Consumer Understanding of the Benefits and Risks of Fish Consumption During Pregnancy

Abstract

Fish consumption during pregnancy is one important area of dietary advice. There are potential benefits for pregnant women and their babies from a diet that contains sufficient amounts of fish. However, methylmercury, which is in most fish in at least trace amounts, can have adverse effects on the cognitive development of fetuses and can have neurological effects on children and adults in high amounts. The Federal government first issued national consumption advice in order to minimize the risk to the developing fetus from methylmercury in fish in the 1990s. This advice was updated in 2001 and again in 2004. Most recently, the US Dietary Guidelines for Americans, 2010 recommends a consumption target for pregnant and nursing women of 8 to 12 oz/wk of a variety of fish lower in methyl-mercury—to take advantage of the potential benefits that fish could provide to children’s development— while avoiding the 4 fish species highest in methylmercury that are named in joint 2004 Food and Drug Administration/Environmental Protection Agency advice (tilefish, shark, swordfish, and king mackerel). The challenge for policy makers, public health officials, and clinicians is to determine how best to communicate with pregnant women about both the benefits and risks associated with fish consumption.

‘Health care providers play an important role in communicating with patients about many food safety and nutrition messages, including the risks and benefits of fish consumption during pregnancy.’

The single biggest problem in communication is the illusion that it has taken place.

George Bernard Shaw

Background/Introduction

“Should I Eat Fish When Pregnant? What Types Are Best for Me and My Unborn Baby? How Often and How Much Fish Should I Eat?”

These questions are some of the many questions pregnant women may pose about fish consumption, and fish consumption is only one of many important food and nutrition topics that may be on their minds.

Because consuming fish and shellfish—good sources of low-fat protein and the omega-3 fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA)—could yield many health benefits to both mother and baby, pregnant women are encouraged to include some fish in their diets. However, fish can also contain methylmercury, which can have adverse health effects on the cognitive development of fetuses. ¹ Therefore, the challenge for policy makers, public health advocates, and clinicians is how best to communicate with pregnant women about the benefits and risks of consuming fish, particularly about how to obtain the most potential benefits while minimizing the potential risk.

Concern about methylmercury in locally caught fish goes back to at least the 1970s, when several states in the Great Lakes region became concerned about mercury contamination in lakes and rivers and issued advisories for many contaminants, including mercury. ² Since 2008, all 50 states and the District of Columbia have issued fish consumption advisories to alert residents about fish consumption restrictions for sport-caught fish from lakes and rivers. ³ The Federal government first issued national consumption advice to minimize the risk to the developing fetus from methylmercury in fish in the 1990s. This advice was updated in 2001 and again in 2004 ⁴ and extends to protecting young children as well as the fetus. Most recently, the Dietary Guidelines for Americans, 2010 ⁵ recommends that pregnant and breastfeeding women consume 8 to 12 oz/wk of a variety of seafood lower in methylmercury by emphasizing the potential benefits from fish in addition to minimizing the risk, whereas the 2004 Federal advice merely stated that women may safely eat up to 12 ounces (on average 2 meals per week) of seafood that is lower in methylmercury. Examples of fish that are higher in EPA and DHA and also lower in methylmercury include salmon, anchovies, herring, sardines, Pacific oysters, trout, and Atlantic and Pacific mackerel (not king mackerel, which is high in methylmercury). ⁵ The recommendation in the Dietary Guidelines for Americans, 2010 for women who are pregnant or breastfeeding is shown in Table 1.

Table 1.

Dietary Guidelines for Americans, 2010—Fish Consumption Advice for Pregnant and Lactating Women.

• Consume 8 to 12 ounces of seafood per week from a variety of seafood types lower in methylmercury

• Due to their methylmercury content, limit white (albacore) tuna to 6 ounces per week and do not eat the following four types of fish: tilefish, shark, swordfish, and king mackerel.

• Check state and local advisories for recommendations about recreationally caught fish from lakes and rivers. This information can be found at http://water.epa.gov/scitech/swguidance/fishshellfish/fishadvisories/index.cfm. a

a

Web site updated from the one listed in the Dietary Guidelines for Americans, 2010.

What Do Women Know About the National Fish Consumption Advice and the Dietary Guidelines Recommendations Related to Fish Consumption?

