Scientific Report of the 2015 Dietary Guidelines Advisory Committee

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Part D. Chapter 5: Food Sustainability and Safety - Continued

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Sustainable Diets

Evaluating the link between sustainability and dietary guidance will inform policies and practice to ensure food security for present and future generations. The DGAC concentrated its review on the inter-relatedness between human health and food sustainability, with a focus on dietary patterns, a theme of the 2015 DGAC.

Dietary Patterns and Sustainability

Question 1: What is the relationship between population-level dietary patterns and long-term food sustainability?

Source of Evidence: Modified NEL systematic review

Conclusion

Consistent evidence indicates that, in general, a dietary pattern that is higher in plant-based foods, such as vegetables, fruits, whole grains, legumes, nuts, and seeds, and lower in animal-based foods is more health promoting and is associated with lesser environmental impact (GHG emissions and energy, land, and water use) than is the current average U.S. diet. A diet that is more environmentally sustainable than the average U.S. diet can be achieved without excluding any food groups. The evidence consists primarily of Life Cycle Assessment (LCA) modeling studies or land-use studies from highly developed countries, including the United States. DGAC Grade: Moderate

Implications

A moderate to strong evidence base supports recommendations that the U.S. population move toward dietary patterns that generally increase consumption of vegetables, fruits, whole grains, legumes, nuts and seeds, while decreasing total calories and some animal-based foods. This can be achieved through a variety of dietary patterns, including the Healthy USDA-style Pattern, the Healthy Vegetarian Pattern, and the Healthy Mediterranean-style Pattern (for more details on the patterns, see Part D. Chapter 1: Food and Nutrient Intakes, and Health: Current Status and Trends). Each of these patterns provides more plant-based foods and lower amounts of meat than are currently consumed by the U.S. population.

Sustainability considerations provide an additional rationale for following the Dietary Guidelines for Americans and should be incorporated into federal and local nutrition feeding programs when possible. Using sustainability messaging in communication strategies should be encouraged. The application of environmental and sustainability factors to dietary guidelines can be accomplished because of the compatibility and degree of overlap between favorable health and environmental outcomes.

Much has been done by the private and public sectors to improve environmental policies and practices around production, processing, and distribution within individual food categories. It will be important that both a greater shift toward healthful dietary patterns and an improved environmental profile across food categories are achieved to maximize environmental sustainability now and to ensure greater progress in this direction over time.

Consumer friendly information that facilitates understanding the environmental impact of different foods should be considered for inclusion in food and menu labeling initiatives.

Careful consideration will need to be made to ensure that sustainable diets are affordable for the entire U.S. population.

Promoting healthy diets that also are more environmentally sustainable now will conserve resources for present and future generations, ensuring that the U.S. population has access to a diet that is healthy as well as sustainable and secure in the future.

Review of the Evidence

A total of 15 studies met the inclusion criteria for this systematic review.33-48 The body of evidence consisted primarily of dietary pattern modeling studies that assessed related environmental outcomes. These studies were conducted between the years 2003 and 2014 in the U.S., the UK, Germany, the Netherlands, France, Spain, Italy, Australia, Brazil, and New Zealand. Dietary patterns that were examined included vegetarian, lacto-ovo vegetarian, and vegan dietary patterns; the average and dietary guidelines-related dietary patterns of respective countries examined; Mediterranean-style dietary patterns; and sustainable diets. The most frequent comparison diet was the average dietary pattern of the country, although numerous studies made additional comparisons across many of the above dietary patterns. Another approach was to examine diet “scenarios” that modeled different percentage replacements of meat and dairy foods with plant-based foods. The modeling studies used cross-sectional assessment of dietary intake from national nutrition surveys of representative adult populations; for example, the British National Diet and Nutrition Survey (NDNS) from studies in the UK,34, 39 the National Nutrition Surveys (NNS) in Germany,40 or the Australian National Nutrition Survey38 were used to determine the observed average dietary patterns. The average dietary patterns were then compared with other modeled dietary patterns, such as vegetarian or Mediterranean- style patterns, as described in detail below. All of the countries were highly developed countries with dietary guidelines and, therefore, generalizable to the U.S. population. The study quality for the body of evidence ranged from scores of 7/12 to 12/12 (indicating the evidence was of high quality) using a modified Critical Appraisal Checklist (see Appendix E-2.37 Evidence Portfolio).

