Your Gut Bacteria May Play a Role in Your Risk for Depression—a New Study Explains Why

While sauerkraut will never be a replacement for SSRIs, we're learning more about how supporting gut health might eventually boost your mood.

Earlier this year, we offered a deep dive into how poor gut health may increase risk for anxiety and depression. Admittedly, both of these mental health states are far more complex than a headline—or even a single study—can explain. With genetics, life circumstances and a variety of external factors at play, it's certainly not as simple as saying, "Eat more yogurt and you'll feel chipper every day!"

Still, there are many scientists digging deeper into the gut-brain connection in an attempt to try to connect the dots—and potentially help those diagnosed with depression experience fewer symptoms. There are millions of reasons why … actually, millions of humans. Depression is such a common condition that it's one of the leading causes of disability around the world, the World Health Organization confirms.

The latest finding in this area was just published December 6 in the journal Nature Communications, and reveals even more about the mood-and-microbiome link. Through the observational study, the researchers were able to identify 13 specific types of gut bacteria associated with depression.

Read on for more details about these findings and what they mean for those who may be diagnosed with or at risk for depression.

an illustration of a silhouette of a person with an illustration of bacteria in a gut overlaid
Images: Getty Images; Collage: Cassie Basford

What This Mental Health Study Found

Before we go any further, a brief refresher on depression (aka major depressive disorder). This condition is something that about 1 in 6 of us experience at some point in our lives, and it involves feelings of sadness and loss of interest in things that used to bring you joy, according to the American Psychiatric Association. Environmental, psychological, social and genetic factors can all play a role, as can levels of neurotransmitters in the brain.

For this study, scientists at Oxford Population Health and from the Netherlands investigated data from 1,133 participants in the Rotterdam Study, a cohort study of about 14,900 residents in Rotterdam, Netherlands. Controlling for lifestyle factors and medication use, including antidepressants, the researchers were able to pinpoint 13 specific types of bacteria associated with depression (check out the study for the specific strains).

The researchers were able to replicate and confirm these findings by tapping into data from another observational study, the HELIUS study.

So why might these bugs make us feel more bummed? The scientists believe it may be due to their impact on how people pump out neurotransmitters, those powerful signaling chemicals that allow our nerves to communicate. These bacteria might affect levels of certain neurotransmitters that have been proven to be related to depression, like glutamate.

The scientists hope that doctors will be able to use these results to eventually make diagnosing and treating depression easier. If they can look for these specific gut bacteria and notice other signs of depression, perhaps they could come up with a treatment plan. And since we know that these gut bacteria can play such a large role in depression risk, we can tailor certain probiotics and diet adjustments to potentially help with recovery.

It might be easy to look at these findings and think that all gut bacteria are bad for our mood, but that's far from the case. The microbiome produces neurotransmitters such as NANA, serotonin and norepinephrine, and billions of good gut bacteria help make that possible. Certain gut bacteria are positively and negatively related to depression and anxiety, and the scientific community is on a continued quest to sort column A from column B.

The Bottom Line

One new mental health study found that certain strains of gut bacteria may be linked to depression. Other species of gut bacteria can also disrupt gut health, and as a result, alter the gut-brain axis, brain chemistry and our overall risk for depression and anxiety. An overgrowth of certain kinds of gut bacteria or undergrowth of favorable gut bacteria might interrupt biochemical actions that relate to mental health and mood.

While we're learning more by the month about the link between gut bacteria and depression, it's fairly clear now that a healthy gut plays a big role in brain functions that relate to our mood, thoughts and actions. So discover 5 things you should do every day to support good gut health (hint: prioritize those prebiotics and probiotics!), and up the optimism ante by stocking up on 12 fiber-rich foods to help with good gut bacteria.

Keep in mind that no food or diet will prevent or cure depression. A multifaceted treatment plan including mental health counseling, medication and lifestyle adjustments is often the preferred approach. Always consult with your health care team if you're noticing any signs of depression (or any other mental or physical illness).

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