Assessment of greenhouse gas emissions and water footprint of national diet in Turkey

This study examined the environmental effects of the national diet in Turkey. The study sample consisted of 9012 (3390 men, 5622 women) and 12318 (5516 men, 6802 women) people aged 15 and older who participated in the 2010 and 2017 Turkey Nutrition and Health Survey (TNHS), respectively. Diet-related greenhouse gas emissions and water footprint were determined based on daily food consumption records. The diet quality consumed by individuals was assessed using the international diet quality index (DQI) and dietary diversity score, and the processed food content was assessed using the NOVA classification. According to the TNHS 2010 and 2017 data, greenhouse gas emissions increased by 16.1% (TNHS 2010: 2.73±2.04 kg CO2eq/person/day; TNHS 2017: 3.17±1.98 kg CO2eq/person/day) and the total water footprint increased by 17.6% (TNHS 2010: 2386.6±1320.1 L/person/day; TNHS 2017: 2805.5±1324.3 L/person/day) (p<0.001). The two food groups with the highest contribution to greenhouse gas emissions in the TNHS 2017 were red meat (40.1%) and dairy products (16.9%), while fats (0.8%) and oils (1.6%) contributed the lowest (p<0.001). Furthermore, the two food groups with the highest contribution to the total water footprint in the TNHS 2017 were red meat (23.6%) and cereals (16.9%), while vegetables (1.8%), fats (2.5%) and black tea (2.5%) contributed the lowest (p<0.001). A positive and weak relationship was found between greenhouse gas emissions and energy intake (r=0.29, p<0.01), the DQI diversity score (r=0.26, p<0.01), the DQI adequacy score (r=0.27, p<0.01) and the dietary diversity score (r=0.29, p<0.01). A negative and weak relationship was found between greenhouse gas emissions and the DQI balance score (r=-0.37, p<0.01). A positive and moderate relationship was found between total water footprint and energy intake (r=0.4, p<0.01). A positive and weak relationship was also found between the total water footprint and the DQI diversity score (r=0.3, p<0.01), the DQI adequacy score (r=0.36, p<0.01) and the dietary diversity score (r=0.37, p<0.01). A negative and moderate relationship was found between the total water footprint and the DQI balance score (r=-0.44, p<0.01). According to the TNHS 2010 and 2017 data, 9.8% and 9.0% of individuals' daily energy intake came from ultra-processed foods, respectively. The highest contribution to energy intake (TNHS 2010: 459.3±331.12 kcal (25.4%), TNHS 2017: 385.6±366.72 kcal (20.2%)) was provided by bread in the processed food group. Although the effect of the national diet on greenhouse gas emissions and total water footprint in Turkey is lower than the global average, it increased in 2017 compared to 2010. When making nutritional recommendations for the population, the environmental effects of the diet should be considered in addition to the health benefits of the individuals.