Fermented foods are made by adding microorganisms, like bacteria or yeast, to a food source. For example, when you add yeast to sweetened tea, it ferments and becomes kombucha. Similarly, bacteria react with milk to create yogurt.
While people first used this ancient practice for its preservative effects, eating fermenting foods has recently gained popularity because of its reported health-promoting effects.
Many fermented foods — such as kefir, kombucha, and fermented vegetables — contain probiotics, but not all do.
Probiotics are foods with living microbes that can travel to your gut and provide some benefit to your health. Prebiotics serve as food for the good microbes living in your gut.
Fermented foods can benefit your health in a variety of ways, such as improving digestion and lowering your risk for certain diseases, like type 2 diabetes and heart disease.
Crucially, they promote a healthier and more diverse gut microbiome, the collection of microorganisms living in your gut.
Everyone’s gut microbiome is unique. The ZOE at-home test gives you a breakdown of the bacteria that live in your gut, as well as personalized recommendations on how to boost your gut health.
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Best fermented foods for your health
Not all fermented foods benefit your health in the same way. Here are nine of the best fermented foods to include in your diet.
Kefir is a fermented milk drink believed to have originated in the Caucasus region thousands of years ago.
You can drink kefir on its own or use it in place of buttermilk, milk, or water in dishes for a nice sour flavor. Thick kefir is similar in consistency to yogurt. You can eat it in the same way, for example, as a breakfast or dessert.
This tart, lightly carbonated drink is made by adding kefir grains to room temperature milk and allowing it to ferment for 10–24 hours.
Kefir has an abundance of diverse microbes, and evidence suggests that it could benefit your health in many ways.
While human research is limited, there is some evidence that kefir may benefit:
blood sugar control in type 2 diabetes
However, more research is needed to understand these effects fully.
Kefir is also a good source of many important vitamins and minerals. This includes vitamins B, C, A, and K, as well as magnesium, calcium, and phosphorus.
Kimchi is a fermented vegetable mixture of spices and vegetables like cabbage, radishes, leeks, cucumbers, or sweet potatoes. Originating in Korea almost 1,000 years ago, this traditional Korean food is now popular across East Asia and all over the world.
Although typically a salty and sour mixture, kimchi comes in a variety of flavors depending on the spices, seasonings, and vegetables used.
Some kimchi can also include meat, such as beef, pork, or seafood. Kimchi is often a side dish, but you can also mix it into other dishes, like dumplings, stew, or rice.
Evidence suggests that eating kimchi may help lower cholesterol and improve blood sugar levels.
The probiotics in kimchi may also help improve gut health and relieve certain digestive issues, such as abdominal pain, bloating, and irregular bowel movements. Other reported potential health benefits include the prevention of certain types of cancer and supporting brain and skin health.
The vegetables commonly used in kimchi are good sources of vitamins A and C, as well as calcium, magnesium, potassium, fiber, and other beneficial nutrients.
Kombucha, or fermented sweet tea, is thought to have originated in Northeast China over 2,000 years ago.
Lightly carbonated and distinctively tart, kombucha is made by fermenting sweet tea with a SCOBY, a symbiotic culture of bacteria and yeast. People often add fruits or herbs to create a variety of flavors.
Despite the many health claims about kombucha, evidence involving humans is limited.
In one analysis of 15 animal studies, evidence suggested that drinking kombucha may help promote a more diverse gut microbiome. Another study found links between kombucha and anti-inflammatory effects and a healthier skin microbiome.
Other studies, however, found that some components in kombucha may worsen gastrointestinal problems, such as irritable bowel syndrome.
Animal studies have also suggested that kombucha may help improve:
heart disease risk
neurodegenerative disease risk
It’s important to be mindful of the sugar content in kombucha. Industrially produced versions can be high in sugar or sweeteners and other additives.
Sauerkraut is fermented cabbage. Although the name sauerkraut is German for “sour cabbage,” it’s believed to have come from China almost 2,000 years ago.