Health outcomes associated with the dietary patterns were most often documented based on adherence to dietary guidelines-related patterns, variations on vegetarian dietary patterns, or Mediterranean-style dietary patterns. Diet quality was assessed in some studies using an a priori index, such as the Healthy Eating Index (HEI) or the WHO Index. In some studies, health outcomes also were modeled. For example Scarborough et al. used the DIETRON model to estimate deaths delayed or averted for each diet pattern.46 One study assessed the synergy between health and sustainability scores using the WHO Index and the LCA sustainability score to assess combined nutritional and ecological value.46

The environmental impacts that were most commonly modeled were GHG emissions and use of resources such as agricultural land, energy, and water. In many studies, the environmental impact for each food/food category was obtained using the LCA method. The LCA is a standardized methodological framework for assessing the environmental impact (or load) attributable to the life cycle of a food product. The life cycle for a food typically includes agricultural production, processing and packaging, transportation, retail, use, and waste disposal.33, 49-51 An inventory of all stages of the life cycle is determined for each food product and a “weight” or number of points is then attributed to each food or food category, based on environmental impacts such as resource extraction, land use, and relevant emissions. These environmental impact results can be translated into measures of damage done to human health, ecosystem quality, and energy resources using programs such as Eco-Indicator.52 In addition to the health assessment approaches listed above, some studies used LCA analysis with a standardized approach to determine damages from GHG emissions and use of resources; these damage outcome included human health as an environmental damage component, such as the number and duration of diseases and life years lost due to premature death from environmental causes.

Few studies assessed food security. These studies assessed food security in terms of the cost difference between an average dietary pattern for the country studied and a sustainable dietary pattern for that population.36, 39, 48 The basic food basket concept was used in some studies, representing household costs for a two-adult/two-child household.

Identified Dietary Patterns and Health and Sustainability Outcomes

Vegetarian and Meat-based Diets

Several studies examined variations on vegetarian diets, or a spectrum from vegan to omnivorous dietary patterns, and associated environmental outcomes.34, 35, 37, 41 Peters et al. examined 42 different dietary patterns and land use in New York, with patterns ranging from low-fat, lacto-ovo vegetarian diets to high fat, meat-rich omnivorous diets; across this range, the diets met U.S. dietary guidelines when possible.41 They found that, overall, increasing meat in the diet increased per capita land requirements; however, increasing total dietary fat content of low-meat diets (i.e. vegetarian alternatives) increased the land requirements compared to high-meat diets. In other words, although meat increased land requirements, diets including meat could feed more people than some higher fat vegetarian-style diets. Aston et al. assessed a pattern that was modeled on a feasible UK population in which the proportion of vegetarians in the survey was doubled, and the remainder adopted a diet pattern consistent with the lowest category of red and processed meat (RPM) consumers. They found the combination of low RPM + vegetarian diet had health benefits of lowering the risk of diabetes and colorectal cancer, determined from risk relationships for RPM and CHD, diabetes, and colorectal cancer from published meta-analyses.53-55 Furthermore, the expected reduction in GHG for this diet was ~3 percent of current total carbon dioxide (CO2) emissions for agriculture. De Carvalho et al. also examined a high RPM dietary pattern with diet quality assessed using the Brazilian Healthy Eating Index.37 They found that excessive meat intake was associated not only with poorer diet quality but also with increased projected GHG emissions (~4 percent total CO2 emitted by agriculture). Taken together, the results on RPM intake indicate that reduced consumption is expected to improve some health outcomes and decrease GHG emissions, as well as land use compared to current RPM consumption. Baroni et al. examined vegan, vegetarian, and omnivorous diets, both organically and conventionally grown, and found that the organically grown vegan diet had the most potential health benefits; whereas, the conventionally grown average Italian diet had the least.37 The organically grown vegan diet also had the lowest estimated impact on resources and ecosystem quality, and the average Italian diet had the greatest projected impact. Beef was the single food with the greatest projected impact on the environment; other foods estimated to have high impact included cheese, milk, and seafood.

