risk of developing an allergic condition, and these findings need to be considered when guidelines for pregnant women are updated,” says Dr. Robert Boyle, lead author of the research.

The NHS advises that it’s better to eat fish than take fish oil supplements, fish being an excellent source of nutrients that are good for pregnant women‘s health and for their unborn baby’s development. The main reason for this is that eating liver and liver products such as liver pâté, liver sausage or fish liver oil supplements such as cod liver oil may contain too much vitamin A, and that can harm unborn babies. The NHS also recommends that tuna and oily fish consumption should be limited, while some types of fish should be avoided completely, such as shark. Also, don’t eat raw shellfish when pregnant, as it can cause food poisoning.

Avoiding foods such as nuts, dairy, and eggs during pregnancy made no difference to a child’s allergy risk. Also, fruit, vegetables, and vitamins seemed to have no repercussion on allergy risk either, the study published in the journal PLOS Medicine showed.

Finally, a large-scale probiotics trial is successful — it combats infant sepsis

For all the air time they’re given, you’d expect probiotics to do wonders but the truth is rigorous studies to back up these claims have been few and far between. The concept seems sound, the theory is there, but practical results just haven’t been that convincing. Well, in the culmination of two decades’ work, Pinaki Panigrahi of the University of Nebraska Medical Center might have just convincingly proven that probiotics work at least in one area: they fight infant sepsis.

Understanding probiotics

It’s one of the few large-scale rigorous probiotic trials that reported great success. Image credits: Brian Gratwicke.

Probiotics are basically live microorganisms that allegedly provide health benefits when consumed. There are numerous commercial claims about the benefits of probiotics, including reducing gastrointestinal discomfort, improving immune health, relieving constipation, or avoiding the common cold. However, these claimed benefits have not been thoroughly proven (though they haven’t been disproven either).

Another problem, writes Ed Yong for The Atlantic, is that commercial strains of probiotics were chosen because they were easy to grow and manufacture, and not based on their performance in the human body. Most times, they completely fail to colonize the human body, becoming, as Yong puts it, a “breeze that blows between two open windows.” But again, since the concept seems sound, researchers haven’t given up on probiotics.

In a massive study, Dr. Panigrahi used them to tackle one of the biggest causes for infant mortality: sepsis.

“This is the largest clinical trial of probiotics in newborns funded by the National Institutes of Health,” Dr. Panigrahi said. The team enrolled more than 4,500 newborns from 149 villages in the Indian province of Odisha and followed them for their first 60 days, the most critical period when they get sick and die.

Fighting sepsis

The probiotic cocktail could save hundreds of thousands of infants in India alone. Image credits: Etan Sivad.

Sepsis arises when the body’s response to infection causes injury to its own tissues and organs. It’s estimated that sepsis kills around one million infants each year, mostly in developing countries. But it’s not just developing countries that are battling the problem. In the US, the inpatient cost for hospitals treating sepsis is nearly $24 billion each year.

Since 2008, Panigrahi and colleagues have been carrying a randomized, double-blind, placebo-controlled study. They traveled 149 villages in rural India, giving infants a concoction containing a strain of Lactobacillus plantarum, chosen for its ability to attach to gut cells. The probiotic cocktail also contained sugar, which was meant to provide nutrients for the microorganisms and help them get a foothold inside the infants’ bodies. “It’s food for the bugs,” Panigrahi says.

The results were so successful that the study was stopped early — when results are so conclusive, studies are often stopped because it is considered unethical to keep adding people to the placebo group.

“We were concerned when the data safety and monitoring board stopped the study prematurely. We had enrolled just about half of our proposed subjects. Typically, a study is stopped when something is wrong.”

“But, it was a moment of superlative thrill when we learned it was stopped due to early efficacy. We were surprised a second time when the complete data analysis showed that respiratory tract infections also were reduced — something we did not anticipate in our population,” Dr. Panigrahi said.

Infants who were given the probiotic cocktail were 40% less likely to develop sepsis. Just 5.4 percent of the infants developed sepsis, compared to the 9% who were given a placebo. The probiotic formula could be a “very cheap oral sepsis vaccine,” Dr. Panigrahi said.

The benefits extend far beyond just saving lives. Infants who get sepsis can suffer from lingering damage their entire life, such as stunted growth and impaired cognitive function.

There are two directions for continuing the study. First, researchers want to try the same thing in different parts of the world, to see if there are cultural or environmental factors which affect the rate of success. Secondly, they want to understand the exact mechanism through which the cocktail fended off sepsis.

“This study has to be replicated in different countries and under different circumstances. We maintained tight controls on the administration of the synbiotic and conducted a rigorous follow-up which will not be available in real life,” he said.

“We have to find out why respiratory infections went down. How does this treatment affect the lungs?”

Journal Reference: Pinaki Panigrahi et al — A randomized synbiotic trial to prevent sepsis among infants in rural India. doi:10.1038/nature23480


Do probiotics actually work? Let’s hear what the science says

You’ll find probiotics stacked on supplement shelves in pharmacies all over the USA. These are essentially live bacteria and yeasts that are supposedly good for your health, especially your digestive system. But despite this $36 billion market in 2015, like most supplements, probiotics are both poorly regulated and poorly understood. There is little to no scientific evidence suggesting that probiotics can help alleviate health problems.


