Presentations by top researchers suggest fish benefits far outweigh risks
by Randy Hartnell and Craig Weatherby
Last week, we journeyed to Washington D.C. to attend a landmark scientific conference titled “Seafood and Health '05: Issues, Questions and Answers.”
Much of what we heard served to confirm or expand the previously documented health benefits of marine omega-3s in heart health, child development, adult brain health, autoimmune diseases, inflammation, weight control, diabetes, and more.
And, we learned a great deal about the science underlying the issue of mercury in seafood. Some advocacy groups issued post-conference press releases asserting that the agenda downplayed mercury concerns. We attended every relevant presentation, and saw no attempt to present an imbalanced picture.
Bill Hogarth, Ph.D., director of the National Marine Fisheries Service—a division within the National Oceanic and
Atmospheric Administration (NOAA)—summarized the import of the existing evidence this way: “The scientific evidence explored today is clear and solid: eating more fish and shellfish will lead to a healthier, smarter and longer-lived U.S. population. While there are risks associated with everything we consume, the health benefits gained from omega-3 fatty acids in fish and shellfish far outweigh the risks from contaminants for the vast majority of the population.”
However, the several presentations regarding mercury in fish sparked lively debates during question and answer periods. Some advocacy groups issued press releases asserting bias in the agenda, and a downplaying of the dangers of mercury. We attended every relevant presentation, and perceived no attempt to present an imbalanced picture.
The conference drew researchers who could illuminate the latest research findings. We hope the gathering will help influence attempts to balance the documented developmental benefits of seafood with the risks a few species higher in mercury may pose to young children's growing brains.
Interestingly, even the speaker most concerned about increasing the frequency and effectiveness of mercury warnings to pregnant/nursing mothers and young children—Caroline Smith DeWaal of the Center for Science in the Public Interest (CSPI)—expressed no particular concerns about fish consumption by older children or adults.
The conference was sponsored by NOAA and its National Marine Fisheries Service, as well as the fisheries ministries of Norway, Canada and Iceland, and the United Nations Food and Agriculture Organization.
Omega-3 benefits confirmed, expanded
The most exciting news fell into three main categories. We'll expand on each topic in future issues of Vital Choices. Much of the information—presented on PowerPoint slides— was complex, and presented too rapidly to record it all in our notes, which focused on speakers' side comments. Here's a brief overview of some of the most important presentations, which we'll cover in greater depth once we've received our post-conference packets, including each presenter's detailed slide show.
The conference program featured presentations from three leading researchers in the field of cardiovascular disease (CVD) and public health:
- William S. Harris, Ph.D. is a leading cardiac and fatty acids researcher and co-author of the American Heart Association's 2002 Scientific Statement on Fish Consumption, Fish Oil, Omega-3 Fatty Acids, and Cardiovascular Disease.
- Eric Rimm, Sc.D. is Associate Professor of Epidemiology and Nutrition at the Harvard School of Public Health's Department of Epidemiology
- Dariush Mozaffarian, M.D., M.P.H., is an instructor and researcher at the Channing Laboratory, jointly operated by Brigham and Women's Hospital, Harvard Medical School, and the Harvard School of Public Health. This lab manages the famous Nurses' Health Study, which examines links between women's diets and their long term health.
On the last day of the conference, the Environment News Service (ENS) released an accurate summary of the cardiac experts' presentations, which encompassed recent research findings: “Eating seafood [regularly] reduces risk for sudden death due to heart disease—the primary killer of Americans—by up to 90 percent… eating a small amount of seafood high in omega-3 fatty acids... daily can cut the risk of death due to heart disease by 20 percent.…”
We heard Drs. Rimm and Mozaffarian expand further on the cardiac benefits of omega-3s.
According to Dr. Rimm, “The reductions in cardiovascular disease seen in epidemiological [population] studies could be greater if people shifted their fish consumption to oily species low in contaminants.”
And Dr. Mozaffarian noted, “The reduction in sudden death [from omega-3s in the diet] is around 50 percent. That's better than any drug or surgery we have.”
Drs. Rimm and Mozaffarian also denounced the detrimental effects of confusing, overblown seafood-contamination campaigns conducted by some consumer and environmental groups.
Dr. Rimm put the point this way: “Unfortunately, reports focused on scares tend to dissuade people from eating fish altogether, when the benefits of seafood outweigh the risk much more often than not. ‘Scare' campaigns can do a disservice to the public because they cause confusion and discourage fish consumption at a time when Americans are at historic risk for coronary heart disease.”
Dr. Mozaffarian was blunter. During a freewheeling floor debate on the risk-reward controversy, he suggested that science-driven proponents of higher seafood consumption could adopt the slogan “Fish Scares Kill.”
The FDA recommends that Americans eat at least eight ounces of seafood every week. But a new national study by the University of Maryland indicates that only 17 percent of Americans meet this guideline, while 11 percent eat no fish at all.
