Is sauerkraut good for gut health?

Maybe slightly, and nobody has pooled the trials of sauerkraut itself because there are too few. A 2025 meta-analysis of fermented foods in healthy adults, mostly fermented milk, found small gains in bowel movement frequency (mean difference 0.60, 95% CI 0.04 to 1.16), stool consistency and gut symptoms, with certainty mostly low. In the one trial of sauerkraut in irritable bowel syndrome, symptom scores in 34 patients fell on both kinds of sauerkraut, and there was no comparison group that ate something else.

Unsettled. The answer stays open because the strong evidence is about fermented foods in general and the sauerkraut evidence is small. Of the 16 fermented food trials in irritable bowel syndrome pooled in 2024, one tested sauerkraut. The three sauerkraut or fermented vegetable trials enrolled 34, 87 and 31 people and lasted 4 to 6 weeks.

What the trials found

Fermented foods in healthy adults

The 2025 review pooled trials of fermented foods in healthy adults, 25 studies with 4,328 participants. Bowel movements became slightly more frequent, stools a little softer on the Bristol scale (mean difference 0.25, 95% CI 0.03 to 0.47) and transit faster (mean difference -13.65, 95% CI -21.88 to -5.43). The studies disagreed with each other a great deal, and when one study at high risk of bias was removed, the gain in stool frequency stopped being significant.

Fermented foods in irritable bowel syndrome

A 2024 meta-analysis gathered 16 randomized trials in 1,264 patients. Across the trials that reported symptom relief, fermented foods made relief more likely, with a relative risk of 1.22 (95% CI 1.04 to 1.42). That is about a fifth more relief in relative terms. The review does not report how many people were relieved in each group, so the absolute gain is unknown. Eight trials used fermented milk, three fermented oats and one sauerkraut, and the authors credit fermented milk with probiotic strains for most of the effect.

Sauerkraut in irritable bowel syndrome

In a Norwegian double-blind pilot, 34 patients with irritable bowel syndrome ate pasteurized or unpasteurised sauerkraut every day for 6 weeks. Symptom scores fell by 38.57 points with pasteurized and 56.99 with unpasteurised, both significant within each group, and the two did not differ from each other. The trial was underpowered and had no arm without sauerkraut. The authors credit its fiber-like content more than its live bacteria.

Sauerkraut in healthy adults

In a crossover trial in Freiburg, 87 healthy adults ate 3.5 oz (100 g) of fresh and of pasteurized sauerkraut a day for 4 weeks each. Single bacterial species changed, the gut microbiome as a whole stayed resilient, and stool form, frequency and fecal pH did not change. A second paper from the same trial found no change in gut barrier markers and no appreciable benefit to health elsewhere in the body. The pasteurized sauerkraut held no living bacteria, yet it produced the more pronounced changes, and only pasteurized sauerkraut raised short-chain fatty acids in the blood. So in that trial, live bacteria do not appear to explain the changes.

In a pilot of 31 women, about 100 g a day of fermented vegetables for 6 weeks raised Faecalibacterium prausnitzii (P = 0.022), a bacterium often studied for gut health, and did not change inflammation markers. In a 17-week trial of 36 healthy adults, a diet high in mixed fermented foods steadily raised microbial diversity and lowered inflammatory markers. Those are changes in the microbiome and the blood. Neither trial shows that a person felt or digested any better.

Who should be careful

Not for everyone. If you take an MAOI antidepressant, sauerkraut is one of the tyramine foods on MAOI diet lists. Across 121 Czech and Austrian samples tested in 1999, tyramine averaged 174 mg per kg, with very wide variation between products. Follow the tyramine advice of whoever prescribes the drug.

If you have histamine intolerance, sauerkraut is named among histamine-rich foods. In a provocation trial, 75 mg of pure histamine gave symptoms to 5 of 10 healthy women, and none reacted to placebo. That trial used histamine, not sauerkraut, and in the same 121 samples histamine was below 2 mg per kg in 44% of them and above 10 mg per kg in 19%.

