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Have you ever had anxiety or depression? Maybe the answer to WHY is in your gut! There has been so much talk lately about the importance of your gut microbiome and the organisms that live in our digestive tract. They can affect everything from our weight to our immune systems, and now even our mood. Recent studies have proven that our gut bacteria can influence how we feel. While it sounds crazy to me even just typing it out, recent studies in animal modeling show that the toxins produced by bacteria in the digestive tract called Lipopolysaccharide (LPS) can induce depression and anxiety when injected in mice. I am not exactly sure what a depressed and anxious mouse looks like, but I sure do know a lot of depressed and anxious humans! So, how does all this research relate to us?
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.
Treating often involves antimicrobial nutrients, either pharmaceutical or herbal, to help heal the tight junctions. An individualized food plan may be prescribed as well as probiotic support. It is also important to think about and treat the cause of the imbalance of bacteria and the gut permeability. For that reason, a thorough history and symptom review is important for each patient.
References:
Increased human intestinal barrier permeability plasma biomarkers zonulin and FABP2 correlated with plasma LPS and altered gut microbiome in anxiety or depression.
Stevens BR, Goel R, Seungbum K, Richards EM, Holbert RC, Pepine CJ, Raizada MK.
Gut. 2018 Aug;67(8):1555-1557. doi: 10.1136/gutjnl-2017-314759. Epub 2017 Aug 16.
Brain-derived Neurotrophic Factor (BDNF)-TrkB Signaling in Inflammation-related Depression and Potential Therapeutic Targets.
Zhang JC, Yao W, Hashimoto K
Behavioral, inflammatory and neurochemical disturbances in LPS and UCMS-induced mouse models of depression.
Zhao X, Cao F, Liu Q, Li X, Xu G, Liu G, Zhang Y, Yang X, Yi S, Xu F, Fan K, Ma J.
Behav Brain Res. 2019 May 17;364:494-502. doi: 10.1016/j.bbr.2017.05.064. Epub 2017 May 29
