Probiotics and Depression

Dr. Shawn Talbott (Ph.D., CNS, LDN, FACSM, FACN, FAIS) has gone from triathlon struggler to gut-brain guru! With a Ph.D. in Nutritional Biochemistry, he's on a mission to boost everyday human performance through the power of natural solutions and the gut-brain axis.

In an outstanding scientific review from Caroline Wallace and Roumen Milev at Queen’s University in Ontario Canada, the effects of probiotics on depressive symptoms in humans is reviewed =

Some highlights from the publication:

  • link between psychiatric disorders and changes in the microbiome
  • majority of the studies found positive results on all measures of depressive symptoms (depending on the specific strain or probiotic, dosing and duration)
  • evidence for probiotics alleviating depressive symptoms is compelling
  • probiotics may reduce depression and improve mood via a variety of complementary mechanisms, including:
    • modulation of stress response
    • increased neurotransmitter production and improved activity
    • reduction in permeability of gastrointestinal lining
    • increased production of brain-derived neurotrophic factor (BDNF), a growth factor crucial for brain plasticity, memory, and neuronal health
    • Reduction in both gastrointestinal inflammation  and neuro-inflammation


Ann Gen Psychiatry. 2017; 16: 14.

The effects of probiotics on depressive symptoms in humans: a systematic review




Patients suffering from depression experience significant mood, anxiety, and cognitive symptoms. Currently, most antidepressants work by altering neurotransmitter activity in the brain to improve these symptoms. However, in the last decade, research has revealed an extensive bidirectional communication network between the gastrointestinal tract and the central nervous system, referred to as the “gut–brain axis.” Advances in this field have linked psychiatric disorders to changes in the microbiome, making it a potential target for novel antidepressant treatments. The aim of this review is to analyze the current body of research assessing the effects of probiotics, on symptoms of depression in humans.


A systematic search of five databases was performed and study selection was completed using the preferred reporting items for systematic reviews and meta-analyses process.


Ten studies met criteria and were analyzed for effects on mood, anxiety, and cognition. Five studies assessed mood symptoms, seven studies assessed anxiety symptoms, and three studies assessed cognition. The majority of the studies found positive results on all measures of depressive symptoms; however, the strain of probiotic, the dosing, and duration of treatment varied widely and no studies assessed sleep.


The evidence for probiotics alleviating depressive symptoms is compelling but additional double-blind randomized control trials in clinical populations are warranted to further assess efficacy.

Keywords: Depression, Anxiety, Probiotics, Gut–brain axis, Microbiome, Systematic review

About the Author

Exercise physiologist (MS, UMass Amherst) and Nutritional Biochemist (PhD, Rutgers) who studies how lifestyle influences our biochemistry, psychology and behavior - which kind of makes me a "Psycho-Nutritionist"?!?!

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