Ever since the first advice about fish consumption was issued, researchers have been studying how target and nontarget audiences have understood and behaved in response to these messages. Research about awareness and behavior related to the national fish advice suggests that overall, consumers, including pregnant women, are generally aware of problems related to mercury contamination in some fish, but many do not know the specifics of the advice.^6,7 Some target and nontarget consumers may have overreacted to the risks from methylmercury in fish and may not be eating enough fish to get all the health benefits that fish could possibly provide.^8,9 In a study of 1286 pregnant, 522 postpartum, and a control group of 1349 nonpregnant/nonpostpartum women, it was found that a majority of women in all 3 groups were aware of methylmercury as a problem in food, and almost none of the women in any of the groups ate more than 12 oz/wk of fish or ate any of the 4 species highest in methylmercury. However, among the women who did eat fish, the median reported intake of total fish was 1.8 oz/wk for the pregnant women, 2.5 oz/wk for the postpartum women, and 3.0 oz/wk for the control group. ¹⁰

In light of data suggesting that median fish consumption by pregnant and lactating women is far below the 8- to 12-ounce weekly target recommended by the Dietary Guidelines, research has also explored potential reasons for these low levels of consumption. Qualitative research involving 5 focus groups with pregnant women (n = 22) who ate less than 2 servings of fish per week found that many had heard of mercury* as a problem in fish, but few knew which fish had higher levels of mercury. ¹¹ Therefore, many decided to reduce the amount of fish eaten or not to eat any fish as a way of avoiding the risks altogether. Grobe et al ¹² who conducted one-on-one interviews with 26 women who consumed fish or seafood at least once per month found that 17 of the 26 participants did not change their seafood consumption because of concern about mercury; 5 women reduced their consumption of specific species of fish or shellfish but did not reduce their overall seafood consumption, whereas the remaining 4 did reduce their overall consumption. Women of childbearing age and those with young children were more likely than other participants to say that they changed their fish consumption, especially by reducing the amount of tuna they ate, as a result of concerns about mercury in fish.

Overall, the quantitative and qualitative research suggests that, whereas a majority of women in the United States are aware of the potential for methylmercury in fish, only a minority of women can recall specific details about the national advice, such as which fish to avoid or how much fish to eat each week. Thus, it appears that some women responded to the advice by continuing to eat the same low amounts of fish and in some cases by reducing their overall consumption of seafood.

Where Do Women Get Information About Fish Consumption During Pregnancy?

Women may receive advice about fish consumption and pregnancy from many different sources. Stories about fish consumption have been widely disseminated by the media both on TV news programs and in local and national newspaper stories. Consumers reported that the media was the most common source of information about seafood. ¹³ From 2003 to 2008, there were 200 stories, 12 op-eds, and 18 editorials about mercury in fish in just 2 newspapers—the New York Times (United States) and the Globe and Mail (Canada). A review of these stories by Fitzgerald and Baralt ¹⁴ found that both newspapers focused their stories on the state’s role in informing the public about the risks from mercury in fish, what the risks are to individuals, and how individuals can lower their risks by limiting consumption or not eating certain types of fish. Similarly, Greiner et al ¹⁵ conducted a trends analysis of how messages related to fish were covered in the US news media from 1993 to 2007. In their analysis of 310 related stories from 5 daily newspapers and 5 television networks, they found that risk messages outweighed benefit messages 4 to 1. They conclude, “With the bulk of messages about fish consumption focused on risk, the benefits may be lost to consumers.”

In addition to the media, health care providers (often via pamphlets and brochures that are disseminated at clinics and doctor’s offices),^16,17 family members, ¹⁸ online medical Web sites, ^† and government Web sites ^‡ are all important sources of information about food safety and nutrition topics, including fish consumption for pregnant women and mothers of young children. A recent study of pregnant women found that 81% said that they received information about diet during pregnancy from doctors, nurses, or other health professionals. The next most prevalent sources were book or videos (62%), newspapers and magazines (55%), and relatives or friends (53%). ¹⁹

What Are the Challenges for Communicating Benefits and Risks of Fish Consumption?

Communicating about the benefits and risks of fish consumption, especially to a group such as pregnant women, can be challenging. In general, people are more sensitive to losses than gains and will not follow a recommended course of action unless they perceive that the benefits significantly outweigh the costs. ²⁰ Such risk aversion is likely to be heightened for pregnant women, who would likely be eager to minimize, if not eliminate, any potential risks to their babies. Moreover, people often evaluate risk based on intuition and feelings rather than using logic or reason. For example, Keller et al, ²¹ found that evoking fear is likely to result in greater perceived risk. Likewise, Grobe et al ¹² concluded that the participants in their qualitative study relied more on “affective” rather than “analytic information processing” when making judgments about fish and seafood consumption. It is, therefore, important to provide women with concrete advice about how the risks of methylmercury exposure can be managed, such as by providing a list of the safest kinds of fish that pregnant women can find in their grocery stores, so that fears about mercury do not seem unmanageable or otherwise overshadow the benefits of fish consumption.