Credit: Flickr, Ryan Snyder.

All medication, whether prescribed or over-the-counter, has to pass very strict ruled enforced by the Food and Drug Administration (FDA) or other similar organizations in other countries before reaching consumers. But not probiotics. Although many people treat them like medicine touting probiotics as remedies for various illnesses ranging from Crohn’s disease to ulcerative colitis, these are classed as supplements. Apparently, if a product is labeled as a “supplement that doesn’t treat a specific condition” in the USA, it doesn’t need to pass the FDA’s tests. You can sell all those pills teeming with millions of bacteria straight away with no one looking over your shoulder, which explains at least partly why the probiotic market is so huge. Suffice to say, these are over-marketed products with many people falling for them. More and more of them to boot.

According to a survey conducted by the National Center for Health Statistics, 3 million more U.S. adults used probiotics or prebiotics (a plant fiber) in 2012 than did so in 2007.

“There’s no way to confirm what is listed on the box is what is in the box, that it’s safe and useful, and that it will help you,” said  Purna Kashyap, an assistant professor of medicine at the Mayo Clinic and a member of the scientific advisory board for the American Gastroenterological Association’s Center for Gut Microbiome Research and Education. An examination of 16 probiotic products in 2015 found that only one contained the bacterial strain listed on the label of every tested sample.

“Right now, we can’t predict who’s going to feel better and who’s not,” he added. 

Bacteria lottery

That’s not to say some probiotics don’t work. There are bad bacteria and there are good bacteria. Inside each of us, in the gut, there’s a highly complex community of microorganisms collectively called the microflora or microbiome. About four pounds of your body weight is actually bacteria which far outnumber human cells — tens of trillions of microorganisms, including at least 1,000 different species of known bacteria with more than 3 million genes (150 times more than human genes).

This huge colony isn’t comprised of freeloaders. When the stomach and small intestine are unable to digest certain foods we eat, gut microbes jump in to offer a helping hand. Gut bacteria also play a major role in immune function and are involved in producing certain vitamins, among other things. In other words, gut bacteria — the stuff of which some probiotics are made of — is terribly important. At the same time, it’s also poorly understood but we do know one-third of our gut microbiota is common to most people, while two-thirds are specific to each one of us, which is why using a general supplement for a specific condition and a specific person doesn’t sound right (that’s how you dodge the FDA, remember?).

According to Matthew Ciorba, a gastroenterologist and director of the Inflammatory Bowel Disease program at Washington University in Saint Louis, there are only a couple of probiotics that can be linked with science to support their efficacy. Align probiotic pills contain a strain of bifidobacteria which studies show it’s an effective treatment for women with irritable bowel syndrome that causes diarrhea. Likewise, patients who have diarrhea following antibiotic use might find Lactobacillus and the probiotic yeast Saccharomyces boulardii effective. That’s a pretty big if. Moreover, there doesn’t seem to be any evidence to support the idea that probiotics alleviate symptoms of diseases where the supplement is most commonly administered for. For instance, irritable bowel syndrome affects 1 in 10 people across the world and some people report feeling better after using probiotics like Bifidobacterium infantis but the science is mixed. It’s also very hard to assess probiotics since:

  • some probiotics have a single strain of organisms, while others contain multiple strains. Different strains of the same species may even be different, and could have different effects on health;
  • there are probiotic products that don’t have fair or accurate microbe counts;

“There is tremendous excitement and enthusiasm about how we are going to use the microbiome in order to change health. But that is a process that is still going to take time,” Ciorba told PopSci.

“The truth is, there’s just not a lot of completed studies out right now that prove that certain probiotics can help people with specific conditions,” he added.

Bottom line: probiotics can work but not in the way most people think. For some people it works, for most people, it doesn’t.  While probiotics are generally harmless, it’s not a good idea to take probiotics if your digestive health is pretty good. The whole field of probiotics, though evidently promising, has a Wild West feel. Are probiotics worth the cash? You be the judge.



The hypothetical mechanism behind the increased lifespan of LKM512-treated mice. Image: Plos ONE

Mice live longer after receiving probiotic supplement

Chronic inflammation of the colon has been recognized as a leading factor contributing to senescence and age-related diseases. Previously, scientists identified polyamines (PAs) levels, which are aliphatic low- molecular compounds, as being linked with systemic inflammation. The more PAs you have, the healthier your gut. But as we age, PAs levels fall and  intestinal barrier dysfunction may occur. To test how significant is this contribution, researchers from Japan fed mice with probiotic supplements than compared them to a control. They found the mice lived longer, suggesting “ingestion of specific probiotics may be an easy approach for improving intestinal health and increasing lifespan.”

