Psychobiotics: How Gut Bacteria Affect Mood, Stress, and Mental Health
Scientists are discovering that what happens in your gut doesn’t stay in your gut. The bacteria living in your digestive tract can influence your mood, stress response, and focus.
Researchers now use the term psychobiotics to describe certain beneficial gut bacteria that appear to support mental health.
Understanding psychobiotics helps explain why gut health, fermented foods, and probiotic supplements are increasingly being discussed in connection with stress resilience, mood, emotion regulation, and mental well-being. These effects are thought to occur through the gut–brain axis, the communication network linking your digestive system and your brain.
What's in this Guide to Psychobiotics
| What are Probiotics? |
| What Are Psychobiotics? |
| My Interest in Psychobiotics |
| How Psychobiotics Improve Mood and Stress Resilience |
| Psychobiotics and Neurotransmitters |
| Which Bacteria Are Classified as Psychobiotics? |
| Example Supplements Containing Psychobiotics |
| More Information About Food and Supplements for Mental Health |
| References: Psychobiotics Mental Health Benefits Research |
Note: This article should not be taken as medical advice. It is always advisable to talk to your personal medical professionals before taking natural remedies. I may receive a small commission from sales through links in this post, but it does not affect your cost or my decision to include the product. They are placed for your convenience.
What are Probiotics?
Psychobiotics are a subset of probiotics. So let's start our discussion by clarifying what probiotics are.
Probiotics are live helpful microorganisms: they are pro-health microorganisms. More specifically, what we are usually talking about when we are dealing with probiotics are pro-health bacteria.
Your digestive tract contains about as many microorganisms as there are human cells in your body. (The ratio used to be reported as about 10:1 microbes to human cells, but the number was revised recently to 1:1. Still — you’ve got lots of microbes.)[1]
Gut microbes include yeasts, fungi, viruses, and other organisms, but it’s mostly bacteria. And there’s typically lots of diversity in there created by a mix of many different species.
Not all gut bacteria treat you nice. The specific species of bacteria in your gut and their relative numbers impact the health of your gastrointestinal tract, the rest of your body, and your mind.
What are Psychobiotics?
Psychobiotics is a relatively new term used for microorganisms that researchers have come to believe specifically help you mentally and emotionally.[2]
My Interest in Psychobiotics
My first career was as a Medical Lab Technologist specializing in Microbiology. I loved microbiology — it's like detective work, trying to figure out what microorganisms are in the specimen you've been handed. But, after I experienced the benefits of mental health therapy to deal with the remnants from a difficult childhood, I decided to shift gears and go back to school to get the degrees to become a counselor so I could help others experience similar positive changes in their life.
I’ve always been fascinated by the connection between biology and psychology, so I was excited when the emerging field of Integrative Medicine for Mental Health began bringing those two areas together. I was eager to join in and earn certification in the discipline.
I spent four years researching and writing Feed Your Calm: Anti-Anxiety Anti-Stress Diet and Supplement Tips for Stress Resilience. My medical background came in very handy during that process, particularly when investigating how gut bacteria influence mental health.
How Psychobiotics Improve Mood and Stress Resilience
Psychobiotics can help your mental health by helping you:[3]
- use glucose,
- heal your gut wall,
- even out your cortisol,
- reduce inflammation, and
- help your brain in stress-reducing ways.
Psychobiotics and Neurotransmitters
While the evidence of probiotics’ positive impact on your mental health piles up, we don’t understand all the mechanisms yet, especially when it comes to neurotransmitter production.
Tryptophan Production in the Gut Boosts Serotonin in the Brain
One way we can see them help with neurotransmitters is that probiotic bacteria enhance tryptophan levels.[4]
Tryptophan is an essential amino acid used in the production of serotonin, so the tryptophan in your gut has the potential of passing into your blood and making its way to your brain to be used to make serotonin there.
The Blood-Brain Barrier Mystery
Mystery remains around the fact that some bacteria in your gut can be mega-producers of the calming neurotransmitters GABA and serotonin. In theory, those substances can’t get past your blood-brain barrier, so it is unknown whether their existence in your gut and blood translates into their use in your brain.[5]
Even though we don’t know yet how gut GABA and serotonin might play into the mood-enhancing and stress-relieving effect of psychobiotics, or if they have a role at all, we have lots of evidence that these beneficial bacteria do help reduce anxiety.
Which Bacteria are Classified as Psychobiotics?
Bacteria have two names. You can think of it as family name first and the equivalent of a given name second.
Psychobiotics include some bacterial names you are probably pretty familiar with, like Lactobacillus, and some others you may not recognize, such as Bifidobacterium longum.
Psychobiotics most often mentioned in anti-anxiety and anti-depression studies include:[6]
- Lactobacillus acidophilus
- Lactobacillus casei
- Lactobacillus plantarum
- Lactobacillus helveticus
- Lactobacillus rhamnosus
- Bifidobacterium breve
- Bifidobacterium infantis
- Bifidobacterium lactis
- Bifidobacterium longum
Sometimes the names are followed by letters or numbers that identify a specific strain. Different strains within the same species may have different health effects. For example, the combination of Lactobacillus helveticus R0052 and Bifidobacterium longum R0175 has been studied in animal and human trials and is associated with reduced psychological distress and lower cortisol levels.[7]
Example Supplements Containing Psychobiotics
Many probiotic supplements contain strains from the Lactobacillus and Bifidobacterium families that appear frequently in psychobiotic research.
