Background and aims
India is the world's third largest contributor to greenhouse gas (GHG) emissions and the world's largest user of groundwater. This is not only due to its large population but also the rapid pace of development and dietary change, which has resulted in diverse diets being consumed by different population groups. This study aimed to quantify the GHG emissions in carbon dioxide equivalent (CO2e) and water usage in litres (L) associated with typical dietary patterns in India.
The GHG emissions and water use of five typical and distinct dietary patterns were quantified using estimates taken from previous studies, and based on the LCA model for GHG emissions and the Water Footprint (WF) Assessment for water use. The dietary patterns were identified from the Indian Migration Study (IMS), a large adult population sample in India, and were named on the basis of the dominant staple grain and one other identifying feature: Rice & low energy, Rice & fruit, Wheat & pulses, Wheat, rice & oils, Rice & meat. Mixed effects regression models were used to quantify the change in environmental impacts that would occur for individuals switching between dietary patterns.
Overall across all dietary patterns, the GHG emissions from Indian diets were 3.6kg CO2e/capita/day (mean ± standard deviation), the green WF (from precipitation) was 2,531L/capita/day and the blue WF (from ground and surface water) was 737L/capita/day. However, there was substantial variability between dietary patterns: the rice-based patterns had higher GHG emissions and green WFs per calorie, while the wheat-based patterns had slightly higher blue WFs per calorie. Switching from the Rice & low energy diet to the Rice & meat pattern would result in a 0.59kg (15%) increase in GHG emissions, a 536L (24%) increase in green WF and a 109L (19%) increase in blue WF. By contrast, switching to the Wheat, rice & oils pattern would result in a 0.82kg (20%) decrease in GHG emissions and a 364L (17%) decrease in green WF, but a 302L (53%) increase in blue WF.
These are the first estimates of environmental impacts from distinct dietary patterns in India. Overall, Indian diets were lower in both GHG emissions and green WFs although higher in blue WFs than diets in high income countries. However, the rice-based patterns were found to have much higher environmental impacts than the wheat-based patterns. As Indian diets continue to transition, it is likely that more people will switch their diets from the most traditional pattern identified (the Rice & low energy) pattern to one of the other rice- or wheat-based patterns. Switching to one of the wheat-based patterns identified would reduce dietary GHG emissions and green WF, but increase blue WF, which may not be desirable in a country already suffering groundwater shortages. Future policies on food will need to balance the various environmental impacts of different diets as well as the possible health implications, and may also need to take into account regional variations in both environmental conditions and cultural diet preferences.