How Fermented Foods can Bolster Gut Health and Combat Stress

By Tim Skwiat, Pn2

If you’re anything like many of my clients, when you shut off the lights at night, your brain doesn’t turn off with them. Anxiety creeps in, and you can’t get your wheels to stop turning. Did you know that what you eat could make a tremendous difference?

What may surprise you is that this may largely be related to the balance of bacteria that reside in your gut—collectively called the microflora.1

The potential impact of the microflora on mental health is so profound that Dr. Ted Dinan and researchers from Ireland coined the term psychobiotics, which refers to probiotics that help reduce depression and ease anxiety.2

In a recent study, Dr. Dinan’s group found that mice fed probiotics showed significantly reduced levels of stress hormones (like cortisol), as well as fewer anxiety- and depression-related behaviors compared to those fed only broth (and no probiotics).3

In another study published in the British Journal of Nutrition, French researchers found that folks who supplemented with probiotics for two weeks experienced significant reductions in depression, anxiety, and hostility.4

Several additional studies have demonstrated that improving the microflora with prebiotics, probiotics, and probiotic-rich fermented foods results in significant reductions in anxiety.5–7

Clearly, there is an enormous amount of promise when it comes to consuming probiotics and easing anxiety. How can you improve the balance of your microflora?

Simple, start consuming more fermented foods. While fermented dairy (like yogurt and kefir) are great choices, it’s a good idea to incorporate a variety of fermented foods (like sauerkraut and other vegetables, miso, kombucha, and even red wine), as research suggests that reduced bacterial diversity may play a role in a number of health conditions, including obesity.8


  1. Selhub EM, Logan AC, Bested AC. Fermented foods, microbiota, and mental health: ancient practice meets nutritional psychiatry. J Physiol Anthropol. 2014;33(1):2. doi:10.1186/1880-6805-33-2.
  2. Dinan TG, Stanton C, Cryan JF. Psychobiotics: a novel class of psychotropic. Biol Psychiatry. 2013;74(10):720-726. doi:10.1016/j.biopsych.2013.05.001.
  3. Bravo JA, Forsythe P, Chew MV, et al. Ingestion of Lactobacillus strain regulates emotional behavior and central GABA receptor expression in a mouse via the vagus nerve. Proc Natl Acad Sci. 2011;108(38):16050-16055. doi:10.1073/pnas.1102999108.
  4. Messaoudi M, Lalonde R, Violle N, et al. Assessment of psychotropic-like properties of a probiotic formulation (Lactobacillus helveticus R0052 and Bifidobacterium longum R0175) in rats and human subjects. Br J Nutr. 2011;105(5):755-764. doi:10.1017/S0007114510004319.
  5. Tillisch K, Labus J, Kilpatrick L, et al. Consumption of Fermented Milk Product With Probiotic Modulates Brain Activity. Gastroenterology. 2013;144(7):1394-1401.e4. doi:10.1053/j.gastro.2013.02.043.
  6. Rao AV, Bested AC, Beaulne TM, et al. A randomized, double-blind, placebo-controlled pilot study of a probiotic in emotional symptoms of chronic fatigue syndrome. Gut Pathog. 2009;1(1):6. doi:10.1186/1757-4749-1-6.
  7. Silk DBA, Davis A, Vulevic J, Tzortzis G, Gibson GR. Clinical trial: the effects of a trans-galactooligosaccharide prebiotic on faecal microbiota and symptoms in irritable bowel syndrome. Aliment Pharmacol Ther. 2009;29(5):508-518. doi:10.1111/j.1365-2036.2008.03911.x.
  8. Turnbaugh PJ, Hamady M, Yatsunenko T, et al. A core gut microbiome in obese and lean twins. Nature. 2009;457(7228):480-484. doi:10.1038/nature07540.