McAuliffe Graham A, Takahashi Taro, Lee Michael R F
1Rothamsted Research, North Wyke, Okehampton, Devon EX20 2SB UK.
2University of Bristol, Bristol Veterinary School, Langford, Somerset BS40 5DU UK.
Int J Life Cycle Assess. 2020;25(2):208-221. doi: 10.1007/s11367-019-01679-7. Epub 2019 Sep 7.
The nutritional quality of final products is attracting an increased level of attention within life cycle assessment (LCA) literature of agri-food systems. The majority of these studies, however, are based on comparisons at the dietary level and, therefore, are unable to offer immediate implications for farmers as to how best to produce food. This article evaluates recent literature examining the nutrition-environment nexus at the commodity level, with the aim to identify potential pathways towards sustainability analysis that can inform both consumers and producers.
A systematic search of literature was carried out to produce a shortlist of studies, and strict exclusion criteria were applied to them afterwards to eliminate irrelevant material. The studies thus selected were classified into one of three tiers based on the level of complexity with regard to their functional units: (1) based on single nutrients, (2) based on composite indicators derived from multiple nutrients and (3) based on commodity-level analysis in a dietary context.
Sixteen papers were identified for inclusion in the review. All of them accounted for climate change either directly or indirectly, whilst only five addressed different impact categories at the same time. Nine studies estimated environmental impacts under functional units associated with nutrient density scores, and the others utilised alternative approaches to account for nutritional value such as linear programming and end-point modelling combined with epidemiological data. A recently developed method to calculate the marginal contribution of a commodity to the overall nutritional value of a specific diet was considered to be a successful first step in bridging the aforementioned knowledge gap.
The LCA community should continue the ongoing effort to link farm management decisions to diet-level environmental impacts through an enhanced focus on human nutrition across the entire value chain. Future research comparing environmental performances of multiple food groups or multiple production systems should acknowledge differences in nutritional composition and bioavailability between the final products and, ideally, the effects of these nutrients on overall dietary quality.
最终产品的营养质量在农业食品系统的生命周期评估（LCA）文献中受到越来越多的关注。然而，这些研究大多基于饮食层面的比较，因此无法就农民如何以最佳方式生产粮食提供直接的指导。本文评估了近期关于商品层面营养与环境关系的文献，旨在确定可持续性分析的潜在途径，为消费者和生产者提供信息。
对文献进行系统检索，以列出一份研究清单，随后对其应用严格的排除标准，以剔除无关材料。根据功能单元的复杂程度，将所选研究分为三个层级之一：（1）基于单一营养素；（2）基于从多种营养素得出的综合指标；（3）基于饮食背景下的商品层面分析。
确定了16篇论文纳入综述。所有论文都直接或间接地考虑了气候变化，而同时涉及不同影响类别的只有5篇。9项研究估计了与营养密度得分相关的功能单元下的环境影响，其他研究则采用替代方法来考虑营养价值，如线性规划以及结合流行病学数据的终点建模。一种最近开发的计算商品对特定饮食整体营养价值边际贡献的方法被认为是弥合上述知识差距的成功第一步。
LCA领域应继续努力，通过在整个价值链中更加关注人类营养，将农场管理决策与饮食层面的环境影响联系起来。未来比较多种食物组或多种生产系统环境绩效的研究应认识到最终产品之间营养成分和生物利用度的差异，理想情况下，还应认识到这些营养素对整体饮食质量的影响。