If you watch your salt, a cup of sauerkraut (140 g) carries about 920 mg of sodium in USDA survey data, 659 mg per 3.5 oz (100 g), and brands and home batches differ.

Bloating happens. In the fermented vegetable pilot, about 50% of eaters reported bloating against 30% of controls, while abdominal pain was reported by 18% against 40%. Across the fermented food trials in irritable bowel syndrome, side effects were no more common than with placebo (relative risk 0.95, 95% CI 0.59 to 1.51), though only 5 of 16 trials gave usable data. In Freiburg, 95% of healthy adults were content with fresh sauerkraut and 90% with pasteurized.

We found no evidence about sauerkraut for gut health in pregnancy, in children or alongside other medicines. That is missing evidence, not a reassurance.

What expert bodies say

The EU did not authorize a claim that sauerkraut juice supports digestion. A refusal means the evidence did not meet the EU bar, not that a lack of effect was shown. We found no position from the NIH, EFSA or the WHO on sauerkraut and gut health.

How we searched

What would change this answer

• A randomized trial of sauerkraut in irritable bowel syndrome with a group that eats something else, large enough to detect a difference. We found no such trial registered for sauerkraut, fermented vegetables or kimchi on ClinicalTrials.gov.
• Trials in people with constipation or other gut complaints, measuring how they feel and how often they go, rather than only which bacteria change.
• A meta-analysis of fermented vegetables separate from fermented milk. Today the pooled evidence is mostly about yogurt-type products.

More on the food itself: sauerkraut page.

Sources

1. ev-skgh-01 · Meta-analysis or systematic review · systematic review and meta-analysis of randomized controlled trials (EFSA-guided, GRADE) · n = 25 studies, 4,328 participants (19 RCTs pooled)
   Meta-analysis demonstrated the beneficial impact of FF consumption on frequency of bowel movements (MD 0.60, CI 0.04, 1.16, p = 0.04, I2 = 74%), stool consistency (Bristol Stool Form Scale) (MD 0.25, CI 0.03, 0.47, p = 0.03, I2 = 72%), gastrointestinal symptoms (SMD -0.60, CI -1.05, -0.15, p = 0.009, I2 = 90%) and intestinal transit time (-13.65 CI -21.88, -5.43, p = 0.001, I2 = 95%), among others. Certainty of evidence was highly variable and mostly low.
   
   Who: healthy adults in trials of fermented foods (mostly fermented milk), searches to January 2025
   Effect: bowel movements MD 0.60 (95% CI 0.04 to 1.16); stool consistency (Bristol) MD 0.25 (0.03 to 0.47); GI symptoms SMD -0.60 (-1.05 to -0.15); transit time -13.65 (-21.88 to -5.43); I2 72-95%
   Certainty: Fermented foods pooled, mostly dairy; high heterogeneity; GRADE mostly low; sensitivity analysis removing one high risk of bias study turned stool frequency non-significant (MD 0.57, -0.03 to 1.17).
   Front Nutr, 2025 · checked 2026-10-07 · we read the abstract
2. ev-skgh-02 · Randomized controlled trial(s) · systematic review and meta-analysis of randomized controlled trials (EFSA-guided, GRADE) · n = 25 studies, 4,328 participants (19 RCTs pooled)
   Briefly, ~50 and 18% of the participants in the intervention group experienced bloating and abdominal pain, respectively, with 30 and 40% of the control group experiencing the same symptoms, respectively, (Supplementary Table S5).
   