Vegetarian diets, dietary guidelines-related diets, and Mediterranean-style diets were variously compared with the average dietary patterns in selected countries.38, 40, 42, 46 Overall, the estimated greater environmental benefits, including reduced projected GHG emissions and land use, resulted from vegan, lacto-ovo vegetarian, and pesco-vegetarian diets, as well as dietary guidelines-related and Mediterranean-style dietary patterns. These diets had higher overall predicted health scores than the average diet patterns. Moreover, for the most part, the high health scores of these dietary patterns were paralleled by high combined estimated sustainability scores. According to van Doreen et al., the synergy measured across vegetarian, Mediterranean-style, and dietary guidelines-related scores could be explained by a reduction in consumption of meat, dairy, extras (i.e., snacks and sweets), and beverages, as well as a reduction in overall food consumption.42

Mediterranean-Style Dietary Patterns

The Mediterranean-style dietary pattern was examined in both Mediterranean and non-Mediterranean countries.44, 46 In all cases, adherence to a Mediterranean-style dietary pattern—compared to usual intake—reduced the environmental footprint, including improved GHG emissions, agricultural land use, and energy and water consumption. Both studies limited either red and processed meat40 or meat and poultry42 to less than 1 serving per week, and increased seafood intake. The authors concluded that adherence to a Mediterranean-style dietary pattern would make a significant contribution to increasing food sustainability, as well as increasing the health benefits that are well-documented for this type of diet (see Part D. Chapter 2: Dietary Patterns, Foods and Nutrients, and Health Outcomes).

Diet Scenarios

Other studies examined different diet “scenarios” that generally replaced animal foods in various ways with plant foods.43, 45, 47 Scarborough et al. found that a diet with 50 percent reduced total meat and dairy replaced by fruit, vegetables, and cereals contributed the most to estimated reduced risk of total mortality and also had the largest potential positive environmental impact.13 This diet scenario increased fruit and vegetable consumption by 63 percent and decreased saturated fat and salt consumption; micronutrient intake was generally similar with the exception of a drop in vitamin B12.

Pradhan et al. examined 16 global dietary patterns that differed by food and energy content, grouped into four categories with per capita intake of low, moderate, high, and very high kcal diets. They assessed the relationship of these patterns to GHG emissions.43 Low-energy diets had less than 2,100 kcal/cap/day and were composed of more than 50 percent cereals or more than 70 percent starchy roots, cereals, and pulses. Animal products were minor in this group (<10 percent). Moderate, high, and very high energy diets had 2,100-2,400, 2,400-2,800, and greater than 2,800 kcal/cap/day, respectively. Very high calorie diets had high amounts of meat and alcoholic beverages. Overall, very high calorie diets, common in the developed world, exhibited high total per capita CO2eq emissions due to high carbon intensity and high intake of animal products; the low-energy diets, on the other hand, had the lowest total per capita CO2eq emissions.

