膳食引导、饮食结构调整与中国食物消费需求——基于消费习惯形成的视角

Dietary guidances have been widely adopted in China and many developed countries as one of the policy measures to affect individuals’ food. Recently, it reaches a consensus that the prediction of demand should be based on the demand for nutrition. Many existing studies have attempted to estimate the potential food demand for a country by turning the dietary guidelines into actual food quantity, and thus to guide the country's food security practices. However, this logic could be correct only when consumers fully accept the dietary guidelines and follow them in their food consumption actions. As indicated by the theory of consumption, dietary guidances can have some "demonstration effects" on consumers’ food consumption habits. However, the degree of consumers’ acceptance to dietary guidelines is also determined by the "taste cost" constraints, namely the cost and inertia of remaining food preferences, which reflects the so-called "ratchet effects". Therefore, the actual impact of dietary guidances on individual food consumption habits would be jointly affected by these two effects, ignoring either of them will lead to an incorrect estimation of the potential food demand. In this study, we intend: firstly, to reveal and test the two effects among Chinese consumers’ food consumption behavior from the micro-level perspective; secondly, to estimate and simulate its impact on China’s potential food consumption on a macro-level; finally, to further analyze and calculate if switching the potential food consumption into production what impact would be imposed on environment and resources as well as food security in China. We hope our study could serve as a complement of the present research in the field, and could provide meaningful reference for the optimization and adjustment of China’s grain production and trade policies in the future.

通过营养标准预测食物消费需求已在理论上基本达成共识，大量国际前沿研究已讨论了采用膳食引导标准后主要发达国家饮食结构的调整及其对食物消费的影响，进而延伸到社会经济各方面。然而，该逻辑成立的前提是膳食引导标准可完全为消费者所接受并反映在其食物消费行动中。基于消费习惯形成理论，膳食引导对居民食物消费具有“示范效应”，但消费者对膳食引导的接受程度会受到改变膳食的口味成本的限制，而口味成本则与饮食偏好的惯性，即“棘轮效应”的强弱有关。因此，膳食引导对个体食物消费的影响会由示范效应与棘轮效应共同决定，忽略这两者的作用可能会造成潜在食物消费的误估。本研究拟基于消费习惯形成效应的视角，首先从微观层面揭示膳食引导影响食物消费的作用机理，并量化示范效应与棘轮效应的大小及影响因素，然后进一步模拟其对中国食物潜在消费及其他社会经济变量的影响，以期能够对相关领域的研究进行补充完善，并为保障国家粮食安全提供决策参考。

课题组构建了“从微观居民食物消费行为-宏观中国食物总消费-农业生产、资源环境与健康”分析框架与范式。研究首先从微观层面验证居民食物消费的习惯形成效应，并模拟国际国内通用膳食引导标准的实施可能会对国内食物消费造成的潜在影响，进而分析其对农产品生产、贸易、粮食安全与资源环境带来的冲击。新冠疫情大流行背景下，课题组将该框架应用到分析疫情的影响上，在从理论与实证两种维度探求其对居民食物消费行为影响的基础上，进一步测度疫情叠加中美贸易摩擦对中国农产品供需、贸易以及粮食安全的潜在影响，并探索中国通过增加国内供应以及进口多元化满足消费需求、保障粮食安全的具体策略与可行路径。结果表明，中国居民食物消费行为存在明显的习惯形成效应，其中棘轮效应的系数略大于示范效应，说明中国居民食物消费较大受制于其口味成本。城镇居民/年轻群体的示范效应大于棘轮效应，表明该类群体更易受膳食引导的影响；假设消费者按WHO标准消费食物，2030年肉类、蔬菜、油籽、奶类的需求会下降10%-50%，这将大幅减少耕地、水资源的使用与环境污染；新冠疫情改变了食物供需，也影响了农产品贸易。从长期来看，外需下降和非关税壁垒的增加将对中国农产品出口产生负面影响，却会使猪肉等畜产品的进口大幅上升。无论是加征关税还是第一阶段协议履行，中美贸易摩擦对农产品进口的影响有限，却会使中国从部分国家部分品种的进口可获性存在不确定性。综合复杂贸易环境对粮食安全的影响，中国应：通过技术进步提高国内供应、要素替代以及产出选择提升竞争力；坚定不移地推进进口多元化战略，特别是大豆的品种及地区多元化；按照经济合理性原则，适度调整从美进口的农产品品种结构等。上述研究首次构建了从微观居民消费到宏观供需、贸易、资源环境与健康的分析框架，从居民食物消费习惯识别到膳食引导及复杂环境对供求、贸易与粮食安全等方面影响的研究均填补了已有文献的空白，具有理论意义；课题组对膳食引导与复杂环境影响的模拟还有助于准确预判中国农产品供需、贸易、粮食安全的形势，对于指导现代农业生产体系建立、应对粮食安全可能遭遇的输入性风险有前瞻性的借鉴价值。