Here at Fix Your Gut we have discussed at length how gut health affects mental health. Many people have written about the importance of understanding the gut/brain axis. We have a new, long-term study that backs up the theory of poor gut health leading to anxiety and depression.

Gut Overgrowth and Mental Issues

Microbiologists have known for years that most medical conditions are caused by infections. There is enough evidence to believe that the cause of schizophrenia is T. gondii, a chronic parasitical infection of the gut and brain. There is plenty of information that links together chronic toxoplasmosis and schizophrenia; it is also linked to developing explosive anger disorders, suicidal behavior, and impulsivity. A recent study may provide clues in how this parasite causes multiple mental illnesses. What about other infections or overgrowth, can they cause mental illness 1 2

Most people that visit their doctor for gut issues leave their doctor’s office with prescriptions to treat depression and anxiety that stem from those issues, instead of trying to improve their gut health. It is the whole what came first scenario, the chicken or the egg, leaky gut or mental health issues? We know that the bacteria in our gut produce the important neurotransmitters serotonin and melatonin, which are important for proper mood and sleep. Gram-negative bacteria produce endotoxins, which in having leaky gut or when in overgrowth trigger inflammation, which causes brain and vagus nerve inflammation, triggering mental issues. People with IBS (SIBO-D mainly) seem to have elevated Th1 cytokines from LPS exposure, causing elevated inflammation which is correlated strongly with anxiety. Also, people with upper gut overgrowth (H. pylori for example) and bile issues also suffer from anxiety. When my gastritis was at its worse from H. pylori overgrowth; my anxiety was through the roof for the excessive inflammation.3 4 5 6

Stress and anxiety can hinder the immune system and over time lead to overgrowth in the gut and rampant digestive issues. Most people under stress binge eat junk food to try to increase dopamine levels and elevate mood, and in doing so imbalance the gut microbiome. I am not saying that stress does not affect the gut (brain-gut pathway), but that overgrowth and gut issues also affect the brain, by manipulating neurotransmitters and inflammatory pathways, causing mental issues (gut-brain pathway). It has been very difficult for mainstream medicine to accept the latter, but maybe with this study and hopefully others, we can further understand the brain-gut axis and how it affects mental health.7

Poor Gut Health Causes Anxiety and Depression

In a survey, 2,885 people were asked about their mental status if they had digestive issues and in people who did not have any issues. A follow-up of 1,900 people a year later showed that in people with digestive disorders that were not remedied, their mental status deteriorated.8

“While the brain–gut axis is thought to account for a significant proportion of people with IBS and FD, our findings suggest that there is also a subset of people with IBS and FD that have a gut-to-brain disorder. In this study, there were 90 individuals who had either an FGID or mood disorder at baseline and who developed the other at follow-up, of whom 1/3 followed the brain–gut pathway and 2/3 the gut–brain pathway. The exact proportions in each pathway, however, do need to be interpreted with caution as we could only ascertain order in a relatively small proportion of the sample. In any case, the evidence suggests that between one-third and two-thirds with an FGID may have a primary gut driven syndrome with the brain secondarily involved.”9

The study mentions that the causes of mental issues stemming from the gut include brain/vagus nerve inflammation from endotoxins, Th1 / Th2 dominance, and inappropriate manipulation of GABA, serotonin, and melatonin production by our gut bacteria. 10

In people that had anxiety and depression at the start of the survey, most developed digestive issues later on.

“We found among those people free of IBS and FD at baseline, higher levels of anxiety and depression were significant predictors of developing IBS and FD, but not among those who already had IBS or FD. These data highlight the importance of the brain–gut axis in people with IBS and FD. Anxiety and depression may affect the gut in several ways including increasing sympathetic and decreasing parasympathetic tone in the autonomic nervous system, up regulating the hypothalamic–pituitary–adrenal (HPA) axis including corticotrophin-releasing factor (CRF) and cortisol, as well as through promoting abnormally increased vigilance for gastrointestinal symptoms via the efferent neuro-endocrine loop.”11

In people with anxiety and depression and digestive issues at the start of the survey, their mental issues did not worsen. In most people when their digestive symptoms improved, their anxiety and depression lessened.

“This study provides strong direct evidence that the gut and brain interact bidirectionally in both IBS and FD. While brain-to-gut pathways were evident in IBS and FD as expected, the data from this study also suggest that many people with IBS and FD have their disorder begin in the gut, and the gut likely drives psychological alterations in a major group of cases with FGIDs.”12

More studies need to be performed before mainstream medicine will accept that gut issues can cause mental disorders. If you suffer from mental issues, some of the things you can do to bring you some relief hopefully are to clean up your diet, fix your circadian rhythm, and Fix Your Gut.