Here are a couple of examples:
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- Contains Lactobacillus helveticus Rosell-52ND and Bifidobacterium longum Rosell-175.
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It has almost 1500 reviews on Amazon with an overall rating of 4.4 stars. Reviews include remarks like "happier, calmer, and more balanced," "I felt calmer, my anxiety was much less and I was able to focus better."
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15 billion CFU per capsule -- so can start out low dose and increase number of capsules you're taking per day.
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Garden of Life Dr. Formulated Probiotics Mood+
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This one contains many probiotics + Ashwagandha.
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Bacteria mix: Lactobacillus acidophilus, Lactiplantibacillus plantarum, Lactobacillus helveticus R0052, Lacticaseibacillus paracasei, Lacticaseibacillus casei, Levilactobacillus brevis, Lacticaseibacillus rhamnosus, Lactobacillus bulgaricus, Lactobacillus gasseri, Ligilactobacillus salivarius, Bifidobacterium lactis, Bifidobacterium longum R0175, Bifidobacterium bifidum, Bifidobacterium breve, Bifidobacterium infantis, Bifidobacterium longum.
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It has almost 700 reviews on Amazon with an overall 4.5 stars. Example review: " have been able to handle stress and anxiety better and my mood (depression and irritability) is more even. A great added benefit is my appetite has decreased and I'm not craving junk food (carbs, chocolate, chips) nearly as much."
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25 billion CFU per capsule, 2 capsules daily recommended — so you can start out with a medium dose and increase the number of capsules you're taking per day.
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More Information About Food and Supplements for Mental Health
Feed Your Calm: Anti-Anxiety Anti-Stress Diet and Supplement Tips for Stress Resilience
In Feed Your Calm, you'll learn:
- What's happening in your body as you try to deal with stress
- How specific vitamins, minerals, fats, proteins, probiotics, and herbs help you deal with stress
- 5 types of foods that add to your stress and hurt your ability to be calm
- 12 anti-anxiety foods for stress resilience
- 10 anti-anxiety supplements for stress resilience
"Anxiety is at epidemic levels today. In Feed Your Calm, Ann Silvers gives readers an approachable antidote to this epidemic."
--Dr. Megan DeBell, MD
References: Psychobiotics Mental Health Benefits Research
[1]. Ron Sender, Shai Fuchs, and Ron Milo, “Revised Estimates for the Number of Human and Bacteria Cells in the Body,” PLOS Biology 14, no. 8 (2016): e1002533, https://doi.org/10.1371/journal.pbio.1002533.
[2]. Amar Sarkar et al., “Psychobiotics and the Manipulation of Bacteria–Gut–Brain Signals,” Trends in Neurosciences 39, no. 11 (2016): 763–781, https://doi.org/10.1016/j.tins.2016.09.002.
[3]. Patrice D. Cani and Nathalie M. Delzenne, “The Gut Microbiome As Therapeutic Target,” Pharmacology & Therapeutics 130, no. 2 (2011): 202–212, https://doi.org/10.1016/j.pharmthera.2011.01.012;
John R. Kelly et al., “Breaking Down the Barriers: The Gut Microbiome, Intestinal Permeability and Stress-Related Psychiatric Disorders,” Frontiers in Cellular Neuroscience 9 (2015): 392, https://doi.org/10.3389/fncel.2015.00392;
Huiying Wang et al., “Effect of Probiotics on Central Nervous System Functions in Animals and Humans: A Systematic Review,” Journal of Neurogastroenterology and Motility 22, no. 4 (2016): 589–605, https://doi.org/10.5056/jnm16018.
[4]. Wang et al., “Effect of Probiotics.”
[5]. Alison C. Bested, Alan C. Logan, and Eva M. Selhub, “Intestinal Microbiota, Probiotics and Mental Health: From Metchnikoff to Modern Advances: Part III – Convergence toward Clinical Trials,” Gut Pathogens 5, no. 1 (2013): 4, https://doi.org/10.1186/1757-4749-5-4;
Timothy G. Dinan et al., “Collective Unconscious: How Gut Microbes Shape Human Behavior,” Journal of Psychiatric Research 63 (2015): 1–9, https://doi.org/10.1016/j.jpsychires.2015.02.021.
[6]. Wang et al., “Effect of Probiotics”; Mikelsaar et al., “Probiotic Preparations.”
[7] Messaoudi, M., Lalonde, R., Violle, N., Javelot, H., Desor, D., Nejdi, A., Bisson, J.-F., Rougeot, C., Pichelin, M., Cazaubiel, M., and Cazaubiel, J.-M., “Assessment of Psychotropic-Like Properties of a Probiotic Formulation (Lactobacillus helveticus R0052 and Bifidobacterium longum R0175) in Rats and Human Subjects,” British Journal of Nutrition 105, no. 5 (2011): 755–764, https://doi.org/10.1017/S0007114510004319
- Ann Silvers
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