Seafood Choices: Balancing Benefits and Risks
Institute of Medicine
October 17, 2006
Malden C. Nesheim, Ph.D.
Provost and Professor Emeritus, Cornell University
Chair, Committee on Nutrient Relationships in Seafood: Selections to Balance Benefits and Risks
Good morning. I too extend my thanks to all the committee members and Food and Nutrition Board staff who worked on this report. In addition to the committee members with me on the panel, we also have two other committee members who have been able to join us today. Steve Otwell, who is a professor in the department of food science and human nutrition at the University of Florida in Gainesville; and Jenny Hillard, who is research director at the Consumer Interest Alliance Inc., in Winnipeg, Manitoba.
It is a pleasure to be here to talk with you about the report Seafood Choices: Balancing Benefits and Risks. Seafood, meaning fish and shellfish, is a widely available, nutrient-rich class of food that provides high-quality protein, and is low in saturated fat and rich in polyunsaturated fats, particularly the omega-3 fatty acids EPA and DHA. Research conducted over the past several years suggests that there are additional benefits linked to eating seafood. These include development of the brain and eyesight in infants and reduced risk for certain forms of heart disease.
As consumption of seafood rises, there has been increasing concern about the potential risks associated with seafood due to the presence of microbial contaminants, persistent organic pollutants, and heavy metals -- especially mercury -- in our oceans and inland waters.
Consumers are therefore confronted with a dilemma. We are told that seafood is good for us and that we should be eating more of it than we already do. At the same time, the federal government and virtually all the states have issued advisories urging cautious consumption of certain species or fish from specific waters.
To address these concerns, our committee was charged with reviewing the available evidence on benefits and risks associated with seafood consumption and recommending ways to help consumers make informed choices. We concentrated primarily on seafood from marine sources, but included freshwater fisheries when appropriate. We were not asked to answer questions or make recommendations about environmental concerns related to seafood, but we recognized that methods of seafood production, harvesting, and processing have important environmental consequences.
In many cases, we deemed the evidence for benefits from seafood consumption as insufficient or too preliminary. Though benefits of seafood have been attributed to their content of EPA and DHA, it is not clear that the benefits derive solely from these omega-3 fatty acids. Similarly, we reviewed the data on toxic contaminants and the risks they imply, and we were surprised by the lack of reliable data on the distribution of some contaminants in the seafood supply. We found little evidence to support how the beneficial effects of seafood might counteract some of the risks from contaminants.
In our report, we provide a summary of current seafood consumption patterns and how those patterns have changed over time. We have collected available data on contaminants and the nutrient content of some types of seafood, and have compared nutrient intakes when seafood is substituted for other animal protein sources. Our report summarizes recommendations for seafood consumption by government and nongovernment groups in the United States and abroad.
Because of the limits of the available evidence, the committee determined that there is no single analytical method that adequately captures the complexity of seafood the trade-offs between benefits and risks. However, on the basis of our analysis of the available evidence and data on consumption patterns, the committee developed guidance on seafood consumption for each of four population subgroups:
1. Women who are or may become pregnant or who are breast-feeding may benefit from eating seafood, especially those kinds which have relatively higher concentrations of EPA and DHA. A reasonable amount would be two 3-ounce servings per week, but they can safely consume up to 12 ounces per week. They can consume up to 6 ounces of white tuna -- that is, albacore -- weekly, and should avoid eating large predatory fish such as shark, swordfish, tilefish, and king mackerel.
2. Children ages 12 and under are given the same guidance as pregnant women, except that serving sizes should be age-appropriate.
3. Adolescent and adult males and women who will not become pregnant may reduce their risk for cardiovascular disease by eating seafood regularly -- for example, two 3-ounce servings per week. Those who consume more than two servings per week should choose a variety of seafood to reduce risk for exposure to contaminants from a single source.
4. Adult men and females who are at risk of coronary heart disease may reduce that risk by consuming seafood regularly -- for example, two 3-ounce servings per week. There may be additional benefits from including seafood selections high in EPA and DHA, although supporting evidence is limited.
In the committee’s judgment, age, gender, pregnancy, and breast-feeding are the factors that distinguish among these target groups who face different benefit-risk trade-offs. An additional target group explored was individuals at risk of coronary heart disease. However, the evidence is insufficient to warrant guidance to this group that is different from the advice given to the general population. Our report includes a decision pathway that considers the factors of age, gender, pregnancy, and lactation. This decision pathway illustrates our final analysis of the balance between benefits and risks associated with seafood consumption.
An additional outcome of the committee’s analysis is a set of recommendations to assist NOAA and other agencies in developing, designing, and disseminating guidance that can help consumers select seafood to obtain the optimal balance between nutritional benefits and exposure to potential toxicants. The report recommends that federal agencies support the position that seafood is part of a healthy diet, because it can substitute for other protein sources higher in saturated fat and often improves the overall nutrient content of the diet. However, given that pregnant women or those who may become pregnant are particularly susceptible to risks from exposure to contaminants and bacterial toxins, federal agencies should inform them that a healthy diet can include seafood as long as any consumption stays within federal guidelines for specific seafoods and within state advisories for locally caught fish.
The committee considered the context within which consumers make seafood choices, such as individual differences in taste, preference, beliefs, attitudes, and situations. Therefore, consumer guidance should be structured to support decision-making and to allow consumers easy access to information. Offering useful guidance on seafood choices will require agencies to develop ways to integrate information about benefits and risks in messages to consumers, including those who may be more vulnerable than the general population. The use of tailored messages and community-level involvement on an ongoing basis will likely improve the effectiveness of communication between federal agencies and target populations. The committee has provided several graphical illustrations of the relationships between the omega-3 fatty acid profile of various types of seafood and their methylmercury content as examples of how information might be presented visually.
To provide the best consumption advice to the general population and specific subgroups, federal agencies should increase monitoring of methylmercury and persistent organic pollutants in seafood and make the results readily available to the public. This is especially important due to the changing sources and availability of types of seafood.
The committee recommends that federal agencies work with one another and with state public health agencies to develop an interagency task force to coordinate data and communications on seafood consumption benefits, risks, and related issues, such as fish supplies and seafood sources. This task force should also begin to develop a communication program to help consumers make informed decisions about seafood consumption. Empirical evaluation of consumers’ needs and the effectiveness of communications should also be an integral part of the program.
For most of the general population, following accepted dietary guidelines when making seafood choices will balance benefits and risks. For specific groups of people, including women who are or may become pregnant, infants, and those who are at risk for cardiovascular disease, making balanced seafood choices requires that these consumers consider both nutrients and contaminants that may be present in seafood, and that they are given useful information on both benefits and risks simultaneously to inform their choices.
This concludes my opening statement. My colleagues and I would be glad to take your questions now. Those of you listening to the live webcast can submit questions via email using a link to the National Academies home page. We ask those of you in the room to step to the microphone, and we ask you to identify yourself by name and organization when asking a question. Thank you.