Lastly, Vieux et al. examined dietary patterns with different indicators of nutritional quality and found that despite containing large amounts of plant foods, not all diets of the highest nutritional quality were those with the lowest GHG emissions.47 For this study, the diet pattern was assessed by using nutrient-based indicators; high quality diets had energy density below the median, mean adequacy ratio above the median, and a mean excess ratio (percentage of maximum recommended for nutrients that should be limited – saturated fat, sodium, and free sugars) below the median. Four diet patterns were identified based on compliance with these properties to generate one high quality diet, two intermediate quality diets, and one low quality diet. In this study, the high quality diets had higher GHG emissions than did the low quality diets. Regarding the food groups, a higher consumption of starches, sweets and salted snacks, and fats was associated with lower diet-related GHG emissions and an increased intake of fruit and vegetables, was associated with increased diet-related GHG emissions. However, the strongest positive association with GHG emissions was still for the ruminant meat group. Overall, this study used a different approach from the other studies in this review, as nutritional quality determined the formation of dietary pattern categories.

Sustainable Diets and Costs

Three studies examined sustainable diets and related costs.36, 39, 48 Barosh et al. examined food availability and cost of a health and sustainability (H&S) food basket, developed according to the principles of the Australian dietary guidelines as well as environmental impact.36 The food basket approach is a commonly used method for assessing and monitoring food availability and cost. The typical food basket was based on average weekly food purchases of a reference household made up of two adults and two children. For the H&S basket, food choices were based on health principles and environmental impact. The H&S basket was compared to the typical Australian basket and it was determined that the cost of the H&S basket was more than the typical basket in five socioeconomic areas; the most disadvantaged spent 30 percent more for the H&S basket. The authors concluded that the most disadvantaged groups at both neighborhood and household levels experienced the greatest inequality in accessing an affordable H&S basket. Macdiarmid et al. examined a sustainable diet (met all energy and nutrient needs and maximally decreased GHG emissions), a “sustainable with acceptability constraints” diet (added foods commonly consumed in the UK; met energy, nutrient, and seafood recommendations as well as recommended minimum intakes for fruits and vegetables and did not exceed the maximum recommended for red and processed meat), and the average UK diet.7 They found that the sustainable diet that was generated would decrease GHG emissions from primary production (up to distribution) by 90 percent, but consisted of only seven foods. The acceptability constraints diet included 52 foods and was projected to reduce GHG emissions by 36 percent. This diet included meat and dairy but less than the average UK diet. The cost of the sustainable + acceptability diet was comparable to that of the average UK diet. These results showed that a sustainable diet that meets dietary requirements and has lower GHG can be achieved without eliminating meat or dairy products completely, or increasing the cost to the consumer. Lastly, Wilson et al. examined 16 dietary patterns modeled to determine which patterns would minimize estimated risk of chronic disease, cost, and GHG emissions.48 These patterns included low-cost and low-cost + low GHG diet patterns, as well as healthy patterns with high vegetable intakes including Mediterranean or Asian patterns, as well as the average New Zealand pattern. The authors found that diets that aimed to minimize cost and estimated GHG emissions also had health advantages, such as the simplified low-cost Mediterranean-style and simplified Asian-style diets, both of which would lower cardiovascular disease and cancer risk, compared to the average New Zealand diet. However, dietary variety was limited and further optimization to lower GHG emissions increased cost.

Overall, the studies were consistent in showing that higher consumption of animal-based foods was associated with higher estimated environmental impact, whereas consumption of more plant-based foods as part of a lower meat-based or vegetarian-style dietary pattern was associated with estimated lower environmental impact compared to higher meat or non-plant-based dietary patterns. Related to this, the total energy content of the diet was also associated with estimated environmental impact and higher energy diets had a larger estimated impact. For example, for fossil fuel alone, one calorie from beef or milk requires 40 or 14 calories of fuel, respectively, whereas one calorie from grains can be obtained from 2.2 calories of fuel.42 Additionally, the evidence showed that dietary patterns that promote health also promote sustainability; dietary patterns that adhered to dietary guidelines were more environmentally sustainable than the population’s current average level of intake or pattern. Taken together, the studies agreed on the environmental impact of different dietary patterns, despite varied methods of assessing environmental impact and differences in components of environmental impact assessed (e.g. GHG emissions or land use). The evidence on whether sustainable diets were more or less expensive than typically consumed diets in some locations was limited and inconsistent.

