An environmental, economic and nutrient index for milk and plant-based beverages in South Africa

Amidst growing global concerns over sustainability, the imperative for sustainable agriculture has become increasingly important. This urgency is propelled by heightened awareness among consumers and policymakers, the pressing demands of an increasing global population, and the critical influence of dietary choices on environmental sustainability. Recognising a gap in the literature, this study aimed to contextualise the sustainability of milk and plant-based beverages within the South African milieu, evaluating their nutritional profiles, environmental footprints and economic affordability through a comprehensive literature review. The investigation challenged the prevailing one dimensional approach in climate-aware consumer choices and policymaking, advocating for a new, contextually relevant perspective. Central to this research is the development of a sustainability model, the dairy index for the environment, economics and nutrition (DiEET) designed to provide a holistic assessment of the economic, nutritional and environmental dimensions of milk and plant based beverages. Based on the model results, milk held a superior nutritional and economic profile with scores of 1.932 and 0.848, respectively, in comparison to plant-based beverages with nutritional scores of 0.766-1.629 and economic scores of 0.574-0.713. Soy beverages obtained the highest scores between the plant-based beverages. Environmental scores highlighted bovine milk, with a score of 0.161, as the least environmentally sustainable beverage in comparison to plant-based beverages with scores of 0.165 to 0.193, showing an environmental trade-off of producing an affordable and nutritious product. In contrast to the nutrient rich food index (NRFi), the model results are less impacted by fortified nutrients. Using NRFi, the study showed that almond beverage has the highest nutrient score (32.573-64.808) in comparison to bovine milk with a maximum score of 8.288, which conflicts with nutrient comparisons and the results of the DiEET model. Environmental and economic results obtained from literature followed similar trends to the results obtained by the DiEET model. The study’s findings, both from literature and using the new DiEET model, underscore the complexity of achieving sustainability in the food system and highlights the trade-offs between nutritional value, environmental impact and affordability. This model is an initial step towards integrating multifaceted sustainability indicators into country-specific sustainability policies, thereby informing consumers and promoting a more sustainable, nutritionally adequate and economically viable food system in South Africa and beyond.