isolated platinum atoms on oxide supports FOOD SCIENCE bind CO too strongly to be active. Rather, the authors find that metallic platinum sites on nanoparticles catalyze the reactions. Designing a sustainable Framing these results in terms of the co- ordination number, single platinum atoms Sustainability as dietary guidance created political debate correspond to the strong-binding regime at the left of the figure. The more highly co- ordinated sites on small nanoparticles are By Kathleen Merrigan,1* Timothy Griffin,2 fewer than 40% of American adults meet the closer to the apex of the figure. Parke Wilde,2 Kimberly Robien,3 Jeanne healthy weight recommendation (1, 3). In contrast to previous work (9), Ding Goldberg,2 William Dietz3 Nevertheless, DGAs have tangible influ- et al.’s results suggest small metallic Pt ence on federal programs. DGAs inform nanoparticles, rather than isolated Pt at- n the United States, a vigorous debate is content for example, for (i) military oms, give rise to enhanced catalysis of CO. under way over government-issued di- personnel; (ii) 8.6 million needy Americans The applicability of these findings will de- etary guidance. A February 2015 report served by the Women, Infants, and Chil- pend on the elemental composition of the by the U.S. Dietary Guidelines Advisory dren program; and (iii) 31 million children catalyst and electronic interactions between Committee (DGAC) recommended, for the served through the National School Lunch the support and the metal. For example, first time, that sustainability Program. DGAC recommended that the unlike platinum, making gold catalytically Ibe an integral part of dietary guidance in government do a better job aligning fed- active requires atomically dispersed atoms the 2015 Dietary Guidelines for rather than larger nanoparticles (15). Fur- Americans (DGAs) (1). With the ther work is needed to identify which exact final decision from the secretar- sites on platinum nanoparticles (for exam- ies of Health and Human Ser- ple, terrace, edge, kink, or corner sites) are vices (HHS) and of Agriculture active for CO oxidation and water-gas shift (USDA) about what parts of the catalysis. Of particular interest is the explo- DGAC recommen- ration of relationships between the rates of POLICY dations to include the CO oxidation/water-gas shift reactions in the 2015 DGAs on platinum and the generalized coordi- expected at the end of this year, nation number introduced by Calle-Vallejo we discuss the need to incorpo-

and co-workers (see the figure). rate sustainability into dietary on February 13, 2016 The implications of reaction rate sen- guidelines and the political ma- sitivity to coordination number for het- neuvering under way to excise it. erogeneous catalysis are both subtle and DGAs, which are updated ev- far-reaching. The rational design of cata- ery 5 years, have consistently lysts for heterogeneous processes requires recommended a diet higher in a detailed understanding of the interplay -based foods and lower in of both the electronic structure of the cata- animal-based foods. This year lyst surface and its local coordination en- DGAC concluded that “consis- Downloaded from vironment. The insights described in (1, 2) tent evidence” suggests that highlight the immense opportunities for such a dietary pattern is not catalyst discovery and improvement pro- only more healthful but also is vided by detailed understanding of the na- associated with less environ- ture of active sites. ■ mental impact than the average American diet (1). This ratio- REFERENCES 1. F. Calle-Vallejo et al., Science 350, 185 (2015). nale has ignited controversy (2). 2. K. Ding et al., Science 350, 189 (2015). Dietary guidelines are not unique to the eral assistance programs [e.g., 3. T. Jiang et al., J. Phys. Chem. C 113, 10548 (2009). United States. The United Nations Food and the Supplemental Nutrition Assistance 4. A. Kuzume, E. Herrero, J. M. Feliu, J. Electroanal. Chem. 599, 333 (2007). Agriculture Organization (FAO) posts di- Program (SNAP)] with DGAs. There are no 5. A. S. Bandarenka, H. A. Hansen, J. Rossmeisl, I. E. L. etary guidelines by 67 national governments. restrictions on how SNAP benefits can be Stephens, Phys. Chem. Chem. Phys. 16, 13625 (2014). The purpose of such guidance historically used, although whether to limit benefits to 6. S. W. Lee et al., J. Am. Chem. Soc. 131, 15669 (2009). has been to educate people on how to avoid healthy food purchases has been debated 7. S. C. S. Lai, N. P. Lebedeva, T. H. M. Housmans, M. T. M. Koper, Top. Catal. 46, 320 (2007). malnutrition. In the United States, DGAs are for years. If DGAC’s recommendation is 8. J. Z. Xu, J. T. Yates, J. Chem. Phys. 99, 725 (1993). important information for nutrition profes- upheld, it would affect 47 million SNAP re- 9. Q. Fu, H. Saltsburg, M. Flytzani-Stephanopoulos, Science sionals. Skeptics argue that DGAs are largely cipients and billions of dollars annually in 301, 935 (2003). 10. J. K. Nørskov et al., J. Phys. Chem. B 108, 17886 (2004). inconsequential. Adherence is problem- government spending. The SNAP debate 11. J. R. Kitchin, J. K. Nørskov, M. A. Barteau, J. G. Chen, Phys. atic; only 4% of Americans meet DGAs, and surely contributes to the DGA controversy. Rev. Lett. 93, 156801 (2004). 12. M. Mavrikakis, B. Hammer, J. K. Nørskov, Phys. Rev. Lett. SUSTAINABILITY. FAO defines sustain- 81, 2819 (1998). 1Trachtenberg School of Public Policy and Public 13. V. R. Stamenkovic et al., Science 315, 493 (2007). Administration, the George Washington University, able diets as those with “low environmen- 14. P. Strasser, Science 349, 379 (2015). Washington, DC 20052, USA. 2Friedman School of Nutrition tal impacts which contribute to food and 15. M. Yang et al., Science 346, 1498 (2014). Science and Policy, Tufts University, Medford, MA 02155, nutrition security and healthy life for pres- USA. 3Milken Institute School of Public Health, the George Washington University, Washington, DC 20052, USA. ent and future generations” (4). By this or

