Anxiety, depression and obesity are common problems that afflict millions of people in the United States. There are numerous potential factors that have been linked to each of these issues. Evidence suggests that that the microbes roaming our gut could also affect both our mental health and our body weight.
Gut Bacteria, Anxiety and Stress Hormones
A team of researchers from the United Kingdom has found that probiotics could be a useful tool for controlling anxiety. Authored by Oxford University microbiologists, this research analyzed a total of forty-five adults between the ages of 18 and 45. All of these participants were all in good health, a fact that allowed the authors to better gauge the effects of prebiotics, supplements designed to foster the growth of “good” bacteria.
Over a three week span, the subjects were required to take either a prebiotic or a placebo substance daily. At the conclusion of this period, these adults underwent multiple computer-based tests, which measured their responses to emotional stimuli. For example, the study documented the group’s reactions to words with either negative or positive connotations.
This testing indicated that the prebiotics had a notable influence on the subjects’ emotional responses. Negative stimuli drew less unfavorable reactions from adults taking a prebiotic, indicating that they were less anxious than those given a placebo. Furthermore, the prebiotic supplements also appeared to have an impact on cortisol, a hormone the body releases when under stress.
Using saliva samples, the authors determined that cortisol was less prevalent in subjects receiving a daily prebiotic. Since research has connected high levels of cortisone to anxiety and depression, this finding strengthens the case that mental health could be linked to gut bacteria. If such a relationship does indeed exist, taking prebiotics may offer some relief to those struggling with mental illness.
Dr. Philip Burnet, the Oxford study’s lead author, believes that both prebiotic and probiotic supplements could play such a role in the future, but only when taken in conjunction with traditional medicines. The journal Psychopharmacology published the study online in December
A Weighty Topic
Aside from influencing your emotional health, digestive bacteria might also have a say regarding the size of your waistline. Evidence for this possible connection was presented in two 2013 studies, both of which were conducted in Europe. One of these reports involved almost 300 Danish subjects; out of this group, 169 qualified as being obese, whereas the remaining 123 volunteers were at healthier weights.
This research didn’t involve the most glamorous work, as the authors reviewed bacterial genes found in these subjects’ stool samples. Though not exactly an alluring process, testing these samples provided the authors with a clear picture of the participants’ gut microbes. The study reported that digestive bacteria in obese subjects was noticeably less diverse than the germs present in the thinner Danes. In turn, this relative lack of bacterial diversity corresponded with signs of metabolic diseases, such as increased insulin resistance and greater amounts of inflammation. The bad news for the heftier volunteers didn’t end there; obese subjects also put on much more weight over a nine-year observation span.
The second study came courtesy of a group of French researchers, who asked 49 overweight or obese individuals to follow a high-fiber, low-calorie diet. By doing this, the authors managed to significantly alter the gut bacteria composition of certain volunteers. Those who originally had comparatively little germ variety acquired more forms of bacteria over the course of the study.
The two studies suggest that a healthy diet may change the makeup of gut bacteria, giving the body a better chance of staying at a thinner weight. The online version of the journal Nature published both studies.