   Who: healthy adults in trials of fermented foods (mostly fermented milk), searches to January 2025
   Effect: bloating ~50% vs 30%; abdominal pain 18% vs 40% (intervention vs control, Galena et al.)
   Certainty: One small pilot (31 women) reported inside the review's safety section; other included trials reported no adverse events or transient diarrhea.
   Front Nutr, 2025 · checked 2026-10-07 · we read the fulltext
3. ev-skgh-03 · Meta-analysis or systematic review · systematic review and meta-analysis of randomized controlled trials · n = 16 RCTs, 1,264 patients
   The proportion of symptom relief was associated with the administration of FFs (RR 1.22, 95% CI 1.04-1.42, p = 0.01, I 2 = 0%).
   
   Who: adults with irritable bowel syndrome in RCTs of fermented foods, searches to August 2024
   Effect: symptom relief RR 1.22 (95% CI 1.04 to 1.42), I2 0%
   Certainty: Authors ask for caution; benefit driven by fermented milk with probiotic strains; sauerkraut contributes one trial.
   Front Nutr, 2024 · checked 2026-10-07 · we read the abstract
4. ev-skgh-04 · Meta-analysis or systematic review · systematic review and meta-analysis of randomized controlled trials · n = 16 RCTs, 1,264 patients
   There were 8 trials used fermented milk, 3 fermented oat, 2 fermented wheat flours, 1 fermented rice, 1 kombucha, and 1 sauerkraut.
   
   Who: adults with irritable bowel syndrome in RCTs of fermented foods, searches to August 2024
   Effect: 8 fermented milk, 3 fermented oat, 2 fermented wheat flour, 1 fermented rice, 1 kombucha, 1 sauerkraut
   Certainty: Shows the evidence gap: no meta-analysis of sauerkraut alone exists.
   Front Nutr, 2024 · checked 2026-10-07 · we read the fulltext
5. ev-skgh-05 · Meta-analysis or systematic review · systematic review and meta-analysis of randomized controlled trials · n = 16 RCTs, 1,264 patients
   Meta-analysis showed that the occurrence rate of AEs was not statistically different from the placebo groups (RR 0.95, 95% CI 0.59–1.51, p = 0.82, I2 = 0%) (Figure 6).
   
   Who: adults with irritable bowel syndrome in RCTs of fermented foods, searches to August 2024
   Effect: adverse events RR 0.95 (95% CI 0.59 to 1.51), I2 0%; mostly mild
   Certainty: Only 5 of 16 trials gave adverse event data usable for pooling.
   Front Nutr, 2024 · checked 2026-10-07 · we read the fulltext
6. ev-skgh-06 · Randomized controlled trial(s) · randomized double-blind pilot trial, pasteurized vs unpasteurised sauerkraut · n = 34
   The mean change in IBS-SSS was -38.57 ± 17.08 PS vs. -56.99 ± 16.92 UPS and was significantly improved in both groups (P < 0.04), while the improvement in symptoms was not different between the intervention groups.
   
   Who: Norwegian patients with irritable bowel syndrome
   Effect: IBS-SSS change -38.57 +/- 17.08 pasteurized vs -56.99 +/- 16.92 unpasteurised, both P < 0.04, between-group difference not significant
   Certainty: No non-sauerkraut control arm, underpowered pilot; authors credit prebiotic content more than live bacteria.
   Food Funct, 2018 · checked 2026-10-07 · we read the abstract
7. ev-skgh-07 · Randomized controlled trial(s) · randomized crossover intervention trial · n = 87
   The gut microbiome of healthy individuals is rather resilient to short-term dietary interventions even though single species might be affected by sauerkraut consumption.
   
   Who: healthy adults eating 3.5 oz (100 g) fresh or pasteurized sauerkraut daily for 4 weeks
   Effect: shotgun metagenomics: changes in single species, larger with pasteurized; serum SCFAs rose only after pasteurized
   Certainty: Short trial in healthy people; no clinical gut outcome changed.
   Microbiome, 2025 · checked 2026-10-07 · we read the abstract
8. ev-skgh-08 · Randomized controlled trial(s) · randomized crossover intervention trial · n = 87
   Consumption of 100 g fresh and pasteurized sauerkraut for 4 weeks was well received and tolerated by our study population (95% and 90% contentment after fresh and pasteurized intervention, respectively, assessed by a questionnaire).
   
