Featured article in the Summer 2018 Issue of Nutrition Close-Up; written by Sarah Rebbert, BS & Bruce Y. Lee, MD, MBA
Nutrition and health are complex. The relationship between a given nutrient and chronic disease is not a simple single cause-single effect relationship. There is a complex system of mediating and modifying factors such as what combinations of nutrients are in the food or beverage, how the food is prepared, when and how the food is consumed, what the person’s health status is and what other risk factors the person may have for obesity and other medical conditions. Therefore, there is a need for more methods and approaches that can help us better understand this complex system.
Not fully understanding the systems that affect nutrition and health can make it challenging to come up with dietary guidance and recommendations that are adaptable enough for different people and situations. In fact, not using a systems approach can even result in unintended consequences.
For example, the 1990 and 1995 Dietary Guidelines for Americans emphasized the dangers of diets high in saturated fat and cholesterol. This then led to many new products advertised as being low in fat and cholesterol hitting the market. However, low in fat and cholesterol does not necessarily mean healthy. A number of low-fat products were also subsequently higher in sugar, salt, artificial ingredients and refined carbohydrates. Obesity, overweight and chronic disease rates rose throughout the popularity of low fat products in the 90’s. Viewpoints on eggs changed over time as well. For example, the 1977 Dietary Goals for the United States report recommended that Americans eat less eggs as a low-fat diet was needed to prevent the two leading causes of death, coronary heart disease and cancer.1 Now, evidence supports that whole eggs can be part of a heart-healthy diet. Eating eggs has been shown to change the size and shape of “bad” cholesterol and increase “good” cholesterol levels – markers of heart disease risk.2
A National Academies of Medicine report recommends integrating systems approaches and methods into the Dietary Guidelines for Americans (DGA) 2020
The National Academies of Science convened a committee to come up with recommendations on how the DGA process should be adjusted. One of the recommendations in the Redesigning the Process for Establishing the Dietary Guidelines for Americans was to use a comprehensive and coordinated systems approach in order to promote health and prevent chronic diseases. The report also indicated that modeling in general can be helpful in examining complex systems, and the food pattern modeling conducted by the United States Department of Agriculture has tremendous potential for showing the simultaneous effects of altering food intake patterns.3
The Global Obesity Prevention Center (GOPC) at Johns Hopkins University
There is now more data, technologies and analysis capabilities than in previous decades to help researchers and health professionals better understand and address the complex systems that affect nutrition and health.4
Computational simulation models can help overcome potential challenges by serving as virtual laboratories to better understand and explore the impact of a policy or intervention before real-world implementation. The GOPC has been working with decision-makers to develop and utilize computational simulation models to design and test different potential interventions and policies, which in turn could save considerable time, effort and resources.
|Figure 1: The global obesity graphic was designed by the GOPC to demonstrate the interconnected, complex network of factors that make-up the epidemic.|
Examples include the GOPC’s VPOP (Virtual Populations for Obesity Prevention) simulation models of cities such as Baltimore, New Orleans, Philadelphia, San Francisco and Washington D.C. Each model includes geospatially explicit virtual representations of people and relevant locations (e.g., households, schools, physical activity sites such as gyms, parks and recreation centers and food sources such as grocery stores, fast food restaurants, corner stores and sit-down restaurants). In the virtual communities, people go about their routine daily activities and make decisions that affect their diet and physical activity levels. Each virtual person has an embedded metabolic model. The virtual residents, like real people, can gain and lose weight depending on how many calories they consume and expend (Think SimCity.).
The VPOP models have helped determine the economic and health impact of increasing US youth physical activity levels 5 and better understand how the implementation of sugar-sweetened beverage (SSB) warning labels can impact obesity prevalence.6
Given the complexity of nutrition, it’s key that a unified, strategic, systems approach that incorporates all the multilevel, multifaceted factors come into play to better understand and improve health.
Sarah Rebbert is the Communications Associate for the Global Obesity Prevention Center (GOPC) in the Department of International Health at Johns Hopkins Bloomberg School of Public Health.
Bruce Y. Lee, MD, MBA is an Associate Professor in the Department of International Health at the Johns Hopkins Bloomberg School of Public Health, Executive Director of the Global Obesity Prevention Center (GOPC) at Johns Hopkins and Director of Operations Research at the International Vaccine Access Center (IVAC) as well as Associate Professor at the Johns Hopkins Carey Business School.
- La Berge, A.F. How the Ideology of Low Fat Conquered America. Journal of the History of Medicine and Allied Sciences. 2008; 139-177.
- Blesso, C.N., et al. Whole egg consumption improves lipoprotein profiles and insulin sensitivity to a greater extent than yolk-free egg substitute in individuals with metabolic syndrome. Metabolism. 2013; 400-410.
- “Front Matter.” Redesigning the Process for Establishing the Dietary Guidelines for Americans. National Academies of Sciences, Engineering, and Medicine. 2017.
- Lee, B.Y., et al. A Systems Approach to Obesity. Nutrition Reviews. 2017; 94-106.
- Lee, B.Y., et al. Modeling the Economic and Health Impact of Increasing Children’s Physical Activity in the United States. Health Affairs. 2017; 902-908.
- Lee, B.Y., et al. Simulating the Impact of Sugar-Sweetened Beverage Warning Labels in Three Cities, American Journal of Preventive Medicine. 2017.