Super-convenient and high in protein, canned tuna is a go-to snack for many – but is it healthy? Nutritionist Nicola Shubrook investigates...
What is tuna?
Tuna is a saltwater fish related to mackerel. There are around eight different commercial varieties that range in size from the small skipjack to the large bluefin – it’s one of the most eaten fish in the world.
Tuna can be eaten fresh; either raw or cooked, and canned (which is always pre-cooked). Canned tuna in the UK can be bought in brine, spring water, sunflower or olive oil.
Nutritional benefits of canned tuna versus fresh tuna
From a macronutrient point of view, there isn't a great deal of difference in the amount of protein or fats when comparing canned tuna in brine to fresh tuna. Fresh tuna is naturally higher in protein and also has a few more calories. There are no carbohydrates in any form of tuna.
100g of canned tuna in brine has 25g of protein, 1g of fat and 109 calories, whereas 100g of fresh, cooked tuna has 32g of protein, 1g of fat and 136 calories.
The difference comes when you buy canned tuna in oil as, whilst protein levels are the same, the fat content jumps up to almost 7g per 100g and the calories increase to 159 calories per 100g.
Looking at the micronutrients, tuna is a good source of B vitamins – especially niacin which is good for the nervous system and skin. As well as this, tuna contains calcium, which supports healthy bones and muscle contractions, magnesium, which is required for energy, and vitamin D, which supports the immune system, bone strength and brain function. Fresh tuna has double the amount of vitamin D compared to canned tuna, per 100g
The other main difference is that canned tuna is a lot higher in sodium than fresh tuna, with over 300 per cent more salt per 100g. Fresh tuna has around 70mg per 100g, canned tuna in brine contains 293mg and canned tuna in sunflower oil has over 365mg per 100g. The recommended daily allowance of sodium for adults is 2.4g.
What are the common concerns about buying tuna?
One of the biggest challenges globally is the sustainability of tuna. Several tuna stocks are currently overfished, both wild and farmed, meaning that adult fish are being caught faster than they can breed. In the UK, bluefin tuna has all but disappeared from our seas and is currently illegal to catch.
Therefore, it’s important when buying fresh or canned tuna, to look for the MSC label (which stands for the Marine Stewardship Council Fisheries Standard), so you know it’s certified sustainable.
What about mercury levels in tuna?
There has been some correlation with people who consume too much tuna and high mercury levels. Research suggests light and skipjack tuna are lower in mercury than larger species such as bigeye and albacore.
The NHS recommends that if you’re pregnant, or trying for a baby, you should not eat more than four cans of tuna, or two tuna steaks, per week. Otherwise, tuna is fine to eat as part of a balanced diet.
How to include tuna as part of a healthy diet
Tuna is a great source of protein and can be eaten for lunch or dinner as part of a healthy diet.
Fresh tuna is best eaten lightly baked or seared and served alongside salad or vegetables. If you like raw tuna, it can be thinly sliced and eaten as sashimi.
Tuna can be enjoyed at least once a week as part of a healthy diet, alongside vegetables and a small amount of starchy carbohydrates such as bread, potatoes, rice or pasta.
Why not try some of our healthy tuna recipes?
Storecupboard tuna bean salad
Tuna & butterbean salad
Lemon spaghetti with tuna & broccoli
Two bean, potato & tuna salad
Tuna steaks with cucumber relish
Sesame tuna steaks with Asian slaw
Tuna, avocado & pea salad in Baby Gem lettuce wraps
This article was published on 25 June 2020.
Nicola Shubrook is a nutritional therapist and works with both private clients and the corporate sector. She is an accredited member of the British Association for Nutrition and Lifestyle Medicine (BANT) and the Complementary & Natural Healthcare Council (CNHC). Find out more at urbanwellness.co.uk.
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