Food production is a major source of environmental degradation around the world and is contributing to the thresholds of several planetary limits being crossed.26,27 It is currently estimated that agriculture and livestock farming are responsible for 20 to 30% of global greenhouse gas emissions.28-30 These emissions are mainly comprised of ni-trous oxide (N2O) emissions due to muck-spreading of fertilizer and manure slurry, and methane (CH4) emissions due to enter-ic fermentation in ruminants. Agriculture uses about half of the non-frozen land on the planet.29 Natural habitats being converted to farmland is the leading cause of deforestation, of natural habitats becoming fragmented, and of a decrease in biodiversity all around the world. These practices threaten natural carbon sinks and thereby contribute to greenhouse gas emissions. The massive supply of synthetic fertilizer and manure leads to excess nitrogen and phosphorus in lakes and coastal areas, leading to a proliferation of algae and plants that, when they decompose, asphyxiate these environments (eutrophication). The use of pesticides is contributing to the decline in biodiversity31 and to ground soil and water reserve pollution. Food production therefore has a major impact on many environmental indicators.
Food has a very variable environmental – including carbon – footprint. Animal-based food production is usually more intensive in terms of the resources it uses, and emits more greenhouse gases, than plant-based products.27 For instance, legumes, eggs, dairy products, poultry, and ruminant meat have average footprints of 0.3, 6.8, 9.1, 10.0, and 62.3g CO2 g-1 of protein.27 It is, however, worth noting that farming practices and transportation also affect the effective carbon footprint of food products.
Global trends show that diets are moving towards a consumption of more highly-carbonated products, including a vast increase in the consumption of animal-based products.26,29,31,32 Based on a projected increase in the global population of around 30% (8.5 to 10 billion by 2050), and a change in diets that follows the projected changes in standards of living, by 2050 food-related greenhouse gas emissions could increase by 80 to 90%, 27,29 farming areas by 67%, the use of drinking water by 65%, and the application of phosphorus and of nitrogen of 54 and 51% respectively.27
While food production has a major impact on the environment, the FAO estimates that 20 to 30% of food products are wasted or lost over the course of the supply chain or by consumers.33 Food that is produced but not consumed therefore takes up around 30% of global farmland, with an estimated carbon footprint of around 4 gigatons of CO2eq per year.34 By comparison, the United States directly emit 6 gigatons of CO2eq per year, and Switzerland around 45 million tons of CO2eq.a
It is also worth noting that food packaging contributes to global plastic pollution. It is estimated that between 4.8 and 12.7 million tons of plastic are poured into the ocean each year, to which can be added 1.5 million tons of microplastics (plastic that is smaller than 5mm). While the effects on health of ingesting plastic remain unclear, it is now an established fact that microplastics are ingested by marine and land organisms all along the trophic chain and are also present in human food.35-37
Overall, malnutrition problems fall into two paradoxical categories: undernutrition and obesity. On the one hand, a food deficit affects around 820 million people around the world, and two billion people suffer from micronutrient deficiency. 26 On the other hand, over two billion people around the globe are struggling with being overweight and obesity in a way that is linked to diets that are too calorie-rich and heavy in refined sugars, meat, and fats that are animal in origin or hydrogenated. 26 This has gone hand-in-hand with a rise in the prevalence of chronic diseases. It is estimated, for instance, that diabetes cases have doubled in the past 30 years and affect over 10% of the Western population, that high blood pressure affects around one third of the global population, and hypercholesterolemia, one quarter.38
There is an overall consensus as to what broadly constitutes healthy eating. The FAO and WHO emphasize the importance of increasing planted-based food intake, including fruits, vegetables (except starchy root vegetables), legumes, nuts, and whole grains, and to limit caloric intake of free sugars and fats, to consume unsaturated fatty acids rather than saturated and hydrogenated fats, and to limit salt intake. Poorly balanced diets that are too high in calories or do not contain enough fruits, vegetables, legumes, whole grains, nuts, seeds, unsaturated fatty acids, calcium, and fiber, as well as excessive red meat, processed meat, sweet drinks, hydrogenated fats, and sodium intake are the greatest risk factors for non-communicable, food-related illnesses.39 The risks linked to an un-balanced diet are responsible for 11 million deaths and 255 million DALYs per year (2017 estimate). Cardiovascular diseases are the primary food-related causes of death, followed by cancer and type 2 diabetes.40 Ex-cessively high sodium intake and excessively low whole grain and fruit intake, in particular, have the biggest impact on food-related mortality and DALYs.39,40
Because a large portion of the global population is malnourished, food production is strongly contributing to the thresholds of planetary limits being crossed, and because these trends are on the rise globally, diets need to change as much for the health of populations as to ensure the sustainability of the food production system. In general, diets should include less animal-based and processed products.29,30,41 Some models suggest, for instance, that a change in the average British diet to make it more in line with the WHO’s nutritional recommendations would result in a concomitant 17% reduction of greenhouse gas emissions.41 These new diets would contain less red meat, dairy, eggs, and ultra-processed foods, and more grains, fruits, and vegetables.
