The environmental cost of animal source foods

We reviewed 148 assessments of animal source food ( ASF ) production for livestock, aquaculture, and capture fisheries that measured four metrics of environmental impact (energy use, greenhouse‐gas emissions, release of nutrients, and acidifying compounds) and standardized these per unit of protein production. We also examined additional literature on freshwater demand, pesticide use, and antibiotic use. There are up to 100‐fold differences in impacts between specific products and, in some cases, for the same product, depending on the production method being used. The lowest impact production methods were small pelagic fisheries and mollusk aquaculture, whereas the highest impact production methods were beef production and catfish aquaculture. Many production methods have not been evaluated, limiting our analysis to the range of studies that have been published. Regulatory restrictions on ASF production methods, as well as consumer guidance, should consider the relative environmental impact of these systems, since, currently, there appears to be little relationship between regulatory restrictions and impact in most developed countries.