Small study shows probiotics can beat back depression

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In March of this year, researchers showed that a probiotic found in yogurt was able to reverse symptoms of anxiety and depression in mice. Now, in a small study involving 44 adults, investigators at McMaster University in Canada have shown a different probiotic can have the same effect in humans.

Increasingly, scientists are exploring the link between our guts and our brains, and finding that the two are very much linked. Earlier this year, researchers found that they could alter the gut microbiota by beaming people’s’ brains with magnetism, and last year, a study indicated that certain molecules in the gut can inhibit inflammation it the brain.

The McMaster research focussed on individuals with irritable bowel syndrome (IBS) which, the university says, is the most common gastrointestinal disorder in the world. The study split 44 adults into two groups. One group took the probiotic Bifidobacterium longum every day for ten weeks, while the other group took a placebo.

At six weeks, in the group taking the probiotic, 14 out of 22 participants (64 percent) had a lower depression score than the group taking the placebo. What’s more, the researchers saw changes in brain areas associated with depression in the probiotic group when they observed them using functional MRI (fMRI) scans.

“The fMRI study showed decreased activity in the amygdala and other fronto–limbic regions of the brain, which are known to be involved in the control of mood, in the patients taking with probiotics compared to those taking placebo,” Premysl Bercik told us. Bercik is an associate professor of medicine at McMaster and senior author on the study.

Of course, one theory is that the symptoms of depression went away in the study subjects taking the probiotic because their IBS symptoms also improved. So we asked Bercik about that, and he said that the effects of the probiotic treatment on mood lasted longer than the effects on the IBS symptoms – longer than the treatment was carried out, in fact.

“You are right,” he told us, “the patients on probiotics also reported improvement in their IBS symptoms (adequate relief of symptoms) at the end of the probiotic treatment, but not four weeks later when the beneficial effect on depression was still present. So one can argue that the primary effect of this probiotic is on depression. Also, the amygdala is one of the important centers in processing abdominal pain so if the probiotic altered the function of this brain region, it could also improve the gut symptoms of IBS (the pain is the hallmark symptom of IBS).”

The study, which was carried out in conjunction with scientists from food giant Nestlé, has been published in the journal Gastroenterology.

Source: McMaster University

BRON: http://newatlas.com/probiotics-fight-depression/49693/

Baanbrekend onderzoek onthult reden voor agressief en asociaal gedrag

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boze man - pixabay.com

(Nine for news) Canadese onderzoekers hebben een baanbrekende studie gepubliceerd waaruit blijkt dat lage doses penicilline kunnen resulteren in gedragsveranderingen.

Muizenbaby’s die tijdens de laatste week van de zwangerschap en de eerste weken na de geboorte penicilline kregen, vertoonden op latere leeftijd agressief gedrag en waren minder sociaal en minder angstig.

Toen de muizen de melkzuurbacterie Lactobacillus kregen, had het antibioticum geen invloed op hun gedrag.

Probiotica
Er zijn steeds meer zorgen over de langetermijneffecten van antibiotica, aldus hoofdonderzoeker John Bienenstock van de McMaster University.

“Uit ons onderzoek blijkt dat probiotica de nadelige effecten van penicilline kunnen voorkomen,” zei hij.

Andere studies hebben al aangetoond dat antibiotica het gedrag van dieren kunnen beïnvloeden.

Vrijwel geen
“Er zijn vrijwel geen baby’s in Noord-Amerika die in hun eerste levensjaar nog geen antibioticakuur hebben gehad,” zei dr. Bienenstock.

“Antibiotica worden niet alleen voorgeschreven, maar ook gevonden in vlees en zuivelproducten,” vervolgde hij.

Als moeders de effecten van deze medicijnen overdragen op hun kinderen, kunnen we ons afvragen wat de langetermijneffecten van de consumptie van antibiotica zijn, aldus Bienenstock.

Obesitas
Na een studie uit 2014 werden er ook al zorgen geuit over het gebruik van antibiotica toen bleek dat muizen die penicilline kregen vatbaarder waren voor obesitas.

Het onderzoeksteam gaat nu kijken wat de effecten zijn als enkel de zwangere muizen penicilline krijgen toegediend.

De onderzoekers gaan ook bestuderen welke bacteriën de muizenbaby’s kunnen beschermen tegen gedragsveranderingen als gevolg van antibioticagebruik.