   Who: healthy adults eating 3.5 oz (100 g) fresh or pasteurized sauerkraut daily for 4 weeks
   Effect: contentment 95% fresh, 90% pasteurized; no significant change in Bristol Stool Form, defecation frequency or fecal pH
   Certainty: Self-reported questionnaire; healthy volunteers only.
   Microbiome, 2025 · checked 2026-10-07 · we read the fulltext
9. ev-skgh-09 · Randomized controlled trial(s) · randomized crossover intervention trial · n = 87
   No change in gut barrier integrity was observed... Four weeks of daily consumption was not linked to an appreciable systemic health benefit in healthy individuals.
   
   Who: healthy participants eating 100 g/day of fresh and pasteurized sauerkraut for four weeks
   Effect: no change in gut barrier integrity; no appreciable systemic health benefit
   Certainty: Healthy people, 4 weeks per arm; modest changes appeared only in subgroups.
   Eur J Clin Nutr, 2026 · checked 2026-10-07 · we read the abstract
10. ev-skgh-10 · Randomized controlled trial(s) · randomized pilot and feasibility trial, three arms · n = 31
    At timepoint 2, group A showed an increase in Faecalibacterium prausnitzii (P = 0.022), a decrease in Ruminococcus torques (P<0.05), and a trend towards greater alpha diversity measured by the Shannon index (P = 0.074).
    
    Who: women aged 18-69 eating 100 g/day fermented vegetables, pickled vegetables or none for six weeks
    Effect: F. prausnitzii up (P = 0.022), Ruminococcus torques down (P < 0.05), Shannon diversity trend (P = 0.074); CRP, TNF-alpha, LBP unchanged
    Certainty: Pilot, small groups, microbial markers only; product is fermented vegetables, not sauerkraut alone.
    PLoS One, 2022 · checked 2026-10-07 · we read the abstract
11. ev-skgh-11 · Randomized controlled trial(s) · 17-week randomized prospective dietary intervention · n = 36
    Alternatively, the high-fermented-food diet steadily increased microbiota diversity and decreased inflammatory markers.
    
    Who: healthy adults on a high-fermented-food or high-fiber diet (18 per arm)
    Effect: microbiota diversity increased and inflammatory markers decreased on the high-fermented-food diet
    Certainty: Mixed fermented foods, not sauerkraut alone (food list in full text, not read here); 18 per arm.
    Cell, 2021 · checked 2026-10-07 · we read the abstract
12. ev-skgh-12 · Randomized controlled trial(s) · randomized double-blind placebo-controlled crossover provocation · n = 10
    Histamine-rich foods such as cheese, sausages, sauerkraut, tuna, tomatoes, and alcoholic beverages may contain histamine up to 500 mg/kg.
    
    Who: healthy females aged 22-36 years
    Effect: 5 of 10 reacted (diarrhea, flatulence, headache, itching), none to placebo
    Certainty: Pure histamine, not sauerkraut; tiny sample; histamine in sauerkraut varies widely.
    Allergy Asthma Proc, 2004 · checked 2026-10-07 · we read the abstract
13. ev-skgh-13 · Observational data · cross-sectional patient survey · n = 139
    Yeast products, dry sausage, corned beef, broad beans, sauerkraut, and beer were used at least monthly by more than 50% of patients.
    