A little salty and a touch sour, this crunchy condiment may be a good option for people who are new to fermented foods. You can eat it on sandwiches, with meat, or on its own.
Raw, uncooked sauerkraut is a good source of probiotics, which may be beneficial for your gut health. In multiple studies involving people with irritable bowel syndrome, eating sauerkraut was associated with reduced symptoms after only 6 weeks.
The microbes in sauerkraut may also help lower cholesterol, according to one animal study.
Sauerkraut is also rich in other health-benefiting nutrients, such as fiber, vitamins C and B6, and iron.
Yogurt is a common food in many cuisines around the world. It dates back to around 8,000 years ago when herdsmen in the Middle East used animal intestines to keep milk from spoiling in the heat. Today, yogurt is made by mixing bacteria into milk.
The slightly sour taste allows yogurt to be used in a variety of ways, including as a marinade, in sauces or smoothies, or on its own. There are different types of yogurt available, but those with no added sugar are best. Add fruit, herbs, rolled oats, or a small drizzle of honey for added flavor.
An analysis of over 100 studies found that yogurt might be associated with many health benefits, including:
improved gut health
better heart health, including cholesterol levels, blood fat, and blood pressure
promoting a healthy body weight
reduced risk of cancers, particularly colorectal, breast, and prostate cancer
reduced risk of type 2 diabetes and better outcomes for those with type 2 diabetes
improved bone health
Lactobacillus acidophilus is the most common probiotic in yogurt. This bug is present in many Greek, Icelandic, traditional, and other yogurts. You may not always see it on the label, but you can look for a “live and active cultures” statement to check if a yogurt contains probiotics.
Yogurt is also a good source of protein, calcium, phosphorus, and B vitamins.
Miso is thought to have originated in China before making its way over to Japan some time during the 7th century.
It’s made by mixing soybeans, fermented rice, and salt, before allowing it to ferment for several months.
Miso has a rich, savory flavor and can be used in soups, sauces, and salad dressings, among other dishes.
There is some evidence that miso has health benefits. This includes better blood sugar control, a lower risk of certain cancers and heart disease, and better gut health.
7. Some cheeses
The first cheese is thought to have been created about 4,000 years ago when a merchant left a sheep-stomach pouch filled with milk out in the Arabian sun.
Today, most cheeses undergo fermentation. Aged cheddar, parmesan, Swiss cheeses, and some cottage cheese contain probiotics.
Some evidence suggests that fermented cheese may help promote gut health and healthy cholesterol levels.
Cheese is also a good source of calcium but can be high in sodium and saturated fat. It is best to eat it in moderation and as part of an overall healthy diet.
8. Sourdough bread
Sourdough bread is thought to have originated in ancient Egypt.
The sourdough starter is made by fermenting a mixture of flour, water, and salt. A portion of this starter is then mixed with more flour and water to leaven the bread dough.
While sourdough starters do contain probiotics, they are killed by the heat in the baking process. However, the baked bread does contain prebiotics.
Similar to other fermented foods, sourdough bread has a slightly sour and salty flavor and is a delicious way to add a little tang anywhere bread features.
Sourdough bread may be a good option for people with moderate gluten intolerance, but this depends on the individual. Despite the fermentation, however, it is not safe for people with celiac disease.
Not all store-bought sourdough bread is actually fermented. You can learn more in our ZOE Science & Nutrition podcast episode about bread with ZOE co-founders Tim Spector and Jonathan Wolf, as well as sourdough expert Vanessa Kimbel.
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9. Apple cider vinegar
The first record of vinegar dates back almost 7,000 years to when the Babylonians used it for food preservation. In ancient Greece, Hippocrates used to prescribe apple cider vinegar for many ailments, like the common cold.
Apple cider vinegar is made by adding yeast to apple juice and allowing it to ferment. It can be used in salad dressing, baking, pickling, soups, or any other dish needing a little tartness.
Unfiltered or raw apple cider vinegar contains live bacteria, some of which may be probiotic. The possible health benefits include better blood sugar control and cholesterol levels.
Where can you find fermented foods?
