The importance of tackling environmental sustainability challenges associated with food systems has gained increasing prominence in recent years – as demonstrated through the 2021 United Nations Food Systems Summit and the prominence of food-related topics in the past two United Nations Climate Change Conferences of the Parties (COPs). One of the top items on the agendas of such discussions is often animal-source foods (ASFs)(Reference Herrero, Mason-D’Croz, Thornton, Von Braun, Afsana and Fresco1), which tend to be associated with higher environmental impacts, particularly emissions of greenhouse gases(Reference Poore and Nemecek2). Attention was particularly focused on ASFs through the 2019 publication of the EAT-Lancet commission on healthy diets from sustainable food systems(Reference Willett, Rockström and Loken3), which took a pioneering approach in integrating environmental concerns with health and nutrition. Among other things, EAT-Lancet noted the large impacts of meat on the environment and suggested a ‘universal healthy reference diet’ – which included only very small amounts of ASFs (about 14 % of energy intake but able to be completely excluded from the diet). EAT-Lancet has since received nearly 10 000 research citations in 5 years, sparking an active, dynamic and fruitful area of research within food and nutrition. The 2024 Nutrition Society Congress was testimony to this growing research interest in environmentally sustainable diets, and specifically in the role of ASFs or their alternatives: numerous conference presentations focused on topics like environmental impacts of diets, awareness of ‘sustainable diets’, likelihood of reducing meat consumption, consumer perspectives on ‘sustainable plant-based products’, nutritional profiles of plant-based meat alternatives, and similar.(Reference Araya-Bastias, Garzillo and Pell4–Reference Benson, Nugent and Dean8)
The topic has also entered the policy sphere: EAT-Lancet garnered more than 600 policy citations in the five years following its publication, which places it among the top-ten most policy-influential papers ever (excluding economics papers), and the only one on food or nutrition, according to an analysis by Nature (Reference Singh Chawla9). Many – though certainly not all – of these citing documents discuss ASFs. For example, the Nordic Nutrition Recommendations aimed to integrate environmental sustainability into their dietary guidelines, recommending a ‘predominantly plant-based diet… [with] limited intake of red meat and poultry’ and citing EAT-Lancet among its sources(Reference Blomhoff, Andersen and Arnesen10). The topic has also entered the media and public sphere, such as through debates over ‘meatless menus’ in schools, taxes on livestock farmers or meat, and bans on the production of cultured meat (meat grown in labs through cell replication)(Reference Henley11–Reference Kainz13).
Growing focus on the intrinsically interlinked issues of nutrition and environmental sustainability is very welcome and should help to further science, policy and action in both areas. However, debates on the topic of ASFs (whether in research, policy, the media or the public sphere) can quickly become polarised or over-simplified. This does a disservice to both nutrition and environmental sustainability issues – and to the other social and development goals that are inherently connected to food production and consumption. As such, this paper (based on a lecture at the 2024 Nutrition Society Congress) will seek to review the topic of ASFs from multiple angles (excluding animal welfare), embracing the nuance and complexity, before suggesting ways forward for balancing them.
Health and nutrition
Nutritional benefits of ASFs
ASFs are a diverse category, including meat, fish, seafood, eggs and dairy products in varied forms. With considerable variation by type of food (and mode of preparation), as a category they tend to offer certain nutritional benefits: they are rich in bioavailable vitamins and minerals, highly bioavailable proteins and unique beneficial compounds(Reference Murphy and Allen14–Reference Neumann, Harris and Rogers17). Some of these nutrients are only available in ASF. For example, ASFs are the only natural dietary sources of vitamin B12 – deficiencies in which can cause anaemia, developmental regression and depression(Reference Black18,Reference Dror and Allen19) – and one of the few dietary sources of vitamin D – deficiencies in which can contribute to weak bones, rickets, and osteoporosis as well as increased risk of infectious disease(Reference Holick and Chen20).
