Dietary Influences on Nitrogen and Phosphorus Footprints in Indian Food Systems: A State and Union Territory-Level Analysis.

Background/Objectives: Nitrogen (N) and phosphorus (P) are essential macronutrients for crop production. However, their losses throughout the agri-food system pose significant environmental and public health risks. India, with its diverse dietary cultures and large agricultural sector, presents a unique context for evaluating nutrient footprints. This study aims to provide the first sub-national assessment of food-related N and P footprints across Indian states and union territories, evaluating how vegetarian and non-vegetarian diets influence these footprints. Methods: This study employed a diet-sensitive bottom-up approach using national dietary consumption statistics from 2011-2012 to estimate food N and P footprints. The analysis incorporated regional dietary profiles and nutrient use efficiencies in crop production, along with food waste data, to quantify the affecting factors. Results: The national average food footprints were estimated at 13.11 kg-N capita-1 year-1 and 1.16 kg-P capita-1 year-1, with sub-national variation ranging from 52% to 144% of the national average for N, and 46% to 166% for P. Regions with prevalent non-vegetarian diets exhibited significantly higher footprints than those with vegetarian diets. Low nutrient use efficiencies (NUE 19%, PUE 31%) and consumer-level food waste (contributing nearly 4%) were also identified as key drivers of elevated footprints. Conclusions: The findings indicate that dietary choices, agricultural nutrient management, and food waste practices collectively contribute to the nutrient-related risks in India. Enhancing nutrient use efficiency, promoting plant-based diets, and improving waste management in culturally and regionally sensitive ways are crucial for reducing N and P losses. These findings provide actionable insights for the development of sustainable nutrition and agro-environmental policies.