Three additional reports on the relationship between dietary patterns and sustainability were published after this systematic review was completed. Two of these reports were consistent with, and provided more evidence to support the Committee’s findings that dietary guidelines-related diets, Mediterranean-style diets, and vegetarian (and variations) diets are associated with improved environmental outcomes. Tilman and Clark showed that following a Mediterranean, vegetarian (lacto-ovo), or pesco-vegetarian dietary pattern would decrease both current and projected GHG emissions and land use.11 Eshel et al. reported on the five main animal-based categories in the U.S. diet – dairy, beef, poultry, pork, and eggs – and their required feeds including crops, byproducts, and pasture. They found that beef production required more land and irrigation water and produced more GHG emissions than dairy, poultry, pork, or eggs.9 In addition, as a standard comparator, staple plant foods had lower land use and GHG emissions than did dairy, poultry, pork, or eggs. In contrast, a report from Heller and Keoleian suggests that an isocaloric shift from the average U.S. diet (at current U.S. per capita intake of 2,534 kcals/day from Loss-Adjusted Food Availability (LAFA) data) to a pattern that adheres to the 2010 Dietary Guidelines for Americans would result in a 12 percent increase in diet-related GHG emissions.10 This result was modified, however, by their finding that if Americans consumed the recommended pattern within the recommended calorie intake level of 2,000 kcal/day, there would be a 1 percent decrease in GHG emissions. This finding reinforces the overriding 2010 DGA recommendation that all of the guidelines need to be followed, including appropriate calorie intake levels for age, gender, and activity level. Furthermore, in contrast to the findings of Eshel et al. regarding dairy, Heller and Keoleian suggest that increases in dairy to follow 2010 DGA recommendations contribute significantly to increased GHG emissions and counters the modeled benefits of decreased meat consumption.10

For additional details on this body of evidence, visit: Appendix E-2.37 Evidence Portfolio

Seafood Sustainability

Background

Seafood is recognized as an important source of key macro- and micronutrients. The health benefits of seafood, including support of optimal neurodevelopment and prevention of cardiovascular disease, are likely due in large part to long-chain n-3 polyunsaturated fatty acids (PUFA), docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), although seafood also are good sources of other nutrients including protein, selenium, iodine, vitamin D, and choline.27 Currently, seafood production is in the midst of rapid expansion to meet growing worldwide demand, but the collapse of some fisheries due to overfishing in past decades raises concerns about the ability to produce safe and affordable seafood to supply the U.S. population and meet current dietary intake recommendations of at least 8 ounces per week.20, 56 Capture fisheries (wild caught) production has leveled-off as a proportion of fully exploited stocks, and this is due in part to national and international efforts on seafood sustainably (e.g., the U.S. Magnuson-Stevens Fishery Conservation and Management Act (2006) mandating annual catch limits, managed by the U.S. National Oceanographic and Atmospheric Administration). In contrast, the increased productivity of worldwide aquaculture (farm-raised) is expected to continue and will play a major role in expanding the supply of seafood.20 Expanding farm-raised seafood has the potential to ensure sufficient amounts of seafood to allow the U.S. population to consume levels recommended by dietary guidelines.57 Productivity gains should be implemented in a sustainable manner with greater attention to maintaining or enhancing the high nutrient density characteristic of captured seafood. Consistent with overall sustainability goals, farm-raised finfish (e.g., salmon and trout) is more sustainable than terrestrial animal production (e.g., beef and pork) in terms of GHG emissions and land/water use.58, 59 Currently, the United States imports the majority of its seafood (~90 percent), and approximately half of that is farmed.60 The major groups commonly referred to as finfish, shellfish, and crustaceans include more than 500 species, and thus, generalizations to all seafood must be made with caution.

Question 2: What are the comparative nutrient profiles of current farm-raised versus wild caught seafood?

