Is trout high in histamine?
Fresh trout is mostly low in histamine: it belongs to the salmon family, which has far less histidine than tuna, and fresh fish measured low in lab tests. Smoked and leftover trout rate higher.
- Histamine
- Varies by sample
- Other amines
- Notable levels
- Liberator
- Not on the lists we use
- DAO blocker
- No evidence
Why sources disagree. Trout belongs to the salmon family, which has far less free histidine than tuna-type fish, and fresh fish measured low on average, but nine of ten published diets exclude fish as a group.
What each source says
| Source | Verdict | What it says, in our words |
|---|---|---|
| Lab measurements, Spain 1 | Measured | Fresh oily fish averaged 3.27 mg/kg in 49 samples; 95% had 6.66 mg/kg or less. Trout was not reported separately. |
| Histamine intolerance review, 2020 2 | Measured | Fresh fish of all kinds averaged 0.79 mg/kg in 136 samples, and at least half had none detectable. |
| FAO/WHO review, 2018 3 | Most salmon-family fish, trout's family, have under 1,000 mg/kg of free histidine, against 5,000–20,000 mg/kg in tuna-type fish. | |
| EU food law 4 | Histamine limits target histidine-rich fish and name six families in particular; trout's family is not one of them. | |
| 10 published low-histamine diets 1 | 9 of 10 exclude fish as a group. | |
| SIGHI food list 5 | See source | See SIGHI's own list for its rating. |
Measured histamine
| Food tested | Samples | Histamine | Other amines |
|---|---|---|---|
| Fresh oily fish sold in Spain (group; species not given) 1 (Table 1 and Section 3) | 49 | mean 3.27 mg/kg, range nd–111.26 mg/kg, 95th percentile 6.66 mg/kg | cadaverine mean 13.22 mg/kg (up to 400.23); the highest histamine sample was salmon |
| Fresh fish, all kinds (group) 2 (Table 1, row "Fresh fish") | 136 | mean 0.79 mg/kg, range nd–36.55 mg/kg | median not detected |
| Semi-preserved fish (group) 2 (Table 1, row "Semipreserved fish") | 49 | mean 3.48 mg/kg, range nd–34.9 mg/kg | median 2.18 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
Low histidine slows histamine build-up but does not stop it, so trout still needs to be fresh. Buy it whole or as fillets, fresh or frozen, and cook it the same day. Smoked trout and leftovers have had more time for amines to form, and cooking does not remove them.
Fresh fish (group) averaged 0.79 mg/kg and fresh oily fish 3.27; trout is a low-histidine species. (measured)
Not measured on its own; semi-preserved fish averaged 3.48 mg/kg, up to 34.90. (estimate)
Not measured. Storage time adds histamine, and reheating does not remove it. (estimate)
Why we rate trout 1
Trout is a member of the salmon family, the Salmonidae, and for histamine that is the most useful fact about it. Histamine in fish is made by bacteria from free histidine in the flesh. A 2018 FAO/WHO review reports that most species in the salmon family have less than 1,000 mg/kg of free histidine, while tuna-type fish have roughly 5,000 to 20,000 mg/kg. EU food law, which sets histamine limits for fish from histidine-rich families such as those of tuna, mackerel, sardines and anchovies, does not name the salmon family. The FAO/WHO review also notes that concerns have been raised about histamine in salmon-family fish, so low histidine does not mean no histamine.
No study we use reports trout on its own, so the figures are for groups. Fresh oily fish sold in Spain averaged 3.27 mg/kg across 49 samples, and 95% had 6.66 mg/kg or less; the highest, a salmon, reached 111.26 mg/kg. A 2020 review by the same University of Barcelona team gives fresh fish of all kinds an average of 0.79 mg/kg across 136 samples, with at least half of the samples below the detection limit and a highest value of 36.55 mg/kg. The papers do not say whether trout was in either group, so we show both.
The published diets do not make the distinction. Nine of the ten low-histamine diets in a 2021 review exclude fish and fish products, and a 2020 review found that more than 60% of the diets it compared exclude oily fish. That is why we mark trout disputed: the biology and the measurements point to a low-risk fish, while most lists leave all fish out.
We rate fresh trout 1, "mostly low", the same as salmon. Histamine was not detected in at least half of fresh fish samples but was found in some, and fish is the food group where storage matters most. Smoked trout has not been measured; semi-preserved fish as a group averaged 3.48 mg/kg with a highest sample of 34.90 mg/kg, and smoked trout has been stored for longer than fresh fish, so we rate it 2 as an estimate. Leftover cooked trout is also a 2, because histamine forms during storage and reheating does not remove it. Whole trout or fillets bought fresh or frozen and cooked that day are the closest match to what was measured, and trout is a good swap for mackerel and sardines, which come from histidine-rich families.
Questions about trout and histamine
Is smoked trout high in histamine?
It was not measured on its own. Semi-preserved fish as a group averaged 3.48 mg/kg, with a maximum of 34.90 mg/kg, and smoked trout has been stored for longer than fresh fish, so we rate it 2 (moderate) as an estimate, higher than fresh trout.
Is trout lower in histamine than salmon?
The studies we use do not separate them. Both belong to the salmon family, which has far less free histidine than tuna-type fish, and we rate fresh trout and fresh salmon 1. How fresh the fish is matters more than which of the two you choose.
Evidence behind this page
- Most species in the salmon family have less than 1,000 mg/kg of free histidine, compared with about 5,000 to 20,000 mg/kg in scombroid fish, although concerns have been raised about histamine in salmon-family fish. 3
- EU histamine limits apply to fish species associated with a high amount of histidine, particularly the families Scombridae, Clupeidae, Engraulidae, Coryphaenidae, Pomatomidae and Scomberesocidae; the salmon family is not named. 4
- Fresh oily fish sold in Spain averaged 3.27 mg/kg of histamine across 49 samples, with 95% at or below 6.66 mg/kg; the highest, a salmon, had 111.26 mg/kg. 1
- Fresh fish of all kinds averaged 0.79 mg/kg across 136 samples, with a median below the detection limit and a highest value of 36.55 mg/kg; semi-preserved fish averaged 3.48 mg/kg, up to 34.90 mg/kg. 2
- Nine of ten published low-histamine diets exclude fish and fish products, and more than 60% of the diets compared in a 2020 review exclude oily fish. 12
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)
- Food and Agriculture Organization of the United Nations; World Health Organization. Histamine in Salmonids: Joint FAO/WHO Literature Review. World Health Organization, Geneva, 2018. Link (Food and Agriculture Organization of the United Nations; World Health Organization 2018)
- European Commission. Commission Regulation (EC) No 2073/2005 on microbiological criteria for foodstuffs. Official Journal of the European Union L 338, 2005. Link (European Commission 2005)
- 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)