Are soybeans high in histamine?
Soybeans are mostly low in histamine: five samples had none, but they carry notable putrescine and a lot of spermidine. One of ten published diets excludes them; fermented soy is a different story.
- Histamine
- Not detected
- Other amines
- Notable levels
- Liberator
- Not on the lists we use
- DAO blocker
- No evidence
What each source says
| Source | Verdict | What it says, in our words |
|---|---|---|
| Lab measurements, Spain 1 | Measured | No detectable histamine in 5 samples; putrescine averaged 19.07 mg/kg and spermidine 99.55 mg/kg. |
| 10 published low-histamine diets 1 | 1 of 10 excludes soybeans. | |
| Review of low-histamine diets, 2020 3 | Fewer than 20% of the diets it compared exclude soybeans; it suggests putrescine may explain reactions to them. | |
| Review of plant foods, 2018 2 | Finds no histamine in soybeans or sprouts and suggests their high polyamine content may justify excluding them. | |
| SIGHI food list 4 | See source | See SIGHI's own list for its rating. |
Measured histamine
| Food tested | Samples | Histamine | Other amines |
|---|---|---|---|
| Soybeans sold in Spain 1 (Table 1, row 'Soybeans') | 5 | not detected | putrescine mean 19.07 mg/kg (15.96–22.17); cadaverine mean 9.04 mg/kg; tyramine not detected; spermidine mean 99.55 mg/kg |
| Soybeans or soybean sprouts, range across studies in the 2018 review 2 (Table 4, row 'Soybean or soybean sprouts') | — | not detected | putrescine 2–57 mg/kg; cadaverine up to 0.3 mg/kg; tyramine not detected; spermidine 33–389 mg/kg; spermine 7–114 mg/kg |
mg/kg = milligrams of histamine per kilogram of food. "Not detected" means below the laboratory's detection limit.
How freshness and processing change it
Dried soybeans keep well. Sprouting changes them: soybean sprouts had 44.71 mg/kg of putrescine in one study, which the 2018 review links to germination rather than spoilage. Cooked soybeans, like any cooked pulse, should be eaten within a day or frozen, because amines form in stored cooked food and survive reheating.
No histamine in 5 samples; putrescine averaged 19.07 mg/kg. (measured)
Histamine not reported on its own; putrescine averaged 44.71 mg/kg in 3 samples. (estimate)
Measured as a group: fermented soy averaged 73.95 mg/kg of histamine. (measured)
Why we rate soybeans 1
Soybeans sit in an odd place on low-histamine lists. They had no histamine in the University of Barcelona team's survey: five samples of soybeans sold in Spain, none detectable. But they carried more of the other amines than most legumes. Putrescine averaged 19.07 mg/kg, from 15.96 to 22.17 mg/kg, cadaverine 9.04 mg/kg, and spermidine, a polyamine, 99.55 mg/kg, the highest spermidine average of any food in the team's 2021 table.
Other studies collected in the team's 2018 review found putrescine in dried soybeans anywhere from 1.6 to 57.2 mg/kg, depending on the study, and the review's summary gives up to 389 mg/kg of spermidine across soybeans and sprouts, with no histamine in either.
That is why the reviews treat soybeans as an other-amines food. The 2021 review names soybeans, with citrus, bananas, pumpkin and nuts, as excluded foods that have no histamine but relevant putrescine, and a 2020 review from the same group suggests putrescine may explain the reactions some people report after eating them. The 2018 review adds polyamines as a possible reason. The 2021 review is frank that the evidence for other amines blocking histamine breakdown is scarce. The published diets are mild about soybeans: one of the ten in the 2021 review excludes them, and the 2020 review found that fewer than one diet in five does.
We rate soybeans 1, "mostly low". On histamine alone they would be 0; the putrescine average, above the 10 mg/kg line our rule uses, moves them up one step and no further. Soybean sprouts are higher in putrescine, 44.71 mg/kg in three samples, which the 2018 review attributes to germination rather than bacteria; their histamine was not reported on its own.
The big divide within soy is fermentation. Fermented soy products in the same survey averaged 73.95 mg/kg of histamine, the highest of any food group tested, so tempeh, miso, natto and soy sauce are a different question from the beans. Plain tofu and soy milk, made from unfermented soybeans, had no histamine and less putrescine than the beans themselves.
Questions about soybeans and histamine
Is soy high in histamine?
Plain soy is not: soybeans, tofu and soy milk had no detectable histamine in the studies we use. Fermented soy is: as a group it averaged 73.95 mg/kg, the highest of any food group measured.
Are soybean sprouts low histamine?
Their histamine was not reported separately, but they had high putrescine, 44.71 mg/kg in three samples, which the study linked to sprouting itself. We rate them 1 as an estimate, the same as soybeans.
Evidence behind this page
- Five soybean samples sold in Spain had no detectable histamine or tyramine; putrescine averaged 19.07 mg/kg (15.96–22.17), cadaverine 9.04 mg/kg and spermidine 99.55 mg/kg. 1
- Other studies found putrescine in dried soybeans from 1.6 to 57.2 mg/kg depending on the study; across soybeans and sprouts the 2018 review reports no histamine and 33–389 mg/kg of spermidine. 2
- Soybean sprouts averaged 44.71 mg/kg of putrescine (3 samples), which the study's authors attributed to germination, as putrescine is a plant growth factor. 2
- The 2021 review names soybeans among excluded foods with no histamine but relevant putrescine, and notes that evidence for other amines blocking histamine breakdown is scarce. 1
- One of ten published low-histamine diets excludes soybeans; a 2020 review found fewer than 20% of diets do. 13
- Soy-fermented products sold in Spain averaged 73.95 mg/kg of histamine (21 samples). 1
Sources
- Sánchez-Pérez S, Comas-Basté O, Veciana-Nogués MT, Latorre-Moratalla ML, Vidal-Carou MC. Low-Histamine Diets: Is the Exclusion of Foods Justified by Their Histamine Content? Nutrients 13(5):1395, 2021. doi:10.3390/nu13051395 (Sánchez-Pérez S et al. 2021)
- Sánchez-Pérez S, Comas-Basté O, Rabell-González J, Veciana-Nogués MT, Latorre-Moratalla ML, Vidal-Carou MC. Biogenic Amines in Plant-Origin Foods: Are They Frequently Underestimated in Low-Histamine Diets? Foods 7(12):205, 2018. doi:10.3390/foods7120205 (Sánchez-Pérez S et al. 2018)
- Comas-Basté O, Sánchez-Pérez S, Veciana-Nogués MT, Latorre-Moratalla M, Vidal-Carou MDC. Histamine Intolerance: The Current State of the Art. Biomolecules 10(8):1181, 2020. doi:10.3390/biom10081181 (Comas-Basté O et al. 2020)
- Swiss Interest Group Histamine Intolerance (SIGHI). Food compatibility list for histamine intolerance. histaminintoleranz.ch (accessed November 2026), 2026. Link (Swiss Interest Group Histamine Intolerance (SIGHI) 2026)