The hypothetical mechanism behind the increased lifespan of LKM512-treated mice. Image: Plos ONE

The hypothetical mechanism behind the increased lifespan of LKM512-treated mice. Image: Plos ONE

Each of us carries a microbiome, also known as the intestinal flora, made up of thousands of species of bacteria which individually outnumber our own  somatic and germ cells ten to one. We’re more bacteria than human, if we’re solely to look at the numbers. Luckily, most of the bacteria are our ‘friends’ – they help digest food and sometimes act as a second barrier keeping harmful species away. Some get past the immune system however and are harmful (i.e. they don’t live in symbiotic relationship with our body). In the healthy intestinal tract, the microbiota and the gut-associated immune system are assumed to share a fine and dynamic homeostatic equilibrium. When bacteria that cause inflammation of the intestines is present, though, this delicate balance is offset.

Although there’s yet to be a study that proves avoiding the chronic gut inflamation increase lifespan, the researchers at Kyoto University and the RIKEN Innovation center think there’s reason to believe this is true. This considering “1) the lifespan of germ-free mice is longer than that of conventional mice; 2_ intestinal microbiota undergoes alterations by ageing ; 3) intestinal microbiota stimulates host mucosal and systemic immunity; and 4), ageing-associated deterioration in intestinal barrier functions may permit increased systemic absorption of intestinal luminal antigens”.

The researchers split 10-month-old mice into two groups. The first received a stable diet which included the probiotic strain Bifidobacterium animalis (LKM512), while the other acted as a control. After almost twelve months, the researchers assessed that the LKM512-treated mice survived significantly longer than controls. At the same time, skin ulcers and tumors were more common in the control mice. Stool samples also show that PAs are significantly higher in LKM512-treated mice.

Previously, some other study showed eating yogurt containing LKM512 increases intestinal PA concentrations and decreased levels of acute inflammation markers in hospitalized elderly patients. Considering all the evidence collected thus far, it’s reasonable to believe LKM512 could also help humans live longer, though we’d have to wait for a clinical trial until we can know for sure.


(c) Flickr Creative Commons

Psychobiotic germs could be the next game changer in psychiatry and recreational drug use alike

An estimate 20% of Americans use some of form of psychotropic medication, amounting to a $34 billion industry. Desperate to ease their problems away with one magic pill, people are flocking in pharmacies to take their regular hits of Prozac, Valium or Vicodin. In the future, however, a new class of drugs may enter the market – drugs that are alive. A new paper published in the journal Biological Psychiatry suggests that there is evidence that after ingestion of some live organisms in adequate amounts patients suffering from psychiatric illness can be treated. Also, if certain receptors are activated by using ingesting these organisms with other probiotics, a natural high may also surface. 

Probiotics are basically micro organisms which have certain health benefits when ingested. Lactic acid bacteria (LAB) and bifidobacteria are the most common types of microbes used as probiotics, as well as other types of yeast for instance. They’re sometimes used to calm gut inflammation, diarrhea, allergies and more, however researchers at the Alimentary Pharmabiotic Centre in Cork, Ireland suggest that some bacteria could be used to treat mental health problems as well such as post-traumatic stress disorder (PTSD).

These probiotics, which affect the patient’s mental disposition, are called psychobiotics. Now, the idea isn’t new, nor quite intuitive. How could bacteria that live in the gut affect the brain, though? Studies have shown that certain probiotic strains are able  to modulate inflammation and bring back a healthy immunological function, so  there should be an effect of improved psychiatric disposition.

Feel good bacteria

(c) Flickr Creative Commons

(c) Flickr Creative Commons

Some psychobiotic strains go further. The researchers talk about certain strains capable to modulate the function of the adrenal cortex, which is responsible for controlling anxiety and stress response. Some bacteria like Lactobacillus helveticus and Bifdobacterium longum have been shown to reduce levels of stress hormones and maintain a calmer, peaceful state. Intuition tells us that there might be many more bacteria, whose psychotropic benefits escape us at the moment, waiting to be discovered.

The last point the authors make that psychobiotics could indeed become an alternative to traditional psychotropic drug is that some bacteria are known to  produce psychotropic signals such as serotonin and dopamine, inducing happy feelings. These chemicals don’t reach the brain directly, instead they stimulate cells in the gut that have the ability to signal the vagus nerve that good chemicals are in the body, which in turn then submits this information to the brain, which then acts as if the chemicals were there. If these bacteria would be used in conjunction with other stimulate the  opioid and cannabinoid receptors, then a natural high effect could be produced. The conclusions were reached following preclinical evaluation in rodents, suggesting certain psychobiotics possess antidepressant or anxiolytic activity.

Dr. Timothy Dinan of University College Cork in Ireland and the psychobiotic study’s lead author says that although the research conducted on humans is sparse, “the animal studies indicate that certain psychobiotics can change brain chemistry.”

In the review, a few of these psychobiotics and their effects on neurotransmitter production are listed:

EscherichiaBacillus, and Saccharomyces produce norepinephrine. Candida,StreptococcusEscherichia, and Enterococcus produce serotonin, while Bacillus andSerratia have the potential to produce dopamine.

The researchers suggest more investigations should be made in the psychotropic effect of micro-organism ingestion, along with actual clinical trials on humans.

via PopSci