Many fermented foods are widely available at most grocery stores. Some foods like yogurt, kombucha, and sauerkraut are very common, with others becoming increasingly available.
If you choose to buy fermented foods at the store, it's important to read the label. Some products contain unnecessary additives or high amounts of sugar.
It can also be tricky to know whether a product has live microbes in it. Sometimes the type and amount of live bacteria are on the label, but not always.
You can also ferment foods at home if you prefer. If you do, make sure to stay safe by using the right sterilization and storage techniques.
How to include them in your diet
Thankfully, the wide range of fermented foods available makes it possible to fit them in to most eating patterns.
ZOE’s co-founder, Tim Spector, recommends consuming small amounts of a variety of fermented foods each day rather than large amounts every once in a while.
If you’re looking to increase your fermented food intake, start slowly and increase gradually to avoid bloating.
Fermented foods are just one part of an overall balanced diet, though, along with plenty of fruits, vegetables, whole grains, and healthy fats.
Fermented foods come in a wide range of guises, but they all have one thing in common: They are made by adding microbes to their raw ingredients.
Many fermented foods contain probiotics, which are beneficial live bacteria.
Regularly eating fermented probiotic foods — such as yogurt, kefir, sauerkraut, and miso — may positively affect your health. But not all fermented foods contain probiotics.
Fermented foods are just one part of a balanced diet. And at ZOE, we know the best foods for your body are unique to you.
Our at-home test gives you insights into your blood sugar and blood fat responses to food, as well as a breakdown of the bacteria that currently live in your gut. Using this information, we provide you with personalized nutrition advice to help you reach your long-term health goals.
To find out more, take our free quiz today.
Antihyperglycaemic efficacy of kombucha in streptozotocin-induced rats. Journal of Functional Foods. (2013). https://www.sciencedirect.com/science/article/abs/pii/S1756464613001928
Diet and gut microbiome in gastrointestinal disease. Gastroenterology and Hepatology. (2021). https://onlinelibrary.wiley.com/doi/full/10.1111/jgh.15728
Eating fermented: health benefits of LAB-fermented foods. Foods. (2021). https://www.mdpi.com/2304-8158/10/11/2639/htm
Effect of fermentation time on the content of bioactive compounds with cosmetic and dermatological properties in Kombucha Yerba Mate extracts. Science Reports. (2021). https://www.nature.com/articles/s41598-021-98191-6
Effect of kombucha intake on the gut microbiota and obesity-related comorbidities: a systematic review. Critical Reviews in Food Science and Nutrition. (2021). https://pubmed.ncbi.nlm.nih.gov/34698580/
Effect of probiotic fermented milk on glycemic control and lipid profile in type 2 diabetic patients: a randomized double-blind placebo-controlled clinical trial. Iranian Journal of Public Health. (2015). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4401881/
Effect of time fermentation kombucha tea on lipid profile of rats (Rattus norvegicus L.). Journal of Physics: Conference Series. (2019). https://iopscience.iop.org/article/10.1088/1742-6596/1217/1/012158/meta
Evaluation of probiotic properties of Lactobacillus plantarum strains isolated from Chinese sauerkraut. World Journal of Microbiology and Biotechnology. (2013). https://link.springer.com/article/10.1007/s11274-012-1202-3
Fermented dairy foods: impact on intestinal microbiota and health-linked biomarkers. Frontiers in Microbiology. (2019). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6545342/
FoodData Central. (2019). https://fdc.nal.usda.gov/fdc-app.html#/food-details/169279/nutrients
Health benefits of kimchi (Korean fermented vegetables) as a probiotic food. Journal of Medicinal Food. (2014). https://www.liebertpub.com/doi/abs/10.1089/jmf.2013.3083
History of cheese. (n.d.) https://www.idfa.org/history-of-cheese
