Introduction:
Recent studies show that changes in gut bacteria make mice less anxious and lowering levels of cortisol, the stress hormone. In humans, the link between gut bacteria and mental health is very evident. The wide range of the many microbes living in the gut affect people's physical health as well as their mental health. New research performed in England discovered that probiotics/prebiotics-strains of good bacteria- in the gut change the way in which people process emotional information, subsequently providing strong evidence that the changes in gut bacteria have anti-anxiety affects. Scientists are studying whether it would be possible to treat anxiety and/or depression with these strains of good bacteria or even improve the response to psychiatric drugs that these individuals take. Researcher, Philip Burnet, from Oxford University postulates these possibilities. There are still many studies that need to be conducted before these hypothesis can be proven as safe as well for the mental health of humans. (B)
This is not the first time that a study was conducted to further investigate the interaction between the nervous system and the gut. Nervous system signaling molecules also live in the intestines of the gut (aka: neurotransmitters) that are also found in the brain. Serotonin also known as the happy hormone is found in both locations. Researchers from Ireland in University College Cork gave a group of healthy men doses of 'Bifido-bacterium longum 1714' as the researchers noted responses to somewhat stressful situations. They found that certain probiotic bacteria might not only be helpful with anxiety but also improve memory. (A)
Research:
In a recent study from England, a larger group than those in Ireland were tested, 45 healthy individuals ranging from ages 18 to 45. These individuals either took a prebiotic or a placebo everyday for the following 3 weeks. At the end of the 3rd week, they had to complete several computer tests to see how well they processed emotional information. (B)
One test had the participants memorizing patterns within boxes in
which those that took the probiotic showed improved performance. To test
stress responses, the participants were asked to put their hands in ice
cold water for 3 minutes. All showed an increase in anxiety, but those
taking the probiotic had less severe of an increase in anxiety compared
to those who had been taking the placebo. These tests also showed that
cortisol- the stress hormone- was lower during the stressful situations.
The participants were also asked to use an online questionnaire to
report their daily stress levels. Towards the end of the study,
decreased levels of stress levels were found in those who took
probiotics. (A)
The loopholes of this study, such as
testing only men, unable to provide evidence that the bacterium made it
to the GI tract (which could be shown through stool samples), nor were
potential mechanisms that show patterns were investigated. The
researchers did not use women in this study because their menstrual
cycles could affect the cortisol levels making the study more difficult
to attain clear results. They also believe that the release of
molecules from the bacteria interact with nerve fibers. (A)
Results:
Subsequently,
the study found that those who took the prebiotics had lower levels of
cortisol in thier salvia when they woke up in the morning. High cortisol
levels have been
linked with stress, anxiety and depression. However, there were no
changes in the levels of stress and anxiety which could have been due to
the fact that the volunteers did not take the prebiotic long enough to
have an effect. Their already low levels of stress and anxiety could
have also been the reason. (B)
However, a 2011 study from France found that people who took probiotics for 30 days did have reduced
levels of psychological distress. Because this is just one study, its
findings need to be confirmed in future research. In a 2013 study, UCLA researchers gave women milk with or without
probiotics, and then scanned their brains while they viewed photos of
people with emotional facial expressions. Those who took the probiotics
had less activity in their brains in areas involved in processing
emotions, compared with those who did not take the probiotic. (B)
(A) http://www.iflscience.com/health-and-medicine/probiotic-bacteria-may-help-reduce-anxiety-and-boost-memory-performance
(B) http://www.livescience.com/49248-gut-bacteria-mental-health.html
*These images do not belong to me- they were found on various tumblr sites! Please let me know if any are yours and I will give you credit for them! Thanks so much~
