Study: Can Adjusting Gut Bacteria Impact Emotions?

By R. Ryan S Patel DO, FAPA OSU-CCS Psychiatrist

An increasing number of studies show that the bacteria in our gut (probiotics) may have an impact on our emotions, depression, anxiety, and other conditions (1,2).

A review of 1,089 abstracts and 183 articles; suggested that probiotics may have a role in anxiety, bipolar disorder, schizophrenia, obesity, and autism (1).

A recent small study had intriguing findings (3).

What did the study involve?

  • 40 individuals with a diagnosis of Major depression.
  • Ages ranged between 20 and 55 years old.
  • Randomized, double-blind, placebo-controlled clinical trial.

What probiotics were given?

  • Lactobacillus acidophilus, Lactobacillus casei, Bifidobacterium bifidum

What were some of the results?

  • After 8 weeks, subjects getting probiotic supplements were slightly less depressed on the Beck Depression inventory scale (5.7 +/- 6.4 vs. 1.5 +/- 4.8, P<0.001) compared with the placebo.

There were also decreases in:

  • Insulin levels and insulin resistance
  • High sensitivity C-Reactive protein (a marker for inflammation)

How can gut bacteria impact your brain health?

Some theories include (1,2,4 ) an impact on:

  • Hormones
  • Serotonin (a brain transmitter, particularly involved in depression and anxiety)
  • Immune/inflammatory system

What are some causes of an imbalance of gut bacteria?

  • Unhealthy consumption of processed grains, unhealthy fats, sugars, refined carbohydrates, junk foods, etc. (1,2,4)
  • Certain antibiotics

Is it possible to improve health/balance of my gut bacteria?

Certain foods may  help the good bacteria (a balance of proteins (lean meats, eggs, seafood, etc) , healthy fats, vegetables, and whole unprocessed grains)

Certain foods contain pro-biotics:

  • Sauerkraut with live cultures
  • Kimchi
  • Unsweetened yogurt (natural artificial and added sugars may negate benefits)
  • Probiotic supplements

What are some caveats?

  • Taking probiotics is NOT safe for everyone and you should check with your doctor first (5).
  • There are many studies linking probiotics to brain health, and this is a small study with a small effect size.
  • Further study is needed.
  • The exact type, amount, and duration of probiotics for emotional health has not been established.
  • While further research is needed, it has been established that unhealthy eating habits can impact emotional health.
  • According to NCCIH, “The people who are most at risk of severe side effects from probiotics include critically ill patients, those who have had surgery, very sick infants, and people with weakened immune systems” (5)

How are you feeling? Could you feel better by eating healthy foods and reducing/avoiding unhealthy foods? How do you know?

What are some resources to improve nutrition?

Disclaimer: This article is intended to be informative only. It is advised that you check with your own physician/mental health provider before implementing any changes. With this article, the author is not rendering medical advice, nor diagnosing, prescribing, or treating any condition, or injury; and therefore claims no responsibility to any person or entity for any liability, loss, or injury caused directly or indirectly as a result of the use, application, or interpretation of the material presented.


  1. G. Fond et al. The ‘‘psychomicrobiotic’’: Targeting microbiota in major psychiatric disorders: A systematic review/ Pathologie Biologie 63 (2015) 35–42.
  2. Luna RA, Foster JA. Gut brain axis: diet microbiota interactions and implications for modulation of anxiety and depression. Current Opinion in Biotechnology 2015, 32:35–41.
  3. Akkasheh G, et. al. Clinical and metabolic response to probiotic administration in patients with major depressive disorder: A randomized, double-blind, placebo-controlled trial. Nutrition (2015) 1-6.
  4. Wang Y, Kasper LH. The role of microbiome in central nervous system disorders. The role of microbiome in central nervous system disorders.
  5. National Center for Complimentary and Integrative Health.