Sauerkraut. Kimchi. Kefir. Miso. These are just a few fermented foods that have gained interest in the food and scientific community as a key to better health. For thousands of years, cultures across the globe have practiced food fermentation, intuitively recognizing its health benefits long before science could explain them.
Research confirms that the foods we eat shape the composition of our gut (intestinal) microbiome, a complex ecosystem of trillions of microorganisms that affect our overall well-being.REF#3339 It also has shown that fermented foods teem with beneficial microbes, loaded with enzymes, vitamins, and minerals that may effectively nourish the microbial flora in this vital inner ecosystem.
If you haven’t experienced the spicy, tangy, or umami-rich flavors of fermented foods, you’re in for a culinary adventure. While you may need to acquire a taste for some of these foods, fermentation may be a delicious way to support your gut health. This article introduces you to fermentation, the different types of fermented foods, and how they may benefit your overall health and wellness.
A Short History of Food Fermentation
Food fermentation dates back to the beginning of human civilization, as it provided a way to preserve food and improve its flavor and texture. Over thousands of years, cultures across the globe fine-tuned fermented foods to local tastes and integrated them into their dietary practices.
Some of the earliest evidence dates back over 7,000 years to China, where pots excavated from Neolithic villages show signs of being used to make a fermented beverage from rice, honey, and fruit. The sedating effects of fermented drinks may have been considered beneficial for mental health. In traditional Ayurvedic medicine, fermentation was used to prepare herbal drugs, perhaps as long ago as 6,000 BC.
In ancient Babylon over 6,000 years ago, early civilizations used fermentation to make leavened bread and beer.
Centuries later, in Egypt, fermentation was used to make an early probiotic yogurt-like drink. Kefir, a tart, frothy fermented milk is thought to have originated in the Northern Caucasus region between what is now Russia, Turkey, and Azerbaijan hundreds (or possibly thousands) of years ago.
Additionally, many vegetables have been preserved by fermentation for thousands of years across European and Asian cultures. Descriptions of the earliest version of kimchi date back to around 32 B.C., while Germanic tribes fermented shredded cabbage with salt around 400 B.C. In India, traditional foods like idli and dosa were made using a naturally fermented batter from rice and lentils.
While food fermentation techniques evolved in isolation, one element connects these diverse food traditions: an intuitive knowledge of using fermentation’s transformative power to unlock new nutrients and flavors, serve as a preservative, and modulate mood.REF#3340
Understanding Your Gut Microbiome
Your gut is home to around 100 trillion tiny microorganisms — bacteria, fungi, viruses, and protozoa. These tiny organisms play a crucial role in maintaining the health and balance of your gastrointestinal (GI) tract].REF#3341
Their metabolic activities contribute significantly to your body’s physiology, with bacteria being the dominant players in this vital ecosystem.
These diverse microbes perform several essential functions:REF#3342
- Digestion: Gut microbes break down complex carbohydrates, fibers, and other dietary components that our bodies cannot digest independently. This process provides us with essential nutrients and supports healthy digestion.
- Nutrient absorption: Gut microbes enhance the absorption of essential vitamins and minerals that your immune system needs to function properly.
- Immune system support: Beneficial gut bacteria produce compounds that strengthen the immune system. Up to 80 percent of your immune cells are present in the gut microbiome and work with gut microbes to support overall health.REF#3341 Major research is underway to understand the relationship between the gut microbiome and brain, heart, liver, and kidney health.
- Inflammatory response support: A balanced microbiome helps support a normal inflammatory response, which is critical for good health.
Maintaining a diverse and balanced gut microbiome is essential for optimal health.
How Fermented Foods May Nourish Your Gut Microbiome
So how do fermented foods support diversity and balance in your gut?
Scientists believe fermented foods contain diverse components that affect the microbes in your gut. Fermentation transforms the food, enhances its nutritional value, creates unique flavors, and extends its shelf life. The process itself generates bioactive compounds, such as conjugated linoleic acids and exopolysaccharides, that have known health benefits.REF#3343
Additionally, the bacteria involved in fermentation may contribute prebiotics, probiotics, and postbiotics that further enrich the gut microbial ecosystem. Current research has identified a small presence of confirmed prebiotics and probiotics in fermented foods, but that research has been limited.
