Human study suggests holistic psychological benefits of multi-strain probiotic

By Nikki Cutler

- Last updated on GMT

Getty | KatarzynaBialasiewicz
Getty | KatarzynaBialasiewicz
A daily dose of a multi-strain probiotic can provide a significant improvement in mood, with a reduction in depressive, anger, and fatigue, and an improvement in sleep quality, according to a new study in Italy.

The double-blind, placebo-controlled study, by researchers from the University of Verona, Azienda Ospedaliera Universitaria Integrata, Microbion SRL, and Biolab Research, extends current knowledge on the beneficial effects of probiotics on psychological wellbeing, as measured by changes in mood, personality dimensions, and quality of sleep.

Results suggest the multi-strain probiotic administered provided a significant improvement in mood, a reduction in depressive mood state, anger, and fatigue, and an improvement in sleep quality.

The research report states: "These findings corroborate the positive effect of probiotics on mood state and suggest that probiotics administration may improve psychological well-being by ameliorating aspects of mood and sleep quality."

For this study, 38 healthy students of the University of Verona, aged 18-35, were allocated to the experimental or control group by simple randomisation through a computer generated list which ensured physical activity, gender or age were balanced between the two groups.

The experimental group consumed a daily dose of a commercially available probiotic strains extensively used for food supplements (Lactobacillus fermentum​ LF16, L. rhamnosus​ LR06, L. plantarum​ LP01, and Bifidobacterium longum​ BL04) for six weeks.


Mood, personality dimensions, and sleep quality were assessed before the study, at three and six weeks, and after a three week washout period. Results were measured using a series of self assessment tests. Those which resulted in a notable outcome are listed below.

The Leiden Index of Depression Sensitivity-Revised test showed a significant between-group difference in acceptance scores at six weeks.

The Profile of Mood State results suggest that the experimental group experienced a reduction in depressive mood state and that this effect remained nearly stable after three weeks of washout

The Temperament and Character Inventory results suggest that the participants who had taken probiotics for six weeks were more prone to look for new experiences more self-focused than those in the control group.

The Pittsburgh Sleep Quality Index results suggest that sleep quality relates to higher anxiety, depression, tension, anger, fatigue, and confusion. Conversely, a good sleep quality relates to higher vigor.

The researchers did not find significant differences between the experimental and control group in mood-related or quality of sleep questionnaires but they found changes in mood state and sleep quality in the experimental group but not in the control group.

In their report, researchers noted: “The exploratory study shows an improvement across time in different aspects of the profile of mood state, like sad mood, anger, and fatigue only in healthy individuals which took probiotics.

“Sleep quality also reportedly improved after probiotics intake. Of note, sleep quality strongly relates to mood.

“More precisely, as suggested by the significant correlations between sleep quality and mood-related questionnaires, the higher the quality of sleep, the better the mood state in the experimental and in the control group.

“Finally, significant differences between-groups have been observed for some personality-related questionnaires.

“In this regard, our findings suggest that improving mood by means of probiotics intake might additionally determine changes in cognitive strategies to deal with problems by reducing sensitivity to negative situations, as well as the need to deal with them.

“Moreover, we speculate that ameliorating mood can differentially affect an individual's predisposition, for instance, by facilitating novelty seeking.”

Mounting evidence

As evidence mounts for the existence of the gut-brain axis, nutritional psychiatry has emerged as a promising research field within the food and nutrition community.

Backed by studies that aim to establish the link between gastrointestinal health with neurological disorders, the association appears to be gathering pace, as nutritional psychiatrists are adamant the “gut-brain” pathway is the key to managing anxiety and depression.

Dr Alex Richardson, visiting senior research fellow, department of physiology, anatomy and genetics at the University of Oxford, told Nutraingredients last year that he sees its promise in a supportive, rather than a main therapeutic approach.

“In my view, nutritional approaches should always be integrated with – and complementary to - standard treatments, rather than being seen as ‘alternative’,” s​he said.

“There’s good evidence that the provision of some essential nutrients via diet or supplements may help to prevent or treat many mental (as well as physical) health conditions.”

Compelling evidence​ exists to back supplementation with L-theanine, beta-alanine, and theacrine to help users increase brain alertness, according to Hofstra University in New York.

Source:​ Frontiers in Psychiatry

"Effects of Probiotics on Cognitive Reactivity, Mood, and Sleep Quality"

Authors: Marotta., A. et al

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