Wei Si’s research while affiliated with China Agricultural University and other places

Reducing greenhouse gas (GHG) emissions in crop production while ensuring emission equity is crucial for sustainable agriculture in China, yet long-term large-scale data on GHG emissions intensity (GEI) are limited. Using an extensive dataset based on surveyed farm households (n > 430,000 households) from 1993 to 2020, we reveal that 2015 was a turning point for GEI levels, which dropped 16% in 2020, while inequality—measured as average GHG emissions per unit planted area—increased 13%. The key driving forces behind such trends included farmland input, all other inputs, agricultural labour input and total factor productivity but not capital input. Notably, farmland input and all other inputs contributed to 80% of the inequality, while contribution of total factor productivity gradually declined and was replaced by migration-induced agricultural labour input differences. Reducing GEI levels and guarding against widening inequality require optimizing production factor inputs.

Purpose: While the adverse health consequences of obesity are well-documented, the causal effect between obesity and economic outcomes, particularly individual income in the labor market, has yielded inconsistent findings. At the same time, China has the highest number of obese or overweight people around the world in recent years. However, limited research has examined the causal effect of obesity on Chinese rural residents’ income. To answer this question, our study aims to identify the causal impact of obesity on Chinese rural residents. Design/methodology/approach: First, we conduct ordinary least squares, instrumental variable and Mendelian randomization methods to evaluate the impact of obesity on Chinese rural residents’ income. Then, we employ quantile regression and instrumental variable quantile regression to investigate the potential distributional impacts of obesity across various income segments. For the generality of our results, we also use 485,849 samples from the UK Biobank and the two-sample Mendelian randomization method to analyze. Findings: Our one-sample Mendelian randomization analysis, based on a sample of 441 people collected from rural China in 2019 and 2021, revealed that obesity reduced residents’ annual income by 647.87 China Yuan. Results from the UK further support our findings. We also find that the adverse causal impact of obesity on income is significant in individuals within the above 50th percentile of the income distribution. Additionally, childhood obesity has a long-term adverse effect on income in adulthood. Research limitations/implications These results contribute to a more nuanced understanding of the economic costs of obesity. Weight penalties may lead to a deviation from the efficiency that should be pursued in the labor market and widen income disparity. Originality/value: We provide novel and robust instrumental variables and utilize the Mendelian randomization method to analyze the effect of obesity on Chinese rural residents.

The popularity of Internet usage in rural China is on the rise while improving the nutritional status of Chinese rural residents remains a major issue due to prevalent unbalanced diets and deficiencies in some nutrients. However, there is a scarcity of empirical evidence linking these two aspects. The relationship between Internet usage and dietary quality remains inconclusive in both developed and developing countries. Using data from a survey of 2053 households in rural China, this paper examines the relationship between Internet usage and dietary quality among Chinese rural residents by employing an endogenous switching regression model to address the issue of selection bias. The empirical results reveal that respondents' gender, age, years of education, and household income significantly influenced their decisions to use the Internet, and Internet usage significantly improve dietary quality of their household. The findings of the heterogeneous analysis show that the impact of Internet usage on dietary quality varies based on respondents' dietary knowledge, per capita annual income, and household food expenditure. Through mechanism analysis, we find that Internet usage can improve the dietary quality by increasing the possibility of online food purchasing and fostering a more positive dietary attitude. [EconLit Citations: I12, O15, O33].

The rapidly growing animal protein demand of Chinese residents has caused multiple pressures, including on food security, health, and the environment. It is critical to study the reasons for the changes in Chinese residents' protein intake structure and make a reasonable judgment about its future trend. This paper uses the Nationwide Urban Household Survey Date from 1992 to 2009 to construct a pseudo panel and conduct research based on the habit formation theory. We find that there is a significant habit formation effect in the consumption of the main protein source foods of Chinese urban residents, especially animal foods. It weakens with the passage of time, which may be the reason for the continuous increase in urbanites' animal protein intake. There are differences in the protein intake structure and changing trend of urban residents in China's different regions. We suggest that government should pay more attention to the development of animal husbandry and the supply security of feed grains; strengthen nutritional intervention efforts to guide residents toward balanced and healthy dietary patterns, with moderate intake of animal protein; and formulate more detailed nutritional standards by region and population to cope with the impact of the growing animal protein demand among China's residents. [EconLit Citations: D12, E21, Q18].

