Mrich foods: The cross-national effects of healthy eating on health outcomes

Purpose: Improving the nutritious quality of diets for individuals and populations is a central goal of many public health advocates and intergovernmental organizations. Yet the outcome of healthy eating has been shown to systematically vary across individual-level socioeconomic lines, and across countries in different locations of the food system. We therefore assess variation in the association between eating nutritionally dense fresh fruits and vegetables and both self-rated health (SRH) and body mass index (BMI) across individual income and country locations in the food system. Methodology/approach: We use nationally representative survey data from 31 countries drawn from the International Social Survey Programme's 2011 Health module. We estimate the effect of the frequency of eating fresh fruits and vegetables using random-intercept, random-coefficient multilevel mixed-effects regression models. Findings: We confirm that eating nutritionally dense fresh fruits and vegetables frequently associates with more positive health outcomes. However, this general conclusion masks substantial individual- and country-level heterogeneity. For both SRH and BMI, the largest beneficial associations are concentrated among the most affluent individuals in the most affluent countries. Moving away from either reduces the positive association of healthy eating. Social and practical implications: Our results provide an important wrinkle for policies aimed at changing the nutritional quality of diets. Adjustments to diets without taking into account fundamental causes of socioeconomic status will likely be met with attenuated results. Originality/value: We compare two important health outcomes across a wide variety of types of countries. We demonstrate that our main conclusions are only detectable when employing a flexible multilevel methodological design.