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Qu: I eat lots of tuna, is this good? What other fish is good to eat.
When it comes to weight loss or muscle gain tuna is one of the staples (for those who can stomach it). Tuna is a very high, lean source of protein which makes it useful for body builders and dieters. It's super convenient, with one large can providing the level of protein that the body can deal with at once.
The composition of tuna (fats, protein, carbs) is dependent on how it's packaged and what with. Tuna in oil will have a far higher fat and Vitamin D content than tuna in brine or water. Flavoured tunas will also contain more sugar or fat depending on the flavour. The packaging can also determine composition also.
Generally speaking, one large tin of tuna contains around 30g of protein and 100mg of Omega 3's. There is no RDI, but the defined ‘adequate intake' of omega 3's is 160mg for women and 90mg men, so the Ω-3 fat in tuna is just right.
There is concern around the levels of mercury in fish - here is an excerpt from the FSANZ website:
"Mercury occurs naturally in the environment and accumulates in the aquatic food chain, including fish, as methylmercury. This means all fish will contain some methylmercury. Because of this, fish is the main source of methylmercury in the diet for most people . The amount of methylmercury in fish depends on how long the fish lives and what it eats. The big, long living or predatory fish, such as swordfish and shark/flake, tend to accumulate higher levels of methylmercury"
Tinned tuna usually consists of the smaller younger fish, so mercury levels are low. The 2006 NZ Total Diet Survey found that mercury exposure was well below acceptable levels. A study from the Journal of Food Science in 2004 showed that mercury levels from tuna in oil ranged from 174 - 191 ppb, while "light tuna in water" ranged from 42-63ppb, which is well below the FDA's Action Level of 1000ppb.
As with anything, moderation is the key, and if you're eating tuna at EVERY meal, then you will be missing nutrients from other protein sources and increasing your risk of mercury overload.
There has been comment that the double cooking of tuna (before canning and after canning), depletes its nutritional value - I couldn't find conclusive evidence on this, but certainly excessive heating of oils make them susceptible to damage and B-Vitamins are depleted in processing also.
The Ω-3 amount listed on the tin of tuna is the level after processing. Other tinned fish you may like to try: salmon, mackerel and sardines. All are great sources of Ω-3 oils and Vitamin D.
Sardines in particular are a fantastic source of calcium. Fresh fish is always nice (if you‘re into it), but again can lose nutrients in the cooking process, and again the bigger and older the fish, the higher the mercury content. 200g of hoki has 30g of protein, the same as a large tin of tuna, most other fish are around 120-150g for 30g of protein.
When it comes to using fish for our weight loss or muscle building goals, tinned, frozen or fresh is perfectly fine and really only dictated by personal preference and taste.
Stacey
6 Apr 10
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