Several other nutrients, such as vitamin A, iron, zinc, choline, vitamin B6 and calcium, are also found in plant-source foods – but they are less abundant or bioavailable in those foods than in ASFs(Reference Gibson, Perlas and Hotz21–Reference Chungchunlam and Moughan23). For example, heme iron is a form of iron that is particularly bioavailable – and is only found in meat (with the highest levels in red meats, like beef and lamb)(Reference Balder, Vogel and Jansen24–Reference Hallberg, Björn-Rasmussen and Howard26). The proteins in ASFs are also of particularly high quality, including all nine essential amino acids in relatively balanced ratios(Reference Semba, Shardell and Sakr Ashour16,Reference Neumann, Harris and Rogers17,Reference Beal, Gardner and Herrero22) . ASFs, particularly fatty fish, also contain essential long-chain n-3 fats, which have numerous health benefits, including improved child development and reduced inflammation(Reference Swanson, Block and Mousa27). While certain algae also contain these compounds, algae-based foods are not widely available and accessible in many areas – and not widely consumed in many cultures. ASFs also contain bioactive compounds, such as creatine and taurine, that can help prevent disease and maintain health(Reference Beal, Gardner and Herrero22,Reference Leroy, Abraini and Beal28,Reference Nordhagen, Beal and Haddad29) .
One key aspect of ASFs is their nutrient density: they provide significant amounts of key nutrients even if only small amounts of the food are consumed. For example, an analysis of common foods’ density in multiple micronutrients (vitamin A, folate, vitamin B12, calcium, iron and zinc), as shown in Figure 1, found that all but one of the 17 foods classified as having ‘high or very high nutrient density’ were ASFs(Reference Beal and Ortenzi30). This nutrient density makes ASFs particularly valuable in the diets of young children, who have small stomachs combined with high nutrient needs to fuel rapid growth, placing them at risk of micronutrient deficiency(Reference Beal, White and Arsenault31–Reference White, Beal and Chimanya33). ASFs are thus excellent additions to complementary feeding diets, and there is some evidence of associations between ASF consumption and reduced odds of child stunting(Reference Krebs, Mazariegos and Tshefu34–Reference Headey, Hirvonen and Hoddinott36) or that ASF consumption can improve child growth, micronutrient status and/or cognitive performance(Reference Asare, Rosi and Faber37–Reference Iannotti, Lutter and Stewart39). Other nutritionally vulnerable populations (such as pregnant and lactating women, adolescents and the elderly) may also particularly benefit from the density in multiple micronutrients provided by ASFs(Reference Neumann, Harris and Rogers17).
Kilocalories (kcal) and grams needed to provide an average of one-third of recommended intakes of vitamin A, folate, vitamin B12, calcium, iron and zinc for women of reproductive age. AR = ‘average requirement’. Source: reproduced from(Reference Beal and Ortenzi30); author’s permission obtained.
These benefits can only be clearly understood when one takes a step back to recall the current state of global nutrition. While there have been major advances in recent years, stunting still affects about 22 % of children under age 5, or 148 million children(40). Micronutrient deficiencies are even more widespread, affecting over 1·6 billion pre-school-aged children and women of reproductive age(Reference Stevens, Beal and Mbuya41). Although data across regions are limited, those that are available suggest micronutrient deficiencies, while worse in low- and middle-income countries (LMICs), cut across all country-income groups, affecting 48 % of women of reproductive age and 45 % of young children in high-income countries. For protein, consumption is thought to be adequate in the vast majority of countries worldwide, but there are likely some populations (particularly in LMICs) that are not consuming adequate amounts of high-quality protein(Reference Lumsden, Jägermeyr and Ziska42).
Undernutrition (including micronutrient deficiencies) is associated with myriad poor health and nutrition outcomes (such as increased risk of infection, increased mortality and blindness) as well as decreased work productivity in adults and cognitive development and educational achievement in children(Reference Beal, Gardner and Herrero22,Reference Nordhagen, Beal and Haddad29) . The consequences can last lifetimes and have society-wide impacts, holding back economic growth. There are thus serious public health and social challenges related to nutrient-inadequate diets, which ASF consumption could help to address.
