Probiotics Reduce Depression and Anxiety

gut bacteria linked to depression

Probiotics boost moods and reduces anxiety.

New research is investigating the effects of probiotics on brain health. And it appears they can affect our moods and even our thinking habits and our feelings of stress.

Who would have thought that the bacteria that dwell not only in our intestines, but in our oral cavity, our sinuses, lungs and elsewhere could have this affect upon our brain’s health and even our thinking? The research is now proving these realities.

Probiotics reduce stress, anxiety and depression

Case in point is a study published in Nutritional Neuroscience. The researchers tested 70 adults who were divided into three groups. The testing lasted six weeks. One group was given 100 grams a day of a probiotic yogurt in addition to a placebo capsule. Another group was given a pasteurized (non-probiotic) yogurt plus a multi-species probiotic capsule each day. The third group was given the placebo capsule and the pasteurized yogurt each day.

Before and after the six weeks of supplementation or not, the 70 workers were tested for mental health and well-being. The General Health Questionnaire measured their feeling of general well-being. And their levels of depression, anxiety and stress were measured using the DASS questionnaire. DASS stands for Depression Anxiety Stress Scales.

The DASS test originated from the University of New South Wales. It measures depression, with includes hopelessness, a lack of self-worth and a lack of interest in life. Anxiety is measured with not only nervousness, but autonomous muscle reactivity. And stress measures ones relaxation states, irritability and impatience.

In addition, blood tests were taken and analyzed for each subject. This was used to test for what is called the hypothalamic-pituitary-adrenal axis. Some consider this a good test for the gut-brain axis. We’ll discuss this in a minute.

Both probiotic groups – the group given the probiotic yogurt and the group given the probiotic cap each day – had significant improvement in both well-being and depression, stress and anxiety scores.

Their well-being scores went from 18 to 13.5 in the probiotic yogurt group and from 17 to 9.8 in the probiotic capsule group. (Lower scores in the GHQ show greater sense of well-being). Meanwhile, the placebo group showed no improvement in scores.

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In the depression, anxiety and stress testing, the probiotic groups also showed far better improvement over the six weeks. The DASS scores for the probiotic yogurt group went from 23.3 to 13 and the probiotic group went from 18.9 to 9.4 during the six weeks. (A lower score in the DASS test shows reduced levels of depressive symptoms, lower stress and less anxiety). Once again, the placebo yogurt and placebo capsule group showed no change over the six weeks.

This study illustrates with clarity that our gut bacteria influences not only our sense of well-being, but also our state of mind.

While the source of depression often lies within a spiritual context, the brain and its neurochemistry can significantly affect our moods. Neurochemicals such as dopamine and serotonin are significant in this area, because they affect our body’s state of relaxation. And this in turn effects how well we can digest – and the general state of our intestinal tract and something called peristalsis.

Probiotics reduce depressed thoughts too

Another study has illustrated that probiotics can directly affect depressed thinking. A spiraling of negative or depressive thoughts is also called negative thinking.

Researchers from The Netherlands – in a study published in the Brain, Behavior and Immunity Journal, studied 40 healthy adults for a month. They gave half the group a probiotic supplement with Lactobacillus acidophilus, L. salivarius, L. brevis, L. casei, Bifidobacterium bifidum, B. lactis and Lactococcus lactis. The other 20 people were given a placebo for the month.

Afterward the subjects were tested for what is called cognitive reactivity for sad mood. Cognitive reactivity for sad mood is a cognitive behavior term, used in cognitive behavior therapy. When a person has less reactivity to a particular mood, they are more removed from the mood – and in the case of sad mood – in a better state of mind.

ProbioticsBook by Case Adams Naturopath

The researchers explained that this reduced reactivity was based upon the subjects’ reduced levels of depressive or negative thoughts.

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Research from Leiden University has studied this element of cognitive reactivity to sad moods along with depression. A questionnaire protocol developed at Leiden – called the Leiden Index of Depression Sensitivity (LEIDS) – has been found to help determine to what degree a person’s negative thinking leads to an increase in depressed thoughts.

The researchers concluded that probiotics could be a potential treatment for depression:

“Probiotics supplementation warrants further research as a potential preventive strategy for depression.”

The Gut-Bacteria-Brain axis

This is typically termed the gut-brain axis. But in this case, we are learning that there is another element of the axis in our gut’s microbial health.

The link between the brain and the gut has been known for quite some time in medicine- even among the oldest medicine – Ayurveda. Today we trace the mechanism to the fact that between the gut and the brain lies the vagus nerve. Thus the state of our mental well-being will affect our intestinal well-being. But this also works in reverse.

Research from Canada’s McMaster University has recently focused upon the gut-brain axis. Studies have linked gastrointestinal conditions such as irritable bowel syndrome to a variety of neurological conditions such as autism and depression.

The link is provided in the reality that microbes signal each other and also signal our nerves and other elements of our body in an attempt to keep everything copasetic. Their survival is certainly linked to ours.

Intestinal communication cells

Research from the David Geffen School of Medicine found that within the lining of our intestinal walls contain cells called enterochromaffin cells. These cells allow signals from our gut bacteria to be communicated to our nerve cells. They also allow nerve cell signals to be communicated to our gut bacteria.

We might just consider these cells to be somewhat like little cell phones – allowing communications between our body and our gut bacteria.

Moreover, the researchers found these enterochromaffin cells sent signals directly to and from the vagus nerve. This of course completes the loop between bacteria and our brain.

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Probiotics communicate differently than pathogenic bacteria

This is a serious consideration. Research from the California Institute of Technology tested several types of bacteria with regard to their affects upon gut immunity and gut motility – the ability of the intestines to move our food along.

They found that probiotics such as Bifidobacterium bifidum and Lactobacillus acidophilus produce signals that increase gut motility and gut immunity. Meanwhile pathogenic bacteria such as Escherichia coli block these processes.

Be serious. Our gut bacteria are communicating with us.

probiotics and microbes webinar


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Case Adams, PhD

Case Adams has a Ph.D. in Natural Health Sciences, is a California Naturopath and is Board Certified as an Alternative Medicine Practitioner, with clinical experience and diplomas in Aromatherapy, Bach Flower Remedies, Blood Chemistry, Clinical Nutritional Counseling, Homeopathy and Colon Hydrotherapy. He has authored 27 books and numerous articles on print and online magazines. Contact: [email protected]

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