Fermented Foods for Brain Health?

Fermented foods have been a part of the human diet in most cultures for many centuries. People used fermentation as a way to preserve food, as well as creating desirable byproducts from fermentation, such as alcohol. Although alcohol is not a health-promoting substance, there are many health benefits to consuming fermented foods that provide probiotic cultures, which can help us maintain a healthy gut and, in turn, a healthier body.

For example, in yogurt and kefir, lactose (milk sugar) is converted into lactic acid. This provides the tangy taste in yogurt and provides a natural probiotic from the lactobacillus bacteria used to ferment the milk. The microbes that naturally ferment the foods are the same microbes we house in our gut, which provide post-biotic substances. Post-biotic substances that are produced by our gut microbes can either positively or negatively impact our health, depending on which microbes are present. Keeping a healthy balance of microbes in our gut provides many health benefits and consuming fermented foods often can help you maintain the right types of microbes which enhance our health.

There are 2 types of fermentation. Wild fermentation is fermentation that happens naturally by microorganisms that are naturally present in the food. Examples include Sauerkraut, Kimchi, or even sourdough bread.

The second method of fermentation is done by adding a starter or a culture of specific microbes to ferment a certain food. Examples of fermentation using a starter include yogurt, cheese, beer and wine.

Fermentation at home is trendy and there is a movement to resurrect the lost art of fermentation. You can find many blogs online and videos on YouTube that show you how to easily ferment foods at home. Making jars of different fermented vegetables, coconut milk yogurt, dairy yogurt and other fermented foods is a great and inexpensive way to enhance the function of your gut. Heating fermented foods past 140 degrees can kill any live probiotic cultures so these foods are often consumed cold or at room temperature, but even dead probiotic cultures have been found to positively impact gut health (de Alamada et al., 2016)

Some people can be sensitive to fermented foods, such as those who have mast cell activation. If you do not feel well or if you have some type of allergic reaction when eating fermented foods, you should avoid any fermented or aged foods.

Health Benefits of Eating Fermented Foods

Fermented foods can be great for your gut because they often contain probiotics—beneficial bacteria that help support a healthy digestive system. These good microbes can improve how your gut breaks down food, boost the immune system, and help balance the bacteria in your intestines, which may reduce bloating, gas, and even symptoms of conditions like irritable bowel syndrome (IBS). Research also shows that regularly eating fermented foods like yogurt, kefir, kimchi, or sauerkraut can increase the diversity of your gut microbiome, which is linked to better digestion and overall health (Zmora et al., 2018, Wastyk et al., 2021).

Fermented foods can also support a healthy metabolism by improving digestion and helping your body absorb nutrients more efficiently. The beneficial bacteria (probiotics) produced during fermentation may also influence how your body handles blood sugar, fat storage, and inflammation—factors closely linked to metabolic health. Some studies suggest that eating fermented foods like yogurt, kefir, and kimchi can help improve insulin sensitivity and reduce markers of metabolic syndrome, which includes conditions like high blood pressure and excess belly fat (Marco et al., 2017, Taylor et al., 2020).

The Gut and Brain Are Connected

The gut and brain are closely connected through what’s called the gut-brain axis—a two-way communication system involving nerves, hormones, and the immune system. The gut has its own network of neurons (often called the “second brain”) and houses trillions of microbes that produce chemicals like serotonin, which affect mood, stress, and even memory. This means your gut health can influence how you feel mentally, and stress or anxiety can, in turn, upset your stomach. For example, studies have shown that gut bacteria can impact depression and anxiety symptoms (Mayer et al., 2015, Cryan & Dinan, 2012).

Research also shows that the gut microbiome—the community of bacteria living in your digestive tract—may play a role in brain health, including the risk of neurodegenerative diseases like Alzheimer’s and Parkinson’s. These gut microbes produce chemicals that can affect inflammation, immune responses, and communication between the gut and brain. When the balance of gut bacteria is disrupted (called dysbiosis), it may increase inflammation in the brain or interfere with how brain cells function. While scientists are still studying the exact links, growing evidence suggests that a healthy gut could help protect the brain as we age (Cryan et al., 2020, Shen et al., 2022).

Shifts in our microbiome are unavoidable. Eating processed foods, drinking too much alcohol, antibiotic use, food poisoning, environmental toxins and even stress can alter the balance of our gut microbes. Consuming fermented foods can help maintain a healthy microbial balance despite the many insults to our gut microbiome. A healthy gut supports your brain function. What you choose to eat is a crucial part of maintaining optimal brain function.

Common Fermented Foods to Add to your Diet

• Yogurt: Plain, full-fat yogurt. Flavor with berries, a small amount of honey, stevia or monk fruit. To ensure you’re getting probiotics, look for the phrase “Contains live active cultures” on the container.
• Kefir: As a fermented dairy beverage, kefir offers a tangy taste that’s similar to yogurt. Choose unflavored varieties for less added sugar.
• Crème fraiche: Similar to sour cream but higher in fat, this rich, tart dairy product is made by fermenting heavy cream with a bacterial culture.
• Sauerkraut: This fermented cabbage has a pungent flavor and is rich in fiber. Sauerkraut is so easy to make at home that it a great way to start experimenting with fermentation at home.
• Kimchi: A staple in Korean cuisine, this spicy fermented vegetable dish provides fiber and a crunchy texture.
• Kombucha: A fizzy, fermented tea, unsweetened kombucha is not only refreshing but provides some probiotic cultures.
• Miso and tempeh: These fermented soy foods provide a great source of easily digested plant-based protein for vegetarians and vegans.
• Apple cider vinegar: Unflavored vinegar is carb-free and rich in the SCFA acetate. However, because it’s highly acidic, it should only be used in small amounts.

