How many times have your meals been saved by a pack of canned tuna? Nutritious and inexpensive, canned tuna is a brilliant invention from the Florio family that allows you to quickly create dozens of delicious recipes. However, canned tuna is often associated with mercury contamination, which unfortunately is present not only in this species but in many seafood products along with a host of other heavy metals. So is eating canned tuna dangerous?
Absolutely not, there are reference limits that we will now explain to you, which can allow you to consume canned tuna without any kind of danger, provided of course you learn to recognize the best quality.
Does Canned Tuna Really Contain Mercury?
Let's get this straight: yes, canned tuna contains a minimal amount of mercury, but its concentration is so far below the safety limit that, to suffer from mercury poisoning, you'd have to eat something like 60 cans a week.
The presence of mercury in tuna, however infinitesimal, is not related to the type of packaging, processing, or preservation method. Unfortunately, it depends on the fish itself, which, living in contaminated seas, accumulates mercury in its bodies in the form of methylmercury.
Several studies have shown that mercury is currently found in all oceans (the situation has not improved in the last 50 years despite all efforts) and is therefore consequently present in many types of fish: partly it is an element found in the environment, but for the most part it is a contamination caused by pollution caused by humans.
In general, larger fish tend to accumulate higher mercury levels than smaller ones (since, by feeding on them, they also absorb their heavy metal contamination), and tuna, given its size, falls into this category.
Please remember that mercury is highly toxic to the human body, as it accumulates in red blood cells and therefore easily enters the bloodstream. However, it must be ingested in large quantities to be dangerous, which is why specific safety limits have been established within which the consumption of fish, even minimally contaminated, does not pose a risk.
The Maximum Limits Established By The Legislation
The currently established safety values, both for mercury intake and for mercury content in fish species used in food chains, were established by a joint FAO-WHO Committee. Based on a series of studies, the tolerable weekly intake limit for mercury is 0.3 mg for a 60-kg adult (1.6 µg of methylmercury per kg of body weight).
In the United States, mercury limits in fish are regulated by the U.S. Food and Drug Administration (FDA), which sets action levels for contaminants in seafood to protect consumers. For methylmercury, the FDA has established an action level of 1.0 parts per million (ppm) in fish and shellfish, which is equivalent to 1 mg of methylmercury per kg of fresh product. This limit applies to commercially sold seafood and is used to determine when products should be removed from the market due to excessive mercury levels. The FDA also provides consumption guidance to help consumers choose fish that are lower in mercury while still benefiting from their nutritional value.
An FDA's TDS Study Ensures the Safety of Canned Tuna
In the United States, an important monitoring is carried out by the FDA through its Total Diet Study, which analyzes common foods — including canned tuna — to assess levels of contaminants such as methylmercury. Independent organizations such as Consumer Reports have also conducted tests on popular canned tuna brands, finding differences in mercury levels depending on the species used and the product type, particularly between light tuna and albacore tuna. These studies help inform FDA recommendations on safe seafood consumption and consumer choices.
The research found that the samples showed methylmercury levels ranging from 0.026 to 0.253 mg per kg of body weight, with an average value of 0.099 mg/kg. This confirms the absolute safety of canned tuna: the presence of the heavy metal is well below the limits set out in the previous paragraph. So, don't worry; you can safely consume canned tuna without any risk in your daily life.
The only caution is reported by the Food and Drug Administration regarding the consumption of large fish, both fresh and canned, for pregnant or breastfeeding women: in this phase, in fact, methylmercury is more absorbable and could penetrate the placenta or reach the mammary glands, endangering the fetus and child.
In particular, as reported in the useful table contained in the article, it is best to avoid larger tuna (for example, bluefin tuna) and other very large fish, while there is no problem with the consumption of smaller breeds of tuna such as the yellowfin species, which absorbs a very minimal amount of mercury.
But how many times a week is it best to consume canned tuna? Due to the possible presence of heavy metals, according to the official ARS (USDA Agricultural Research Service) guidelines, the ideal consumption frequency is a maximum of once a week (a standard portion is approximately 50-80 grams of drained product, equivalent to one large or two small cans for adults).
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