This Dr. Axe content is medically reviewed or fact checked to ensure factually accurate information.
With strict editorial sourcing guidelines, we only link to academic research institutions, reputable media sites and, when research is available, medically peer-reviewed studies. Note that the numbers in parentheses (1, 2, etc.) are clickable links to these studies.
The information in our articles is NOT intended to replace a one-on-one relationship with a qualified health care professional and is not intended as medical advice.
This article is based on scientific evidence, written by experts and fact checked by our trained editorial staff. Note that the numbers in parentheses (1, 2, etc.) are clickable links to medically peer-reviewed studies.
Our team includes licensed nutritionists and dietitians, certified health education specialists, as well as certified strength and conditioning specialists, personal trainers and corrective exercise specialists. Our team aims to be not only thorough with its research, but also objective and unbiased.
The information in our articles is NOT intended to replace a one-on-one relationship with a qualified health care professional and is not intended as medical advice.
Gut Bacteria Is Linked to Depression
March 4, 2022
Our gut microbiome is composed of the trillions of microorganisms, mostly bacteria, and their genetic material that exist in our intestinal tract. Now we know that this bacteria is involved in functions critical to our health and wellbeing.
Our individual microbiomes are sometimes called our “genetic footprints” since they help determine our unique DNA, hereditary factors, predisposition to diseases, body type or body “set point weight,” and much more. The bacteria that make up our microbiomes can be found everywhere, even outside our own bodies, on nearly every surface we touch and every part of the environment we come into contact with.
A recent study involving thousands of people in Finland now indicates that a gut microbe may be directly linked to some cases of depression. This finding bring researchers closer to potentially using microbes to combat mood disorders like depression.
Study Findings: Gut Microbe Linked to Depression
In a recent Nature Genetics study of how genetics and diet affect the microbiome, randomization analysis indicated a potential causal effect of the gut microbe Morganella on major depressive disorder — and “this was consistent with observational incident disease analysis.”
Previously, Morganella and leaky gut was implicated in depression, which was accompanied by an inflammatory response and that pro-inflammatory cytokines and lipopolysacharide may induce depressive symptoms. The study appeared to prove that inflammation caused by gut microbes could cause depression and other mood issues.
So, is there a link between gut bacteria and depression? These studies appear to indicate that the answer is yes. For years, researchers have found that certain brain conditions and gut microbes are connected. For instance, people with autism have deficits of certain key gut bacteria. In fact, bacteria in your gut can simply affect your current mood.
This study examined the genetic makeup of 6,000 adults, including their gut microbes, diets, prescription drug use, diets and overall health. They were tracked over 40 years.
Researchers investigated the data to find out how a person’s diet and genetics might affect the microbiome. In terms of depression, the bacteria Morganella was significantly increased in the 181 people who were later diagnosed with depression.
How to Optimize the Gut Microbiome for Depression
So while figuring out how to eliminate Morganella from the gut to relieve depressive symptoms is a ways off, there are some promising ways to harness the gut microbiome to naturally treat depression and mood disorders.
1. Eat more organic whole foods
Dietary changes over the last century — including industrial farming, the use of pesticides and herbicides, and the degradation of nutrients in foods — are the primary forces behind growing mental health issues like depression. Low nutrient availability, inflammation and oxidative stress affect the neurotransmitters dopamine, norepinephrine and serotonin, which control your moods, ease tension and raise alertness.
2. Begin taking a soil-based probiotic
Probiotics benefits seem to include a reduction in depression symptoms, according to a 2016 meta-analysis — the first review of its kind.
A 2017 study illustrated the correlation between gut health and depression. Researchers studied 44 adults with irritable bowel syndrome and mild to moderate anxiety or depression. Half of the group took the probiotic Bifidobacterium longum NCC3001, and the other was given a placebo.
Six weeks after taking probiotics daily, 64 percent of the patients taking the probiotic reported decreased depression. Of the patients taking a placebo, only 32 percent reported decreased depression.
3. Consider getting a fecal transplant
Either due to a disorder or certain lifestyle factors, like a poor diet and long-term antibiotic use, the good bacteria that are normally present have been killed or suppressed. So, for those people with such a compromised gut, a fecal transplant is worth considering. They essentially benefit from having another person’s good bacteria inhabit their own gut and getting their digestive system rebalanced.
The best way to take advantage of living bacteria is to transplant them directly from a donor to a receiver while the bacteria is still living — this way the healthy microbes take hold in the receiver’s gut and reside and repopulate there. You can think of the process almost like someone receiving an organ transplant, or even like an entire immune system transplant!
Researchers are hopeful that fecal transplants will help prevent or treat brain disorders due to the strong relationship between gut health and brain health. Scientists know that patients with these brain conditions suffer from abnormal GI microbiota, and so it’s believed that improved gut health will work to signal messages to the brain that may turn off causes of mood disorders such as depression or even learning disabilities like ADHD.