Equipment

• Wide Mouth Mason Jars 32 oz [4 Pack]
• Ball Wide-Mouth Plastic Storage Caps, 8-Count
• Redmond Real Salt – Ancient Fine Sea Salt, Unrefined Mineral Salt

Ingredients

• sliced or chopped vegetables anything will do. I really like broccoli, radishes and carrots
• 2 cups water
• 1 1/2 tablespoon coarse sea salt
• 1 quart wide mouth mason jar with plastic lid not necessary, but if you’re going to do this often, the regular metal lids will corrode from the acid
• any spices or herbs you like peppercorns, dill, basil, bay leaf, etc.
• 1 small cabbage leaf

Instructions

1. Place vegetables and any spices/herbs you’re using in the mason jar right up to the bottom of the neck, there should be about 1 inch of space to the top.
2. Stir the salt and water together until dissolved.
3. Pour the salt water over the vegetables until it reaches just below the top of the jar. There should be about 1/2 inch of room left.
4. Fold a small cabbage leaf and press it down on top of the vegetables so that it keeps the vegetables submerged in the salt water. This isn’t necessary, but helps make sure the vegetables are submerged. Feel free to skip this step if you don’t have cabbage on hand.
5. Close the lid on the jar tightly and place the jars out of direct sunlight in a relatively moderate temperature (68-75 degrees).
6. You will start to see some bubbling around day 2 or so. After day 2, over a sink (in case it leaks/drips), gently loosen the lids to let some of the gas escape once or twice a day.
7. The vegetables are ready anywhere from day 4-10. The longer they sit, the more tangy they’ll be. Taste them starting on day 4 to figure out your preference. I like them best around day 5 or 6.

Once you decide they’re the level of sourness you’re looking for, place the jar in the refrigerator where it will keep for a couple of months (not that they’ll last that long!)

References

Cryan, J. F., & Dinan, T. G. (2012). Mind-altering microorganisms: The impact of the gut microbiota on brain and behaviour. Nature Reviews Neuroscience, 13(10), 701–712. https://doi.org/10.1038/nrn3346

Mayer, E. A., Tillisch, K., & Gupta, A. (2015). Gut/brain axis and the microbiota. The Journal of Clinical Gastroenterology and Hepatology, 13(5), 737–739. https://doi.org/10.1016/j.cgh.2015.04.002

Wastyk, H. C., Fragiadakis, G. K., Perelman, D., Dahan, D., Merrill, B. D., Yu, F. B., … & Sonnenburg, J. L. (2021). Gut-microbiota-targeted diets modulate human immune status. Cell, 184(16), 4137–4153.e14. https://doi.org/10.1016/j.cell.2021.06.019

de Almada, C. N., Almada, C. N., Martinez, J. A., & Sant’Ana A. S. (2016). The immunomodulatory properties of probiotic microorganisms beyond their viability (Ghost probiotics: proposal of paraprobiotic concept). Microbial Cell Factories, 15(1), 1–14. https://doi.org/10.1186/s1293401604759 [Review referenced in PMC]

Zmora, N., Zilberman-Schapira, G., Suez, J., Mor, U., Dori-Bachash, M., Bashiardes, S., … & Elinav, E. (2018). Personalized gut mucosal colonization resistance to empiric probiotics is associated with unique host and microbiome features. Cell, 174(6), 1388–1405.e21. https://doi.org/10.1016/j.cell.2018.08.041

Marco, M. L., Heeney, D., Binda, S., Cifelli, C. J., Cotter, P. D., Foligné, B., … & Hutkins, R. (2017). Health benefits of fermented foods: Microbiota and beyond. Advances in Nutrition, 8(2), 373–381. https://doi.org/10.1093/advances/nmx002

Taylor, B. C., Leong, L. X., Mobarhan, M., Wang, S., Woller, A. J., & Layden, B. T. (2020). The role of fermented foods and food components in metabolic health. The Journal of Nutrition, 150(5), 1218–1225. https://doi.org/10.1016/j.tjnut.2019.10.001

Cryan, J. F., O’Riordan, K. J., Sandhu, K., Peterson, V., Bastiaanssen, T. F. S., Moloney, G. M., … & Dinan, T. G. (2020). The microbiota–gut–brain axis. Neuron, 101(6), 977–999. https://doi.org/10.1016/j.neuron.2020.01.022

Shen, L., Liu, L., Ji, H. F. (2022). Alzheimer’s disease histological and behavioral manifestations in transgenic mice correlate with gut microbiota dysbiosis. Ageing Research Reviews, 78, 101678. https://doi.org/10.1016/j.arr.2022.101678