Child brain development
One of several compelling presentations came from psychology researcher Peter Willats, Ph.D. of the University of Dundee, Scotland. Dr. Willats summarized the findings of recent research—much of it presented in prior issues of Vital Choices—showing that infants who consume ample amounts of omega-3 fatty acids through breast milk or supplemented formula enjoy enhanced brain function as they reach toddler-hood and beyond.
Much of what we learned on this topic came from Commander Joseph Hibbeln, M.D. of the National Institutes of Health: a renowned researcher who has explored deeply the connection between omega-3 intake and mental health. His findings dovetail with others indicating that the long-chain omega-3s from fish play a key role in brain health, especially in the growing years, and may help alleviate certain mental conditions.
Fatty acid balance: omega-3s versus omega-6s
William Lands, Ph.D. is widely considered the world's most eminent expert on this topic, and his presentation served to highlight the dangers of the extreme excess of omega-6s in the standard American diet. Dr. Lands mentored several of the renowned researchers who spoke at the conference, and their high regard for his work was apparent throughout, with his name cropping up repeatedly during presentations. We will delve deeply into his presentation once we receive his highly detailed slides.
Mercury controversy makes waves
Lake fish in certain regions—and, to a far lesser extent, ocean fish—are the leading sources of potential exposure to “methyl” mercury. This form of mercury is more toxic than elemental mercury (i.e., the “quicksilver” in old thermometers), but it occurs at significant levels only in the flesh of a few commercial ocean species: specifically, swordfish, shark, Gulf tilefish, king mackerel and the older, larger “light” and albacore tuna that go into standard canned brands. This is why we offer only young, low-weight, minimal-mercury albacore tuna.
Mercury contamination of ocean fish sparked the sharpest debate among attendees and speakers. All of the health researchers who spoke expressed concern that exaggerated, frequently misunderstood mercury warnings may suppress fish intake.
While per capita consumption has risen in recent years, Americans still eat far less fish than the amounts government agencies and health experts recommend to reduce the risk of heart attacks and strokes, and to promote optimal brain health in infants and adults alike.
Ms. Smith DeWaal of CSPI noted, accurately, that mercury scares have not prevented seafood consumption from rising in recent years. But this ignores the very low level of fish consumption in America, even after recent increases in consumption. And it is unclear how much more fish Americans would have eaten, absent issuance in 2001 of the federal government's widely misunderstood seafood-and-mercury advisory.
Subsequent surveys have shown that very few Americans understand that the 2001 federal advisory was aimed primarily at pregnant or nursing women and young children, and that even they were not told to stop eating fish.
Fishy mercury facts?
Legitimate concerns about fish-borne mercury's potential threat to young, developing brains have been leveraged by environmental organizations to help force new restrictions on mercury emissions from coal-burning power plants.
This strategy has impacted public perceptions and the policy debate very effectively, despite persuasive evidence that coal-related mercury emissions account for only a tiny percentage of mercury measured in ocean waters. In fact, most of the methyl mercury in ocean waters comes from natural ocean sources such as underwater volcanoes and geothermal vents.
As we learned at the conference, evidence of the natural origins of most ocean mercury comes from measurements of mercury levels in preserved fish from the 1870's and early 1970's, which show that the concentrations of mercury in ocean fish have, if anything, decreased over the past 120 years.
Unfortunately, some advocacy groups seek to achieve a worthy end—reduced mercury emissions from coal-burning power plants—via exaggerated mercury-in-fish concerns that may put public health at risk by suppressing seafood consumption.
In a future issue, we will explore the complex science underlying mercury/seafood warnings, and tell you why the National Research Council and the U.S. EPA ignored the most relevant, solid research when they set safety margins: findings from an American-led study of people in the Seychelles islands, which indicate no harm to children, despite dietary levels of mercury in their pre- and post-natal diets far higher than any that have ever been measured in Americans.
Selenium: the anti-mercury nutrient
One of the most unexpected revelations of the conference came during the presentation by biomedical researcher Nicholas Ralston, Ph.D. of the University of North Dakota. His findings show that the relationship between mercury and selenium is a critical factor in the seafood-safety debate.
He informed the audience that selenium-dependent enzymes in the body detoxify mercury, and noted that the levels of mercury exposure in people with poisoning symptoms typically exceed the levels of selenium in their diets.
As Dr. Ralston noted, commercial ocean fish are uniformly rich in selenium, and 16 of the top 25 sources of selenium are ocean fish. He told the audience that selenium-dependent enzymes in the body protect fish consumers from mercury toxicity very effectively, and can reduce the risk of certain cancers, such as prostate cancer, by up to 50 percent.
Stay tuned: there's more to come
As we've said, many of the presentations were too complex and comprehensive to cover here, but we look forward to sharing them with you in future issues of “Vital Choices”!
- Seafood and Health '05: Issues, Questions and Answers. December 5-7, 2005, Washington, DC USA.
- Environment News Service. “Seafood Health Benefits Outweigh Toxic Risks, Scientists Say”. http://www.ens-newswire.com/ens/dec2005/2005-12-07-02.asp