Faculté de Médecine, Université de Tours, INSERM, N2C UMR 1069, 37032 Tours, France.
Nutrients. 2020 Sep 28;12(10):2965. doi: 10.3390/nu12102965.
Food choices affect the isotopic composition of the body with each food item leaving its distinct isotopic imprint. The common view is that the natural abundance of the stable isotopes of nitrogen (expressed as δN) is higher in animals than in plants that constitute our contemporary diets. Higher δN is thus increasingly viewed as a biomarker for meat and fish intake. Here we show that organic compared to conventional farming increases plant δN to an extent that can appreciably impact the performance of δN as a biomarker. The error that can arise when organic plants are consumed was modelled for the entire range of proportions of plant versus animal protein intake, and accounting for various intakes of organic and conventionally grown crops. This mass balance model allows the interpretation of differences in δN in light of organic food consumption. Our approach shows that the relationship between δN and meat and fish intake is highly contextual and susceptible to variation at the population, community or group level. We recommend that fertilization practices and organic plant consumption must not be overlooked when using δN as a biomarker for meat and fish intake or to assess compliance to nutritional interventions.
食物选择会影响人体的同位素组成，每种食物都会留下其独特的同位素印记。一般认为，构成我们现代饮食的动物体中氮稳定同位素的自然丰度（用δN 表示）高于植物体。因此，较高的 δN 逐渐被视为肉类和鱼类摄入量的生物标志物。在这里，我们表明与常规农业相比，有机农业会增加植物的 δN，这在一定程度上会显著影响 δN 作为生物标志物的性能。我们针对植物蛋白与动物蛋白摄入的各种比例，以及有机和常规种植作物的各种摄入量，对食用有机植物时可能产生的误差进行了建模。这种质量平衡模型允许根据有机食品的消费情况来解释 δN 的差异。我们的方法表明，δN 与肉类和鱼类摄入量之间的关系具有很强的背景依赖性，并且容易在人群、社区或群体层面上发生变化。我们建议，在将 δN 用作肉类和鱼类摄入量的生物标志物或评估营养干预措施的依从性时，不能忽视施肥实践和有机植物的消费。