History of yogurt and current patterns of consumption. Nutrition Reviews. (2015). https://academic.oup.com/nutritionreviews/article/73/suppl_1/4/1819293
How to ferment vegetables. (n.d.) https://www.bbcgoodfood.com/howto/guide/beginners-guide-fermented-foods
Kefir and its biological activities. Foods. (2021). https://www.mdpi.com/2304-8158/10/6/1210/htm
Kefir drink leads to a similar weight loss, compared with milk, in a dairy-rich non-energy-restricted diet in overweight or obese premenopausal women: a randomized controlled trial. European Journal of Nutrition. (2016). https://pubmed.ncbi.nlm.nih.gov/25648739/
Kombucha: a systematic review of the empirical evidence of human health benefit. Annals of Epidemiology. (2019). https://www.sciencedirect.com/science/article/pii/S1047279718307385#bib18
Kimchi, a fermented vegetable, improves serum lipid profiles in healthy young adults: a randomized clinical trial. Journal of Medicinal Food. (2013). https://www.liebertpub.com/doi/abs/10.1089/jmf.2012.2563
Kimchi and its functionality. Journal of the Korean Society of Food Culture. (2019). https://www.koreascience.or.kr/article/JAKO201914456459821.page
Kimchi and other widely consumed traditional fermented foods of Korea: a review. Frontiers in Microbiology. (2016). https://www.frontiersin.org/articles/10.3389/fmicb.2016.01493/full
Low-FODMAP diet improves irritable bowel syndrome symptoms: a meta-analysis. Nutrients. (2017). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5622700/
Metabolomics investigation to shed light on cheese as a possible piece in the French paradox puzzle. Journal of Agricultural and Food Chemistry. (2015). https://pubs.acs.org/doi/abs/10.1021/jf505878a
Milk kefir: nutritional, microbiological, and health benefits. Nutrition Research Reviews. (2017). https://pubmed.ncbi.nlm.nih.gov/28222814/
Miso. Fermented Foods in Health and Disease Prevention. (2017). https://www.sciencedirect.com/topics/food-science/miso
New potentially antihypertensive peptides liberated in milk during fermentation with selected lactic acid bacteria and kombucha cultures. Journal of Dairy Science. (2017). https://www.sciencedirect.com/science/article/pii/S0022030217308846
Oral administration of kefiran exerts a bifidogenic effect on BALB/c mice intestinal microbiota. Beneficial Microbes. (2015). https://www.wageningenacademic.com/doi/10.3920/BM2015.0103
Origin and history of miso. (n.d.) https://www.marukome.co.jp/global/en/foodculture/aboutmiso/originandhistoryofmiso/
Properties and benefits of kefir -a review. Songklanakarin Journal of Science and Technology. (2013). https://kefirsa.co.za/wp-content/uploads/2019/01/Kefir-report-1.pdf
Sauerkraut: a probiotic superfood. Functional Foods in Health and Disease. (2016). https://ffhdj.com/index.php/ffhd/article/view/262/519
Sourdough fermentation of wheat flour does not prevent the interaction of transglutaminase 2 with α2-gliadin or gluten. Nutrients. (2015). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4425136/
Sourdough microbiome comparison and benefits. Microorganisms. (2021). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8306212/
The history of sourdough bread. (2015). https://www.sourdough.co.uk/the-history-of-sourdough-bread/
The microbiota and health promoting characteristics of the fermented beverage kefir. Frontiers in Microbiology. (2016). https://www.frontiersin.org/articles/10.3389/fmicb.2016.00647/full
Traditional low-alcoholic and non-alcoholic fermented beverages consumed in European countries: a neglected food group. Nutrition Research Reviews. (2017). https://www.cambridge.org/core/journals/nutrition-research-reviews/article/traditional-lowalcoholic-and-nonalcoholic-fermented-beverages-consumed-in-european-countries-a-neglected-food-group/F7DBC2D563B72D393E1EC47F4B228877
Why is apple cider vinegar so popular? (n.d.). https://extension.wvu.edu/food-health/cooking/apple-cider-vinegar-myths-facts
Yogurt. (n.d.) https://www.hsph.harvard.edu/nutritionsource/food-features/yogurt/
Yogurt, cultures fermented milk, and health: a systematic review. Nutrition Reviews. (2020). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8579104/