Can you eat too much tinned tuna?

Nazar Rybak/Getty Images Tinned tuna is a lunchbox staple for many people.

It’s affordable, high in protein and doesn’t need cooking, making it a nutritious and convenient option for busy days.

But if you’re eating tuna most days, you might have wondered whether it’s possible to have too much.

Or perhaps you’ve watched your child happily eat a tuna sandwich every day for a week and wondered if that’s too much of a good thing.

The concern usually comes down to mercury .

Mercury can be harmful in high amounts , particularly during pregnancy and early childhood.

But the amount of mercury in seafood varies considerably between species – and that’s where much of the confusion begins.

For most Australians, the evidence on tinned tuna is reassuring.

Let’s unpack this.

Why does tuna contain mercury? Mercury is a naturally occurring element in the environment.

It enters rivers and oceans through natural processes , such as volcanic activity and weathering of rocks, as well as from some industrial activities.

In water, bacteria convert mercury into a form called methylmercury.

Fish absorb it from the water and food they eat.

When larger fish eat smaller fish, the mercury builds up inside them over time.