Gut-Brain Connection & Addiction


Scientific evidence now suggests that the microbiota–gut–brain axis is involved in a variety of neurological and psychiatric conditions, such as depression & anxiety, addiction, and even stroke and Parkinson’s disease.

A healthy gut microbiome is full of beneficial bacteria that break down, absorb, and assimilate nutrients from the foods you eat, which fuel every process in your body. Gut microbes also have another important job to do, which is to produce serotonin and dopamine, the “feel good” chemicals that help regulate and boost your mood. Approximately 90% of serotonin and 50% of dopamine are produced by the bacteria in your gut.

Gut-Brain Research

In one study, scientists collected gut bacteria from a strain of mice prone to anxious behavior and then transplanted these microbes into another strain inclined to be calm. The result: The calm animals appeared to become anxious.

In another study, scientists gave mice either bifidobacterium or the antidepressant Lexapro and then subjected them to a series of stressful situations, including a test which measured how long they continued to swim in a tank of water with no way out (they were pulled out before they drowned). The microbe and the drug were both effective at increasing the animals’ perseverance and reducing levels of hormones linked to stress.

In one human study, scientists transferred gut bacteria from anxious humans into “germ-free” mice—animals that had been raised (very carefully) so their guts contained no bacteria at all. After the transplant, these animals also behaved more anxiously.

Perhaps the most well-known human study was done by Mayer, a UCLA researcher. He recruited 25 subjects, all healthy women, for four weeks. 12 of them ate a cup of commercially available yogurt twice a day, while the rest didn’t. Yogurt is a probiotic, meaning it contains live bacteria, in this case strains of four species. Before and after the study, subjects were given brain scans to gauge their response to a series of images of facial expressions—happiness, sadness, anger, and so on. The results, which were published in 2013 in the journal Gastroenterology, showed significant differences between the two groups; the yogurt eaters reacted more calmly to the images than the control group.

Gut Bacteria and Addiction

In a study which was recently published in the journal PNAS, Bäckhed and his colleagues from Belgium and Sweden analyzed the intestinal bacteria composition of 60 alcoholics who had equal use of alcohol. After the participants had spent 19 days in rehab it became apparent to the scientists that there was a big difference in how well the participants recovered: their well-being and risk of relapse was connected to their gut flora.

26 out of the 60 alcoholics suffered from leaky gut syndrome and generally had a low amount of intestinal bacteria. Leaky gut syndrome is linked to inflammation of the gut and diseases like Crohn disease. After 19 days without alcohol the 26 test subjects still scored high on tests that measured depression, anxiety, and alcohol cravings. There was in fact not much difference from before they went to rehab.

In comparison, the remaining 34 subjects with normal gut flora were recovering much better, scoring low on depression, anxiety, and alcohol cravings. In fact, their scores decreased to levels comparable with the control group who didn’t have a drinking problem. On the basis of these results the scientists concluded that intestinal flora is connected to the likelihood of relapse after sobering up in rehab.

When your gut is healthy, the lines of communication between your gut and brain will function properly. Adequate serotonin is produced, proper nutrients are synthesized, and you’ll feel energized, calm, and experience an overall greater sense of well being.

How To Improve Gut-Brain Function

  • Diet – A diet rich in whole foods, vegetables, and fruits help cultivate a healthy gut environment. Adding fermented foods like kimchi, pickles, sauerkraut, apple cider vinegar, kefir, Kombucha (has a trace amount of alcohol, however) and tempeh add helpful bacteria. The elimination of processed foods also keeps inflammation at bay.
  • Supplements  – Taking probiotics, specifically strands of good bacteria like bifidobacterium and lactobacillus. These keep pathogenic bacteria low. When good bacteria is in place it interacts with hormone levels, helping turn off cortisol and adrenaline which can cause long-term harm to the body.
  • Relaxation – Emotions play a huge role in gut health. One’s ability to calmly attend to the stresses of life creates a peaceful body. Meditation, breath work and simply making time to relax can do a world of good for one’s overall well-being.
  • Avoid Antibiotics Whenever Possible and increase intake of probiotics if they are necessary.

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