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  • br The study by Jesse Berman and

    2019-04-28


    The study by Jesse Berman and colleagues published in is the first to systematically analyse the risk of hospital admissions and mortality associated with drought periods in the USA. As the authors state, this is an understudied topic, but of great concern in the USA and globally as climate change is expected to worsen the severity and frequency of droughts in various regions.
    Achievement of sustainable food systems is one of the most important global challenges and the need for a combined discussion of sustainability and health aspects is increasingly acknowledged. Climate change plays a dominant role in this issue. Notably in this regard, ruminant meat and milk production contributes roughly 40% to the total direct agricultural greenhouse gas emissions via enteric fermentation in ruminants\' intestinal tracts. Another 40% stems from soil borne nitrous oxide emissions from mineral and organic nitrogen fertilisers applied to crops. Emissions from crop production can be reduced by reducing nitrogen inputs and optimising their application, but crop production inevitably leads to such emissions because nitrogen is a key input that cannot be replaced. For animals, however, the unique role of ruminants in agricultural greenhouse gas emissions has fuelled a discussion on the benefit of their substitution with monogastric (poultry or chicken) meat that comes with substantially lower emissions per kg, and positive health effects. Nevertheless, environmental sustainability covers more than greenhouse gas emissions, and aspects such as Cy3 hydrazide Supplier loss, soil fertility, or water scarcity are equally relevant in agriculture. In , James Milner and colleagues address these issues by pointing to the key challenge of water availability and use in India in the context of increasing water scarcity, as the population grows but freshwater availability does not. Milner and colleagues investigate in detail the potential for reduced water use and increased health from dietary shifts. They Cy3 hydrazide Supplier find important synergies in diets with lower water use and positive health effects. However, they also identify—but lack room for further expansion—a trade-off between water use and greenhouse gas emissions, because one of the key measures for reducing water footprints is a switch from monogastric towards ruminant meat. This effect is mainly due to the relatively high levels of water embodied in the feed fed to monogastrics, whereas ruminants thrive on grasslands with lower blue water footprints (although an increasing amount of concentrates is being fed to ruminants and this advantage is at stake). In this diet, greenhouse gas emissions are also slightly lower, and the named trade-off thus does not become explicit. However, such a reduction is only achieved through a considerable reduction in consumption of milk from ruminants, as far as can be seen from the supplementary appendix. All of these factors highlight several key issues when assessing sustainable and healthy food systems. First, efficiency indicators, such as litre water use per 1000 kcal or kg greenhouse gas emissions per kg protein draw an incomplete picture, and recommendations based on them will not necessarily point to the optimum approach at a systemic level, and they can lead to conflicting statements. Second, total production and consumption levels and thus total impacts (and not only impacts per kg produce) need to complement the analysis. Switching from monogastrics to ruminants with lower water use per kg meat reduces the water footprint of the meat-rich diet that Milner and colleagues analyse, but only the overall reduction in milk consumption then prevents greenhouse gas emissions from overshooting. Thus, besides efficiency, “sufficiency” targeting reduction of total levels needs to be considered. Clearly, food security comes first, but the rather high per capita daily calorie intake levels provided by the diets analysed in their study (up to 3344 kcal per person per day) suggest further potential for reductions from lowering total production and consumption levels. For the diet rich in ruminant meat, this could thus also result in positive health effects from reduced red meat consumption. Third, considerations related to consistency of resource use should be added—ie, those related to how and where a scarce resource can be used optimally within a whole food systems context. Again, ruminants provide a good example, as they are able to transform grasslands, which are land areas without any direct food value into a source for high quality food. When focusing on monogastrics—eg, in the context of greenhouse gas reductions per unit food—this potential is untapped and a trade-off emerges on the level of cropland use and scarcity.