Anxiety - Depression And Probiotics

  • Nature's Source

When assessing one’s health, mental health is an aspect which should be taken into consideration to ensure a comprehensive treatment plan to improve overall well-being. Mental health issues such as anxiety and depression are prevalent in today’s society as our lives can be fast-paced, stressful, and demanding. While anxiety is beneficial in moderation, excessive anxiety can be detrimental to our health.  

Anxiety is described as negative apprehension and tension about the future and symptoms include: excessive worrying which is difficult to control, restlessness, fatigue, gastrointestinal issues, irritability, muscle tension, and difficulty sleeping. Anxiety is also closely linked to depression, which can present as: feelings of worthlessness and helplessness, trouble concentrating, feelings of guilt, chronic pain, overeating or loss of appetite, persistent sadness or anxiety, and digestive issues. While common treatment methods for anxiety and depression include psychotherapy and pharmaceuticals, research indicates that the gut microbiota may have an impact on mental health matters, such as anxiety and depression.

The Gut Microbiota

The gut microbiota contains microorganisms which contribute to the overall functioning on the gastrointestinal tract. The gut microbiota is influenced throughout our entire lives based on the foods we consume, the environment in which we live, the season, and individual health status. That being said, the average adult microbiota is dominated by Bacteroidetes and Firmicutes phyla species as well as proteobacteria, verrucomicrobia, actinobacteria, and cyanobactera phyla in smaller quantities. Symbiotic bacteria (the beneficial bacteria) work with our bodies to assist our immune system, amino acid and vitamin synthesis, and intestinal homeostasis thereby improving our health status and metabolism.

So, why does this matter and what could it possibly have to do with anxiety and depression?

The Gut-Brain-Axis

The gut is able to send information to the brain which can then influence how we feel mentally, emotionally, and physically. When facing issues such as stress, antibiotics, or diet alterations, the normal microbiota undergoes changes. Interestingly enough, changes in diet can change the microbiota in only 24 hours; however, once normal diet patterns resume, the bacterial composition will return to normal. When there is dysbiosis (microbial imbalance) and inflammation in the gut, this information is relayed to the brain and can lead to mental health issues. Dysbiosis can lead to increased permeability in the intestines which means that things that are normally not allowed to pass through to systemic circulations, can now do so. The bacterial metabolites and bacterial themselves can enter the systemic circulation and, in turn, inflammatory markers and neurotransmitters are released and go to the brain to influence its functioning. The inflammatory markers can also stimulate the Hypothalamic-Pituitary-Adrenal (HPA) axis leading to an increase in cortisol production. Hyperactivity and dysregulation of the HPA axis has been linked to anxiety and depression.



Research indicates that the supplementation of probiotics, particularly the Lactobacilli and Bifidobacteria species, have been shown to mitigate symptoms of anxiety and depression. Probiotics also have the potential to influence the HPA axis by diminishing the response to chronic stressors and possibly preventing or reversing physiologic damage. While more research is needed in the area, probiotics may also have the potential to decrease intestinal permeability and restore the gut microbiota, thereby downregulating the systemic inflammation as previously described. It is also worth noting that the use of antidepressants and/or anxiolytics may be integral to those suffering from depression and/or anxiety, the use of pharmaceuticals may be disruptive to the gut microbiota and the addition of a probiotic should be discussed with a doctor.

Through the reduction in inflammation, decreased intestinal permeability, and modulation of the HPA axis and gut microbiota, probiotics have the potential to be moderate symptoms of anxiety and depression and improve intestinal health.

If you are experiencing symptoms of anxiety or depression, contact your health care provider to discuss treatment options and inquire on whether a probiotic can be included in your treatment plan.


By: Adriane Alexander, BA (Hons.) Psychology, 3rd Year Naturopathic Medicine Student


Barlow, D., Durand, D., Hoffman, S., & Lalumiere, M. (2020). Abnormal psychology: An integrative approach. (6th Ed.). Nelson Cengage Adapted.

Clapp, M., Aurora, N., Herrera, L., Bhatia, M., Wilen, E., & Wakefield, S. (2017). Gut microbiota’s effect on mental health: The gut-brain axis. Clinical Practice, 7(4), 987. doi: 10.4081/cp.2017.987