Are walnuts high in histamine?
Walnuts are probably mostly low in histamine: they were not tested on their own, but nuts as a group had none in 47 samples in one survey and an average of 0.45 mg/kg in another.
- Histamine
- Varies by sample
- Other amines
- Notable levels
- Liberator
- Claimed, unproven
- DAO blocker
- No evidence
What each source says
| Source | Verdict | What it says, in our words |
|---|---|---|
| Lab measurements, Spain (nut group) 1 | Measured | No detectable histamine in 47 nut samples; walnuts were not reported separately. |
| Review of low-histamine diets, 2020 2 | 41 nut samples averaged 0.45 mg/kg of histamine, up to 11.86 mg/kg; nuts are excluded by 20–60% of the diets it compared. | |
| 10 published low-histamine diets 1 | 2 of 10 exclude nuts as a group. | |
| Clinical review, 2024 4 | Lists nuts among foods a low-histamine diet avoids. | |
| Histamine-liberator claim 1 | Nuts are listed among suggested histamine-releasing foods; no human study supports the claim. | |
| SIGHI food list 5 | See source | See SIGHI's own list for its rating. |
Measured histamine
| Food tested | Samples | Histamine | Other amines |
|---|---|---|---|
| Nuts sold in Spain (group) 1 (Table 1) | 47 | not detected | putrescine mean 4.40 mg/kg (ND–39.51); cadaverine mean 0.25 mg/kg; tyramine mean 0.11 mg/kg; spermidine mean 28.64 mg/kg (6.21–140.55) |
| Nuts (group) 2 (Table 1) | 41 | mean 0.45 mg/kg, range nd–11.86 mg/kg | median not detected |
| Nuts, range across studies (group) 3 (Table 4) | — | not detected | putrescine nd–40 mg/kg; cadaverine nd–23 mg/kg; spermidine 6–40 mg/kg; spermine 2–33 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
Walnuts were not measured on their own, and no study we use followed amines in nuts during storage. The 2018 review puts differences between samples of the same food down mainly to production, transport and storage. Histamine is heat-stable, so toasting walnuts would not remove any.
Measured only as part of the nut group: none in 47 samples in one survey, up to 11.86 mg/kg in another. (measured)
Why we rate walnuts 1
Walnuts have not been measured on their own in the studies we use. What exists are figures for nuts as a group, and for a few individual nuts that sit next to walnuts on most shelves. This page is marked "measured as a food group" for that reason.
The group figures are mostly reassuring. A University of Barcelona team tested 47 samples of nuts sold in Spain and found no detectable histamine in any of them, though the paper does not list which nuts were included. A 2020 review from the same group, using a different set of 41 nut samples, gives a less tidy picture: an average of 0.45 mg/kg of histamine, at least half the samples with none, and the highest at 11.86 mg/kg. It does not say which nuts carried the histamine. For scale, fresh tomatoes in the team's survey averaged 2.51 mg/kg.
Nuts are richer in other compounds. Across the 47 samples, putrescine averaged 4.40 mg/kg and spermidine, a polyamine, 28.64 mg/kg, reaching 140.55 mg/kg in one sample. Diamine oxidase (DAO), the enzyme that breaks histamine down in the gut, also breaks these down, though it has less affinity for polyamines, and the 2018 review suggests this, rather than histamine, may be why some low-histamine diets exclude nuts. Two of the ten diets in the 2021 review do, and a 2024 clinical review lists nuts among the foods to avoid at first.
We rate walnuts 1, "mostly low". Almonds and hazelnuts, measured on their own, had no histamine and are rated 0. Walnuts get one step more because their only figures are group figures, and one of the two group surveys found histamine in some nut samples without naming them. If you want a nut with its own clean measurements for baking, salads or a walnut-style pesto, hazelnuts are the closest swap. Walnut oil and pickled walnuts were not measured. A walnut allergy is a different condition from histamine intolerance and has its own tests.
Questions about walnuts and histamine
Are walnuts low histamine?
They were not measured on their own. Nuts as a group had no histamine in 47 samples in one survey and an average of 0.45 mg/kg, up to 11.86 mg/kg, in another, so we rate walnuts 1, "mostly low".
Are almonds or walnuts better on a low-histamine diet?
Almonds have their own measurements: seven samples with no histamine and little putrescine, so we rate them 0. Walnuts have only group figures, so we rate them 1.
Evidence behind this page
- Across 47 nut samples sold in Spain, no histamine was detected; the paper does not list which nuts were included. 1
- A 2020 review reports an average of 0.45 mg/kg of histamine in 41 nut samples, with a median of not detected and a maximum of 11.86 mg/kg. 2
- Nuts are classed among plant foods without histamine but with high levels of other amines, and their exclusion may be explained by putrescine and polyamines, which DAO also breaks down. 3
- Almonds and hazelnuts tested on their own had no detectable histamine. 3
- Two of ten published low-histamine diets exclude nuts. 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)
- 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)
- 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)
- Jochum C. Histamine Intolerance: Symptoms, Diagnosis, and Beyond. Nutrients 16(8):1219, 2024. doi:10.3390/nu16081219 (Jochum C 2024)
- 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)