Dieting & Canned Tuna: Confessions of a Food Safety Worrier


I seem to be on a food safety jag these days. I don’t think I’m looking for things to worry about, but I do keep running into a lot of articles about the subject in the professional journals I read. The one that grabbed my attention this week is about fish and mercury content. I posted a note about fish and mercury on this blog several months ago, but I totally forgot about it. So assuming many of you did, too, I thought I write again on the subject.

The dieters and ex-dieters among us surely remember (and may still partake of) those endless lunches of canned tuna sans mayo over lettuce. Canned tuna was a simple lunch and fairly satisfying, if you liked it. Plus, tuna and other fish seemed to be just the food to help us reach healthy weights – rich in protein with the right kind of dietary fat that made the American Heart Association recommend eating fatty fish twice a week for heart health.

But in recent years, we’ve been warned away from eating too much tuna and other high-fat fish because of its mercury content. Which, of course, made me worry how much mercury my body had accumulated from those years of tuna lunches (and dinners). I don’t have any answer for that except to think that I should probably get tested to put my mind at ease, or to find I need to take some steps to detoxify – whatever those steps are. I have no idea.

Aside from airing my neuroses, I thought readers might appreciate a look at how different fish rank in mercury content, as listed in an article in Nutrition Reviews titled “Too Much of a Good Thing? Update on Fish Consumption and Mercury Exposure.” It was written by two seemingly credible folks – a professor with the Program in Neuroscience and the Department of Nutrition, Food & Exercise Sciences at Florida State University, and another PhD with the Florida Department of Environmental Protection.

It appears you can’t access the journal online without a subscription so I’ll just repeat the bottom line here. It lists tilefish from the Gulf of Mexico (also known as golden snapper), mackerel from the Gulf (also known as gulf king mackerel), shark and swordfish as fish that should not be eaten by men or women (based on a 154-pound man and 110-pound woman. Women weighing 100 pounds or less also apparently should avoid grouper, orange roughy and marlin. If your weight is higher, you can probably feel safe eating those latter fish, but I wouldn’t recommend anyone eating the others, even if you do weigh more than 154 pounds.

Other fish – including tuna – appear to be okay to eat especially if fish is eaten in 3-ounce portions not more than twice a week. If fish is eaten daily, fresh and canned albacore tuna falls off the list of okay to eat, as well as bluefish, Pacific croaker, saltwater bass, halibut, sable, snapper, monkfish, Spanish and south Atlantic mackerel and Atlantic tilefish.

Fish that are low in mercury (listed from lowest to highest) include whiting, ocean perch, fresh salmon, tilapia, sardines, freshwater haddock, freshwater trout, herring, mullet, catfish, Atlantic croaker, flounder/sole, North Atlantic mackerel, Pollack, squick, shad, whitefish, Pacific mackerel, cod, canned light tuna. Lobster ranks up with bluefish in its mercury content, so it shouldn’t be eaten daily by women (as if). Crab, crawfish, oysters, shrimp, clams and scallops are all fairly low in mercury.

Hope this post gives you some good info and doesn’t warn you off fish altogether! The authors of the journal article did conclude that the AHA recommendation to eat at least two 3-ounce servings of fish a week was supported by their review. They conclude with this recent advisory from the Environmental Protection Agency:

1) Do not eat shark, swordfish, king mackerel or tilefish.
2) Eat up to 12 ounces (two average meals) a week of a variety of fish and shellfish that are lower in mercury; and
3) Check state advisories about the safety of fish caught by individuals in local lakes, rivers, and coastal areas. If no advice is available, eat up to 6 ounces (one average meal) per week of fish you catch from local waters, but do not consume any other fish during that week.

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About the Author

Marsha Hudnall, MS, RDN, CD

If you’re looking for an embodiment of dedication disguised as obsession, look no further. Marsha is a registered dietitian who has spent the last four decades working to help women give up dieting rules and understand how to truly take care of themselves. Her mission in life is to help women learn to enjoy eating and living well, without worries about their weight. She encourages women to embrace their love of food, which you might call being a foodie. If so, it’s appropriate because being a foodie means you pay attention when you eat. That’s a recipe made in heaven for eating well. Marsha is the President and Co-Owner of Green Mountain at Fox Run.

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