Health risks of ASF
Certain ASFs, however, are also associated with health risks, particularly of non-communicable diseases (NCDs), which are responsible for an estimated 73 % of all deaths globally(Reference Roth, Abate and Abate43). The strongest evidence exists for processed red meats, high intakes of which have been associated with increased risk for chronic diseases, such as heart disease, stroke, diabetes and cancer(Reference Bouvard, Loomis and Guyton44–Reference Godfray, Aveyard and Garnett47). This is likely due to the presence of preservatives such as sodium, nitrates and nitrites or carcinogenic compounds that are generated from certain cooking processes(Reference Beal, Gardner and Herrero22). As a result, the World Cancer Research Fund recommends consuming little or no processed meat to reduce the risk of cancer, particularly colorectal cancer(48), and the World Health Organization has previously classified processed meat as ‘carcinogenic to humans’(Reference Bouvard, Loomis and Guyton44). Despite this, large proportions of the populations of many middle- and high-income countries regularly consume processed meat (around half in countries such as the United States, Russia, Kazakhstan, Brazil and the Dominican Republic(49)).
High intakes of unprocessed red meat have also been associated with increased risk of NCDs and mortality(Reference Bouvard, Loomis and Guyton44–Reference Godfray, Aveyard and Garnett47,Reference Grosso, La Vignera and Condorelli50–Reference Zhong, Van Horn and Greenland54) . However, the level of risk associated and the strength of the evidence have been disputed(Reference Johnston, De Smet and Leroy55), and there is not clear evidence of increased risk connected with consumption of moderate amounts of unprocessed red meat in the context of a healthy dietary pattern(Reference Markova, Koelman and Hornemann56–Reference O’Connor, Paddon-Jones and Wright59). Saturated fat and dietary cholesterol, both of which are found in ASFs, have historically been associated with increased risk of NCDs, particularly CVD. Recent research has largely overturned this understanding for cholesterol(Reference Rong, Chen and Zhu60–Reference Mah, Chen and Liska64). For saturated fat, the evidence is mixed and an area of active research but suggests that risks may vary by the type of saturated fat consumed and the role in the overall diet(Reference Beal, Gardner and Herrero22). In sum, consumption of processed meat, and probably also high intakes of red meat, likely raise the risk of NCDs. There is little evidence of health risk associated with moderate consumption of unprocessed or minimally processed ASF other than red meat, such as poultry, fish, eggs or dairy(Reference Nordhagen, Beal and Haddad29).
Public health risks associated with ASFs also arise from other areas, such as zoonotic diseases, foodborne disease, and medication and hormone use in livestock production. In particular, ASF production is thought to be responsible for around half of global antibiotic use.(65) For example, in the US, about 70–80 % of antibiotics are consumed by animals.(Reference Mole66) This can contribute to antibiotic resistance in bacteria, with data showing that an increasing proportion of bacteria show resistance to commonly used antibiotics in humans(65–Reference Reardon67). Moreover, ASFs are ranked among the top foods implicated in causing foodborne disease, particularly for bacterial diseases(Reference Painter, Hoekstra and Ayers68,Reference Hoffmann, Devleesschauwer and Aspinall69) . Foodborne disease results in an estimated 600 million illnesses and 500 000 deaths annually, with the burden being considerably higher in LMICs, particularly in Africa(Reference Havelaar, Kirk and Torgerson70). Foodborne disease and nutrition are inherently interlinked, with foodborne disease increasing the risk of malnutrition – and malnutrition exacerbating the severity of foodborne disease(Reference Nordhagen, Lambertini and DeWaal71).
Vegetarian, vegan and low-ASF diets
Moreover, ASF are often not necessary parts of the diet: well-planned vegetarian and vegan diets, and low-ASF diets, can be healthy for most populations. Some studies have found vegetarian, vegan, low-ASF or pescatarian diets to be associated with significantly lower mortality, heart disease and/or cancer risk(Reference Orlich, Chiu and Dhillon72–Reference Oussalah, Levy and Berthezène76).
However, achieving a nutritionally adequate vegetarian or vegan diet can require careful planning and access to a diverse range of foods and, for vegans, supplements of nutrients such as vitamin B12. The ease of meeting nutrient needs varies by nutrient. For example, even though vitamin A precursors in plants have less-efficient conversion into retinol, these compounds are found widely in many different types of plant-based foods, sometimes in large amounts – making it relatively easy to meet vitamin A requirements through diverse plant-based diets, with little or no ASFs(Reference Beal, Gardner and Herrero22,Reference Beal and Ortenzi30) . In contrast, meeting iron or zinc needs from no-ASF diets may be harder. Regarding protein quality, diets without ASFs require combining various food types to provide all amino acids in adequate quantities(Reference Young and Pellett77). As plant-based foods can include inhibitors that can prevent nutrient absorption, such as iron and zinc, more of these nutrients may need to be consumed or the timing of consumption varied to prevent inhibition.