Source of evidence: USDA Agriculture Research Service (ARS) National Nutrient Database (NND)25 updated with USDA-funded survey of most commonly consumed species in the United States.26

Conclusion

For commonly consumed fish species in the United States, such as bass, cod, trout, and salmon, farmed-raised seafood has as much or more of the omega-3 fatty acids EPA and DHA as the same species captured in the wild. In contrast, farmed low-trophic species, such as catfish and crawfish, have less than half the EPA and DHA per serving than wild caught, and these species have lower EPA and DHA regardless of source than do salmon. Farm-raised seafood has higher total fat than wild caught. Recommended amounts of EPA and DHA can be obtained by consuming a variety of farm-raised seafood, especially high-trophic species, such as salmon and trout.

Implications

The U.S. population should be encouraged to eat a wide variety of seafood that can be wild caught or farmed, as they are nutrient-dense foods that are uniquely rich sources of healthy fatty acids. It should be noted that low-trophic farm-raised seafood, such as catfish and crayfish, have lower EPA and DHA levels than do wild-caught. Nutrient profiles in popular low-trophic farmed species should be improved through feeding and processing systems that produce and preserve nutrients similar to those of wild-caught seafood of the same species.

Review of the Evidence

The USDA-Agricultural Research Service (ARS) National Nutrient Database (NND) for Standard Reference, Release 27 was used to address this question (http://www.ars.usda.gov/ba/bhnrc/ndl).25 The section on finfish and shellfish products included nutrient profiles for both farm-raised and wild-caught seafood for some species. These data were augmented using a USDA-funded report on fatty-acid profiles of commercially available fish in the United States that assessed additional farmed species and compared results26 with the USDA-ARS NND.25 The samples collected were from different regions of the United States during different seasons. For wild-caught species, the nutrient profile is determined by changes in environmental conditions, whereas, for farmed species, the nutrient profile is dependent on the amount, timing, and composition of the feed.26 Because aquaculture diets can be continually modified, updates are important to monitor EPA and DHA in commercial seafood species, to provide consumers with the most accurate information. The NND provided nutrient profiles for six seafood species with data on both wild-caught and farm-raised versions: four fish (rainbow trout, Atlantic and Coho salmon, and catfish), eastern oysters, and mixed species crayfish. The key nutrients EPA and DHA were on average comparable or greater for farmed trout, salmon, and oysters compared to wild capture, reflecting the higher total fat content of these farmed species. On the other hand, low-trophic species, such as catfish and crayfish, when farmed, were lower in EPA and DHA compared to wild capture. Cladis et al. determined EPA and DHA levels for five farmed and wild fish species (rainbow trout, white sturgeon, Chinook salmon, Atlantic cod, striped bass), providing an update and comparison for some of these species (Figure D5.2).26 Farmed Atlantic salmon was similar between the NND and the update and most other species compared well; however, Chinook salmon and sturgeon showed differences in EPA and DHA content (although farmed and wild were not distinguished in the NND). Overall, these data showed that existing DGAC recommendations to consume a variety of seafood can be met by consuming a diverse range of species, including farmed species.

Figure D5.2. Comparison of EPA and DHA drawn from data in USDA National Nutrient Database25 and update from Cladis et al.26

Bar graph of EPA and DHA levels (mg/100 g raw serving) in farm-raised compared to wild-caught seafood.  Seafood species include catfish, crawfish, bass, cod, salmon, sturgeon, and rainbow trout.

For additional details on this body of evidence, visit: Appendix E-2.38 Evidence Portfolio and http://www.ars.usda.gov/ba/bhnrc/ndl

Question 3. What are the comparative contaminant levels of current farm-raised versus wild caught seafood?

