Friday, December 10, 2010

Is eating tuna bad for you?

Weighing the health benefits of eating seafood can be a confusing, to say the least. Last week, Consumer Reports produced an article that suggests that pregnant women and young children should avoid eating more than a small amount of tuna. Let's take a look at how they made their recommendation.

In the study, a total of 42 samples (including white or albacore tuna and light or skipjack tuna) were collected and mercury levels were measured by an independent lab. The results found that white tuna had 0.217 to 0.774 parts per million (ppm) of mercury, averaging 0.427 ppm. Light tuna had much lower mercury levels; 0.018 to 0.176 ppm, with an average of 0.071 ppm. None of the samples exceeded the Food and Drug Administrations mercury limit of 1ppm. However, Consumer Reports based its recommendation on the Environmental Protection Agency's reference dose (RfD) for mercury. This reference dose is the recommended limit for daily intake of mercury throughout an individual's lifetime.

Consumer Reports is recommending that at-risk populations (pregnant women and young children) avoid going over this limit so they should not consume more than 2.5 ounces of white (albacore) tuna or 5 ounces of light (skipjack) tuna a day is unsafe for at-risk populations.

Skipjack tuna is sold as "light tuna" and is relatively low in mercury
Health benefits of eating fish complicate the issue.  As many of us know, there are significant health benefits for eating tuna which are high in Omega-3 fatty acids. Experts suggest that individuals in the at-risk population consider focusing on eating fish species that are associated with low mercury thereby still getting the cardiac and developmental benefits of Omega-3's. 

All this information can make decision-making about seafood very complicated and you must seek out the best information and make your own choices. Here is a good news article from the medical community from WebMD Health News and a website from the American Heart Association that gives some additional information that you might find useful.

What do you think?


  1. Are there particular species of Tuna that are more "sustainable" than others? In other words, if eating Tuna won't kill us, and might make us more healthy, what should we look for to make sure we are making good decisions for the fish population/fishery industry?

  2. There are nine different species of true tuna (of the genus Thunnus, in the family Scombridae) and these species live in oceans all over the world. Many different fishing techniques are used to capture these tuna which are managed with varying degrees of effectiveness by both international and national regulatory agencies. We also have to consider that much of tuna biology that is critical to effective management remains a mystery to fisheries scientists. Oh, and one more thing, the status of all fisheries are changing constantly due to natural and fishing effects. For these reasons, a simple guide to sustainable tuna fisheries does not exist. There are many sources of information on the status of different tuna fisheries and many groups that offer their assessment of which fisheries are sustainable. We recommend that you look for these, but understand that many of their recommendations are glossing over important subtleties about the situation and may also be out of date. The one we recommend highest is FishWatch, produced by the National Ocean and Atmospheric Administration ( You can also get good information about tuna from the managing bodies themselves, such as ICCAT ( Overall, it's best to do your own investigation, ask questions, think critically, and to judge for yourself. Good luck!

  3. Some fish markets that are trying to support sustainable practices have decided to sell only "pole-and-line caught" tuna (see This is a fishing method that has a much lower impact on a fish population than purse seine, long-line or other methods that are less selective. As a consumer it's not always easy to know how your fish was caught, but if you ask at the restaurant or fish market - you may nudge people toward providing sustainable fish.....