Review

Meat consumption, health, and the environment

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Science  20 Jul 2018:
Vol. 361, Issue 6399, eaam5324
DOI: 10.1126/science.aam5324

Figures

  • Total consumption of meat (in million metric tons) in different regions and (inset) globally.

    [Data are from www.fao.org/faostat/en/?#data.]

  • Fig. 1 The economics of meat production.

    (A) The value of livestock (globally and by region) as a proportion of total agricultural value in 2014. Numbers above bars are absolute values in billion dollars adjusted for purchasing parity power using constant 2006 dollars (1). (B) Growth of exports of soya feed for livestock from South America to China (1). (C) Predicted change in price and consumption of different food types after the introduction of a globally uniform tax related to GHG emissions. Meat products are some of the most strongly affected food types (94).

  • Fig. 2 Meat and health.

    (A) The relative risk of colorectal cancer as a function of average processed meat intake [from (95)]. (B) The relative risk of cardiovascular death as a function of average processed meat intake [from (27)].

  • Fig. 3 Meat and climate change.

    (A) GHG emissions from the production of different food types in 2005–2007 and projections for 2050 (assuming an emissions pathway that would keep global temperatures below 2°C). The y axis is the percentage of total GHG emissions. Animal-sourced foods are the major source of food-system GHGs, and their relative importance is likely to increase in the future (43). (B) The three major GHGs have quite different effects on climate. The figure shows the effect on climate warming of each gas if emissions at the current rate produced by livestock operations were introduced in Year 0 and thereafter held fixed indefinitely [methodology from (54)]. The warming due to methane is substantial and rises quickly but, because of the gas’s short residence time in the atmosphere, ceases growing after about two decades, whereas the warming due to carbon dioxide continues to grow throughout the two centuries shown and indeed would continue to grow indefinitely so long as emissions continue. The warming due to nitrous oxide has begun to level off at the end of the two centuries and grows little in subsequent years. Although the warming in response to a fixed methane emission rate levels off rather quickly, an increase in the rate of methane emissions, caused by an increase in livestock production, would still cause proportionate increases in the methane-induced warming.

  • Fig. 4 Meat and the environment.

    (A) The proportion of global freshwater withdrawals (out of a total of 4001 km3 year−1) used in agriculture for arable (directly) and livestock (of which most is used to grow crops to feed animals), industry and energy, and in the municipal and domestic sectors. [Data are from FAO AquaStat 2016, www.fao.org/nr/water/aquastat/main/index.stm.] (B) Use of antibiotics in agriculture in different countries [expressed as milligrams of antibiotics per kilogram of meat PCU (population correction unit) to allow comparison]. [Data are from (96).] (C) Fate of deforested land in Mato Grosso, Brazil. “Small area conversion” refers to areas <25 ha (97).

  • Fig. 5 The dual-process model of motivation and interventions that target automatic and deliberative decision-making.

    Examples of (i) situational factors are events, moods, and emotions; (ii) the environment are the layout of products in a shop or the marketing experienced by an individual; and (iii) personal characteristics are factors such as values, beliefs, and traits such as self-restraint or impulsivity.

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