With increasing population and changing demographics, food consumption has experienced a significant transition in quantity and quality.  However, a dearth of knowledge remains regarding its environmental impacts and how it responds to demographic dynamics, particularly in emerging economies like China.  Using the two-stage Quadratic Almost Demand System (QUAIDS) model, this study empirically examines the impact of demographic dynamics on food consumption and its environmental outcomes based on the provincial data from 2000 to 2020 in China.  Under various scenarios, according to changes in demographics, we extend our analysis to project the long-term trend of food consumption and its environmental impacts, including greenhouse gas (GHG) emissions, water footprint (WF), and land appropriation (LA).  The results reveal that an increase in the proportion of senior people significantly decreases the consumption of grain and livestock meat and increases the consumption of poultry, egg, and aquatic products, particularly for urban residents.  Moreover, an increase in the proportion of males in the population leads to higher consumption of poultry and aquatic products.  Correspondingly, in the current scenario of an increased aging population and sex ratio, it is anticipated that GHG emissions, WF, and LA are likely to decrease by 1.37, 2.52, and 3.56%, respectively.  More importantly, in the scenario adhering to the standards of nutritional intake according to the Dietary Guidelines for Chinese Residents in 2022, GHG emissions, WF, and LA in urban areas would increase by 12.78, 20.94, and 18.32%, respectively.  Our findings suggest that changing demographics should be considered when designing policies to mitigate the diet-environment-health trilemma and achieve sustainable food consumption.

过去几十年里，中国互联网迅速普及，对农村地区经济和社会发展产生了深远的影响。一些研究发现互联网接入对农业生产率和农民收入具有显著正向影响，但有关互联网对农村居民福利影响的研究仍相对不足，尤其是在关注互联网对农村居民膳食质量方面的研究缺乏。本研究利用全国农村固定观察点2009年到2015年的多期面板数据，使用双向固定效应模型，分析互联网接入对农户膳食质量水平和食物消费的影响。该模型同时控制农户个体层面和时间层面的固定效应，不仅保证研究结果的稳健性，也降低由于遗漏变量导致的内生性问题。本研究发现互联网接入可以显著提高农户的膳食质量（膳食平衡指数，DBI-16）水平，增加动物性食物（如水产品和乳制品）的消费量。进一步的机制分析发现互联网接入主要通过增加农户收入和食品支出两个渠道改善农户膳食质量水平。这些发现不仅有助于推动互联网接入作为提高农村居民营养水平的有价值工具，同时也为相关政策的制定提供了有力支持。

This study provides empirical evidence on the link between economic growth and nutrition transition in two emerging economies, China and Russia. Both countries have experienced rising average incomes, accompanied by an increasing rate of nutrition-related chronic diseases in recent years. Given the regional heterogeneity between these two countries, we analyze the extent to which income growth as a major driver of nutrition transition has a significant effect on the consumption of different food aggregates and how these effects differ between Chinese and Russian consumers. Our results indicate that with increasing household incomes over time the demand for carbohydrates decreases, while the demand for meat and dairy products, as well as fruits increases. This is a development generally known as nutrition transition. Further, we estimate a Quadratic Almost Ideal Demand System (QUAIDS) for nine different food aggregates for China and Russia. Our results indicate that in both countries all food aggregates have positive expenditure elasticities and are thus normal goods. Moreover, our results indicate that in 2008/2009 meat is still a luxury good in China yet a necessity good in Russia. For 2009, the highest own-price elasticities in China are found for non-meat protein sources and dairy products. Within the meat group, beef, poultry and mutton have the highest price elasticities in China. In Russia, the milk and dairy group, together with the vegetable group, is the most price-elastic food group in 2008. In line with the definition of a nutrition transition, our overall results underscore the finding that income growth in China and Russia tends to increase the demand for animal-based products much stronger than, for example, the demand for carbohydrates. Despite being a positive signal for problems of malnutrition in rural China, this trend of increasing meat consumption might further increase the incidence of chronic diseases in urban areas since there is convincing scientific evidence that increasing meat consumption, especially red and processed meat, is associated with an increased risk of chronic diseases.