Source of evidence: Report of the Joint United Nations Food and Agriculture Organization/World Health Organization Expert Consultation on the Risks and Benefits of Fish Consumption. Rome, 25–29 January 2010. FAO Fisheries and Aquaculture Report No. 978.27

Conclusion

The DGAC concurs with the Consultancy that, for the majority of commercial wild and farmed species, neither the risks of mercury nor organic pollutants outweigh the health benefits of seafood consumption, such as decreased cardiovascular disease risk and improved infant neurodevelopment. However, any assessment evaluates evidence within a time frame and contaminant composition can change rapidly based on the contamination conditions at the location of wild catch and altered production practices for farmed seafood. DGAC Grade: Moderate

Implications

Based on risk/benefit comparisons, either farmed or wild-caught seafood are appropriate choices to consume to meet current Dietary Guidelines for Americans for increased seafood consumption. The DGAC supports the current FDA and EPA recommendations that women who are pregnant (or those who may become pregnant) and breastfeeding should not eat certain types of seafood—tilefish, shark, swordfish, and king mackerel—because of their high methyl mercury contents. Attention should be paid to local seafood advisories when eating seafood caught from local rivers, streams, and lakes.

Based on the most current evidence on mercury levels in albacore tuna provided in the Report of the Joint United Nations Food and Agriculture Organization/World Health Organization Expert Consultation on the Risks and Benefits of Fish Consumption, 2010,27 the DGAC recommends that the EPA and FDA re-evaluate their current recommendations61 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.

Review of the Evidence

The Report of the FAO/WHO Expert Consultation on the Risks and Benefits of Fish Consumption27 was used to address this question. This report was chosen as the most current and comprehensive source on contaminants in wild-caught and farm-raised seafood, and the DGAC focused on data that addressed the specific comparison between the two. The sections of the report that were used to address the question were “Data on the composition of fish” and “Risk-benefit comparisons.” The consultancy took a net effects approach, balancing benefits of seafood, especially benefits associated with EPA and DHA, against the adverse effects of mercury and persistent organic pollutants (POPs), including polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins, and polychlorinated dibenzofurans, collectively referred to as dioxins. The Expert Consultancy compiled EPA and DHA, mercury, and dioxins compositional data from national databases of the United States, France, Norway, and Japan, as well as an international database. Together, these provided information on total fat, EPA and DHA, total mercury, and dioxins for a large number of seafood species, including three farmed and wild species (salmon, rainbow trout, and halibut). Two specific outcomes were considered for risk/benefit: 1) prenatal exposure and offspring neurodevelopment, and 2) mortality from cardiovascular diseases and cancer.

Overall, for the species examined, levels of mercury and dioxins were in the same range for farmed and wild seafood. Related to risk/benefit, at the same level of mercury content (lowest [≤ 0.1 μg/g] and 2nd lowest [0.1 - 0.5 μg/g] levels), farmed seafood had the same or higher levels of EPA and DHA as wild-caught. At the same level of dioxin content (2nd lowest [0.5 – 4 pg toxic equivalents (TEQ)/g] level), farmed seafood had the same or higher levels of EPA and DHA as wild-caught. Only wild-caught Pacific salmon had the lowest level of dioxins (<0.5 pg TEQ/g). Overall, the quantitative risk/benefit analysis was not different for farmed compared to wild-caught seafood. For both, using the central estimate for benefits of DHA and for harm from mercury, the neurodevelopmental risks of not eating seafood exceeded the risks of eating seafood. Similarly, for coronary heart disease (CHD) in adults, there were CHD mortality benefits from eating seafood and CHD risks from not eating seafood, except for seafood in the highest dioxin category and lowest EPA and DHA category, which did not include any of the farm-raised species considered.

Albacore tuna, produced only from wild marine fisheries, is a special case of a popular fish highlighted by the 2004 FDA and EPA advisory.61, 62 For all levels of intake including more than double the 12 ounces per week recommendation, all evidence was in favor of net benefits for infant development and CHD risk reduction.