Het onderzoek is gepubliceerd in het tijdschrift Nature Communications.
Bron: EarthmattersNine for NewsNewswise

 

Microbes may encourage altruistic behavior

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(Left) The payoff matrix and (right) an illustration of horizontal transmission probability of microbes between hosts. Using this model, researchers have found that microbes may induce their hosts to help other hosts, benefitting the microbes and the other hosts, but not always the original hosts. Credit: Lewin-Epstein et al. Nature Communications

(Phys.org)—Why do people commonly go out of their way to do something nice for another person, even when it comes at a cost to themselves—and how could such altruistic behavior have evolved? The answer may not just be in our genes, but also in our microbes.

In a new paper, researchers Ohad Lewin-Epstein, Ranit Aharonov, and Lilach Hadany at Tel-Aviv University in Israel have theoretically shown that could influence their hosts to act altruistically. And this influence could be surprisingly effective, with simulations showing that microbes may promote the evolution of altruistic behavior in a population to an even greater extent than do.

“I believe the most important aspect of the work is that it changes the way we think about altruism from centering on the animals (or humans) performing the altruistic acts to their microbes,” Hadany told Phys.org.

It’s already well-known that microbes can affect the behavior of their hosts, with a prime example being how the rabies virus increases aggressive behavior in infected individuals. Research has also shown that the microbiome—the community of microorganisms that inhabit our gut—can even manipulate the hosts’ social behavior by infecting neurons and altering neurotransmitter and hormone activity.

Against this backdrop, the researchers in the new study have proposed that microbes may induce a person to help others because the close physical contact (for example, food-sharing, co-sheltering, and grooming) increases the transmission of the microbes from one person to another. So when someone does something nice for us, we are not just the recipient of a kind act, but also of their microbes.

To show that this idea can have a prevailing effect on a population over time, the researchers designed simulations of interacting individuals, some with altruism-inducing microbes, and some without. Then using a prisoner’s dilemma payoff scheme, the researchers investigated what happens to this population, its microbes, and its altruistic behavior over many generations.

The results showed that, as long as horizontal transmission (between individuals) of microbes is allowed, altruism-inducing microbes can take over the population, leading to microbe-induced altruism. This result occurs even when only a very small percentage of the initially carries these altruism-inducing microbes. The simulations also revealed that the evolution of altruism is successful because the microbes have a chance to either meet genetically related microbes in the recipient or infect and transform some of the recipient’s microbes into relatives.

In a variation of this model in which altruism can also be induced by host genes, the researchers found that genetically encoded altruism does not evolve, but microbe-induced altruism continues to evolve whether or not genetic factors are present. Further simulations showed that, although there are some cases in which altruism encoded in genes can persist, microbe-induced persists more often. Overall, the results suggest that microbes may play a dominant and previously overlooked role in the evolution of altruistic behavior.

If microbes do exert such large sway on altruistic behavior, then it raises other intriguing questions, such as whether antibiotics, probiotics, and foods affecting the microbiome may influence the of their hosts. In the future, the researchers plan to address these possibilities, as well as to test the theory.

“We are now collaborating with experimental biologists in order to empirically validate the predictions of our theory,” Hadany said.

BRON: https://phys.org/news/2017-01-microbes-altruistic-behavior.html

 

Fat or thin: can the bacteria in our gut affect our eating habits and weight?

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Our gut does more than help us digest food; the bacteria that call our intestines home have been implicated in everything from our mental health and sleep, to weight gain and cravings for certain foods. This series examines how far the science has come and whether there’s anything we can do to improve the health of our gut.


When we can’t lose weight, we tend to want to blame something outside our control. Could it be related to the microbiota – the bacteria and other organisms – that colonise your gut?

You are what you eat

Our gut harbours some trillion microorganisms. These are key in harvesting energy from our food, regulating our immune function, and keeping the lining of our gut healthy.

The composition of our gut microbiota is partly determined by our genes but can also be influenced by lifestyle factors such as our diet, alcohol intake and exercise, as well as medications.

What is the human microbiome?

The bacteria in the gut obtain energy for growth when we metabolise nutrients from food. So our diet is a crucial factor in regulating the type of bacteria that colonise our gut.

One key role of the gut microbiota is degrading the carbohydrates we can’t digest into short-chain fatty acids. These help regulate our metabolism and are also important for keeping our colon cells healthy.

