The rule of thumb for a while now has been one tin a week is safe, even for pregnant and nursing mothers. Medical News Today has just published a handy guideline that shows just how much tuna is safe to eat by bodyweight, and their safe levels are a bit different, so be sure to check them out.
Using figures taken from US Food and Drug Administration's (FDA) test results for mercury and fish, and the Environmental Protection Agency's (EPA) findings for safe levels of mercury, MNT suggests that a 150-pound person should not consume a can of white albacore tuna more often than every 9 days, and one can of chunk light tuna more than every three.
You can find their chart showing body weights from 20 to 150 pounds, here.
Mercury may not be the only thing of concern. Bluefin tuna caught off the coast of California two years after the earthquake-triggered leak at Japan's Fukushima Dai-ishi nuclear plant show traces of radiation.
Scientists note the levels allow us to trace the extent of the effects of the Fukushima leak, but that radiation is present in all food we eat, and the levels in the fish are not of concern, as a food source.
Food for thought.
If you're looking for options, there are numerous other tinned fish available, and other sources of protein, so you can choose from a wide variety.
Once opened, it's best to recycle the tin and store its contents in your lidded containers in the fridge.