As such, improperly planned diets containing limited ASF have been associated with risk of inadequate intakes of iron, zinc and calcium(Reference Dror and Allen78–Reference Hunt, Gallagher and Johnson80). Indeed, an analysis of the EAT-Lancet planetary health diet considering nutrient requirements for adults and women of reproductive age found the diet to be largely adequate in folate and vitamin A but to provide below-recommended amounts of vitamin B12, calcium, iron and zinc, with the shortfalls being particularly large for iron in women of reproductive age (55 % of recommended intake) and zinc in adults (78 % of recommended intake)(Reference Beal, Ortenzi and Fanzo81). The study’s authors recommended that, in order to achieve micronutrient adequacy, the amount of ASFs in the diet (expressed in share of kilocalories) would need to approximately double, or fortification and/or supplementation would be needed to fill the nutrient gaps. The risks of nutrient inadequacy through no- or low-ASF diets are most acute for those with the most specific nutrient needs, such as the elderly, pregnant and lactating women, and young children.
Importantly, many of the benefits of vegetarian and vegan diets in terms of NCD risk reduction can be obtained from predominantly plant-based diets that include small amounts of red meat, fish and/or dairy(Reference McEvoy, Temple and Woodside82). Including some ASF can also increase the absorption of iron from plant-sourced foods(Reference Bender83).
In summary, ASFs are rich in essential nutrients, in readily absorbable forms; these are particularly important for young children. Healthy diets can be attained without ASFs, and some forms of ASFs (highly processed or excess red meat) should be avoided for optimal health. But certain populations may benefit from increased consumption of other types.
Environmental sustainability
ASF production has numerous environmental impacts. The most prominent of these in global debates is greenhouse gas (GHG) emissions. Food systems as a whole are responsible for about 21–37 % of GHG emissions(Reference Rosenzweig, Mbow and Barioni84). Livestock (land-based animals, which are the source of about 83 % of animal-source protein) are responsible for 40 % of this, or about 12–14 % of total emissions(Reference Godfray, Aveyard and Garnett47,Reference Gerber, Steinfeld and Henderson85) , with estimates varying, and aquaculture and fishing are responsible for about 3 %(Reference Barange, Bahri and Beveridge86). Livestock emissions come mostly from feed production(Reference Gerber, Steinfeld and Henderson85) and from enteric methane in ruminants, followed by nitrous oxide from manure and slurry and carbon dioxide, primarily from land use and land use change(87–Reference Steinfeld, Gerber and Wassenaar89). Over half of the GHG emissions from livestock are from LMICs(Reference Herrero, Grace and Njuki90).
ASF production also has other negative environmental impacts. Livestock use about half of global agricultural land, or 20 % of all land(91). Much of this land does not compete with food crop production, since grazing can happen on land unsuited for crop production, but it does come with an opportunity cost, and conversion of land for livestock is key driver of emissions as well as biodiversity loss. Fisheries and aquaculture have negative impacts on aquatic biodiversity and mangroves(Reference Barange, Bahri and Beveridge86). Livestock also use a significant share of water(Reference Heinke, Lannerstad and Gerten92), and unsustainable production can leak nutrients and veterinary medicines and chemicals into ecosystems, harming plants and animals(Reference Pelletier and Tyedmers93).
All of these impacts vary by type and by setting, depending on both the context and production system – making local analyses and estimates essential. In general, beef and lamb/mutton have relatively large impacts, while pork, poultry, eggs, milk, fish and seafood have lower impacts. Data consistently show that emissions per unit (weight or amount of protein) are higher for ASF than for plant-source foods, often by very large amounts (Figure 2).
Greenhouse gas emissions (top) and land use (bottom) per 100 g of protein of common ASF and plant-source foods. Purple bars indicate ASF; green bars indicate plant-source foods. GHG emissions are measured in terms of carbon-dioxide equivalents. Source: adapted from(Reference Ritchie, Rosado and Roser94), using data from(Reference Poore and Nemecek2).
