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Symposium: Evidence-Based Public Nutrition: An Evolving Concept

Evidence-Based Public Nutrition: An Evolving Concept¹

² Connecticut National Institutes of Health EXPORT Center of Excellence for Eliminating Health Disparities among Latinos and Department of Nutritional Sciences, University of Connecticut, Storrs, CT 06269-4017 and ³ Children's Hospital Oakland Research Institute, Oakland, CA 94609

^* To whom correspondence should be addressed. E-mail: rafael.perez-escamilla{at}uconn.edu

Mason et al. define Public Nutrition as "The field of study that deals with nutrition-related population problems and public policies and programs to address these ... with many of the topics of relevance going well beyond the sole domain of public health" (1).

The Evidence-Based Public Nutrition (EBPN) framework posits 3 key steps involving 1) the discovery and characterization of the problem, 2) addressing the problem through multisectorial initiatives, and 3) determining if the problem was properly addressed.

Discovery and characterization of the problem

Discovering the nature of the nutrition-related problem involves first an in-depth understanding of the frequency and distribution of the public nutrition problem. Second, it involves understanding the socioeconomic, demographic, and biocultural factors associated with the problem. Third, the EBPN framework calls for understanding the cost to society of not addressing the problem. This process of understanding usually starts with nonexperimental research designs and randomized controlled trials (RCTs) conducted under ideal conditions. The end result of this process should be the identification of diet-health causal relationships.

Addressing the problem through multisectorial initiatives

Once the process of discovery is well advanced, it is essential to translate the policies or recommendations into "real world" programs. This is the step that perhaps is most misunderstood, as moving forward with it requires "real world" research; i.e., it can not rely solely on the "ideal world" or efficacy RCTs that were carried out during the process of discovery of the public nutrition problem. Addressing the problem under "real world" conditions involves a complex iterative process requiring formative evaluation [i.e., community needs and wants assessment(s)], proposing alternative solutions, choosing the best solutions, implementing the program, and evaluating its process and impact. The formative evaluation phase is needed to understand not only the extent of the problem but also the social and cultural context in which it needs to be addressed. This requires the application of both qualitative and quantitative research methods. Proposing alternative solutions based on context-specific needs assessments requires solid grounding in theory and empirical evidence. However, more often than not this is initially done based mostly on common sense. Selecting the best solutions requires in-depth health economic analyses that have to be interpreted and understood within the target sociocultural context. Monitoring the implementation of a program requires in-depth process evaluations based on solid quantitative and qualitative research methods.

Finding out if the problem was properly addressed

Whenever possible, RCTs should be conducted to assess "real world" program impacts or outcome evaluation. However, conducting RCTs under real-world conditions is very challenging and often impossible because of enormous logistical, ethical, and political challenges (2). In addition, even when feasible, RCTs have serious external validity limitations because it is commonly found that not all population subgroups respond in the same way to programs or other interventions. For example, baseline nutritional status, gender, age, and socioeconomic status often modify the relation between a program and the outcomes of interest. The bottom line recognized by the EBPN framework is that casual inference from real-world translational research should be based not only on the probability (i.e., RCTs) but also on the plausibility approach (i.e., nonexperimental designs), and thus, causality inference should be based on a high-level integration of evidence derived from both experimental and nonexperimental designs (2).

The objective of this symposium was to present 5 real-world examples where the EBPN framework has been applied to different extents. The article by Janet King on evidence-based dietary guidelines and that by Barbara Schneeman on evidence-based review of health claims illustrate why the EBPN should be applied more comprehensively to improve the public health impact of 2 major public nutrition tools (i.e., dietary guidelines and food labels). The article by Pérez-Escamilla on evidence-based breast-feeding promotion provides an example of an initiative, the Baby-Friendly Hospital Initiative (BFHI) that was launched globally, mostly based on "common sense." Since then, BFHI's efficacy, effectiveness, and cost-effectiveness have been evaluated through sound observational and experimental studies. In other words, this article illustrates how "it is never too late" to start applying the EBPN framework. Tim Byers' article on the obesity epidemic illustrates the price that we are paying for not using an evidence-based approach or developing and implementing cost-effective programs in this area.

The symposium presentation on evidence-based folic acid fortification is not included in this publication as this work has been reported elsewhere (3,4). The fortification of the food supply with additional folic acid for the prevention of neural tube defects (NTDs) represents the first time in the history of public nutrition that such a massive effort has been put into place for a condition likely to be explained primarily by genomic alterations (i.e., polymorphisms) (5). This is an interesting public nutrition case study because in the United States the end result has been chronically exposing close to 300 million people since 1997 to additional folic acid, via fortified products, with the goal of preventing 1500 NTDs per year. This case is one of the best examples of how a rigorous implementation of the first step of the EBPN framework (i.e., discovering the nature, extent, determinants, and consequences of the periconceptional folic acid–NTDproblem) coupled with strong leadership from the Centers for Disease Control and Prevention has led to the implementation of a nutrient-specific fortification effort worldwide. However, this case also illustrates how important it is to understand the impact of the fortification program in the real world. As of today, the United States does not have a system in place to detect the possibility of side effects as a result of chronic exposure to folic acid (3), nor is it clear if and how the fortification policy has influenced different socioeconomic and ethnic/racial subgroups. It is our hope that the discussion that this symposium generates will contribute toward a better coordination and understanding of how the EBPN framework can be applied to improve the quality and impact of public nutrition policies and programs worldwide.

	FOOTNOTES

 
¹ Presented as part of the symposium "Evidence-Based Public Nutrition: An Evolving Concept" given at the 2006 Experimental Biology meeting on April 4, 2006, San Francisco, CA. The symposium was sponsored by the Dannon Institute and the Connecticut EXPORT Center of Excellence for Eliminating Health Disparities among Latinos (NIH-NCHMD grant 1P20MD001765-01). This supplement is the responsibility of the guest editors to whom the Editor of The Journal of Nutrition has delegated supervision of both technical conformity to the published regulations of The Journal of Nutrition and general oversight of the scientific merit of each article. The opinions expressed in this publication are those of the authors and are not attributable to the sponsors or the publisher, editor, or editorial board of The Journal of Nutrition. Guest editors for the symposium publication are Rafael Pérez-Escamilla, University of Connecticut, Storrs, CT, and Janet King, Children's Hospital Oakland Research Institute, Oakland, CA.

	LITERATURE CITED

TOP LITERATURE CITED

 

1. Mason JB, Habicht JP, Greaves JP, Jonsson U, Kevany J, Martorell R, Rogers B. Public nutrition. Am J Clin Nutr. 1996;63:399–400.[Free Full Text]

2. Victora CG, Habicht JP, Bryce J. Evidence-based public health: Moving beyond randomized trials. Am J Public Health. 2004;94:400–5.[Abstract/Free Full Text]

3. Cornel MC, de Smit DJ, de Jong-van den Berg LT. Folic acid: The scientific debate as a base for public health policy. Reprod Toxicol. 2005;20:411–5.[Medline]

4. Honein MA, Paulozzi LJ, Mathews TJ, Erickson JD, Wong LY. Impact of folic acid fortification of the US food supply on the occurrence of neural tube defects. JAMA. 2001;285:2981–6. Erratum in. JAMA. 2001;286:2236.[Free Full Text]

5. Willet W. Folic acid and neural tube defects. In: Willet W, editor. Nutritional epidemiology. New York: Oxford University Press; 1998. p. 467–483.

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