In its recently released report, the EAT-Lancet Commission brought together scientists from the fields of health, nutrition, agriculture and environment to quantitatively define a universal reference diet that is both healthy and environmentally sustainable. The targeted diet was developed with respect to a safe operating space for food systems within planetary boundaries and promoting dietary and food production practices to ensure that the UN Sustainable Development Goals relating to hunger, health, and environment are achieved. Their reference diet presents a substantial shift from current diets, requiring a greater than 50% decrease in unhealthy foods such as red meat, sugar, starchy roots and refined grains and a greater than 100% increase in consumption of healthy foods such as nuts, fruits, vegetables and legumes, which will require changes in current food production patterns.
In developing the reference diet, the EAT-Lancet Commission proposes that the categories developed are universal for all food cultures and production systems and have a high potential for local adaptability and scalability. The report also notes that the reference diet is applicable to future projections of world development, particularly the expectation of a global population of 10 billion by 2050, while remaining within a safe operating space with regards to food production and planetary boundaries.
While the proposed diet presents a transformational approach to tackling current unhealthy and unsustainably produced food, it is challenged by some of its own assertions about the feasibility of the diet both in terms of current consumption patterns as well as ability of the food systems to meet the diet’s future demands. One aspect of the diet we intend to examine in regard to feasibility of production is the recommendation of increased daily intake of tree nuts to approximately 25 grams per day (Table 1), an increase of almost five-fold from current consumption patterns.
The dietary importance of nuts cannot be overstated: they provide a relatively large quantity of calories including essential polyunsaturated and monounsaturated fats, vitamins, and essential amino acids from a high protein content. Nuts have also been proven to have critical health benefits, with studies showing nut consumption associated with reductions in the risk of cardiovascular disease, type 2 diabetes and overall mortality. Nut consumption has also been strongly linked to inducing satiety and reduction of weight gain (or reduced weight) in observational and clinical trials. While nuts have been traditionally associated with snacking and desserts in ‘Western’ cultures, they are increasingly being used as a plant-based protein and dairy alternative. Almond and cashew ‘milks’ are popular substitutes for dairy, and nuts and nut butters are being incorporated instead of meat as fat and protein sources in meals.
The Current State of Tree Nut Production
According to the United National Food and Agriculture Organization statistics (FAOSTAT), in 2017 the harvested area of tree nuts was approximately 12.7M hectares, spanning 108 countries and including the following crops: almonds, pistachios, hazelnuts, walnuts, cashews, chestnuts, brazil nuts, and other minor nuts that include pecans, macadamias, pine nuts and others. Just 15 countries make up 76% of total tree nut production area, of which Ivory Coast has the largest share (14% of total tree nut hectares). The production volume in nut crops was 13.9M tonnes in 2017¹
The top 10 producing countries in 2017 for each tree nut crop and overall are shown in Figure 1, it illustrates that tree nut production is concentrated to a few key countries, each of which specialize in one or two particular crops. China stands out as not only the largest producer of chestnuts and walnuts, but also the largest producer of tree nuts overall, producing more than twice the volume of the next highest producing country, USA (3.1 million tonnes vs 1.2 million tonnes). From the figure below, it is noteworthy that most tree nuts are produced mainly in tropical and sub-tropical areas of the world, and are likely specialized to a few unique agricultural environmental zones.
Improving production volume can happen through increasing yields, increasing area, or a combination of the two. In recent years, production volumes have increased at a greater rate than harvested area (Figure 2), which translate to increased yield rates since the 1990s. The growth in yields in the past twenty years is most notable in chestnuts and walnuts. The yield growth of other tree nuts such as almonds, walnuts, hazelnuts and pistachios have been much lower, growing approximately 1–2% per year since the 1980s.
Tree Nut Production into the Future
The context of tree nut production illustrates that nuts are highly specialized crops, growing in a few key regions and at relatively low yields per hectare. Divided equally among the current population, tree nut production works out to approximately 5 grams per day per person. Using the values put forth in the EAT-Lancet reference diet, for a future scenario in 2050 where approximately 10 billion people eat 25 grams of nuts daily would require an annual production of 89.2 million tonnes (Table 2), increasing current production by almost 540% and requiring an annual growth rate of 2.3 million tonnes, or 17%, per year. This would imply an increase in either tree nut area, yields or both. A key question that emerges is whether this is even feasible given current and future land-use scenarios as well as past yield trends.
Projecting into the future up to 2050 where different scenarios of yield increase and expansion of harvested area are combined, only one scenario, where both harvested area and yield increase by 200%, makes it possible to reach the production volume for the EAT-Lancet tree nut dietary recommendation (Table 3). A 200% expansion in harvested area would add an additional 25.4M HA of tree nut plantations to the current 12.7M HA by 2050, which begs the question of where this expansion would take place.
In the EAT-Lancet report the International Model for Policy Analysis of Agricultural Commodities and Trade (IMPACT) model was used to construct food systems that connect food consumption and production across regions. In the report they note that in their modelling, they used the strategy by which “…reductions in cropland use for feed crops was, to a large extent, compensated by large increases in cropland use for legumes and nuts which are relatively low-yielding” so that the impacts of the proposed dietary change resulted only in small reductions in cropland use (0–2%). This substitution of feed for nut (or legume) cropland is problematic for several reasons, chief among them being that for the most part, animal feed and nuts are grown in vastly different agricultural, climatic and land-use contexts. We are currently developing a map that illustrates the disparity between land used for feed and land used for nut production to show that a substitution of one for the other is likely not feasible; this implies that the expansion of tree nuts will displace other crops or happen on previously undisturbed land.
As with any food production system, expanding tree nut production would have its own social, environmental and economic impacts that would need to be taken into account. Tree nut crops are labour intensive with harvesting and processing of most crops happening by hand with very few areas outside of North America and Europe using mechanization. Several organizations have highlighted the unsafe working conditions for harvesting and processing cashews, one of the world’s most popular nuts, produced in a few countries but processed largely in Vietnam and India. Cashews are currently the top tree nut crop in terms of harvested area at 6 million HA and are grown almost exclusively in tropical countries. An expansion into wild forests would mean an increase in GHG emission due to land use change, and loss of habitat in highly biodiverse regions. Nut production is also challenged by input costs, with a high barrier to entry posed both by tree costs and a long time to harvest after first planting, which can vary from 4–6 years for almonds to 10+ years for pecans. This is not to suggest that the impacts of tree nut production are worse than those of livestock or grain production, only that this food system comes with its own baggage.
In this regard, particularly in environmental impacts of tree nut orchards, there are very few studies on which global modelling efforts are based. Poore and Nemecek did an exhaustive meta-analysis of the impacts of different food groups in 2018. In their results only three papers have measurements on the impacts of tree nuts. One for hazelnuts in Iran, a second one for almonds, pistachios, and walnuts in California, US, and the third one for chestnuts produced in Portugal. Life Cycle assessment of tree nut orchards is at the most a nascent field, and the environmental consequences of this expansion are very uncertain at the moment.
We welcome the analysis by the EAT-Lancet report authors, and appreciate that it opens the door for further research on the challenges of dietary transitions. Tree nuts will necessarily be one of those fields, with more detailed information needed on suitable regions for growth and expansion, improvement of yields, as well as greater analysis of environmental, social and economic impacts of tree nut production and processing.
¹ This value is calculated by using FAOSTAT production figures and removing shell weights (using FAO shell weight standards) from the production volumes of almonds, brazil nuts, cashews, hazelnuts and walnuts that are all either consumed or sold without their shell. The shell weights of ‘nuts, nes’ are not removed because of the variation of crops in this category.