1 Field Science Center for Northern Biosphere, Hokkaido University, Kita-9, Nishi-9, Kita-ku, Sapporo, 060-0809, Japan, firstname.lastname@example.org
2 Graduate School of Environment and Information Science, Yokohama National University, 79-7 Tokiwadai, Hodogaya, Yokohama 240-8501, Japan
Nitrogen (N) footprint is a powerful parameter to understand loss of reactive N (i.e. all forms of nitrogen except N2) to the environment by use of food, and energy in human’s daily life. The amount and composition of the N footprint differs among communities, countries and regions depending on various factors such as environment, economy, technological development and their culture. Japan is the top net importer of embodied reactive N emissions in food, feed, energy, and goods among countries, resulting in large loss of reactive N to the environment both inside and outside of Japan. Here we present updated information of N footprint in Japan by synthesizing the recent research findings. Virtual N factors (VNFs) of meat processed food in Japan are mostly higher than those in other countries while fish and seafood (especially wild-caught fish) is also important source of animal protein with generally lower VNFs than that of animal meat. It was suggested that shifting consumer preferences from meat- and dairy-intensive diets to diets with more fish and vegetables would have potential to reduce the N footprint in Japan. Increase of N use efficiency during production, processing, and consumption of food through technological improvements in agriculture and food industries with changes in personal dietary choices are needed to decrease loss of reactive N to the environment both in Japan and countries that provide food and feed to meet demand of Japan.