Changes in our diet can rapidly change the gut microbiota. Generally, a high-fibre diet which is low in saturated fat and sugar is associated with a healthier gut microbiome, characterised by a greater diversity of organisms.

On the other hand, diets high in saturated fat and refined sugars with low fibre content reduce the microbial diversity, which is bad for our health.

Our animal studies have shown that consuming an unhealthy diet for only three days a week has detrimental effects on the gut microbiota, even when a healthy diet is eaten for the other four days.

This may be because the gut microbiota are under selective pressure to manipulate the hosts’ eating behaviour to increase their own fitness. This may lead to cravings, akin to your system being “hijacked” by your microbiota.

Can gut microbiota changes lead to obesity?

Bacteria in humans fall into two major classifications: bacteroidetes and firmicutes. Obesity is associated with a reduction in the ratio of bacteroidetes to firmicutes but weight loss can reverse this shift.

Many studies have found that the gut of an obese person is more likely to contain bacteria that inflame the gastrointestinal tract and damage its lining. This allows the bacteria in the gut to escape.

The gastrointestinal tract. Christos Georghiou/Shutterstock

We still don’t know definitively if changes in the gut microbiota from an unhealthy diet can contribute to obesity. Most evidence supporting this hypothesis comes from animal studies; for instance, the transfer of faecal material from an obese human can lead to weight gain in a recipient mouse.

One possibility is that the obese microbiota may be more efficient in harvesting energy, in part, by influencing the host to eat foods which favour its growth. This could ultimately contribute to weight gain.

Gut changes after weight-loss surgery

Bariatric surgeries such as gastric bypass, are one of the most effective treatments for obesity because they reduce the size of the stomach. This limits how much food can be eaten and has also been shown to promote the release of hormones which make us feel full.

But other factors may be involved. Intriguingly, some patients report a shift in food preference away from energy-dense foods after surgery. This may contribute to the success of the procedure.

Gastric bypass-induced weight loss has also been associated with increased diversity of the gut microbiota. But how much this contributes to the success of the procedure remains to be determined.

One possibility is that the changes in food preferences reported in bariatric patients may relate to changes in the composition of their gut microbiota.

How gut microbiota affect our behaviour

Apart from regulating gut health, there is compelling experimental evidence that gut microbiota play a role in regulating mood.

Several studies have shown that depression is associated with changes in the gut microbiome of humans.

Depressed patients showed changes in their abundance of firmicutes, actinobacteria and bacteroidetes. When these patients’ gut microbiota was transferred to mice, the mice showed more depressive behaviour than mice that received biota from healthy people.

More work still needs to be done as it is unclear whether this may indicate a causal relationship, or be related to other factors associated with depressive disorders such as a poor diet, changed sleep patterns and drug treatment.

Emerging evidence suggests that gut microbiota can influence other behaviours through the “microbiota-gut-brain axis”. Put simply, the gut and the brain communicate in part via the microbiota, which links the emotional and cognitive centres of the brain with our intestinal functions.

Recent work from our lab showed that rats consuming diets high in saturated fat or sugar, for just two weeks, had impaired spatial memory. These rats consumed the same amount of energy as the control rats (those on a regular diet) and were also a similar body weight.

We found that the memory deficits were associated with changes in the gut microbiota composition and genes related to inflammation in the hippocampus, which is a key brain region for memory and learning.

Similar memory deficits have also been reported when healthy mice were transplanted with microbiota from overweight mice who had been fed a high-fat diet.

Together, studies such as these suggest the gut microbiota could play a causal role in regulating behaviour. This may, in part, be due to the different microbiota profiles influencing the production of key transmitters such as serotonin.

What can you do now?

Further research is needed into the relationship between poor diet, the gut microbiota and behavioural changes. In the long term, such knowledge may be harnessed to develop targeted therapeutic interventions to replace relevant microbiota diminished by an unhealthy lifestyle.

Meanwhile, the good news is that the gut microbiota can change relatively quickly and we have the capacity to promote the growth of beneficial bacteria which may ultimately improve a range of health outcomes. Eating a healthy diet of unprocessed foods, including adequate fibre, avoiding excess alcohol and getting enough exercise are key.

BRON: http://theconversation.com/fat-or-thin-can-the-bacteria-in-our-gut-affect-our-eating-habits-and-weight-65103

Depressed? Anxious? What If Your Bacteria Are Playing a Part?

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The fascinating world of the gut-brain axis.

