Fermented foods appear in everyday diets in many forms, from cheese, yogurt, and bread to soy sauce, kimchi, kefir, beer, and wine. Available studies measure both familiar foods and less common home-fermentation habits, while intervention research measures how a deliberately fermented-food-rich diet changes intake and selected immune markers.
Contents
- How often people eat fermented foods
- Fermented foods in everyday European diets
- Korean staples and sodium contribution
- Common fermented foods and cooking ingredients
- Fermented-food patterns and gut-microbiome measurements
- What a 10-week intervention measured
How often people eat fermented foods
A nationally representative survey of Canadian adults conducted in September–November 2023 asked about 18 fermented-food items. The results suggest that fermented foods are broadly familiar, but the number of foods tried varied substantially. Participants reported consuming an average of 10.7 of the 18 items, with a standard deviation of 5.8 items. One-quarter, or 25.7%, had consumed all 18 surveyed foods at least once. About 1% reported consuming none of them. These figures come from the Canadian survey described in Consumer Perceptions and Behaviors Toward Fermented Foods: Insights From a Canadian Survey.
The most widely consumed items were conventional foods and ingredients rather than specialized ferments:
| Fermented food or ingredient | Canadian participants who had consumed it |
|---|---|
| Cheese | 95.7% |
| Yogurt | 93.2% |
| Soy sauce | 85.7% |
| Sour cream | 81.8% |
| Vinegar | 80.5% |
The same survey recorded lower but still substantial exposure to several less universal categories. Plant-based yogurt had been consumed by 41.1% of participants, fermented cereals or grains by 40.4%, and fermented fish by 38.9%. Kefir had been tried by 53%, but only 6% of kefir consumers said they drank it daily. That distinction separates having tried a fermented food from making it a regular part of the diet.
Home fermentation was less common than consumption of commercially familiar foods. Only 9.0% of Canadian participants reported fermenting foods at home, while 30.0% said they were willing to engage in home fermentation. The willingness figure is an attitude measure, not a measurement of actual home-fermentation behavior.
Fermented foods in everyday European diets
The Dutch NQplus validation population provides a food-intake view based on baseline cohort measurements from June 2011 through February 2013. In that population, fermented foods represented approximately 16–18% of foods consumed. Dishes containing at least one fermented ingredient represented an additional 9–14% of foods consumed. Because the categories are reported separately, they should not be added into a single total without knowing how the study handled overlap. The findings are from Prevalence of fermented foods in the Dutch adult diet and validation of a food frequency questionnaire for estimating their intake in the NQplus cohort.
Average daily amounts for selected foods show how fermentation can be embedded in ordinary meals and beverages. Dutch participants consumed about 453 g of fermented coffee per day on average, 88 g of yogurt, 84 g of beer, 81 g of wholegrain bread, 65 g of wine, and 32 g of cheese. These are reported population averages from the baseline measurements, not recommended serving amounts.
Using 24-hour recalls, the Dutch validation sample averaged 609.6 g of fermented beverages per day, 176 g of fermented dairy, and 143 g of fermented cereals and grains. The same recall-based estimates assigned 0.8% of daily energy to coffee, 1.8% to beer, 9.3% to wholegrain bread, and 5.2% to cheese. The energy figures describe the Dutch sample and measurement method; they do not represent all European diets.
Korean staples and sodium contribution
A separate analysis of Korean adult survey data, analyzed in 2026, examined fermented-food energy and sodium contributions by age group. Among adults aged 20–39, fermented foods supplied 10.180% of total energy and 1,588.3 mg of sodium per day. Among adults aged 40–64, they supplied 9.126% of energy and 1,823.6 mg of sodium. Among adults aged 65 and older, they supplied 7.180% of energy and 1,682.8 mg of sodium.