ILLUSTRATION: TANG YAU HOONG YAU TANG ILLUSTRATION: 10.1126/science.aad3716 *Corresponding author. E-mail: [email protected] any other definition of sustainability, no

SCIENCE sciencemag.org 9 OCTOBER 2015 • VOL 350 ISSUE 6257 165

Published by AAAS INSIGHTS | PERSPECTIVES country has achieved a sustainable diet. Administration proposal to require labels and elevate discussion of sustainable diets. Current and emerging dietary patterns for added sugar; industry may see transpar- The U.S. government has been careful to threaten human health in developing and ency as a step toward a ban, as happened relegate oversight of to a gov- developed countries (5, 6) and negatively with trans fats. ernment marketing program, which makes affect long-term food security (7). It is thus The feels especially under it safe for politicians to support organic as a not unreasonable that government-issued attack. Much discussion of sustainable di- matter of consumer choice without having dietary guidelines take sustainability into ets has focused on the increase in livestock to say whether it is healthier or has fewer account. The Netherlands, Brazil, and Swe- production that will result from popula- environmental impacts than conventionally den have already done so. Germany and the tion growth and adoption of Western-style produced food. By acknowledging benefits United States have active, but unresolved, diets by an expanding middle class in the of sustainability, the government would discussions. developing world. Whether from a health open itself up to greater demands for sus- As required by law, the DGAC based its perspective (e.g., reducing coronary heart tainability investments and would signal to report on scientific evaluations (4, 8). Oppo- disease) or an environmental perspective consumers that such foods are preferred. nents of the sustainability language assert (e.g., reducing methane emissions and de- Exponential growth in sales of organic, lo- that DGAC has overstepped its statutory forestation) the dietary advice is the same: cal, and sustainably harvested seafood sug- bounds (2). But nothing in the 1990 DGA eat less meat (7). But reducing discussion gests an appetite for sustainably produced statute prevents inclusion of sustainability, to a meat-focused debate ignores larger food. People are motivated to change behav- and the DGAC argument that future food points around food production. For exam- ior for different reasons. Although shifting insecurity is predictable without attention ple, it takes up to 2.8 liters of water to pro- dietary choices for health reasons alone has to sustainability is relevant and compelling. duce a single “heart-healthy” almond (9). not worked well, some people may be com- Pending House and Senate appropriations With 80% of the world’s almonds grown pelled to change diets to achieve sustain- bills that govern HHS and USDA propose in drought-stricken California, should con- ability goals. new statutory language that would require sumers be advised to limit almond con- In addition to the environmental impacts the secretaries to consider diet and nutrient sumption and consider alternatives that of food production, its economic sustain- intake only, which would prevent sustain- consume fewer resources? ability must also be considered. The chal- ability considerations. DGAC sent a letter to Second, sustainability has potential to lenge is how to produce the most healthful move dietary guidance from a system based foods in a way that sustains employment on food groups (e.g., , , and in the agricultural sector and minimizes protein) to individual foods within a food adverse impacts on the environment. All “The U.S. debate has group (e.g., chicken versus beef). The environ- major constituencies concerned with food awakened civil society… mental footprint may elevate certain foods security and health must wrestle with sus- over others. The Dutch 2011 dietary guid- tainability and dietary choices together. It and has aligned public ance presented four sustainability-related is right and proper for the DGA process to health and sustainability recommendations, including advice to eat lead the way. ■ two portions of fish per week (10). However, REFERENCES AND NOTES advocates.” fishing has sustainability issues, and the rec- 1. Dietary Guidelines Advisory Committee, “Report of the ommendation was deemed “ecologically det- Dietary Guidelines Advisory Committee, 2015” (HHS and congressional appropriators protesting this rimental.” The Dutch Health Council is now USDA, Washington, DC, 2015). 