Reducing nitrogen footprints of consumer-level food loss and protein overconsumption in Japan, considering gender and age differences

Abstract

The agro-food system perturbs the nitrogen (N) cycle through its N loads to the environment. The present study focused on food-related consumer-level N loads in Japan from 1961-2015, with a particular focus on food loss and protein overconsumption. Gender and age differences were also analyzed. Consumer-level food loss was negligible until the 1970s, when it began to slowly increase, accounting for an average of 13.2% of the annual net supply during 2011-2015. Japanese people have consumed more protein than the World Health Organization's recommended intake since 1961. Protein overconsumption increased until the mid-1990s, when it began to decrease, but it still accounted for an average of 32.3% of total annual protein consumption during 2011-2015. The national mean of food N footprints (total release of reactive N into the environment related to individual food consumption) in the same period was 18.3 kg N capita -1 yr -1 , of which food loss accounted for 4% and protein overconsumption for 37%. The food N footprint of each sex/age class varied from 16.0-21.6 kg N capita -1 yr -1 , males had a larger footprint in each age class. Seven scenarios to reduce the N footprints were evaluated; a scenario that included halving protein overconsumption, livestock meat consumption, and food loss was estimated to reduce the food N footprint by 31%. Thus, there is room for reducing consumer-induced N loads to the environment. Campaigns aimed at boosting healthy and environmentally friendly diets should consider the diverse consumption patterns of different sex and age classes.

Concealed nitrogen footprint in protein-free foods: an empirical example using oil palm products

“…The food N footprint of oil palm products calculated in the present study was compared with previously reported N footprints of several countries and the world average (Gu et al 2013, Pierer et al 2014, Shibata et al 2014, Stevens et al 2014, Liang et al 2016, Oita et al 2016, Hutton et al 2017, Shindo and Yanagawa 2017, Hayashi et al 2018 (table 3). The food N footprint of oil palm products in these countries ranged from 0.07 to 0.18 kg N capita -1 yr -1 , whereas their food N footprint ranged from 8.9 to 32 kg N capita -1 yr -1 .…”

“…In many cases, the N footprint is calculated on a national scale (e.g. Leach et al 2012, Shibata et al 2014, Hayashi et al 2018. The N-calculator method expresses the food N footprint of item i as:…”

“…African and Latin American countries were also included in the top 20. Hayashi et al (2018); 10, Shindo and Yanagawa (2017); 11, Hutton et al (2017). PO, palm oil; PKO, palm kernel oil.…”

“…The agro-food system's NUE is affected by both food production and food consumption. With regard to food consumption, both food choice and unnecessary protein supply affect the agro-food NUE; the latter corresponds to food loss and protein overconsumption by consumers (Hayashi et al 2018). Consumer behaviors such as preferring livestock meat with a relatively low NUE (Smil 2002), increasing food waste/loss, and consuming more food protein than necessary to meet the nutritional demand all lower the NUE.…”

“…The N-calculator method is a bottom-up approach for calculating the N footprint that has the advantage of reflecting individual differences in consumption directly in the calculation (e.g. Leach et al 2012, Shibata et al 2014, Hayashi et al 2018. The N-calculator method expresses the food N footprint as the sum of the N footprint of food production and that of food consumption; the former is derived by multiplying the consumed (ingested) food N by a virtual nitrogen factor (VNF) converting the consumed N to the amount of N released into the environment during production until just before consumption (Leach et al 2012).…”