Preexisting beliefs also affect how receptive people are to information they receive. If women have prior positive or negative perceptions about fish, these perceptions will likely affect how the women process any new information about the benefits and risks of fish consumption.^22,23 People who have favorable attitudes toward fish, who perceive greater social encouragement to eat and buy fish, and who believe that fish is relatively easy to buy and prepare are more likely to eat fish more often. ²⁴ Another important driver, of course, is taste: Verbeke and Vackier ²⁴ found that people who enjoyed the taste of fish reported the highest intentions to eat fish in the near future. Research by Mintel Food and Drink ²⁵ has shown that the high price of fish, lack of familiarity with preparing fish, or other household members who do not like the taste or smell of fish can discourage people’s fish consumption in general. Given the multitude of potential barriers that are likely to influence fish consumption by pregnant women, it is not surprising that when the risks of fish consumption are discussed more frequently than the benefits or when messages about which fish to avoid and limit are complicated, many consumers, particularly pregnant women, may be tempted to conclude that avoiding fish altogether is the simplest course of action.

Another challenge with communicating about fish consumption during pregnancy is that mercury is just one of many fish-related topics. Pregnant women are told to avoid refrigerated smoked fish such as smoked salmon, trout, whitefish, cod, tuna, or mackerel (often labeled as nova-style, lox, kippered, smoked, or jerky) because it poses a risk for contamination with Listeria monocytogences. ²⁶ They are also advised to avoid raw fish (such as sushi or sashimi) because it is more likely to contain parasites or bacteria than cooked fish. ²⁷ Some worry about ecological harms from overfishing or pollution from poorly managed farmed fisheries. ²⁸ In a review of the issues surrounding fish consumption, Oken et al ²⁸ found that there were 21 unique major seafood consumption guidelines or advisories from governments (state and national), nonprofit, and other nongovernmental organizations that targeted various North American populations. Additionally, fish consumption is just one of many food safety and nutrition topics that are important for pregnant women.

How to Communicate With Pregnant Women About Fish Consumption?

Health care providers are a trusted source of information for pregnant women ¹⁹ and are able to see pregnant patients at regular visits throughout pregnancy. They occupy a unique and influential role in helping patients navigate risk and benefit information related to fish consumption. ²⁹ Research in risk communication suggests that tailoring messages can enhance the patient’s ability to engage in desired behaviors and overcome barriers to performing those behaviors.^1,30 Health care providers have the opportunity to talk with their pregnant patients about their food and nutrition behaviors. Taking a few moments to ascertain patients’ prior knowledge about fish and their current fish consumption behavior can enable providers to target specific aspects of the advice for each patient. When possible, providers also can determine if the patient understands the information by having them explain it back to them. ³¹

In addition to health care provider counseling, Oken and colleagues have demonstrated ³² that fish consumption behavior can be changed via an educational intervention that provides detailed information about the health benefits of eating fish and types of fish that are lower in mercury and suggesting ways to prepare fish. Their intervention was evaluated in a study of 55 pregnant women in the Boston area who were randomly assigned to a control group or 1 of 2 treatment groups. Both treatment groups received a booklet that summarized the beneficial effects of DHA from lower mercury fish during pregnancy, encouraged fish consumption, and listed 29 recommended lower-mercury fish sorted by their DHA levels. The booklet also included information about which fish to avoid or limit for reasons of contamination with mercury and other substances. In addition to the booklet, the women received a shopping list notepad that included the list of lower-mercury fish and 2 copies of wallet-sized cards that summarized the information in the booklet. The researchers also e-mailed participants each week during the 12-week intervention. The e-mails encouraged the recipients to eat 2 servings per week of fish, included information about the health benefits of fish, and provided a recipe about how to prepare one of the suggested fish. A Web site address of where they could find additional information was also included. One of the treatment groups also received $40 each month (a total of $120) in addition to the information booklet and companion materials over the course of the intervention. Women in the control group received a standard “Pregnancy Food Guide” and list of “Food Don’ts,” which covered the 2004 Food and Drug Administration/Environmental Protection Agency national advice about mercury in fish along with general nutrition advice. Researchers sent weekly e-mails to the control group that shared tips on general pregnancy health and recipes but did not focus on fish.

At the end of the intervention, Oken et al ³² found that none of the control women consumed the recommended 200 mg/d of DHA from fish, whereas 33% of women in the fish advice group and 53% of women in the advice plus monetary incentive group achieved this goal. At the same time, blood and hair measurements did not show any significant changes in mercury levels across any of the groups. Although this was a small study, it showed that educational information about fish was able to persuade some pregnant women to consume more fish and that this increased consumption did not increase their mercury intake significantly.

Summary

Health care providers play an important role in communicating with patients about many food safety and nutrition messages, including the risks and benefits of fish consumption during pregnancy. Whenever possible, it is useful to ascertain each woman’s current fish consumption habits and related attitudes and knowledge in order to understand what information she most needs to know to optimize her fish consumption levels during pregnancy and beyond. Advice that acknowledges barriers to eating more fish and provides specific, clear recommendations for minimizing the risks of methylmercury exposure and maximizing the potential benefits should go far in helping pregnant women understand how to achieve and maintain the healthiest levels of fish and seafood consumption to support their developing babies and young children.