    Who: 139 psychiatric patients assessed before possible MAOI treatment
    Effect: monthly use by more than 50% of patients
    Certainty: Survey of eating habits, not of reactions; people taking MAOI antidepressants should follow their prescriber's tyramine advice.
    J Clin Psychiatry, 1995 · checked 2026-10-07 · we read the abstract
14. ev-skgh-14 · Position of an expert body · reference dataset of household portion weights and nutrient values · n = 2 measures
    Sauerkraut, FNDDS 75230000, fdc_id 2709982: 1 cup 140 g | Quantity not specified 30 g || Sodium, Na 659 mg per 100 g
    
    Who: USDA FNDDS Sauerkraut (75230000)
    Effect: sodium 659 mg per 3.5 oz (100 g); 1 cup 140 g = 922.6 mg; unspecified quantity 30 g = 197.7 mg
    Certainty: Per-portion values recalculated from 100 g; brands and home-made batches differ in salt.
    USDA FNDDS (FoodData Central survey 2024-10-31), Sauerkraut, food code 75230000, fdc_id 2709982 · checked 2026-10-07 · we read the dataset
15. ev-skgh-15 · Position of an expert body · entry in the EU Register on nutrition and health claims, non-authorized list · n = —
    POL-HC-7906 Sauerkraut Saft (milchsauer vergorener Weißkohl (Brassica oleracea var. capitata) [In German:] Sauerkrautsaft regt die Verdauung an. Clarification provided Helps to support the digestion / contributes to the normal function of intestinal tract / functioning of the stomach / sauerkaut juice activate the eupepsia. Non-authorised
    
    Who: EU food labeling
    Effect: claim POL-HC-7906 (sauerkraut juice stimulates digestion, normal function of intestinal tract), status Non-authorized
    Certainty: Refused means the evidence did not meet the EU bar, not that a lack of effect was shown.
    EU Register on nutrition and health claims (European Commission), claim POL-HC-7906, snapshot 2026-09-21 · checked 2026-10-07 · we read the dataset
16. skrt-b1-02 · Randomized controlled trial(s) · randomized crossover intervention trial · n = 87
    More pronounced changes were observed in the pasteurized sauerkraut intervention arm. Only pasteurized sauerkraut consumption increased serum short-chain fatty acids (SCFAs).
    
    Who: 87 healthy adults aged 21-69, 100 g fresh or pasteurized sauerkraut a day for 4 weeks each
    Effect: serum SCFA increased after pasteurized arm only
    Certainty: exploratory metabolome outcome
    Microbiome, 2025 · checked 2026-09-23 · we read the abstract
17. skrt-b1-03 · Laboratory or animal data · metagenomic analysis of the trial sauerkraut, lab measurement · n = 87
    After 7 weeks of cooled storage—still before the expiration date—Limosilactobacillus reuteri was the dominant species (60.8% mean relative abundance)... The pasteurized sauerkraut contained no living bacteria and little bacterial DNA.
    
    Who: 87 healthy adults aged 21-69, 100 g fresh or pasteurized sauerkraut a day for 4 weeks each
    Effect: L. reuteri 60.8% mean relative abundance after 7 weeks cooled storage
    Certainty: one commercial product
    Microbiome, 2025 · checked 2026-09-23 · we read the fulltext
18. skrt-b1-09 · Laboratory or animal data · laboratory analysis of 121 sauerkraut samples · n = 121
    Biogenic amines were determined in 121 sauerkraut samples... Mean concentrations were 174, 146 and 50 mg kg−1 for tyramine, putrescine and cadaverine, respectively. However, very wide variations occurred. The lowest concentrations were found in household-prepared sauerkraut.
    
    Who: 121 sauerkraut samples, Czech and Austrian manufacturers, household and jarred
    Effect: tyramine mean 174 mg/kg, putrescine 146, cadaverine 50
    Certainty: Czech and Austrian products, 1999
    Food Chem, 1999 · checked 2026-09-23 · we read the abstract
19. skrt-b1-10 · Laboratory or animal data · laboratory analysis of 121 sauerkraut samples · n = 121
    Histamine levels were below 2 mg kg−1 in 44% of samples and above 10 mg kg−1 in only 19%
    
    Who: 121 sauerkraut samples, Czech and Austrian manufacturers, household and jarred
    Effect: histamine mostly low
    Certainty: one survey, 1999
    Food Chem, 1999 · checked 2026-09-23 · we read the abstract