2. H. Knotter, “How to sustain sound dietary guidelines “unduly narrow” restriction, which fails to evaluating the sustainability of individual for Americans: Mission creep within the federal Dietary consider topics already within the scope of fish species, with a new version of the dietary Guidelines Advisory Committee threatens Americans’ DGAs, e.g., guidance on physical activity. guidance expected this October. health and well-being” (Hudson Institute, Washington, DC, 2014). It is increasingly likely that Congress will Third, the sustainability discussion has 3. A. D. Liese et al., J. Nutr. 145, 393 (2015). fail to pass these appropriations bills and potential to forge new political coalitions. 4. B. Burlingame, S. Dernini, Eds., Sustainable Diets and instead will fund the government through The 2014 Brazilian dietary guidelines : Directions and Solutions for Policy, Research, and Action (FAO, Rome, 2010). a continuing resolution. Even in that sce- were adopted despite pro- 5. FAO, Focus: The Developing World’s New Burden: nario, the congressional language poses a tests over the recommendation to avoid (FAO, Rome, 2012); www.fao.org/focus/e/ serious challenge to the secretaries of HHS ultra-processed food (e.g., chicken nuggets obesity/obes1.htm. and USDA. rather than freshly prepared chicken) (11). 6. F. Imamura et al., Lancet Global Health 3, e132 (2015). 7. D. Tilman, M. Clark, Nature 515, 518 (2014). This bold approach may be attributed to 8. Food and Nutrition Board, Institute of Medicine, POLITICAL MANUEVERING. We believe engagement by civil society and the break- Sustainable Diets: Food for Healthy People and a Healthy the issue of scope is not the overarching down of the traditional coalition of farm- Planet: Workshop Summary (National Academies Press, Washington, DC, 2014). concern but a political maneuver to excise ers and over ultra-processed 9. M. M. Mekonnen, A. Y. Hoekstra, Hydrol. Earth Syst. Sci. 15, sustainability from dietary discussions for food guidance, which garnered farmer sup- 1577 (2011). four reasons. First, many industry leaders port. The U.S. debate has awakened civil 10. Health Council of the Netherlands, Richtlijnen voed- selkeuze [Guidelines for healthy dietary choices] (Health do not want any food disparaged, and a society to the potential influence of DGAs Council of the Netherlands, The Hague, 2011). DGA process that evaluates sustainability beyond food consumption and has aligned 11. Ministry of Health of Brazil, Secretariat of Health Care, will likely lead to conclusions that some public health and sustainability advocates. Primary Health Care Department, Dietary Guidelines for the Brazilian Population (Ministry of Health of Brazil, foods are better than others. Although Although not much difference is expected Brasília, DF, Brazil, 2014). DGAs are advisory (not mandatory, except in 2015, the debate has activated political as previously described for government coalitions that could organize for the next ACKNOWLEDGMENTS programs), the worry is that sustainabil- DGA iteration in 2020. The commentary grew out of a November 2014 symposium on sustainability and dietary guidance supported by the W.K. ity evaluations may lead to future regula- Fourth, and perhaps most important, Kellogg Foundation and Grace Communications Foundation. tion. Fear of regulation underlies industry if the U.S. government adopts the DGAC’s protest of the current U.S. Food and Drug reference to sustainability, it will sanction 10.1126/science.aab2031

166 9 OCTOBER 2015 • VOL 350 ISSUE 6257 sciencemag.org SCIENCE

Published by AAAS