Livestock also have beneficial effects: animals contribute nutrients to agricultural systems through manure(Reference Fuhlendorf and Engle95), rangelands help to sequester soil carbon, and livestock can play a role in supporting biodiversity and grassland ecosystems(Reference Sheldrick, Keith Syers and Lingard96). For example, European grasslands’ high levels of biodiversity are supported by a long history of livestock farming, alongside which other species have adapted(Reference Bignal and McCracken97). Livestock themselves also represent biodiversity, with large numbers of different breeds.
In the past 60 years, ASF production has increased significantly, particularly in LMICs. Yet there remain large gaps in consumption between the highest-consuming countries and the lowest-consuming ones (Figure 3). This suggests that there is pent-up demand that could drive growth in the future, alongside population growth, which is expected to lead to increases in aggregate ASF consumption in many LMICs, particularly in Africa. Such a trajectory of strong growth is incompatible with keeping the earth’s systems within safe planetary boundaries(Reference Rockström, Steffen and Noone99). The effects on climate change are particularly worrying: despite policy efforts, GHG emissions continue to increase, as do average global temperatures(Reference Ritchie, Rosado and Roser100). Further warming is likely to lead to changes in precipitation, rising sea levels, greater flooding, and increased frequency and severity of extreme events; these, in turn, will contribute to lowered agricultural productivity and increased hunger and malnutrition – making the two goals of improving nutrition and achieving environmental sustainability inseparable, from a long-term perspective(Reference Fanzo, Davis and McLaren101).
Global meat demand if everyone ate the average citizen of a given country, 1961–2022. The line ‘world’ indicates the actual trajectory in meat demand, while that of Australia, for example, indicates the trajectory that would have been followed in everyone in the world consumed the same amount of meat as the average Australian citizen. Source:(Reference Ritchie, Rosado and Roser98)
In summary, with important variations, ASFs generally have larger negative impacts on the environment than plant-based foods, although they also have some environmental benefits when produced appropriately. The current trajectory of ASF consumption and production practices is environmentally unsustainable and cannot continue in the long-term while meeting environmental goals.
Livelihoods and society
Animal production also plays a central role in human society. As a livelihood, it provides incomes – and thus supports food security and nutrition. Livestock production directly supports about 1 billion low-income smallholder farmers in LMICs, including over 80 % of low-income Africans(87), while broader livestock value chains (including post-production) employ at least 1·3 billion people globally(Reference Herrero, Thornton and Gerber102). About 117 million people worldwide work in fisheries and aquaculture, including postharvest jobs(Reference Mills, Westlund, de Graaf, Pomeroy and Andrew103). These jobs make important contributions to income for the majority of households in LMICs(87) and can be particularly important in marginal areas with limited capacity to support other types of production – such as the Sahel and Horn of Africa or coastal and island nations ill-suited to agriculture. Pastoralists are a particularly important population to consider, as they are often among the poorest, live in the most marginal areas and have few other livelihood options.
For an economy as a whole, livestock products tend to be comparatively high-value agricultural products and are responsible for 17–47 % of the agricultural value of production in LMIC regions(Reference Herrero, Grace and Njuki90). Livestock thus play important roles in poverty reduction at both the household and national levels in LMICs. In high-income countries, their role tends to be smaller – for example, only 1 % of the population of the US is employed in agriculture, including but not limited to livestock – but remains highly meaningful for those who have made their livelihoods in the sector and for the rural areas in which livestock-raising or fishing underpins a strong historic cultural identity.
Beyond providing incomes, livestock also play other roles. In mixed crop-livestock systems, livestock manure is key for enriching soil nutrients, some animals help pull machinery or carry loads for crop production, and livestock grazing can improve soil structure and control insects and weeds(87,Reference Thornton and Herrero104) . Certain livestock also provide non-food products, such as wool from sheep and goats. Livestock can also function as an asset: they can be sold to respond to economic shocks and address immediate needs or used as collateral for loans(Reference Nordhagen, Beal and Haddad29). This can be particularly important for women in LMICs, who may face barriers to acquiring land or other physical or financial assets(Reference Njuki, Waithanji and Lyimo-Macha105,Reference Kristjanson, Waters-Bayer and Johnson106) . Larger livestock, such as cattle or camels, may also be used to demonstrate social status.