Prebiotics and probiotics are some of the most well-studied components of gut health:
- Prebiotics act as fuel, nourishing the good bacteria in your gut. These non-digestible fibers, found in various fruits, vegetables, and whole grains, provide a steady energy source for these beneficial microbes, promoting their growth and activity.
- Probiotics are live bacteria found in fermented foods like yogurt, kefir, sauerkraut, and kimchi, which directly contribute to the gut's diversity and balance when consumed in appropriate amounts.
- Postbiotics are inactive components left behind by the metabolism of gut microbes or their fermentation process.
While fermentation introduces beneficial microorganisms to food, it’s important to note that not all fermented products retain them.
How the Fermentation Process Affects Probiotics
Here are several ways specific fermentation processes limit or deactive microbes in the food:
- Inactivation by heat: Probiotics are sensitive to heat. When fermented foods undergo processes like baking (sourdough bread), pasteurization (some kombucha), or canning (commercial sauerkraut), these living microbes can’t tolerate the temperatures involved. This exposure denatures their proteins and enzymes, essentially rendering them inactive. While the beneficial metabolites produced during fermentation might still be present, the missing microbes eliminate the probiotic potential.
- Filtering and removal: In the case of beers and wines, the fermentation process itself aims to produce alcohol rather than maintain a thriving probiotic culture. Once fermentation reaches desired levels, breweries and wineries filter out the yeast and bacteria used, leaving a clear and stable product devoid of living microbes. Therefore, while these beverages boast unique flavors and aromas, they lack the probiotic element.
- Lack of continuous fermentation: Certain fermented foods, like raw sauerkraut or live-culture yogurt, rely on ongoing fermentation to maintain their probiotic content. However, heating or canning disrupts this process, preventing the ongoing growth and activity of beneficial bacteria. Consequently, any initial probiotic content gradually dwindles over time, leaving the food with just the remnants of a once-active microbial community.
It's worth noting that not all fermentation methods employ heat or extensive filtering. Some traditional kimchi and kefir preparations, for example, utilize naturally present yeasts and bacteria, allowing them to remain alive and active in the final product. Additionally, kombucha brewers may choose not to pasteurize their products, maintaining the live cultures and associated probiotic benefits.
Even though some fermented foods may lack some of the probiotic activity associated with live cultures, these fermented foods still offer vitamins, minerals, and other nutrients, making them beneficial to gut health.
3 Potential Health Benefits of Fermented Foods
Much of the research on the health benefits of fermented foods is based on the effect of their components. Studying the link between fermented foods and the gut microbiome in humans has been challenging due to several factors:
- Fermented foods are complex mixtures containing diverse microbes and bioactive compounds, making it difficult to isolate and measure their individual effects.
- The gut microbiome itself is highly individual, affected by diet, genetics, age, medications, environmental factors, and lifestyle factors.
- Each individual has a unique mix of bacteria, shaped by their specific life experiences and choices. This can make it hard to control for variations between participants in research studies.
- The distinctive flavors of fermented foods can make it difficult to design studies where participants are unaware of what they are consuming.
However, a 2021 clinical trial done by scientists at Stanford University concluded that incorporating fermented foods into your diet may be more effective than eating a fiber-rich diet.REF#3344 The study, published in the journal Cell, compared the effects of a 10-week diet rich in fermented foods (such as yogurt, kefir, kimchi, and kombucha) to a high-fiber diet in healthy adults. It concluded that the high-fiber diet did not have the same beneficial effects on the gut microbiome or inflammation as the fermented food diet.
The researchers found that participants in the fermented food group experienced:
- Increased gut microbiome diversity: This is beneficial because a diverse gut microbiome is associated with improved digestion, immune function, and overall health.
- Decreased levels of inflammatory proteins: High levels of these proteins are linked to an increase in chronic diseases, which you want to avoid.
- Reduced activation of immune cells: This suggests that fermented foods may help to support a normal inflammatory response in the body.
According to associate professor of microbiology and immunology, Justin Sonnenburg, PhD, the study, “provides one of the first examples of how a simple change in diet can reproducibly remodel the microbiota across a cohort of healthy adults.”
The study also suggests that fermented foods may offer unique health benefits beyond those associated with fiber alone, which include digestive and immune system support.
