Is Canned Tuna High in Histamine?

Canned tuna can contain meaningful levels of histamine, but most commercially sold cans fall well within safety limits set by regulators. The real issue is not the canning process itself but what happens to the fish before it reaches the can. Tuna belongs to a family of fish that is naturally rich in the amino acid histidine, which bacteria convert into histamine when temperature control breaks down at any point from ocean to factory. That makes canned tuna one of the foods most closely associated with histamine-related illness, even though the majority of cans on a grocery shelf will test at low levels.

Why Tuna Is Especially Prone to Histamine

Tuna, mackerel, and other fish in the scombroid family carry unusually high concentrations of a free amino acid called histidine in their muscle tissue. When certain bacteria land on the fish and find the right conditions, they produce an enzyme that converts histidine into histamine. The conversion can happen fast, sometimes within hours of the fish being caught if the temperature rises above safe refrigeration levels.¹

The bacteria responsible for this conversion are varied and widespread. Research on decomposing skipjack tuna has isolated histamine producers including species of Clostridium, Enterobacter, Klebsiella, Proteus, and Vibrio.² A broader review of marine bacterial contaminants lists more than two dozen species capable of the same trick, spanning many genera that are common in ocean water, on fishing equipment, and in processing facilities.³ Because these bacteria are so common in the marine environment, the question is never whether they are present on a given tuna but whether they are given time and warmth to do their work.

Canning Does Not Remove Histamine Already Formed

A widespread misconception is that the high temperatures involved in canning would break down histamine. They do not. Histamine is a small, heat-stable molecule. Research tracking histamine levels through the canning process found that normal cooking did not affect histamine concentration in naturally contaminated tuna samples.⁴ The heat does kill the bacteria, which means histamine will not keep climbing inside a sealed can. But whatever histamine was in the fish when it went into the can stays there for the life of the product.

This is the central paradox of canned tuna and histamine. Canning is actually good at freezing the problem in place: once sealed and sterilized, the histamine level cannot increase. The danger lies entirely in the hours and days before the can is sealed, when live bacteria on improperly chilled fish can generate large amounts of histamine. A can made from well-handled, promptly chilled tuna will contain very little histamine. A can made from fish that sat too long in a warm hold will contain whatever those bacteria produced, locked in permanently.

How Much Histamine Is Typically in Canned Tuna

Studies measuring histamine in canned tuna from retail shelves generally find levels that are low but not zero. A survey of canned tuna sold in Tehran found average histamine concentrations of roughly 29 to 34 mg/kg, depending on whether the product included vegetables.⁵ A more recent multi-product survey found much lower average levels in canned tuna, around 7 mg/kg.⁶ A study assessing commercial tuna across species and processing methods confirmed that all canned samples tested stayed within the FDA’s regulatory ceiling of 50 mg/kg.⁷

That FDA threshold of 50 mg/kg is the action level, meaning products above it are considered adulterated and subject to enforcement. The European Union uses a somewhat different system, with limits that depend on whether the fish is fresh or processed. The spread of average values across different studies, from around 7 to 34 mg/kg, reflects real variation driven by geography, supply chain quality, and brand practices. The takeaway is that a typical can from a well-regulated market is unlikely to pose a problem for most people, but outliers exist, and certain populations are more vulnerable to even moderate levels.

The Cold Chain Is What Actually Matters

Because histamine forms before the can is sealed and cannot be undone afterward, the entire safety story of canned tuna hinges on temperature control from the moment the fish leaves the water. A review of the tuna supply chain concluded that maintaining a continuous cold chain, from catch through processing, storage, and distribution, is the single most important factor in preventing histamine poisoning outbreaks.¹

Seasonal effects offer a useful window into how this plays out. A study of tuna caught off the coast of Brazil found detectable histamine in only about 5% of fresh samples. The two batches with detectable levels were both caught during months of lower production, when fishing boats had to stay out longer before returning to port, meaning the fish spent more time aboard before being properly chilled.⁸ That extra time in suboptimal conditions was enough to push histamine into the detectable range. The pattern holds globally: anywhere the cold chain is stretched, histamine risk climbs.

What Happens After You Open the Can

The sterilization that canning provides ends the moment you pop the lid. Once exposed to air and room temperature, the tuna becomes a fresh product again from a microbial standpoint. Research tracking histamine in opened canned tuna stored at different temperatures found that refrigeration made a substantial difference. Samples held at 4°C (standard fridge temperature) reached a peak histamine level of about 3.5 mg/kg, while samples left at 28°C hit roughly 9.6 mg/kg, and those at 31°C climbed to about 28.2 mg/kg.⁹

The same study noted that some histamine was already present at the moment of opening, confirming that a baseline amount had formed before canning. The practical lesson here is straightforward: if you do not eat the entire can at once, refrigerate leftovers immediately. Leaving an opened can of tuna on the counter for a few hours, especially in a warm kitchen, can push histamine levels up meaningfully.

Does the Packing Medium Make a Difference

Canned tuna comes packed in oil, water, brine, or sometimes with added vegetables, and people often wonder whether the medium affects histamine levels. The evidence is mixed but leans toward modest differences. A Brazilian study found that canned tuna packed in salt water had somewhat lower histamine than tuna packed in oil, and that solid-pack tuna had lower levels than grated versions of the same product.¹⁰ The Tehran survey, by contrast, found no meaningful difference between tuna canned in oil with vegetables and tuna canned in oil without them.⁵

The grated-versus-solid distinction is worth noting because it may reflect handling practices. Grated tuna often uses smaller or lower-grade pieces that have been processed more extensively, which could mean more surface area exposed to bacteria during handling. But the packing liquid itself is not the main driver. Whether you buy tuna in oil or water, the histamine that matters was generated before the fish was placed in the can.