Of course, animal products also play a central role in culture as food. ASFs, such as roast beef, leg of lamb or steak, are considered by many to be the central component of a meal, and particularly of culturally important meals, such as a ‘Sunday Roast’ or a Christmas dinner. The consumption of meat has connections to social status, masculinity and cultural traditions in many world populations(Reference Eckl, Biesbroek and Van’t Veer107–Reference Szenderák, Fróna and Rákos109).
As a result, the topic of reducing ASF consumption and production can be very sensitive. For ASF consumers, the idea of reducing consumption can engender worries about no longer being able to enjoy beloved foods and cultural traditions. For those working in the sector, thoughts can quickly turn to the implications for their livelihoods. For example, farmers interviewed about their perceptions of lab-cultured (cell-based) meat in the UK(Reference Manning, Dooley and Dunsford110) largely agreed that industry changes were needed to improve environmental sustainability – but also worried about losing jobs, farms and rural communities – while farmers interviewed for a similar study in Finland also saw opportunities alongside risks like obsolescence, job loss and rural depopulation(Reference Räty, Tuomisto and Ryynänen111). Such fears are not unfounded. For example, a modelling study in the US that examined the potential consequences of replacing beef with novel plant-based beef alternatives showed that, while this would have only small effects on the overall economy, it would likely result in large reductions in employment in cattle ranching and beef processing(Reference Mason-D’Croz, Barnhill and Bernstein112).
In summary, ASFs are more than food: they underpin livelihoods for a large share of the world’s populations and occupy a central place in cultures worldwide. This can make discussions related to ASF fraught with emotion and significance.
Applying an equity lens to ASFs
ASFs thus raise a host of challenging questions: how to balance their high nutrient value against potential health downsides? How to weigh those aspects against environmental impacts? How to consider effects on livelihoods and culture when evaluating potential trajectories of change? Simultaneously answering these questions requires close consideration to equity and to multiple angles to equity.
One angle to consider is the need for (or capacity to benefit from) increased (or decreased) consumption of ASFs. At the national or regional level, it is clear that many countries in South Asia and Sub-Saharan Africa have low levels of ASF consumption at present. On average, people in South Asia eat less than a serving a day of ASF and those in Sub-Saharan Africa eat about 1 serving a day – while in other regions 2–5 servings a day are consumed(Reference Miller, Reedy and Cudhea113). Consumption of egg and dairy is particularly low in these regions. The increase in ASF consumption in Sub-Saharan Africa and South Asia in the past 30 years has also been smaller than elsewhere. (Despite these trends across national and regional averages, some subnational populations in low-consuming countries, such as urban and wealthier populations, and some middle-income countries, do have higher consumption levels.)
A second angle to capacity to benefit from increased ASF consumption is nutritional needs and how these vary across the life course. Certain population groups needing particular consideration include older adults, who are at risk of poor bone health and other health consequences of ageing, and pregnant and lactating women, who have high needs for certain nutrients such as iron and are at increased risk of nutrient deficiencies – which can also affect foetal growth and development(Reference Beal, Gardner and Herrero22). As noted above, ASFs can be particularly important to young children, and the consequences of inadequate intake can be particularly severe: poor nutrition during the first 1000 d of life can contribute to increased illness and mortality, poor growth and development, and decreased economic potential(Reference Black, Victora and Walker114).
Layering these two considerations of geography and life stage gives a particularly stark picture for young children: despite their large nutrient needs, about 39 % of young children worldwide eat no meat, fish or egg on the average day, with this exceeding 75 % of young children in several countries in Africa and South Asia(115). These are also amongst the regions with the highest burdens of child stunting and micronutrient deficiencies(Reference Stevens, Beal and Mbuya41). And they are the regions with the largest share of the population employed in agriculture(115). In contrast, GHG emissions per capita show a very different distribution. Cumulative historic carbon-dioxide emissions from Africa contribute only 3 % of the global total, with South Asia contributing about 4 %, whereas North America and Europe have contributed 25 % and 22 %, respectively(Reference Ritchie116). The impacts of climate change are also likely to be felt most acutely by lower-income residents of LMICs(Reference Paavola and Adger117).
