Much research has shown that the microbes in our intestines are capable of affecting our mood; and, while psychiatry is increasingly aware of this situation, it still requires further clinical research to be completed to replace antidepressants with probiotics. However, a group of researchers decided to test what would happen if probiotics were used as an adjunct to treatment for depression. In their study they found that, even as a complement, probiotics significantly improve antidepressant therapy (Schaub et al., 2022).
What methodology did they use?
The sample was made up of patients with major depressive disorder, who were divided into two groups: one that received a probiotic and another that received a placebo. All remained on their current antidepressants.
What did you find
After one month, the group that took probiotics had a significant improvement in their mood, compared to the group that received the placebo.
These results suggest that additional probiotic treatment improves depressive symptoms and increases specific health-related bacterial taxa. At the neural level, probiotics alter negative biases and emotional valence in addition to the usual treatment for depression.”
What are psychobiotics
Probiotics that can improve mood are called psychobiotics, and the main component of the probiotic used in this study was Lactobacillus. This research follows a meta-analysis conducted in 2021 that also found large improvement when combining antidepressants with probiotics (Nikolova et al., 2021).
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How can microbes improve depression?
Much of this has to do with how they help repair leaky intestines. Some researchers don’t like that term, because the intestinal lining is actually designed to leak a little: that’s how nutrients are absorbed.
The term may be imprecise, but it is certainly evocative. Pathogens can destroy the mucus layer and erode the gossamer intestinal lining over time. That can allow pathogens and their toxins to enter the bloodstream. The heart then happily pumps them to all the body’s organs, triggering an immune war, where inflammatory cells are recruited to chase and kill the pathogens. That response will eliminate the intruders and return things to normal, assuming the gut heals.
If leakage persists, chronic systemic inflammation can result. Scientists now realize that most chronic diseases start this way, with bacteria causing damage to various organs, including the brain. As Hippocrates noted, “All disease begins in the intestine.”
Probiotic microbes produce butyrate, which nourishes and heals the intestinal lining. That decreases the chances of a leaky gut and stops inflammation (Yong et al., 2019).
Some bacteria can activate interleukins that reduce inflammation. This is because these microbes snuck in early in your development and trained your immune system to give them a permanent pass. When your immune system sees them, it treats them like old friends and reduces inflammation.
Bad bacteria have the opposite effect, initiating an inflammatory response designed to decisively eliminate them. In its rush, the immune system creates a lot of collateral damage, often making the situation worse. Still, bacterial infections can kill, so the price we pay is some damage. The immune response does everything it can to keep our system in balance, but sometimes the choices are difficult.
Good bacteria and bad bacteria
Psychobiotic microbes produce BDNF, a chemical that stimulates the growth of new brain cells. They also produce neurotransmitters such as GABA, dopamine and serotonin. These various microbial secretions have important effects on brain health and may explain how they support antidepressants.
It can be difficult to distinguish good bacteria from bad, because many supposedly bad bacteria are good when their numbers are kept under control. However, we can list some of the main actors.
The good bacteria:
- Bifidobacteria
- Lactobacillus
- faecalibacterium
- Akkermansia
- Marker
- Bad bacteria:
- Streptococcus
- Klebsiella
- Oscillabacter
- alístipes
- Lachnospiraceae
- Turicibacter
- Paraprevotella
Good bacteria include familiar probiotics such as Lactobacillus and Bifidobacteria, found in yogurt, kefir, kraut, and other ferments. Specific species of these genera are also psychobiotics. Eating fermented foods is a popular way to get probiotics.
If you are depressed, whether or not you take antidepressants, there are very few downsides to taking probiotic or prebiotic supplements. At the very least, they can calm the gut and protect against dozens of chronic inflammatory diseases. There’s a good chance they can help improve your mood, too. It’s low risk, cheap, easy and doesn’t carry any stigma. Talk to your doctor; They will likely give you specific recommendations for your case.
Bibliographic references:
- Nikolova, V.L., Cleare, A.J., Young, A.H., & Stone, J.M. (2021). Updated Review and Meta-Analysis of Probiotics for the Treatment of Clinical Depression: Adjunctive vs. Stand-Alone Treatment. Journal of Clinical Medicine Research, 10(4). https://doi.org/
- Schaub, A.-C., Schneider, E., Vazquez-Castellanos, JF, Schweinfurth, N., Kettelhack, C., Doll, JPK, Yamanbaeva, G., Mählmann, L., Brand, S., Beglinger, C., Borgwardt, S., Raes, J., Schmidt, A., & Lang, UE (2022). Clinical, gut microbial and neural effects of a probiotic add-on therapy in depressed patients: a randomized controlled trial. Translational Psychiatry, 12(1), 227. https://doi.org/
- Yong, S.J., Tong, T., Chew, J., & Lim, W.L. (2019). Antidepressive Mechanisms of Probiotics and Their Therapeutic Potential. Frontiers in Neuroscience, 131361. https://doi.org/
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