Purpose Food choices profoundly affect one's dietary, nutritional and health outcomes. Using alcoholic beverages as a case study, the authors assess the potential of genetic data in predicting consumers' food choices combined with conventional socio-demographic data. Design/methodology/approach A discrete choice experiment was conducted to elicit the underlying preferences of 484 participants from seven provinces in China. By linking three types of data (—data from the choice experiment, socio-demographic information and individual genotyping data) of the participants, the authors employed four machine learning-based classification (MLC) models to assess the performance of genetic information in predicting individuals' food choices. Findings The authors found that the XGBoost algorithm incorporating both genetic and socio-demographic data achieves the highest prediction accuracy (77.36%), significantly outperforming those using only socio-demographic data (permutation test p -value = 0.033). Polygenic scores of several behavioral traits (e.g. depression and height) and genetic variants associated with bitter taste perceptions (e.g. TAS2R5 rs2227264 and TAS2R38 rs713598) offer contributions comparable to that of standard socio-demographic factors (e.g. gender, age and income). Originality/value This study is among the first in the economic literature to empirically demonstrate genetic factors' important role in predicting consumer behavior. The findings contribute fresh insights to the realm of random utility theory and warrant further consumer behavior studies integrating genetic data to facilitate developments in precision nutrition and precision marketing.

Alcohol consumption has been associated with the risk of mild cognitive impairment (MCI) in observational studies. The result is inconsistent and whether the association is causal remains unknown. To examine the causal effect of alcohol consumption on MCI in rural China, this study used a cross-sectional dataset that included 1966 observations collected in rural China, of which 235 observations’ genotyping were collected. All participants accepted the MCI evaluation using Mini-Cog and were asked about the participants’ alcohol consumption behavior. The causal effect of alcohol consumption on MCI was investigated by Mendelian randomization (MR) of genetic variation in the aldehyde dehydrogenase 2 (ALDH2 rs671) gene. The risk of MCI in Chinese rural areas was 43%. Alcohol consumption was causally associated with a higher risk of MCI under MR design. Parameter estimates of drinking or not (b = 0.271, p = 0.007, 95% CI = 0.073 to 0.469), drinking frequency during the past 30 days (b = 0.016, p = 0.003, 95% CI = 0.005 to 0.027), and the weekly ethanol consumption (b = 0.132, p = 0.004, 95% CI = 0.042 to 0.223) were all positive and statistically significant at the 5% level. In conclusion, there was a high risk of MCI in rural China, and alcohol consumption was causally associated with a higher risk of MCI.

The consumption of sugar-sweetened beverages (SSBs) in China is rising rapidly and has become a major source of added sugar, which may pose a threat to human health. Intervention policies represented by consumption tax may be introduced to reduce sugar consumption. Few studies have addressed the consumption tax on SSBs in emerging countries like China, where beverage consumption is increasing considerably. Based on the scanner data of Chinese urban households from 2014 to 2017, this paper used the Quadratic Almost Ideal Demand System (QUAIDS) model to estimate the Marshallian (uncompensated) price elasticity of various beverages. We then conducted a simulation of the effect of the consumption tax on the consumption of sugar-sweetened beverages. The simulation results under different tax rates suggest that the tax on SSBs will significantly reduce the consumption of SSBs and bring about a slight increase in the consumption of diet drinks, thereby promoting beverage consumption in the low-calorie direction. This effect was particularly obvious in low-income groups with a smaller tax burden, unlike the situation in developed countries represented by the U.S. The findings imply that the consumption tax on SSBs is conducive to lowering added sugar intake and, as a result, reducing obesity. China should levy a consumption tax on SSBs and all sugar-sweetened foods in the future. Tax revenue can be used to fund research and development to reduce the production costs of sugar-free foods and encourage healthy eating behavior.

食物系统转型已成为国际共识，联合国食物系统峰会的中国方案能够在全球食物系统治理上发出更多的中国声音，推动中国和全球食物系统转型。改革开放以来，中国渐进式地选择适应不同发展阶段的制度和政策，高度重视粮食安全、农业农村基础设施建设和农业科研推广，大力实施减贫和国民营养计划，积极保护自然资源环境和应对气候变化，努力推动减少食物损失与浪费，大力发展农村电子商务，增强食物系统抗风险能力。这些措施使得中国在推进食物系统转型取得了巨大成就，但仍面临诸多挑战，包括农业生产增速放缓且小农依旧占据主导地位、多重形式的营养不良问题并存、水土气资源约束趋紧和灾害频发、城乡和区域发展不平衡、进口依赖持续和国际市场波动、部门间缺乏有效协作等。为推动中国食物系统向高产高效、营养健康、环境可持续、更具韧性、更具包容性的目标转型，应构建跨部门的综合管理决策机制，加大农业产业发展支持力度，构建现代农产品流通体系，改革农业支持和科研政策，建立营养导向型和可持续的农业生产体系，促进居民膳食结构转型。同时应加快乡村振兴，加强公共服务和社会保障，积极参与国际合作和国际食物系统治理。