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Psychobiotics – Mood supportive probiotics?

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Have you heard about psychobiotics yet? This is an emerging topic in the gut-brain connection world that’s just beginning to be explored. Watch this space though, it will only continue to grow in the next 5-10 years. 


Although there are several probiotic strains that fall into the category of “psychobiotics” or mood supportive probiotics, there are two that are more frequently referenced in this space. They are Lactobacillus helveticus R0052 and Bifidobacterium longum R0175. 

Quick Note on Probiotic Strains 

Also, a quick side note on these strains. The whole name (yes even the numbers after) matters when discussing probiotics. You’ve likely heard me say this before. But just to reiterate- Bifidobacterium longum for example has many different strain types and R0175 is the strain studied for mood. Some of the other Bifidobacterium longum strains do have benefit but not the same benefits I’m discussing. 

Here is What Researchers Found Using the Probiotic Strains Lactobacillus helveticus R0052 & Bifidobacterium longum R0175:

  • One human study showed a 50% improvement in depression scores with these two probiotics, and another showed a 55% improvement in anxiety scores- all without side effects
  • In a randomized, placebo controlled human study of 55 volunteers (age- 33-60) with mild depression or anxiety, some took a placebo while others took a mixture of 3 billion CFU’s of the probiotic and they found:
    • 50% improvement in depression scores
    • 36% improvement in hospital anxiety and depression scale
    • 49% improvement in global severity index (measures stress)
    • 60% improvement in anger-hostility scores
    • 13% decrease in urinary cortisol (measure of stress)
    • Improvements also in self blame and problem solving
    • Three weeks after, probiotic group had 7.6 times the reduction in abdominal pain compared to placebo, 2.1 times less stress induced nausea and vomiting, 2.9 times less gas and bloating
  • NOTE: These strains are more difficult to find in products – reach out directly if you are looking for this strain. Currently, I wasn’t able to find these strains in over the counter products to date. I’ll update this as we find products that contain these strains.

Psychobiotic Studies vs. Medications

There have been some studies that compared these probiotic strains to medications. In one study, the strains were compared with Valium (also known as diazepam) a drug well known for it’s calming affects. In this rat study, they were given either saline, Valium or the probiotic mixture. In just a two week study, the probiotic group showed similar anxiety reducing properties like the Valium group. 

A Lesser Known Psychobiotic

L.Plantarum 299V is found naturally in fermented foods like fermented pickles, kimchi, olives and sauerkraut. It has been shown to reduce pain and bloating in IBS patients significantly (50-60% over 6 weeks). In fact many of my patients that have dealt with bloating for years without resolution do really well with this strain and for some it’s a lifesaver! You can check out Biome Restore which has this strain HERE. There is early research on this strain being also connected to some cognitive improvement and decreased stress markers. Read more below.

  • Lactobacillus plantarum 299v is thought to modulate the gut-brain axis through the neuroendocrine system by preventing a rise of cortisol in individuals during times of acute stress.[1] A randomised, double-blinded, placebo-controlled trial was conducted to clarify the effect of Lactobacillus plantarum 299v on salivary cortisol and salivary immunoglobulin A (salivary IgA) levels, as markers of stress response, in young adults during examination stress (acute stress).[2]
  • The study details (Markers of Stress Decreased): Forty-one students aged 18 to 30 years with an upcoming exam were randomized to receive either 10 billion of Lactobacillus plantarum 299v or placebo once daily after lunch for 14 days.[2] Prior to the commencement of the intervention, participants entered a two week wash out where they were instructed to avoid the intake of probiotic products. Psychological assessment was conducted via a questionnaire to evaluate self-perceived stress, and saliva sampling for cortisol and secretory IgA (sIgA) were taken at baseline and day 14, with additional cortisol samples taken at day five and 10. Results revealed statistically significant changes in median cortisol levels between baseline and day 10 between the treatment group and the placebo group.  A statistically significant increase in the levels of lactobacilli was also noted in the treatment group compared to placebo. Lactobacillus plantarum 299v was shown to prevent the rise of cortisol in students suffering from exam stress.
  • Study on Cognition (Improvements in speed & recall): A clinical trial showed 20 billion CFU per day of Lactobacillus plantarum 299v improved cognitive function in patients with major depressive disorder. A double-blinded, randomized, parallel, placebo-controlled trial was conducted to assess the effects of Lactobacillus plantarum 299v on several parameters, including cognitive function, in patients with major depressive disorder. Sixty patients in Poland who were classified as having major depression received either Lactobacillus plantarum 299v or placebo twice daily alongside a selective serotonin reuptake inhibitor (SSRI) over eight weeks. There were significant improvements in cognitive functioning (speed and recall) in the l.plantarum 299v group studied [3]. Anxiety & depression scores didn’t improve in this group however.

What are Probiotics & How does it all work?

All of this might sound too good to be true, so let’s dial it back and understand how probiotics work. First what are probiotics? Probiotics are bacteria that have decades of documented evidence in supporting digestive, immune, oral, cardiovascular, urinary and even vaginal health. Also keep in mind that not all probiotics have documented evidence. 

Here’s some thoughts on how psychobiotics could work:

  • The digestive system has it’s own neural system called the enteric nervous system
  • The enteric nervous system has around 200-600 million neurons that receive, process and transmit information
  • Gut organisms can secrete neurotransmitters such as GABA which theoretically relieves anxiety and boosts mood
  • Although we don’t know the exact mechanism of how GABA in the intestine can reach the brain, we do know there is a connection referred to as the gut-brain axis
  • There is communication between the gut and the brain through the vagus nerve which is a nerve that runs from the intestine to the brain
  • Neurotransmitters from the gut are thought to possibly reach the brain through something called the kynurenine pathway
  • Certain intestinal bacteria can increase something called BDNF (brain-derived neurotrophic factor) which helps with promoting cognition and neurological development

Bottom Line:

Psychobiotic strains show a lot of promise as adjunct support to other treatments. However, my preference with our patients is to first focus on dietary strategies as the primary strategy alongside other treatments.


[1] Andersson H, Tullberg C, Ahrné S, Hamberg K, Lazou Ahrén I, Molin G, et al. Oral administration of Lactobacillus plantarum 299v reduces cortisol levels in human saliva during examination induced stress: a randomized, double-blind controlled trial. Int J Microbiol. 2016;2016:8469018. doi: 10.1155/2016/8469018.

[2] Andersson H, Tullberg C, Ahrné S, Hamberg K, Lazou Ahrén I, Molin G, et al. Oral administration of Lactobacillus plantarum 299v reduces cortisol levels in human saliva during examination induced stress: a randomized, double-blind controlled trial. Int J Microbiol. 2016;2016:8469018. doi: 10.1155/2016/8469018.

[3] Rudzki L, Ostrowska L, Pawlak D, Malus A, Pawlak K, Waszkiewicz N, et al. Probiotic Lactobacillus plantarum 299v decreases kynurenine concentration and improves cognitive functions in patients with major depression: a double-blind, randomized, placebo controlled study. Psychoneuroendocrinology. 2019 Feb;100:213-222. doi: 10.1016/j.psyneuen.2018.10.010.