Michael Roberts

Sugar consumption has long been linked with a host of chronic health problems, including obesity, diabetes, and cardiovascular disease. To reduce Americans’ intake, many have called for taxing sugary products or limiting access in certain environments like schools and workplaces. These sometimes controversial calls for new public policy to curb consumption may soon be eclipsed by newly emerging links between sugar and addiction.Attaching the label “addictive” to a substance like sugar, which is necessary for human life, challenges widely held beliefs about addiction. But the extraordinary increase in sugar consumption during the past century, with related tripling of chronic diseases like obesity and diabetes, means our common understandings may be outdated.Part I of this paper will define “addiction” — especially as it relates to what was once a naturally occurring food nutrient and now is a highly concentrated food additive — and present evidence of the addictive potential of sugar.

Deterministic models have a long history of being applied to the study of infectious disease epidemiology. We highlight and discuss nine challenges in this area. The first two concern the endemic equilibrium and its stability. We indicate the need for models that describe multi-strain infections, infections with time-varying infectivity, and those where superinfection is possible. We then consider the need for advances in spatial epidemic models, and draw attention to the lack of models that explore the relationship between communicable and non-communicable diseases. The final two challenges concern the uses and limitations of deterministic models as approximations to stochastic systems.