Limitations in the evidence included the small number of farmed and wild seafood species comparisons considered by the Expert Consultancy, and the possibility of rapid change that may occur in the concentration of contaminants locally. In addition, seafood contaminants are closely linked to levels of contaminants in feed.

For additional details on this body of evidence, visit: Report of the Joint Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO) Expert Consultation on the Risks and Benefits of Fish Consumption, 2011. Available at http://www.fao.org/docrep/014/ba0136e/ba0136e00.pdf [PDF - 516 KB]

Question 4: What is the worldwide capacity to produce farm-raised versus wild-caught seafood that is nutritious and safe for the U.S. population?

Source of evidence: United National (UN) Food and Agriculture Organization (FAO) report on The State of World Fisheries and Agriculture.20

Conclusions

The DGAC concurs with the FAO report that consistent evidence demonstrates that capture fisheries increasingly managed in a sustainable way have remained stable over several decades. However, on average, capture fisheries are fully exploited and their continuing productivity relies on careful management to avoid over-exploitation and long-term collapse. DGAC Grade: Strong

The DGAC endorses the FAO report that capture fisheries production plateaued around 1990 while aquaculture has increased since that time to meet increasing demand. Evidence suggests that expanded seafood production will rely on the continuation of a rapid increase in aquaculture output worldwide, projected at 33 percent increase by 2021, which will add 15 percent to the total supply of seafood.20 Distributed evenly to the world’s population, this capacity could in principle meet Dietary Guidelines recommendations for consumption of at least 8 ounces of seafood per week. Concern exists that the expanded capacity may be for low-trophic level seafood that has relatively low levels of EPA and DHA compared to other species. Under the current production, Americans who seek to meet U.S. Dietary Guidelines recommendations must rely on significant amounts of imported seafood (~90 percent). DGAC Grade: Moderate

Implications

Both wild and farmed seafood are major food sources available to support DGAC recommendations to regularly consume a variety of seafood. Responsible stewardship over environmental impact will be important as farmed seafood production expands. Availability of these important foods is critical for future generations of Americans to meet their needs for a healthy diet. Therefore, strong policy, research, and stewardship support are needed to increasingly improve the environmental sustainability of farmed seafood systems. From the standpoint of the dietary guidelines this expanded production needs to be largely in EPA and DHA rich species and supporting production of low-trophic level species of similar nutrient density as wild-caught.

Review of the Evidence

The UN FAO report on The State of World Fisheries and Agriculture issued in 2012 formed the basis of the DGAC’s evidence review on this topic.20  The FAO report addresses a wide variety of issues affecting capture fisheries and aquaculture, including economics, infrastructure, and labor and government policies. The DGAC focused on matters that directly address the world production of one important food—seafood—as a first attempt by a DGAC committee to consider the implications of dietary guidelines for production of a related group of foods.

The production of capture fisheries has remained stable at about 90 million tons from 1990-2011 (Figure D5.3).20  At the same time, aquaculture production is rising and will continue to increase. FAO model projections indicate that in response to the higher demand for seafood, world fisheries and aquaculture production is projected to grow by 15 percent between 2011 and 2021. This increase will be mainly due to increased aquaculture output, which is projected to increase 33 percent by 2021, compared with only 3 percent growth in wild capture fisheries over the same period. It is predicted that aquaculture will remain one of the fastest growing animal food-producing sectors and will exceed that of beef, pork, or poultry. Aquaculture production is expected to expand on all continents with variations across countries and regions in terms of the seafood species produced. Currently, the United States is the leading importer of seafood products world-wide, with imports making up about 90 percent of seafood consumption. Continuing to meet Americans needs for seafood will require stable importation or substantial expansion of domestic aquaculture.

Figure D5.3. Comparison of fishery production and aquaculture, 1950-2010

Graph of wild capture production compared to aquaculture production (in million tons) from 1950-2010.

For additional details on this body of evidence, visit: UN FAO report on The State of World Fisheries and Agriculture, 2012. Available at http://www.fao.org/fishery/sofia/en

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