The EATLancet Commission has studied the dilemma of feeding the global population a diet that is both healthy and sustainable.26,42 It recommends a diet that mostly features vegetables, fruits, whole grains, legumes, nuts and seeds, unsaturated fats, includes a small or medium amount of sea food and poultry, a small amount of dairy products, little or no red meat and no processed meats, added sugars, or refined grains. From an environmental point of view, its authors base themselves on the significant impact that animal-based products, particularly red meat and dairy, have on all environmental indicators, including greenhouse gas emissions. In terms of health, they highlight the importance of increasing whole grain, fruit, vegetable, nut, seed, and legume consumption and reducing red meat and processed meat consumption. The authors also note the importance of balanced caloric intake and weight, which is a place where sustainability and health challenges can converge. Indeed, once nutritional needs have been met, questioning the need to consume more offers an additional path for lowering one’s environmental footprint.
The nutritional intake of the diet the EAT Lancet commission advocates covers nutrient and micronutrient needs. Compared to the average diet, their suggested one increases mono- and poly-unsaturated fatty acids and reduces the consumption of saturated fatty acids. The authors nonetheless suggest that vitamin B12 supplements may be necessary, particularly when a diet falls within the bracket of the suggested small intake of animal-based products. Table 1 illustrates average daily quantities of different foods for a healthy and sustainable diet according to the EAT Lancet report.
National dietary recommendations rare-ly mention the environmental impact of the food choices they advocate for. Yet, in countries with moderate to high incomes, following those recommendations, including by reducing red meat, dairy product, and egg, and ultra-processed food consumption, as well as reducing caloric intake in general, is largely aligned with environmental goals.31,39,41 Models show that following the dietary recommendations in high-revenue countries would result in reducing greenhouse gas emissions by 13 to 25%, eutrophication by 10 to 21%, and surface area occupation by 6 to 18%.31
Nonetheless, a study of environmental impacts related to eighty national nutritional recommendations suggests that these do not generally allow for a sufficient reduction of environmental impact and are often incompatible with greenhouse gas reduction goals, preserving biodiversity, and, in general, with respecting planetary limits.43 The results of this study, however, suggest that the recommendations developed by the EAT Lancet Commission26 are associated with more significant gains in terms of health than the national recommendations studied, all while enabling us to reduce environmental impact so as to be in keeping with ecological aims. From an environmental point of view, the fundamental difference between national dietary recommendations and the EATLancet Commission’s is the suggested amount of animal-based products, particularly red meat and dairy products (figure 3). While most national recommendations do, indeed, suggest that the amount of meat be reduced, the amount it suggests they be reduced by is considerably less than those suggested by the EATLancet Commission. The latter is based, among other things, on studies that establish links between red and processed meat consumption and acute mortality risks through a certain amount of incommunicable diseases to justify this lesser quantity. At the same time, most national dietary recommendations advocate for an increase in dairy product consumption as compared to current consumption, which would result in a large increase of the impact on all environmental indicators. The EAT Lancet Commission encourages limiting dairy product intake to one portion per day. The authors indicate that while consuming dairy products is recommended to ensure calcium intake, the evidence remains unclear regarding the optimum daily intake of calcium, and the links between consuming dairy products and bone health.44 Recommendations vary considerably. In Switzerland, the daily recommended calcium (Ca) intake for adults is 1,000mg of Ca/day,b in the United Kingdom 700mg Ca/day,c and the WHO concludes that a 500mg Ca/dayd is sufficient. Since many foods contain calcium, and a varied, dairy-free diet therefore provides 300 to 400mg of calcium a day, and the vegetable oils are associated with a lower risk, of cardiovascular disease than the fat in dairy products, the EAT Lancet Commission recommends that around 250g of milk per day (which contains 300mg of calcium) be consumed, suggesting milk protein intake be replaced by nut and vegetable protein intake.26
These results therefore suggest that national recommendations should be adapted to incorporate environmental criteria, providing margins that would make them both healthier and more sustainable.43 The authors note, in particular, that recommendations regarding vegetable-based protein, such as legumes, nuts, and seeds, are absent from many national dietary recommendations, or too vague. They also note the importance of adapting recommendations to different cultural, socioeconomic, and territorial contexts, as well as to local agricultural production methods.26,31,41
The conclusions of studies comparing the nutritional value (in terms of mineral, protein, and vitamin content) of organic food versus food that comes from conventional farming methods differ. A systematic review conducted in 2012 concludes that the proof to date remains insufficient to say that organic farming products have greater nutritional value as compared to products that come out of conventional farming methods.45 Several studies nevertheless show that organic products contain less pesticide and nitrate residue, as well as antibiotic-resistant bacteria,45-48 even though the clinical implications of that remain poorly understood. Direct proof therefore remains insufficient to date to encourage organic product consumption solely on the grounds of improving one’s own health. It should be further noted that the variability of organic versus conventional practices, as well as the heterogeneity of the factors that must be taken into account (weather during cultivation, types of soil, maturity at harvest time, variet-ies grown, storage methods) make such com-parisons difficult.