The age-specific energy contributions were distributed across food groupings as follows, according to The Association Between Fermented Food Intake and Hs-CRP Across Age Groups in Korean Adults: Effect Modification by Sodium Intake:
| Age group | All fermented foods, % of energy | Grain-based, % | Jang, % | Vegetable-based, % |
|---|---|---|---|---|
| 20–39 | 10.180% | 3.845% | 1.500% | 1.395% |
| 40–64 | 9.126% | 2.250% | 1.782% | 1.960% |
| 65 and older | 7.180% | 1.544% | 1.808% | 1.990% |
Vegetable-based fermented foods contributed 611.7 mg of sodium per day for adults aged 20–39, 807.5 mg for those aged 40–64, and 742.7 mg for adults aged 65 and older. These are measured contributions in the analyzed Korean data. They should not be interpreted as sodium targets or as evidence that every fermented vegetable has the same sodium content.
Common fermented foods and cooking ingredients
The American Gut Project research used two related study groups. A targeted 115-person cohort reported six major fermented foods: beer, kimchi, kombucha, pickled vegetables, sauerkraut, and yogurt. Its questionnaire and four-week longitudinal work took place in 2019. In the larger 2019 cross-sectional cohort, 6,811 retained participants were classified for fermented-plant consumption. Of those participants, 30.5% were fermented-plant consumers, and 45.3% of those consumers reported occasional intake, defined in the study as one to two times per week.
The targeted cohort also illustrates why a single food list may miss part of fermented-food behavior. Only 7.0% of the 115 participants who said they never ate fermented plants reported eating another fermented food. This represented eight people. Five reported unspecified fermented foods; two reported wine or beer; and one reported yogurt, cider, wine, and beer. The small subgroup should be read descriptively rather than generalized to the wider population.
The study is titled Consumption of Fermented Foods Is Associated with Systematic Differences in the Gut Microbiome and Metabolome. It also detected eight fermented-food-associated bacterial species in the metagenomic comparison. Separately, the Swiss classification study identified 186 microorganisms across six taxonomic levels in fermented foods. That Swiss result comes from 2014–2015 Swiss National Nutrition Survey analysis published in 2025, as reported in the Korean study; it is a classification finding, not a count of organisms in one serving or one person’s gut.
Fermented-food patterns and gut-microbiome measurements
The American Gut Project analysis began with 28,114 stool samples from 21,464 individuals before retaining 6,811 participants for the cross-sectional analysis. In a metagenomic subset, fermented-plant consumers had a higher fermented-food-associated taxa log ratio than nonconsumers, with Cohen’s d = 0.851. The corresponding t-test p-value was 0.0001838. A second 40-versus-40 microbial feature log-ratio comparison also differed between consumers and nonconsumers, with Cohen’s d = 0.692 and a t-test p-value of 0.0024.
These effect sizes and p-values describe associations and group differences in the study’s microbiome measurements. They do not by themselves establish that fermented foods caused the differences. The study also reported a result that is easy to overlook: in the 115-person longitudinal cohort, microbiome alpha-diversity showed no significant consumer-versus-nonconsumer difference over four weeks, with Shannon-index p = 0.20.
Together, the results distinguish several kinds of microbiome evidence. The cross-sectional comparisons found differences in specified fermented-food-associated features, while the short longitudinal comparison did not find a significant difference in the Shannon alpha-diversity measure. Those outcomes are not contradictory measurements of the same endpoint: they concern different analyses, samples, and microbiome metrics.
What a 10-week intervention measured
An intervention study recruited participants from August 2016 through January 2017 and followed a 10-week fermented-food diet. Eighteen participants were assigned to the high-fermented-food diet arm. During the maintenance period, intake in that arm increased from 0.4 ± 0.6 servings per day at baseline to 6.3 ± 2.9 servings per day at the end of maintenance.
The intervention’s listed foods included yogurt, kefir, fermented cottage cheese, kombucha, vegetable-brine drinks, and fermented vegetables including kimchi. The measured dietary change was therefore a multi-food pattern rather than a test of one isolated ingredient. The intervention is described in Gut Microbiota-Targeted Diets Modulate Human Immune Status.
Among 93 measured cytokines, chemokines, and other inflammatory serum proteins, 19 decreased over the intervention in the fermented-food arm. This is a count of measured proteins that decreased in that study and period. It is not a claim that all inflammatory markers decreased, nor does the supplied result establish that a particular fermented food was responsible for any individual change.