by Marion Nestle
Apr 30 2014

The never-ending fish dilemmas

Mal Nesheim and I have an editorial in a recent issue of the American Journal of Clinical Nutrition: “Advice for fish consumption: challenging dilemmas.”

We commented on a research article evaluating blood mercury levels in adults eating seafood.

In it, we point out that

the 2010 Dietary Guidelines for Americans advise Americans to consume 8 ounces (227 g) of seafood per week to reach an average intake of 250 mg/d of the omega-3 fatty acids EPA and DHA.

This recommendation represents a substantial increase over current consumption amounts of ∼3.5 oz/wk. It is based on “moderate, consistent evidence” that the health benefits of increased seafood consumption outweigh the risks associated with methylmercury, a toxic contaminant of large predatory food fish (tilefish, shark, swordfish, king mackerel) and, to a lesser extent, albacore (white) tuna.

To avoid this toxin, the guidelines advise eating seafood typically found to be low in methylmercury, such as salmon, anchovies, sardines, and trout.

Such advice, however, leads to at least 3 dilemmas. Eating more fish might raise methylmercury intake above safe amounts. Pressures to consume more fish might place impossible demands on an already threatened seafood supply. And the obvious solution—fish farming—raises concerns about what farmed fish are fed and how farmed fish affects the environment.

We urge the 2015 Dietary Guidelines committee to take all this into consideration when making recommendations about fish consumption: “We hope that its advice for seafood consumption will help a confused public resolve some of these dilemmas and make wise seafood choices.”

Wise seafood choices may be an oxymoron, alas.

  • gattrell

    There is the issue of radiation in Pacific fish. The government won’t warn us to avoid it because of the economic stakes on the Pacific coast and Alaska. And there is the upcoming issue of GMO salmon. I fear for the environment because so many things could go wrong with that endeavor. Shipping the baby fish from Newfoundland to Panama leaves much to the whims of nature. I imagine bad weather or human error, and the Salmon ecology could forever be changed. Fish are very scary things right now. If I had a pond I would raise trout so I would know they were raised in a clean environment. But alas…

  • Novagene

    Wise seafood choices may be an oxymoron, alas.

    Plant seafood is healthful, humane, and very sustainable.

    Also quite savory.

  • misterworms

    I’ve decided that not consuming enough fish outweighs the risks of contamination. I grew up with a mouthful of mercury laden fillings and I live in a dirty city so fish are probably the least of my problems anyway. My family and I enjoy fish like wild salmon, sardines, wild mahi mahi, hake, and even some farmed varieties two to five times a week.

  • Eric

    I’m surprised that two issues are missing from this discussion.

    First, I thought that the latest thinking/research on the Hg in fish issue is that absolute mercury levels of fish are less important than the mercury-selenium ratio. If I recall correctly, this is because (i) when selenium binds to mercury we flush it rather than store it, and (ii) Se replenishes the antioxidant delivery that Hg uses up.

    Second, I thought that absolute levels of n3 intake matter less than the n3-n6 ratio of our overall PUFA consumption (who knows about n-9, which nobody ever seems to talk about). This would mean that farmed sources of high n3 fish, which have very high n6 levels and thus poorer n3-n6 ratios, are much less effective than wild caught sources of the same fish. I’d expect this to change the recommendations if true.

    Maybe research on these two issues is less established than I thought, or maybe it is too recent to be well disseminated. Fwiw, I couldn’t tell if the editorial discusses them because the link didn’t work.

  • Rand Thomas Santor

    I understand your criticism, however I’m not seeing an alternative solution. Where can people expect to consume adequate amounts of omega-3s if not from fish? Other sources of omega-3s contain mostly ALA and our body is not efficient at converting it to EPA and DHA, rendering those sources inadequate to meet our needs. To me, the encouragement of consuming fish is sound knowing this information, less we resort to relying on supplements to obtain enough omega-3s.

  • The Dish on Fish

    It should be noted that the 2010 DGA did look into the issue of seafood health and safety, extensively. They answered the questions “What are the effects of maternal dietary intake of n-3 fatty acids from seafood on breast milk composition and health outcomes in infants?” and “What is the relationship between consumption of seafood n-3 fatty acids and risk of cardiovascular disease?” and “What are the benefits in relationship to the risks for seafood consumption?” by reviewing 37 studies and concluded that the overall effect of eating seafood – traces of mercury and all – is a heart and brain health benefit. Similarly, the 2011 FAO/WHO report, which reviewed 150 studies and articles, recommends experts charged with giving seafood advice emphasize the benefits of eating seafood along with the risks of avoiding fish. Just like we are moving away from nutrient-based recommendations to food-based guidance, we need to give advice based on the health effects of eating (or not eating) fish as a whole food, not any one component of fish in isolation.


    Jennifer McGuire, MS, RD
    National Fisheries Institute

  • Ervin

    I love seafoods. I can consume seafoods for the whole week. Its healthy and you can cook in any menu you want.

  • MaryFinelli

    Regarding seafood and Food Politics, the column’s conclusion is not surprising. In addition to the valid concerns about mercury, there are also such toxins as dioxins and PCBs to take into account, along with cholesterol and saturated fat. Considering the high rate of illegal fishing; the rampant mislabeling of seafood; the extent of human slavery within the fishing industry, the appalling numbers of birds, turtles, dolphins, whales, seals, fish and other nontargeted animals caught and killed by fishing gear; and the fact that fish and other aquatic animals have been shown to be able to suffer fear and pain and are cruelly obtained and horrifically killed, should put any responsible person off of animal-based seafood.

    The great news is that vegan seafood is available, affordable, healthful and delicious. Recipes, products and more can be found on the Vegan Seafood Resources page of the Fish Feel website.

    Mary Finelli
    President, Fish Feel

  • MaryFinelli

    Rich sources of healthful, humane and environmentally responsible omega-3s include walnuts, flaxseed oil and freshly ground flaxseed, soy products, chia seeds, and algae supplements – algae being the source from which fish obtain omega-3s.

  • KristenParks

    It seems like a no-brainer to me to avoid eating seafood. There are plenty of other sources of omega-3s, including supplements and fish oil capsules (which are safe from contamination).

  • 360CompleteLiving

    Mercury adulteration is a very critical part in fish consumption. The source and storage of fish matters a lot. thats why it is advised to not to include fish during pregnancy.