Probiotic mix may boost mood for people with moderate depression

By Stephen Daniells

- Last updated on GMT

© nensuria / Getty Images
© nensuria / Getty Images

Related tags Probiotics mood support Depression gut-brain axis

A multispecies probiotic product may improve mood and some cognitive measures, says a new study from the University of Oxford that suggests the product may be an “early intervention strategy” for people with moderate depression.

Four weeks of supplementation with ADM Protexin’s 14 species Bio-Kult Advanced product led to less processing of negative emotional cues and/or increased attention to positive emotional stimuli in people with moderate depression.

The probiotic was also associated with improvements in some cognitive measures.

“Taken together these data suggest that the intake of this probiotic alters emotional processing in moderately depressed people in a different way to that previously reported with conventional antidepressant treatments,” ​wrote the Oxford scientists in Psychological Medicine.


The study’s findings were welcomed by Richard Day, Medical Director, Health & Wellness, ADM, which funded the study and provided the supplements used.

“This single research study […] is one of a small number of clinical trials examining changes in psychological processing and measurements of low mood using a microbiome product,” ​said Day. “The fact that the researchers saw results in a relatively short space of time – participants took the product or placebo for only 4 weeks – is also extremely interesting, as other similar trials typically take place over a longer timeframe.

“Previously we have published research looking at how this combination of live microorganisms affects measures related to irritable bowel syndrome (IBS) and migraines. Now we have results in people experiencing low mood, and we are starting to get a better idea of how this particular microbiome intervention might be working – through the microbiome-gut-brain-axis.

“The next step is to better understand how each of the 14 strains might be working to contribute to this overall picture; and this work is on-going.”

Study details

For the new study, the Oxford-based scientists recruited 71 people with confirmed mild to moderate depression. The participants were randomly assigned to consume four capsules per day of Bio-Kult Advanced or placebo every day for four weeks.

The total probiotic dose per day was 8 billion CFUs. Bio-Kult Advanced consists of 14 species of bacteria: Bacillus subtilis​ PXN 21, Bifidobacterium bifidum​ PXN 23, Bifidobacterium breve​ PXN 25, Bifidobacterium infantis​ PXN 27, B. longum​ PXN 30, Lactobacillus acidophilus​ PXN 35, Lactobacillus delbrueckii​ ssp. bulgaricus​ PXN 39, Lactobacillus casei​ PXN 37, Lactobacillus plantarum​ PXN 47, Lactobacillus rhamnosus​ PXN 54, Lactobacillus helveticus​ PXN 45, Lactobacillus salivarius​ PXN 57, Lactococcus lactis​ ssp. lactis​ PXN 63, and Streptococcus thermophilus​ PXN 66.

“[O]ur data show that the repeated intake of multispecies probiotic changes emotional processing in people with moderate depression, in ways that are different from those seen with contemporary antidepressant therapies in healthy volunteers and in subjects with a major depressive disorder,” ​they added. “This may indicate the involvement of a different neurotransmitter system or the modulation of groups of pathways that are sensitive to peripheral signals.”

The results indicated that depression scores decreased by 50% in the probiotic group, compared to baseline levels, said the researchers. However, these changes were not correlated with the changes in emotional processing.

Improvements in select cognitive measures were also recorded, specifically for reduced reward learning (−9%), and interference word recall on the auditory verbal learning task (−18%).

No significant changes were observed in salivary cortisol levels or circulating levels of CRP (C-reactive protein), a marker of inflammation.

“These observations may suggest […] that probiotic administration may be an ‘early intervention’ strategy to reduce the risk of people with mild to moderate depression developing a major depressive disorder,” ​wrote the researchers. “Further work is required to test the duration of the beneficial effects of the current probiotic at the levels of emotional processing, mood and metabolism.”

Building the science

ADM’s Day added: “This research adds to the growing body of evidence for the important role of the gut microbiome in overall health. Where previously the gut microbiome was understood to be important for gastrointestinal health, we now understand that the microorganisms found in the gut can have far-reaching effects on seemingly distant physiological systems.

“In this case, we have an exciting addition to the body of scientific evidence which provides preliminary evidence pointing towards this important link between the combination of these specific microorganisms, the gut and the brain.”

Source: Psychological Medicine
Published online ahead of print, doi: 10.1017/s003329172100550x
“Multispecies probiotic administration reduces emotional salience and improves mood in subjects with moderate depression: a randomised, double-blind, placebo-controlled study”
Authors: R. Baião et al.


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