I admit to being very skeptical when I first came across the idea that probiotics could help to alleviate depression. Any lesser known remedy for depressive illness has to be treated with trepidation as it is difficult to quantify a standardized dosage when dosage could vary from one person to another. However, there is a well established theory that gut health is linked to mental health so I felt compelled to find out more about the probiotic revolution.

Firstly, what are probiotics? Probiotics are non-pathogenic bacteria known to be beneficial to our intestinal system. They are the good bacteria that we need. Naturally, we harbor trillions of bacteria in our bodies and many are essential for keeping us ticking over in a healthy manner. Our intestinal system also, somewhat surprisingly, produces neurotransmitters such as seratonin and dopamine (Strandwitz, 2018) and it is believed that “the brain and the gut can talk to each other” (Bousvaros, 2017). Leo Galland in his paper The Gut Microbiome and the Brain states that “Gut bacteria directly stimulate afferent neurons of the enteric nervous system to send signals to the brain via the vagus nerve” (Galland 2014). In theory, communication between gut and brain indicates that one can affect the health of the other. Gastric problems can upset the mind and mental problems can cause gut issues. This connection is known as the gut-brain-axis. Several studies have been undertaken on patients with varying mental health disorders from Bipolar to Schizophrenia on the use of probiotics as an aid to redress the balance and it is theorized that by manipulating the neurotransmitters released by the gut a beneficial effect on mood and symptoms can be reached, achieving this by using specific probiotics, bacteria that help us nurture the neurotransmitters.

One study tested forty patients with Major Depressive Disorder in a double-blind placebo-controlled trial in which half were administered a placebo and half a probiotic containing Lactobacillus acidophilus, Lactobacillus casei and Bifidobacterium bifidum (Akkasheh et al, 2016) . The results showed that “After 8 wk of intervention, patients who received probiotic supplements had significantly decreased Beck Depression Inventory…compared with the placebo”(Akkasheh et al, 2016). Which means that the symptoms of MDD were decreased in the probiotc test group. Probiotics are shown here to have a positive effect on the neurotransmitters that affect us in periods of depression. More research has been undertaken with patients living with Bipolar Disorder as it is thought that “probiotic supplement may reduce inflammation of the gut, which is known to exacerbate bipolar disorder” (Science Daily, 2018). In the article Probiotics could help millions of patients suffering from bipolar disorder published in Science Daily it is stated that:

“A group of patients recently hospitalized for mania participated in a 6-month study to track the effects of probiotic treatment on both their mood and the status of their immune system.
The patients were randomly selected to receive either the probiotic supplement or a placebo in addition to their usual medications. The results showed that the group receiving the probiotic supplement, on average, didn’t return to the hospital as quickly and required less in-patient treatment time compared to the placebo group. The beneficial effects were most pronounced in those patients who exhibited abnormally high levels of inflammation at the beginning of the study.
Overall, these results indicate that changes in intestinal inflammation can alter the trajectory of psychiatric mood disorders and that modulating the intestinal microbiota may be a new avenue of treatment for patients suffering from these diseases” (Science Daily, 2018)

Another study looked at how probiotics helped with the symptoms of Schizophrenia. An article in the Psychiatry & Behavioural Health Learning Network entitled Probiotics May Decrease Schizophrenia Symptoms in Some claims that:

“Probiotics may decrease delusions and hallucinations in some people with schizophrenia, researchers from Johns Hopkins Medicine and Sheppard Pratt Health System found in a small pilot study” (Psychcongress.com, 2017).

This study used the bacteria Lactobacillus rhamnosus and Bifidobacterium animalis on a control group over fourteen weeks and positive symptoms were seen to be improved upon.

In conclusion, the trials that have been undertaken may be small, but, they are promising and as probiotics can’t hurt us there is no harm in trying them for ourselves alongside any medication (although it is still always best to check with a healthcare professional if you are taking any medication before taking any supplements). By looking after our gut health, we are looking out for our mental health too.


Akkasheh, G. et al (2016). Clinical and metabolic response to probiotic administration in patients with major depressive disorder: A randomized, double-blind, placebo-controlled trial. [online] Science Direct. Available at: https://www.sciencedirect.com/science/article/pii/S0899900715003913 [Accessed 6 Apr. 2019].

Bousvaros, A., MD. (2017). Can probiotics help treat depression and anxiety? – Harvard Health Blog. [online] Harvard Health Blog. Available at: https://www.health.harvard.edu/blog/can-probiotics-help-treat-depression-anxiety-2017072612085 [Accessed 6 Apr. 2019].

Galland, L. (2014). The Gut Microbiome and the Brain. [online] NCBI. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4259177/ [Accessed 7 Apr. 2019].

Psychcongress.com. (2017). Probiotics May Decrease Schizophrenia Symptoms in Some Psychiatry & Behavioral Health Learning Network. [online] Available at: https://www.psychcongress.com/article/probiotics-may-decrease-schizophrenia-symptoms-some [Accessed 6 Apr. 2019].

ScienceDaily. (2018). Probiotics could help millions of patients suffering from bipolar disorder. [online] Available at: https://www.sciencedaily.com/releases/2018/12/181213083653.htm [Accessed 6 Apr. 2019].

Strandwitz, P. (2018). Neurotransmitter modulation by the gut microbiota.. [online] NCBI. Available at: https://www.ncbi.nlm.nih.gov/pubmed/29903615 [Accessed 7 Apr. 2019].

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