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I love tuna and it's cheap. I have been eating it most days taking a sandwich to work. Is this a problem?
There's no doubt that tuna contains mercury and you do need to be cautious. When it comes to canned tuna for a long time it is has been felt that eating "light" tuna is safer as reported by the FDA. It has been thought that albacore contains more mercury and that this is the higher risk of canned tuna.
Because of the uncertainty it's probably best to limit the amount of tuna whether fresh or canned. Consumer Reports did some off the shelf research in 2006 showing that canned light tuna often had as much as 1/3 the amount of mercury as albacore.
The best rule of thumb for fish is to mix it up. Eat fish 2 - 3 times per week but don't eat the same fish more than 2 - 3 times per month.
One important consideration is for kids who should really limit tuna and other fish that are high in mercury to no more than a couple of times per month. The same holds true for women who are pregnant or who are trying to get pregnant.
Here's a link to more info:
Thanks for writing,
Timothy S. Harlan, M.D.