The adoption of vegetarian, vegan and other low-ASF diets that are nutritionally adequate can also be more difficult for those with fewer resources. In high-income countries, many convenient alternatives to ASF (e.g. plant-based meat analogues, non-dairy milks) are available – but most of them tend to be more expensive than the ASF they are positioned to replace(118–Reference Clegg, Tarrado Ribes and Reynolds120), making it difficult for people with lower incomes to adopt them. While traditional minimally processed protein-rich plant-based foods like beans, tofu and tempeh are relatively cheaper, they may face barriers associated with desirability, convenience, knowledge and cooking skills. In LMIC contexts, even optimised diets based on locally available plant-source foods may not meet nutrient requirements(Reference Osendarp, Broersen and van Liere121). Layering on constraints related to low knowledge and skills related to plant-based nutrition may make this even more challenging.
Key principles of equity relevant to policy decisions on ASF include the concept of ‘common but differentiated responsibility’ (that industrialised nations should do the most to mitigate climate change, given historic GHG emissions and current capacity); that those with the most resources should contribute most to a shared endeavour; that, given adequate supplies of a key resource, everyone should have access to at least the minimum adequate amount; and that the most vulnerable populations deserve special consideration(Reference Nordhagen, Beal and Haddad29). The current situation of ASF consumption is thus deeply inequitable – and paths forward to a more equitable (and planet-supporting) outcome will need to vary across countries, regions and subnational groups. High-ASF consumers (at the individual and national average level) will need to reduce their consumption in order to allow low-ASF consumers who could benefit from greater consumption to increase theirs. Policies will also be needed to support those whose livelihoods could be displaced or reduced through such a transition.
In summary, when considering how to address ASF production and consumption, applying an equity lens is essential. This should consider not only imbalances across countries but also across groups within them, with a particular focus on the most vulnerable.
Ways forward
Ways forward for rebalancing ASFs’ role in the food system can follow two general paths: reducing the environmental harms of ASF production and reducing consumption of ASFs, particularly those with the highest impacts. On the first path, there is a clear opportunity in LMICs to boost productivity of ASF production – and in so doing to lower the resource-intensity of ASF production. At present, ASF productivity in high-income countries is much higher than in low-income countries and has increased considerably over the past 60 years, while that in lower-income countries has increased only slightly. This low productivity connects directly to environmental impact: low-productivity animals consume resources at a higher rate, and produce more emissions per unit yield, than high-productivity animals(87,122) . For example, per-unit emissions from milk production in Africa are about twenty times larger than those in high-income countries(115). Raising the productivity of livestock in LMICs could thus allow for a reduction in GHG emissions without reducing the quantity produced(Reference Herrero, Thornton and Gerber102,Reference Mottet, Henderson and Opio123) . Globally, it is estimated that if all producers adopted the technologies and practices of the most efficient producers (e.g. high-quality feed, good veterinary care, improved breeds), GHG emissions from the livestock sector could fall by 14–41 %(Reference Mottet, Henderson and Opio124). Such approaches, however, may have unintended impacts, such as increased use of nitrogen fertilisers to increase feed production(Reference Davis, Yu and Herrero125).
While productivity and efficiency increases are most relevant in LMICs, other options for reducing environmental harms of ASF production are also relevant in high-income countries. This includes the adoption of circular production approaches, which seek to reuse waste, reduce loss and minimise the use of external inputs, such as by better integrating production of crops and livestock(Reference Van Zanten, Herrero and Van Hal126). It also includes improved grazing management, which can increase carbon sequestration in soil, reduce water use and support biodiversity, and shifting production to ensure ruminants are raised on natural rangelands ill-suited for crop production(Reference Beal, Gardner and Herrero22,87) . Reducing methane emissions from ruminants is also a promising option (e.g. through feed supplementation and methane vaccines), as is improved manure management to reduce emissions of nitrous oxide(Reference Herrero, Mason-D’Croz, Thornton, Von Braun, Afsana and Fresco1). For fisheries and aquaculture, better technology, regulations to reduce over-fishing in wild populations, improved feed for farmed populations and application of best practices could all help to reduce environmental impacts. Reducing waste along food value chains and improving the use of non-flesh animal parts could also play roles in both fish and livestock value chains(Reference Nordhagen, Beal and Haddad29). While promising, promotion and adoption of all of these approaches run into challenging barriers in the ‘real world’, making the realistic impacts of supply-side practices far less than the theoretically possible reductions and underlining the importance of simultaneously pursuing the second path (consumption changes)(Reference Herrero, Wirsenius and Henderson88).
