Did you know that humans have used fermentation to produce and preserve food for roughly 13,000 years?
It’s true. And, as it turns out, this ancient practice of fermentation has proved to be vital to human health. Indeed, modern science continues to reveal significant health benefits—such as better gut health, immune health, brain health, and more—from consuming fermented foods.
That’s because fermented foods are rich in probiotics, which are healthy microorganisms or “good bugs” that surprisingly provide us with health benefits when we consume them. Common examples of fermented foods include sauerkraut, kimchi, miso, unsweetened Greek yogurt, kombucha, and kefir.
An exciting new study from researchers at the University of Virginia School of Medicine suggests that a common strain of probiotics found in many fermented foods may help reduce anxiety and depression.
Remarkably, an exciting new study from researchers at the University of Virginia School of Medicine suggests that a common strain of probiotics found in many fermented foods may help reduce anxiety and depression by positively influencing gut bacteria and neurotransmitters. It’s an important finding in terms of understanding the association between fermented foods and mental health and the gut-brain connection.
Here’s what you need to know about probiotics for depression and fermented foods and anxiety, plus a list of probiotic-rich foods to enjoy.
There’s a communication system between your gut and brain called the gut-brain axis or simply the gut-brain connection. Some refer to the gut as the “second brain” because your gut is lined with nearly 170 million neurons.
These neurons are in near constant, bidirectional communication with your brain. The neuronal network of the gut, called the enteric nervous system, manages the functions of the gastrointestinal (GI) tract.
Communicating primarily through the vagus nerve, there are both physical and biochemical messaging between these two areas of the body that can influence the health of the other. What’s more, the microorganisms in your gut appear to play a vital role in this communication.
In an animal study published in December 2024, UCLA researchers demonstrated causal evidence that the gut’s microflora has a direct influence on messaging between the gut and brain through the vagus nerve. It’s another piece of the puzzle in helping scientists understand how probiotics affect the brain.
Considering all the neurons in your GI tract and the direct communication it has with the brain, it makes sense that gut health and mood are closely linked. When your gut health is off, you are more likely to have mental health problems and vice versa.
Related: Long COVID, Inflammation, and the Gut-Brain Axis
This is evident in scientific studies. For example, inflammatory bowel disease is associated with higher rates of anxiety and depression, research has found.
Research points to other connections, too. Although it is not fully understood, increased intestinal permeability (more commonly known as “leaky gut” syndrome) and the inflammation it causes is believed to play a role in a number of mental health conditions – including:
To help protect and/or boost your mental health, it is necessary to have a basic understanding of how your microbiome works and take steps to keep it healthy. You might be surprised to learn the extent of your gut’s microorganisms.
Collectively, bacteria, yeast, and other microorganisms total about 100 trillion! That is 10 times the total number of cells in the rest of your body. This community of microorganisms is called the microbiome.
The microbiome plays an essential role in the synthesis of neurotransmitters—such as glutamate, GABA, serotonin, and dopamine. Serotonin has a strong influence on mental well-being.
Related: 9 Natural Ways to Balance Dopamine
Maintaining a balanced ratio of healthy bugs to harmful ones in your microbiome is key to gut health. Optimally, in a healthy gut, beneficial bugs make up about 85 percent of the microflora, while harmful bugs are limited to roughly 15 percent.
Of course, there are times when the balance is temporarily disrupted. However, when lifestyle factors lead to chronic disruption, problems arise in your gut—and your mental health can suffer.
The following lifestyle factors can negatively impact the balance of microflora in your microbiome:
In this video, Amen Clinics Integrative Nutritionist Cindy Santa Ana reveals what helps and what hurts the health of your microbiome to enhance overall wellness:
The good news, though, is that you have a lot of power to make a difference in the health of your microbiome. Fermented foods can bolster the gut microbiome, helping to create a healthier mix of microbes and even strengthening intestinal walls to protect against leaky gut.
According to recent research, consuming fermented foods routinely may help your mental well-being by improving your gut health.
In the new University of Virginia study mentioned earlier, researchers discovered that Lactobacillus (a “good bug” commonly found in fermented foods) appears to help the body to manage stress better and may help prevent anxiety and depression in animal subjects.
This research is particularly important because it isolates Lactobacillus from other microorganisms that commonly live in and on our bodies. The study suggests that Lactobacillus may potentially influence mood disorders in humans by calibrating the immune system.
Specifically, the researchers found that a lack of Lactobacillus was highly associated with worsening depression and anxiety symptoms in the animal subjects. Also, they found the bacteria appears to help to maintain levels of an immune mediator known to manage the body’s response to stress, helping to keep depression at bay.
The study validates previous research exploring the link between frequently consumed fermented foods and lowered symptoms of depression and anxiety—and improved cognition as a result of reduced anxiety symptoms.
While medical doctors are not yet suggesting probiotics for depression, the evidence so far points to fermented foods being important to a balanced mood.
If you want to include foods that help with depression and anxiety in your diet, consider these popular Lactobacillus-rich fermented foods:
Fermented foods are safe and healthy for most people. However, in some instances, fermented food products (and particularly raw fermented foods) may not be suitable for pregnant women and infants, elderly individuals, and people with health issues such as digestive disorders, compromised immune systems, and histamine intolerance. These individuals should consult a medical doctor before adding fermented foods to their diet.
Keep in mind that for some individuals, adding probiotic cultures to their digestive systems can cause some temporary discomfort, gas, and bloating. The new microorganisms may not immediately mix well with the existing microorganisms, leading to a temporary period of adjustment in the gut microbiome. But with time, the gut typically adapts.
Merchak A et al. Lactobacillus from the Altered Schaedler Flora maintain IFNγ homeostasis to promote behavioral stress resilience. Brain Behav Immun. 2024 Jan:115:458-469.
Michel K et al. How big is the little brain in the gut? Neuronal numbers in the enteric nervous system of mice, Guinea pig, and human. Neurogastroenterol Motil. 2022 Dec;34(12):e14440.
Jameson, KG et al. Select microbial metabolites in the small intestinal lumen regulate vagal activity via receptor-mediated signaling. IScience. 2024 Dec 27;28(2):111699.
Leone D et al. Psychological Characteristics of Inflammatory Bowel Disease Patients: A Comparison Between Active and Nonactive Patients. Inflamm Bowel Dis. 2019 Jul 17;25(8):1399-1407.
Wasiak J and Gawlik-Kotelnicka O. Intestinal permeability and its significance in psychiatric disorders – A narrative review and future perspectives. Behav Brain Res. 2023 Jun 25:448:114459.
Karbownik, MS et al. Association Between Consumption of Fermented Food and Food-Derived Prebiotics With Cognitive Performance, Depressive, and Anxiety Symptoms in Psychiatrically Healthy Medical Students Under Psychological Stress: A Prospective Cohort Study. Front Nutr. 2022 Mar 3;9:850249.
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