The Surprising Connection Between Fermented Foods and Anxiety

August 11, 2024

by Cathe Friedrich

Just as a garden thrives with the right balance of soil, sunlight, and water, our brains require the right balance of gut bacteria to stay healthy. Could fermented foods be the missing piece of the puzzle for mental health?

There’s little doubt that what we eat affects how our brain functions. The brain is an organ that greedily sucks up oxygen and nutrients due to its high metabolic rate. Our job is to keep it fed, so we can feel and think our best. But there’s also a connection between what we eat and our mental health.

Fermented Foods and Their Effect on Mood

While the best approach to mental health is to eat a balanced, whole food diet low in sugar, science is also looking at the role fermented foods play in mental health. It might not seem that fermented goodies, like sauerkraut, kimchi, and yogurt, would directly affect your mood, yet there is evidence that they do. But why?

The Gut-Brain Axis: A Complex Partnership

Your gut, also known as the second brain, is home to your digestive organs. It earns the name second brain because it produces many of the neurotransmitters, or brain chemicals, your brain makes. These include serotonin, dopamine, and gamma-aminobutyric acid. (GABA).

In fact, around 90% of the serotonin your body makes is produced by cells that line your intestines called enterochromaffin cells. The serotonin these cells make can enter your bloodstream and make the journey to your brain.

For example, serotonin from your gut crosses your blood-brain barrier with the help of serotonin transporters. Here, it can impact your mood, mental health, and appetite. Research shows that people who are depressed or anxious often have low levels of serotonin.

Your brain and gut are also interconnected through a major nerve called the vagus nerve. To say the vagus nerve is important is an understatement. It connects to your major organs, including your heart and lungs, and tells them how to function. For example, increased vagal stimulation causes your heart rate to slow and digestion to increase. This happens when you’re in a relaxed state.

Fermented Foods and Mental Health

Are you familiar with fermented foods? These are foods that contain gut-friendly live microorganisms called probiotics, derived from a fermentation process. Examples of fermented foods include:

Dairy Ferments

Yogurt: An old favorite, available in dairy and non-dairy forms. It should contain active cultures.
Kefir: A fermented milk that contains probiotic bacteria.
Cheese: Some types of cheese, such as feta, cheddar, mozzarella, are fermented.
Buttermilk: A tangy type of dairy product with probiotics. and probiotic benefits.
Vegetable Ferments

Sauerkraut: Fermented cabbage that contains probiotics.
Kimchi: A Korean fermented vegetable dish made with cabbage and spices.
Pickles: Vegetables fermented in a brine solution. A source of probiotics.
Fermented carrots: Shredded or sliced carrots fermented in a brine solution.

Legume Ferments

Miso: A fermented soybean paste with probiotics. Popular in Japanese dishes.
Tempeh: A fermented soybean product. It’s high in protein and contains probiotics.
Natto: A fermented soybean dish popular in Japan. It’s one of the best sources of vitamin K2 and contains probiotics.

Grain Ferments

Sourdough bread: A type of bread that comes from fermented starter culture that produces probiotics.
Mochi: A fermented rice product from Japan, high in probiotics and antioxidants.

Beverage Ferments

Kombucha: A fermented, fizzy tea drink that contains probiotics and is rich in antioxidants.
Kvass: A fermented, probiotic-rich beverage derived from rye bread or beets.
Jun: Like kombucha, Jun is fermented and rich in probiotics.

Studies show that the probiotics in fermented foods benefit gut health and cognitive function. This comes from the way organisms in your gut (probiotics) affect the connection between your gut and brain. However, it may be that not all fermented foods have the same benefits. It’s an area that needs more research.

The Science Behind Fermented Foods and Mental Health

What evidence is there that fermented foods benefit mood? Studies show mental health issues are less common in people who eat a traditional diet, one that includes whole foods and fermented foods.

Plus, people who enjoy a Mediterranean diet, a diet built around fiber-rich plant foods, whole grains, fish, and healthy fats from sources like olive oil have a lower risk of mental health issues, like anxiety and depression.

Certain strains of bacteria in fermented foods also seem to have brain health benefits. Research shows some strains boost levels of BDNF (brain-derived neurotropic factor) in portions of the brain involved in mood and cognitive function. This is a boon for memory and mood. Fermented foods, particularly fermented vegetables, also have antioxidant and anti-inflammatory activity that may benefit cognitive function and mental health.

Of particular interest for people who have anxiety is the neurotransmitter GABA. Some fermented foods, like legumes, and rice brain, produce GABA when you ferment them. GABA activates brain waves called theta waves that help your body relax. So, an increase in GABA has a calming effect on your nervous system.

Does Science Support the Benefits of Fermented Foods for Anxiety?

Several studies show that consuming fermented foods with probiotic bacteria like Lactobacillus casei, Lactobacillus helveticus, and Bifidobacterium longum reduce anxiety scores in people with anxiety issues. The same studies show a drop in stress hormones.

However, scientists believe the benefits of fermented foods vary from person to person. They can also have different effects based on the specific probiotic strains, as well as the individual’s gut microbiome composition. We’re all a little different, based on genetics and the gut microbiome we start out with.

Adding Fermented Foods to Your Diet

Although the role of fermented foods in treating anxiety is an area that needs more research, there are reasons to add more of these foods to your diet. Doing so will benefit your digestive and immune health. If you decide to add fermented foods to your diet, talk to your doctor first. But if they give you the okay, here are tips for starting:

If you’re new to fermented foods, don’t go overboard at first. Introduce small amounts to your diet. This will allow your gut to adapt. Otherwise, you could experience gas or bloating.
Experiment with a variety of fermented foods. Explore recipes and get inspired. Don’t forget that you can make your own fermented foods at home using simple recipes and ingredients.
If you have mental health issues, make diet part of your treatment but also consult with your doctor. They can rule out conditions, like an overactive thyroid, which might be fueling your anxiety.
If you have a mental health issue, make fermented foods part of an integrated approach that includes counseling and exercise. They’re not a standalone cure for these issues.

Hopefully, you’ll enjoy the unique taste and health benefits of these foods too.

References:

Selhub EM, Logan AC, Bested AC. Fermented foods, microbiota, and mental health: ancient practice meets nutritional psychiatry. J Physiol Anthropol. 2014 Jan 15;33(1):2. doi: 10.1186/1880-6805-33-2. PMID: 24422720; PMCID: PMC3904694.
Merkouris E, Mavroudi T, Miliotas D, Tsiptsios D, Serdari A, Christidi F, Doskas TK, Mueller C, Tsamakis K. Probiotics’ Effects in the Treatment of Anxiety and Depression: A Comprehensive Review of 2014-2023 Clinical Trials. Microorganisms. 2024 Feb 19;12(2):411. doi: 10.3390/microorganisms12020411. PMID: 38399815; PMCID: PMC10893170.
Kathrin Cohen Kadosh, Melissa Basso, Paul Knytl, Nicola Johnstone, Jennifer, and Glenn R Gibson. 2021. “Psychobiotic Interventions for Anxiety in Young People: A Systematic Review and Meta-Analysis, with Youth Consultation.” Translational Psychiatry 11 (1). https://doi.org/10.1038/s41398-021-01422-7.
Hilimire, Matthew R, Jordan E DeVylder, and Catherine A Forestell. 2015. “Fermented Foods, Neuroticism, and Social Anxiety: An Interaction Model.” Psychiatry Research 228 (2): 203–8. https://doi.org/10.1016/j.psychres.2015.04.023.