Although we’re used to science advancing at the speed of light these days, it hasn’t always been like this.

Take the Greek physician Hippocrates, for example, born around 460 BC.

He proposed that the human body contained four fluids or “humors”—blood, phlegm, yellow bile, and black bile, usually in balance.

When one of them became more or less present, illness could ensue.

He believed that an excess of black bile, for example, could cause someone to become melancholic.

What we now call depressed.

In fact the term “melancholic” comes from the ancient Greek words “melas” and “kholé”, meaning black bile.

This theory of “humorism,” certainly nothing to do with comedy, stuck around for almost 2,000 years.

Jumping ahead to the 19th century, many scientists argued that a buildup of waste matter in the colon could trigger something they called “auto intoxication”, poisoning the gut and producing infections linked with depression, anxiety and psychosis.

So if you were depressed in those days you might get treated with a colonic purge, which doesn’t exactly sound like something guaranteed to put a smile on your face.

This poisoning idea was eventually dismissed as quackery after direct observation of the colon during surgery and autopsies showed zero evidence for hardened feces accumulating on the walls of the intestine.

However, although it’s clear that both of these schools of thought were distinctly not on the right track, there’s increasing (and exciting) evidence of a very real connection between the gut and the brain.

You see, it’s now widely believed that there is a “gut-brain axis”, which is in fact a two-way street.

Your brain acts on your gut, shaping its microbial makeup, while your gut is busy manufacturing neurotransmitters including dopamine, gamma-aminobutyric acid (GABA) and serotonin.

In fact the vast majority of your serotonin originates in your intestine.

Talk about gut feelings, eh?

There have been many remarkable experiments showing ways in which the function of the brain can be affected by the gut microbiome.

Nobuyki Sudo and colleagues at Japan’s Kyushu University published pioneering work in 2004 by experimenting with mice that had been specially bred to be germ-free giving them, effectively, sterile guts.

When these mice were placed in a tube that restricted their movement, their levels of stress hormones became far higher than those of mice in the same situation whose microbiomes were not germ-free.

Fascinatingly, the scientists were able to re-engineer these germ-free mice, turning them into relaxed rodents simply by adding one species of bacteria to their guts: Bifidobacterium infantis (now viewed as a subspecies of Bifidobacterium longum) which is one of the very first types of bacteria acquired by a baby, particularly one born vaginally.

The amazing studies kept coming.

Researchers at McMaster University in Ontario were able to change the behavior of germ-free mice by colonizing their intestines with bacteria from other mice—giving them what you might call a poop-personality transplant.

This led naturally daring mice to become apprehensive and shy, for example, leading scientists to suggest that microbial interactions with the brain could induce psychological change.

Although some are understandably uncomfortable with experiments such as these, other researchers from McMaster later joined forces with scientists from University College Cork to show that mice fed a broth containing Lactobacillus rhamnosus were far less likely to relapse into “behavioral despair” when dropped into a tall cylinder, from which there was no escape, than mice without these microbes.

The same experiment has been used to test antidepressants, leading one scientist to suggest that the broth-fed mice were behaving as though they were on Prozac.

Lactobacillus rhamnosus is a bacterium commonly found in the human body, and also used in the fermentation of milk as it is turned into yogurt.

It hasn’t all been about mice, however.

A 2013 proof-of-concept study at UCLA showed through fMRI scans that women who ate yogurt containing active probiotics twice a day for a month showed a reduced reflexive response to photos of actors with frightened or angry faces.

The researchers warned that their results were rudimentary, but there was at least an indication that consumption of probiotic bacteria such as Bifidobacterium animalis subsp Lactis, Streptococcus thermophiles, Lactobacillus bulgaricus, and Lactococcus lactis subsp Lactis could have been making the participants less prone to anxiety.

Another study, in Norway in 2014, found significant correlations between bacteria in stool samples and depression, with elevated levels of the order Bacteroidales and a reduced abundance of the family Lachnospiraceae.

Advances in the mental health/microbiota world are certainly moving faster than the science of Hippocrates’ day, but there’s still a lot of work to be done.

It’s an area of great promise, though.

Who knows?

When the bottom’s fallen out of your world, the day may come when microbes, delivered in various ways, are used instead of standard prescription medicines.

Have a great week!
Alexandra 🙂

Alexandra Carmichael
Director of Product, Community, and Growth
uBiome

Bron: uBiome nieuwsbrief