Nonetheless, from a systemic point of view that links food choices not only to individual health but also to community health and to the health of ecosystems in the long-term, indirect evidence clearly encourages consuming products that come out of farming methods that are respectful of the environment and that limit the use of plant pro-tection and veterinary products. Food production is a major source of environmental degradation around the world and is contributing to the thresholds of several planetary limits being crossed. The use of pesticides exposes farming and local populations to molecules that are known to be toxic, or to combinations of those molecules.49 These molecules also contribute to a decline in biodiversity in fields, forests, soil, surface water, and groundwater tables, which constitutes a major risk for life on Earth. Furthermore, the widespread use of antibiotics in intensive farming is contributing to the emergence of bacteria that are antibiotic-resistant,50 with immediate consequences on health, and also posing ethical questions with regard to future generations.51
A criticism that is commonly levied at organic farming is that, given its lower yield per surface unit compared to conventional farming, it requires more surface area to feed the same amount of people, and that it could therefore contribute, if rolled out on a large scale, to deforestation, in order to obtain more farming area. However, a systemic perspective allows one to respond to this critique: by combining diets that limit animal-based product, diminishing food waste, and developing agro ecological practices, models suggest that organic farming could feed the global population without contributing to deforestation and the destruction of natural habitats.52
Privileging local, seasonal, unprocessed products further allows us to limit energy consumption and greenhouse gas emissions related to food product transportation, the heating of greenhouses, or refrigerating food products.
Lowering the environmental footprint of food production will require significant efforts on different levels. Diminishing animal-based product consumption and favoring fresh, local, seasonal products from sustainable agriculture would allow us to significantly reduce our impact on various environmental indicators. Individual consumption habits are, however, highly influenced by the structural frameworks and social norms within which a given population is evolving. For instance, the difficulty finding fresh, seasonal produce, the lack of appetizing vegetarian menus in institutional catering, as well as national dietary recommendations that struggle to incorporate vegetarian options can all hold up the ambitions of individuals who wish to change their diets.
On the consumer level, economic constraints offer overall effective levers for changing behaviors, for instance through taxation measures, if taxes are sufficiently high (15 to 20%, according to studies).53,54 Taxing soft drinks is also under consideration55 A more radical move would be for there to be legal constraints banning certain food products. While consumers have a certain leeway when it comes to privileging some products, legal measures and international trade agreements have a major role to play in the lead up to those individual choices to encourage sustainable means of production and the sale of products that will limit environmental impact and be beneficial to populations.
In a hospital environment, an appreciation of the health & environmental co-benefits of certain changes in habits could enable us to approach nutritional recommendations from a dual perspective of nutrition and sustainability. To encourage the environmental impact of food being taken into account, the Swiss Nutritional Society (SSN) has published a plate that provides an ecological assessment of various foods on the food pyramid (figure 4). But outside EAT Lancet’s detailed recommendations and the SSN’s food pyramid, there are no practical tools that have been approved for clinicians.
An article published in 2018 in an American review geared at family physicians outlines the concept of a healthy diet for patients.56 One must admit that when it comes to mod-ifying eating behaviors in the clinic, the results of studies are often disappointing.57,58 Including when it comes to quite a few studies of weight loss when going on various diets. Few of them work, and it is often relatively intense, multi-modal interventions that are most effective (changing mobility, behavioral interventions, etc.).58-60 Caregivers nonetheless do have an important role to play in supporting patients and contributing to dis-seminating quality food-related information. And while interventions on an individual level do not necessarily bring about easily measurable behavioral change, they do contribute to helping along societal change. Such is the case, for instance, with tobacco, where the combination of public health efforts, structural measures (banning smoking in public spaces), and individual counselling has been synergetic, and contributed overall to less tobacco consumption. Furthermore, caregivers can base themselves on quality documentation to help along and reassure patients who wish to consume less or no meat when it comes to there being any potential risks of deficiencies or harmful effects on health. Since, in fact, the opposite is true, as multiple studies show the positive impact of meatless diets on morbidity.61,62
It comes as no surprise that not a single study, whether it be conducted at the level of the population or on an individual (clinical) level, has investigated the effectiveness of interventions that are coming from the perspective of co-benefitting both the environment and human health. We can, however, offer a summary of the overall approach as far as food is concerned, as illustrated in figure 5.
• Food production is responsible for 20 to 30% of greenhouse gas emissions. It is a major cause of deforestation and of the loss of biodiversity.
• Animal-based food production is generally more intensive in terms of the resources it uses and emits more greenhouse gases than plant-based products.
• Red meat has a significant impact on the environment, which is considerably higher than that of other protein sources.
• Consuming too much red meat is associated with the onset of cardiovascular disease and various types of cancer.
• Optimal following of current dietary recommendations could lead to a 13 to 25% reduction in food production-related greenhouse gas emissions.
• Organic agriculture could feed the global population without increasing deforestation if combined with less food waste and less meat consumption.