Can you eat too much tinned tuna?

Tinned tuna is a popular and affordable lunch option, often consumed daily by many Australians. While it is generally considered a nutritious choice, high consumption may raise concerns about mercury intake, particularly during pregnancy and early childhood. Mercury is a naturally occurring element that can accumulate in fish, with larger predatory fish generally containing higher levels due to their longer lifespan.

However, tinned tuna sold in Australia typically comes from smaller species, such as skipjack and yellowfin, which contain lower mercury levels compared to larger predatory fish like shark, swordfish, and certain marlin. The safety of mercury consumption is determined by the provisional tolerable weekly intake (PTWI), which varies by age and pregnancy status. For adults, the PTWI is 3.3 micrograms per kilogram of body weight per week, while pregnant women should limit their intake to about half that amount.

Research suggests that a small 95g can of tuna contains approximately 13 micrograms of mercury. For a 70kg adult, consuming one can of tuna per week would provide less than 6% of the recommended weekly limit, whereas daily consumption over a week would account for around one-third of the limit. For a four-year-old weighing 20kg, one can of tuna per week would use up about one-fifth of their weekly mercury allowance, translating to approximately 20% of their limit.

Overall, the likelihood of experiencing mercury poisoning from regularly consuming tinned tuna is extremely low for most Australians. Instead of avoiding tinned tuna due to mercury concerns, it is advisable to incorporate it as part of a diverse protein-rich diet, alongside other sources of nutrients such as eggs, legumes, lean meats, tofu, nuts, and seeds. This approach ensures a balanced intake of essential nutrients necessary for optimal health.