You Cannot Tell by Smell or Taste

One of the most dangerous things about histamine in fish is that it does not announce itself. Fish with dangerously elevated histamine can look, smell, and taste perfectly normal. A classic review of histamine poisoning emphasized that foods containing unusually high levels of histamine may not appear to be outwardly spoiled.¹¹ Some people report a peppery or metallic taste when histamine levels are very high, but this is unreliable. A can of tuna that has passed its safety margin might taste identical to one that is well within limits. This makes laboratory testing the only dependable safeguard, which is why regulatory systems rely on chemical analysis rather than sensory inspection.

Scombroid Poisoning Versus Histamine Intolerance

When people talk about getting sick from canned tuna, they could be describing two very different conditions that share overlapping symptoms but have different thresholds and different underlying causes.

Scombroid poisoning, also called histamine fish poisoning, happens when anyone eats fish containing a large dose of histamine. Symptoms typically appear within 30 minutes to a few hours and can include flushing, headache, nausea, palpitations, abdominal cramps, and diarrhea. A case report described a 51-year-old woman who developed headache, nausea, palpitations, and hypertension half an hour after eating tuna salad.¹² In rare and more severe cases, the reaction can involve cardiovascular effects; one report documented a 57-year-old man who collapsed with cardiac ST-elevation after eating canned tuna.¹³ These cases involve histamine doses high enough to overwhelm anyone’s ability to metabolize them.

Histamine intolerance is a separate issue. In people with this condition, the body’s capacity to break down histamine is reduced, meaning that even normal levels of histamine in food, amounts that would cause no symptoms in most people, can trigger reactions. A review of histamine intolerance noted that in healthy individuals, high histamine intake causes acute intoxication, while in people with intolerance, normal dietary histamine is enough to cause symptoms because their histamine-degrading enzymes are insufficient.¹⁴ For this group, even a can of tuna that tests well below the 50 mg/kg regulatory limit could be problematic. The symptoms, flushing, headache, digestive upset, hives, can look identical to scombroid poisoning or even a food allergy, which makes the condition tricky to diagnose.¹⁵

Medications and Other Compounds That Lower Your Threshold

Your body normally handles moderate amounts of dietary histamine through enzymes that break it down, primarily diamine oxidase (DAO) in the gut. But certain medications and naturally occurring compounds in food can inhibit those enzymes, leaving more histamine to enter the bloodstream. Animal research demonstrated that simultaneous administration of inhibitors such as aminoguanidine, isoniazid, and certain biogenic amines like cadaverine and putrescine resulted in significantly more unmetabolized histamine reaching the bloodstream, and that pharmacologic inhibitors were more potent than food-derived ones.¹⁶

This matters practically because isoniazid is a common tuberculosis drug, and many other medications, including certain antidepressants and blood pressure medications, can affect DAO or monoamine oxidase activity. If you are taking any drug that inhibits these enzymes, you may be more sensitive to histamine in food than you would otherwise be. And the biogenic amines cadaverine and putrescine, which occur naturally in aged and fermented foods, can have an additive effect. Eating canned tuna alongside a meal that includes aged cheese or cured meats could compound the histamine load beyond what any single food would deliver.

How Canned Tuna Compares to Other Canned Fish

Tuna tends to carry higher average histamine than other commonly canned fish. The multi-product survey mentioned earlier found mean histamine of about 7 mg/kg in canned tuna, compared to roughly 4 mg/kg in canned sardine and about 4.7 mg/kg in canned anchovy.⁶ The difference traces back to the higher free histidine content in tuna muscle compared to most other species. All three types of canned fish in that study were well within safe limits, but tuna consistently comes in higher.

If you are managing histamine intolerance and looking for lower-histamine canned fish options, sardines and anchovies offer somewhat lower average levels, though neither can be considered truly “low histamine” in the way that freshly caught and immediately frozen white fish might be. The same caveat about cold chain management applies to all canned seafood: a well-handled sardine will have less histamine than a poorly handled one, regardless of species.

Cooking Method After Opening

Some people heat canned tuna before eating it, whether in pasta, casseroles, or melts. Research on the effect of cooking methods on histamine in tuna found that grilling increased histamine roughly five-fold, while boiling caused a slight decrease.¹⁷ The likely explanation is that grilling concentrates the fish by driving off water without dissolving histamine out, while boiling leaches some histamine into the cooking water, which is typically discarded. For someone trying to minimize histamine exposure, boiling the tuna and discarding the liquid is marginally better than dry-heat methods, though neither cooking technique will eliminate histamine that is already present.

Industry Testing and Rapid Screening

Regulatory agencies require histamine testing of commercially canned tuna, and the testing technology has become faster and more portable over the years. A study applying a rapid ELISA screening method to canned tuna used as an ingredient in commercial catering found it to be practical for quick quantitative checks.¹⁸ Italian researchers screened 165 samples of canned yellowfin tuna using a rapid test designed for field use.¹⁹ Lateral-flow immunochromatographic test kits, which work somewhat like a pregnancy test, have shown strong potential for onsite screening at fish processing plants and ports.²⁰

For consumers, home testing remains impractical. The rapid kits are designed for industry professionals and typically require sample preparation steps that are not realistic in a kitchen. A few enzymatic test kits marketed toward consumers have appeared online, but their accuracy outside controlled lab conditions is unvalidated. For now, the consumer’s best defense is buying from reputable brands in well-regulated markets, checking can integrity, refrigerating leftovers immediately, and being aware of personal risk factors like histamine intolerance or DAO-inhibiting medications. If a can of tuna produces symptoms like flushing, headache, or gastrointestinal distress within an hour of eating, the likeliest explanation is elevated histamine, and the episode is worth reporting to a doctor and to the retailer.