Gut Bacteria and Your Brain

Researchers took 50 subjects with no history or symptoms of digestive disorders that had a history of depression or anxiety.  They then then measured their LPS and other markers of increased intestinal permeability, the most well-known of them being zonulin.  Zonulin is a protein that when produced disassembles the tight junctions or “glue” that allows for cells to form a tight intestinal wall.  When this barrier is compromised, toxins from LPS type bacteria are exposed to the gut and cause inflammation.  It is believed that a compromised gut barrier can lead to systemic inflammation, including to the brain. The researchers found that levels of LPS were higher in the subjects who had symptoms of anxiety and depression compared to those that had no symptoms. They also were shown to have higher levels of zonulin.  High levels of LPS are associated with systemic inflammation which is not good for any part of you, including the brain. 

This is perhaps why omega 3 fats and probiotics are sometimes recommended for depression.  In functional medicine we ask the personal question of “why?”.  We have billions of bacteria in our gut, so how do we go about diagnosing and treating this as a root cause for some of our patients?  It is often not enough to just take fish oil and probiotics, sometimes testing is required to identify and treat unfriendly microorganisms that reside in our intestinal tract.  To complicate this even further, sometimes the issue is not the abundance of unfriendly bacteria, but more so that the bacteria is in the wrong place (as in the case of Small Intestinal Bacterial Overgrowth -SIBO).  There are markers of intestinal permeability that we can test for in the blood (zonulin and LPS) which can play a role in your symptoms.  Reducing gut inflammation and reducing LPS may be able to improve depressive symptoms.