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Should Pregnant Women Eat More Tuna?


4 Star

Should Pregnant Women Eat More Tuna?

Our Review Summary

The story provides an overview of the debate on whether pregnant women and nursing mothers should eat tuna — which is high in omega-3 fatty acids and other nutrients that are important to prenatal and infant development, but which can also contain relatively high levels of mercury. The debate has come back to the fore after the 2015 Dietary Guidelines Advisory Committee submitted its scientific report to the U.S. Department of Health and Human Services and the U.S. Department of Agriculture last month. The committee called on EPA and the FDA to “re-evaluate their current recommendations for women who are pregnant (or for women who may become pregnant) or breastfeeding to limit white albacore tuna to not more than 6 ounces a week.” The story does not take a position on increasing tuna consumption, but offers a concise summary of the arguments for it and against it.


Why This Matters

Few subjects are as emotionally loaded as those pertaining to what a mother could or should do to protect the health of her children during and after pregnancy. And there is a great deal of (often conflicting) guidance for new and expecting mothers on what they should eat. That’s particularly true for tuna, which can be a source of both much-needed nutrition (which is good) and high levels of mercury (which is bad). In the case of mercury, exposure during pregnancy can affect a child’s cognitive thinking, memory, attention, language, and fine motor and visual spatial skills. But a diet that doesn’t provide adequate nutrition during pregnancy, such as insufficient B vitamins, can increase the risk of low birthweight in infants and a range of other adverse health effects for babies and mothers. This story offers is a good starting point for women and medical professionals who want to educate themselves on the subject. It would be even better if it compared the nutritional value and health effects of tuna with other types of fish (such as salmon or sardines — which are mentioned in the story).


Does the story adequately discuss the costs of the intervention?

Not Applicable

The gist of this story is to compare the health effects of tuna vs. other types of fish during pregnancy. We don’t think there’s a significant cost difference between tuna and most other types of fish — at least not one that we’d expect to see addressed in an article like this. So while the story could have mentioned the relatively high cost of seafood compared with other nutrient-rich foods, we won’t penalize it for not addressing the cost of tuna. We’ll call it Not Applicable.

Does the story adequately quantify the benefits of the treatment/test/product/procedure?

Not Satisfactory

The story explains that fish are rich in nutrients that “are particularly important for brain development in fetuses and nursing infants,” and discusses a 2005 study that found a link between fish consumption in general by pregnant women and how well their children later scored on visual recognition memory tests. While that’s useful context, the story is specifically about tuna and the supposed fact that tuna is a “special case” — i.e. a high-mercury fish that doesn’t require strict consumption limits. Quoting the Dietary Guidelines Committee, the story says that “all evidence [for tuna] was in favor of net benefits for infant development and (cardiovascular disease) risk reduction.” But what specifically were those tuna-related benefits? Why should we make an exception for tuna? The story would have been stronger if it had quantified these tuna-specific benefits, and discussed the nutrient profile that makes tuna different from other fish.

Does the story adequately explain/quantify the harms of the intervention?


The story does discuss the aforementioned 2005 study, which found that a baby’s score on visual recognition memory tests was affected by the amount of mercury in the mother during pregnancy, so we’ll give it a pass. However, the story would have been better if it had — even briefly — addressed the full suite of possible health risks associated with mercury exposure during pregnancy. Also, the story discusses the findings of the 2005 study by referring to mercury measured in parts per million, but discusses mercury levels in tuna in terms of micrograms per ounce. It would have been great if the story had used the same units of measurement in both cases, so that readers could understand the significance of the 2005 study’s findings in regard to levels of mercury actually found in tuna. (A back-of-the-envelope calculation finds that if six ounces of tuna contains 60 micrograms of mercury, the mercury is present at a level of about 0.35 parts per million. But the story could have cited an expert.)

In addition, while the story does briefly discuss the advantages of eating fish, it does not really address the potential harms of not getting adequate amounts of omega-3 fatty acids or other nutrients found in tuna and other fish.

Does the story seem to grasp the quality of the evidence?


The story cites the 2005 study on the benefits (and risks) of fish consumption during pregnancy. It also links to the relevant report from the Dietary Guidelines Advisory Committee, and to the current FDA and EPA advisories on fish consumption. Overall, we think the treatment of the evidence was satisfactory, but we’d like to have seen more detail. As noted above, we’d like to see the evidence suggesting that tuna specifically is better for health than other fish species. And while the 2005 study is a good example, it’s just one small piece of evidence among many that have been collected on this topic. What kinds of studies are these? What are their strengths limitations? Delving deeper into those details would perhaps help illuminate why there’s so much controversy on this topic.

Does the story commit disease-mongering?


No disease mongering here.

Does the story use independent sources and identify conflicts of interest?

Not Satisfactory

The story quotes only three sources. Two of the sources are members of the Dietary Guidelines Advisory Committee, which released the very report they were asked to comment on. One of those two sources is Alice Lichtenstein. While the story tells readers that Alice Lichtenstein is “senior scientist and director of the Cardiovascular Nutrition Laboratory at Tufts University,” it failed to note that she is also the vice chair of the Dietary Guidelines Advisory Committee. The third source is a co-founder of the Mercury Policy Project, which is a longtime advocate for limiting mercury exposure. Input from an outside expert on prenatal or pediatric nutrition would have been great.

Does the story compare the new approach with existing alternatives?


The story notes that health officials recommend fish that “are lower on the food chain and have accumulated less mercury in their tissue,” such as sardines and salmon. The story also states that salmon contains significantly less mercury than tuna, and lists other types of seafood that are recommended by Consumer Reports as being low in mercury. We’ll call that good enough for a satisfactory rating. The story could have mentioned other factors — for example, reading aloud to your child — that are also associated with improved childhood brain development.

Does the story establish the availability of the treatment/test/product/procedure?

Not Applicable

The story does not address the availability of tuna fish. However, most readers can be expected to be familiar with canned tuna, which is widely available.

Does the story establish the true novelty of the approach?


The story makes clear that the debate over tuna consumption by pregnant and nursing women is longstanding, and points to the new report from the Dietary Guidelines Advisory Committee as the reason for renewed interest in the issue.

Does the story appear to rely solely or largely on a news release?


The story does not appear to draw on a news release at all.

Total Score: 6 of 8 Satisfactory


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