Rutgers Study Fails the Test
The Journal of Risk Research recently published a study from Rutgers University researchers entitled Sushi consumption rates and mercury levels in sushi: ethnic and demographic differences in exposure. The study warns that consumption of certain kinds of fish, including tuna, can lead to negative cardiovascular outcomes, purportedly due to methylmercurywhich occurs naturally in our oceans as a result of volcanic activity.
Unfortunately, the report is highly flawed on a number of fronts, and flies in the face of common sense, not to mention advice from governmental and health organizations, who stress we should be eating more fish to improve heart health. The American Heart Associations guidelines, for instance, include the recommendation to eat fish at least twice per week. The FDAs Dietary Guidelines for Americans echoes the recommendation to eat at least two to three servings (8-12 ounces) of fish per week. And research in the Journal of the American Medical Association specifically demonstrates that increased fish intake reduces the relative risk of coronary heart disease (CHD) death by 36 percent.
The real health crisis here is that Americans eat less than 15 pounds of fish a year, compared with more than 70 pounds of chicken, 100+ pounds of beef, and 600 pounds of dairy. Low consumption of the omega-3 fatty acids abundant in fish is the second-biggest dietary contributor to preventable deaths in the United States, taking a total of 84,000 lives each year. In fact, the FDA has suggested that 50,000 deaths from heart disease alone could be avoided through a diet rich in omega-3 fatty acids.
Put another way, the average American currently eats less than half of the weekly recommendation of seafood, and shoddy studies like this have the unfortunate effect of encouraging Americans to eat even less of it. Ostensibly in the name of public health, this sort of research will undoubtedly make the public less healthy.
Some of the most problematic aspects of the study:
- The studies authors looked at sushi consumption rates but did not record what kind of sushi (species of fish and quantity) respondents ate. Indeed, the researchers gave up on the task of making these distinctions because they found respondents were themselves confused about what kind of fish they were eating.
- The study therefore assume[s] that all meals are tuna sashimi (the dish with the highest measured mercury content) to compensate for ignor[ing] other fish intake in the study, meaning researchers essentially guessed at respondents fish consumption habits. The researchers go on to state that tuna sashimi they measured contained the most methylmercury of the samples they measured, and extrapolated from this purely hypothetical mercury levels in respondents. This is faulty analysis based on assumption, not evidence.
- The study relies on equally problematic research to support the claim that mercury may increase risk of cardiovascular disease (CVD). One infamous study cited by the Rutgers researchers looks at men from the Faroe Islands who eat high-mercury whale meatwhich is neither a fish nor a staple of the American diet. Much of that studys population had other, significant risks for CVD. On average, the participants were overweight or obese (BMI 27.4 +/- 3.2), and 58 percent were former or current smokers.
This last is perhaps the most troubling, becausethough the Rutgers study only briefly mentions CVD and relies on data that has no application to American dietsnearly all of the press mentions of the study highlight a purported link between mercury in sushi and CVD, leaving viewers and readers with a distorted and dangerous view of the facts.
But then, the studys authors themselves suggest that environmental activism, and not public health, is a prime motivation. In one passage, they write that although salmon is much lower in mercury than tuna, it should not be considered a substitute because farmed salmon entails other ecological problems. They then assert:
[I]t is important to point out that as fish consumption in general, and sushi consumption in particular are on the rise, the basic resource, the fish are not. Fish populations, even in the ocean, are being depleted. . . . Moreover, the growing appetite for sushi, particularly in Japan, has placed sushi-grade tuna species and particularly the Atlantic Bluefin Tuna in jeopardy. . . .
Is this a health study or environmental propaganda? The Rutgers study risks great harm in misguiding the public about the risks and benefits of eating fish. It would be worse still if its authors did so in the name of an environmentalist agenda.