Consumption changes can include eating less of the highest-impact ASFs (chiefly beef, lamb and mutton) and shifting towards lower-impact ASFs, such as chicken, fish, seafood and certain dairy products. For example, replacing the expected future growth of beef production with that of poultry production could reduce environmental impacts by up to 13 %(Reference Pelletier and Tyedmers93). However, such changes would need to consider the different nutrient profiles of different ASFs and potential implications for nutrient adequacy of diets (and, though beyond the scope of this paper, animal welfare). Consumption changes can also include eating more of nutrient-dense (but sometimes wasted) organ meats instead of flesh cuts.
To meet climate mitigation goals, however, consumption changes involving a shift away from ASF and towards non-ASF alternatives are likely needed, as the reduction in environmental footprint from dietary change tends to be proportional to the amount of ASF reduction(Reference Aleksandrowicz, Green and Joy73). As noted above, such shifts do not need to be towards full vegetarian or vegan diets but can instead be towards diets that still contain ASF, just in smaller amounts. Such shifts will be particularly meaningful – and can likely be done with no adverse consequences for nutrition – among those who currently consume the largest amounts of ASF. Replacements for ASF can encompass both traditional plant-based foods (like legumes, nuts, seeds, and moderately processed foods based on them, such as tofu and tempeh) as well as more ‘modern’ options, like plant-based meat analogues and cultured meat. Where culturally appropriate, edible insects may also be an option. However, diverse alternatives to ASFs each have nutritional advantages and drawbacks, particularly when it comes to micronutrient content(Reference Nájera Espinosa, Hadida and Jelmar Sietsma127). Care is needed to ensure nutrient adequacy – which is not always the case with the ‘sustainable’ diets used in modelling studies(Reference Payne, Scarborough and Cobiac128,Reference Chen, Chaudhary and Mathys129) . The capacity to adopt these types of dietary changes is likely highest among those currently consuming larger amounts of meat and other ASF, particularly high-income consumers who have access to a wider range of nutritious alternatives, as well as greater capacity to afford them.
Conclusion
ASF production and consumption bring considerable value to diets, to livelihoods and to societies worldwide. Yet their production at large scale has adverse environmental consequences that are incompatible with keeping the Earth on track towards a liveable future. These issues must be balanced, and doing so is not easy – but a few key principles can help.
First, context matters crucially. ASFs are diverse, and their environmental impacts vary widely – as do their roles in current diets and the capacity of populations to benefit from increased (or decreased) consumption of them. The relative importance of the different social goals to which ASFs contribute also varies by context and changes over time. Constraints on change are tighter in some places (and for some people) than others. There is thus no universal solution; policy decisions related to ASFs should be made inclusively, to ensure these diverse needs are considered and balanced.
Second, the topic is complicated, and about values and beliefs as well as facts. It is important to engage in balanced discussions that respect the emotional nature of the issue for some stakeholders, to avoid simplistic narratives, to steer away from strict dichotomies and to acknowledge where there are complexities and grey areas.
Finally, equity is key. When studying and proposing ways forward for ASF consumption and production, we need to pay attention to how different groups are affected, particularly the most vulnerable. We must seek to rebalance current global inequities related to nutrition and environmental impacts, recognising that this may entail difficult changes for some, to safeguard a more sustainable future for all.
Acknowledgements
This paper, and the conference lecture based on it, draws on two previously published papers(Reference Beal, Gardner and Herrero22,Reference Nordhagen, Beal and Haddad29) . I thank all the co-authors on those papers – Ty Beal, Lawrence Haddad, Christopher D Gardner, Mario Herrero, Lora L Iannotti, Lutz Merbold and Anne Mottet – for their collaboration on those, many of the insights of which are reflected here, while acknowledging that the additional views represented herein are my own. The opinions expressed herein also do not necessarily reflect the views of the Global Alliance for Improved Nutrition. I also thank Ty Beal for his review of and comments on an earlier draft of the paper.
Financial support
This research received no specific grant from any funding agency, commercial or not-for-profit sectors
Competing of interests
The author declares none.
