Which tuna is better for your health?

Canned tuna, along with sardines, seems to be one of those fish varieties you see more in the can than in the flesh. 

Maybe that’s because fresh tuna can be eye-wateringly expensive and those tiny cans come in at under $2 on special.

But what provides better health benefits – tuna in oil or tuna in water? You’d think the water option, but the answer is … it depends.

Tuna in oil vs Tuna in water

If it’s your weight that’s a concern it’s no contest. A small can of tuna in water contains 289 kilojoules while the one in oil totals 591kj.

If it’s those omega-3 fats so good for your health you are after, you’d think the one in oil  would be better. But the oil in cans isn’t fish oil, but canola sunflower or olive oil.

Read: How the Mediterranean diet can save your health and the planet

When you drain the tin of the oil, all the fish oil drains with it as it has mixed with the surrounding oil.

Drain a can of tuna in water, and much of the oil – and all that omega-3 goodness – stays in the fish.

But, there’s always a but, if you are looking to boost your vitamin D or selenium levels, oil-packed tuna is better.

Regardless of what you are looking for in your can of tuna, serving size is the key.

Should you be worried about the mercury content?

The bad news is that as a larger fish species, tuna carries a high mercury load. The good news is that the species used for canned tuna are generally smaller and younger, so there is less risk.

Read: Jamie Oliver’s tuna carpaccio

Lab tests run by the ABC’s Catalyst program found you would have to eat anywhere between 25 and 35 small tins a week before you hit maximum mercury levels, so a couple of tins a week should be fine.

In fact, according to Food Standards Australia and New Zealand, it’s safe for everyone, including pregnant women, to consume canned tuna. And it has lower levels of mercury than fillets.

The history of tuna

Health concerns aside, canned tuna has an interesting history, and possibly a sad future.

Tuna has been fished in the Mediterranean for 2000 years but due to their nature as generally ocean-going fish, with big migrations over large areas, it wasn’t until industrial levels of fishing became viable that tuna became accessible to more people.

You need to go a long way to catch them and an equally long way to get them back to land, so large ships with freezing facilities are needed to fish them with any regularity.

Tuna’s high fat content and relatively high body temperature also means it spoils easily, so before flash freezing it was considered a bit of a rubbish fish. 

Read: Jamie Oliver’s tuna carpaccio

Tuna became more popular during WWII when general shortages meant people became less fussy about what they were eating and tuna’s suitability for canning made it perfect for troop rations.

Sadly, like many large fish species, tuna populations are over-exploited and face “severe and alarming stock declines”, according to the World Wide Fund for Nature (WWF). 

And it’s not just tuna. The fishing methods also snare large amounts of ‘by-product’ including shark, dolphin fish, manta rays, turtles, whales and dolphins that are all thrown back into the water, dead. 

Do you eat a lot of canned tuna? What’s your preference? Fresh or canned? In water or oil? We’d love to hear why in the comments section below.

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