Fermented Foods May Support Mental Health
Emerging evidence suggests a link between the gut microbiome and mental health. Certain gut microbes may produce neurotransmitters that influence mood and brain function. It’s thought that a beneficial shift in gut bacteria may improve gut-brain communication.REF#3340
Fermented Foods May Support Appetite Regulation
Studies suggest that fermented foods may influence appetite by promoting gut health. Low gut microbiome diversity correlates with long-term weight gain in animal studies, and low diversity has been associated with low-fiber diets.REF#3345 High-fiber fermented foods, as noted above, increase diversity.
Fermented Foods May Support Heart Health
Some research suggests that fermented foods, especially those with high levels of Lactobacillus, may contribute to heart health by improving cholesterol levels and supporting a normal inflammatory response.REF#3344
Scientists are still working to determine not only the extent of the health benefits of fermented foods but also the individual components in different foods that are responsible for each benefit. While studies explore the mysteries behind these age-old staples, you can tap into fermented foods’ overall wellness promise based on their wealth of beneficial microbes.
8 Gut-Friendly Fermented Foods to Support Wellness
With so many types of fermented foods to choose from, each with its unique flavor profile, finding your favorite options may take some time and trial. Here are eight of the most popular foods from cuisines around the world.
High Prebiotic Content Foods
- Sauerkraut: Fermented cabbage rich in fiber and known to promote gut health. Avoid heat-treated, commercially produced sauerkraut. Instead, choose brands labeled "live cultures" or "unpasteurized" that are kept in the refrigerated section of your store. These typically rely on active lactic acid fermentation, preserving the gut-friendly probiotic bacteria. Sauerkraut has long been popular in Germany and other parts of Central Europe.
- Kimchi: A spicy Korean staple made with fermented cabbage, chili peppers, garlic, ginger, that is a rich source of vitamins, and minerals and offers prebiotic benefits. It is a staple in Korean cuisine and is also most likely to offer live cultures if made with non-heated fermentation.
- Tempeh: Fermented soybean cake that is very popular in Indonesia and other Southeast Asian cuisines with a high fiber content, providing prebiotic fuel for gut bacteria.
- Miso: A staple in Japanese cuisine, this fermented soybean paste adds umami flavor and prebiotic fiber to dishes and is a good source of protein, vitamins, and minerals.
High-Probiotic Food Sources
- Yogurt: Plain yogurt with live and active cultures offers a dose of beneficial probiotics. Live cultures naturally decrease over time, so choose yogurt with a closer expiration date for optimal benefit. Make sure the yogurt you choose has the "Live and Active Cultures" seal. This ensures that it contains enough probiotics to offer health benefits.
- Kefir: A fermented milk drink with a higher concentration of probiotics compared to yogurt and a slightly tart flavor. It may be easier to digest than yogurt for some people.
- Kombucha: A fermented tea beverage with potential probiotic benefits, although research is still ongoing. It has a fizzy texture and tart, slightly vinegary flavor.
- Natto: Fermented soybeans with a strong flavor and aroma, popular in Japan. It is considered a superfood due to its high vitamins, minerals, and probiotic content.
Whatever fermented foods you add to your diet, it's important to note that their specific components can vary depending on their ingredients, fermentation process, and storage conditions. Also, in order for these foods to have impact, you’ll need to eat them consistently. A taste here and there will do nothing to alter your gut microbiome.
Alternatives to Fermented Foods to Support Gut Health
If you want to experience the potential benefits of fermented foods but can’t adapt to their flavor, you may get health benefits from a gut health supplement.
Long before clinical trials, traditional healers worldwide observed how certain herbs helped soothe sour stomachs, calmed cramping, and relieved bloating after meals. Modern research is now backing these botanical remedies, suggesting some of the following herbs support a healthy gut microbiome:
- Turmeric: Keeps your digestion running smoothly by supporting systems that break down fats, making your digestion process more efficient.
- Ginger: Used traditionally and proven by research to calm a queasy or nauseous stomach.
- Peppermint: Shown by research to have a relaxing effect on digestion.
- Cardomom: Contains antioxidants and potent plant compounds that may offer substantial health benefits.
You can also find herbal blends that combine a number of different beneficial herbs and roots to support a healthy and balanced GI tract.
Gaia Herbs is in the process of developing formulas that use fermented food extracts to support gut health. Keep an eye on this blog and sign up for email alerts for important announcements about these new supplements.
While targeted supplements can help balance your gut microbiome, don’t forget there is no substitute for a healthy lifestyle with whole foods rich in fiber and nutrients, ideally with a balance of fermented foods. We are, as they say, what we eat.