A multi-dimensional Sustainable Diet Index (SDI) for Ghanaian adults under transition: the RODAM Study

The sustainability of diets consumed by African populations under socio-economic transition remains to be determined. This study developed and characterized a multi-dimensional Sustainable Diet Index (SDI) reflecting healthfulness, climate-friendliness, sociocultural benefits, and financial affordability using individual-level data of adults in rural and urban Ghana and Ghanaian migrants in Europe to identify the role of living environment in dietary sustainability.

We used cross-sectional data from the multi-centre Research on Obesity and Diabetes among African Migrants Study (N = 3169; age range: 25-70 years). For the SDI construct (0-16 score points), we used the Diet Quality Index-International, food-related greenhouse gas emission, the ratio of natural to processed foods, and the proportion of food expenditure from income. In linear regression analyses, we estimated the adjusted ß-coefficients and 95% confidence intervals (CIs) for the differences in mean SDI across study sites (using rural Ghana as a reference), accounting for sociodemographic and lifestyle factors.

The overall mean SDI was 8.0 (95% CI: 7.9, 8.1). Participants in the highest SDI-quintile compared to lower quintiles were older, more often women, non-smokers, and alcohol abstainers. The highest mean SDI was seen in London (9.1; 95% CI: 8.9, 9.3), followed by rural Ghana (8.2; 95% CI: 8.0, 8.3), Amsterdam (7.9; 95% CI: 7.7, 8.1), Berlin (7.8; 95% CI: 7.6, 8.0), and urban Ghana (7.7; 95% CI: 7.5, 7.8). Compared to rural Ghana, the differences between study sites were attenuated after accounting for age, gender and energy intake. No further changes were observed after adjustment for lifestyle factors.

The multi-dimensional SDI describes four dimensions of dietary sustainability in this Ghanaian population. Our findings suggest that living in Europe improved dietary sustainability, but the opposite seems true for urbanization in Ghana.