Is lettuce high in histamine?
Lettuce is low in histamine: four lettuces tested in Spain had none, and in a storage study no histamine appeared in lettuce over six days in the fridge.
- Histamine
- Not detected
- Other amines
- Low
- 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 histamine, tyramine or cadaverine in 4 lettuces; putrescine averaged 2.85 mg/kg. |
| Other studies in the 2018 review 1 | Five studies reported putrescine, averaging 5.6 to 20.7 mg/kg where an average was given; none reported histamine. | |
| Storage study cited in the 2018 review 1 | Over six days at 5 °C putrescine rose in lettuce, but histamine was found only in Chinese cabbage. | |
| 10 published low-histamine diets 2 | Lettuce is not on the review's chart of foods the diets exclude. | |
| SIGHI food list 3 | See source | See SIGHI's own list for its rating. |
Measured histamine
| Food tested | Samples | Histamine | Other amines |
|---|---|---|---|
| Lettuce sold in Spain 1 (Table 1) | 4 | not detected | putrescine mean 2.85 mg/kg (2.20–3.90); tyramine and cadaverine not detected |
mg/kg = milligrams of histamine per kilogram of food. "Not detected" means below the laboratory's detection limit.
How freshness and processing change it
In a storage study, lettuce kept at 5 °C for six days gained putrescine as microbes grew on the leaves, and tyramine rose slightly, but no histamine appeared. Use lettuce while it is crisp. Bagged mixed salads may contain other leaves, such as baby spinach, that are rated separately or were not measured.
No histamine in 4 lettuces; putrescine averaged 2.85 mg/kg. (measured)
Not measured as such; in a 6-day storage study, putrescine rose but no histamine appeared in lettuce. (estimate)
Why we rate lettuce 0
Lettuce had no detectable histamine in the measurements we have, and it is the leafy green where the evidence is most reassuring. A University of Barcelona team tested four lettuces sold in Spain. None contained histamine, tyramine or cadaverine. Putrescine averaged 2.85 mg/kg, from 2.20 to 3.90 mg/kg.
Five other studies collected in the team's 2018 review measured lettuce, mostly for putrescine only. Four gave averages from 5.6 to 20.7 mg/kg, and one gave only a range, 3.3 to 4.8 mg/kg. The 20.7 mg/kg figure, from seven samples, is the outlier; the other averages were under 8 mg/kg. One study also found cadaverine at 3.27 mg/kg. As on our other vegetable pages, we rate from the Spanish measurement, because it is the only one that also tested for histamine.
Storage is where lettuce differs from spinach. In a study cited by the review, lettuce, endive, Chinese cabbage and radicchio were kept at 5 °C for six days. Putrescine rose clearly, in step with the number of microbes on the leaves, and tyramine rose slightly. Histamine was found only in the Chinese cabbage, at very low levels that did not change. Spinach behaved differently in another study: its histamine rose significantly over 15 days in the fridge.
Lettuce does not appear among the foods charted as excluded by the ten published low-histamine diets in the team's 2021 review. Because that chart covers only some foods, we say that no diet in our sources excludes it, not that all ten allow it.
We rate lettuce 0, "low". It is the measured choice for a raw green salad if spinach leaves are off your list, and it pairs with cucumber and carrot, which also had no detectable histamine. The studies did not separate iceberg, romaine, little gem or other types, so we rate them together. Bagged mixed salads often include baby spinach, rocket or other leaves, so check what is in the bag. Lettuce kept for days gains putrescine even if no histamine appears, so crisp leaves are the better pick.
Questions about lettuce and histamine
Is bagged salad high in histamine?
Bagged salads were not measured as such. In a storage study, lettuce gained putrescine over six days at 5 °C but no histamine appeared. Mixed bags may contain baby spinach, which does carry histamine.
Is iceberg lettuce lower in histamine than romaine?
The studies did not separate lettuce types, so we cannot say. The four lettuces tested in Spain had no detectable histamine.
Evidence behind this page
- Four lettuces sold in Spain had no detectable histamine, tyramine or cadaverine; putrescine averaged 2.85 mg/kg (2.20–3.90). 1
- Five other studies reported putrescine in lettuce, four with averages from 5.6 to 20.7 mg/kg and one with a range of 3.3–4.8 mg/kg; none reported histamine. 1
- When lettuce, endive, Chinese cabbage and radicchio were stored at 5 °C for six days, putrescine rose in line with microbial counts and tyramine tended to rise slightly; histamine was present only in Chinese cabbage, at very low and stable levels. 1
- Histamine in spinach rose significantly over 15 days of refrigerated storage. 2
- Lettuce does not appear among the foods charted as excluded by ten published low-histamine diets. 2
Sources
- 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)
- 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)
- 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)