Water Resources for Sustainable Healthy Diets: State of the Art and Outlook

Optimized crop distributions in Egypt increase crop productivity and nutritional standards, reducing the irrigation water requirement

Feeding a growing population with healthy food while preserving the natural ecosystem's resources is a critical challenge of our century. In Egypt, the increasing demand for food commodities and the intensive consumption of freshwater resources by the agricultural sector is hindering the food system capability to achieve sustainable food and nutrition security. The Egyptian government has recently prioritized the improvement of dietary supply through the efficient use of the locally available natural resources. However, strategies to transform the Egyptian agri-food system towards the sustainable satisfaction of healthy dietary needs have not been yet studied. Here, a novel approach has been introduced, able to combine the environmental advantages of an optimized crop allocation with the benefits of providing a healthy diet. First, a physically based agro-hydrological model is used to assess the crop water needs associated with the current cropland and diet (baseline). Subsequently, a linear optimization crop allocation algorithm is designed to replace crops in order to maximize green water productivity, while meeting the dietary requirements of the EAT-Lancet diet. Our results show that through an optimized crop allocation entailing the production of healthy and varied food, it is possible to reach an average 95 % satisfaction of the demand for healthy food items by local agricultural products, with an 8 % reduction in local freshwater consumption and a 90 % increase in crop profitability. Our study suggests the prioritization of the promotion of the dietary guidelines by the EAT-Lancet Commission at the national level in Egypt, to support human health against malnutrition and the development of a more sustainable and efficient food system.

Environmental assessment of diets: overview and guidance on indicator choice

Comprehensive but interpretable assessment of the environmental performance of diets involves choosing a set of appropriate indicators. Current knowledge and data gaps on the origin of dietary foodstuffs restrict use of indicators relying on site-specific information. This Personal View summarises commonly used indicators for assessing the environmental performance of diets, briefly outlines their benefits and drawbacks, and provides recommendations on indicator choices for actors across multiple fields involved in activities that include the environmental assessment of diets. We then provide recommendations on indicator choices for actors across multiple fields involved in activities that use environmental assessments, such as health and nutrition experts, policy makers, decision makers, and private-sector and public-sector sustainability officers. We recommend that environmental assessment of diets should include indicators for at least the five following areas: climate change, biosphere integrity, blue water consumption, novel entities, and impacts on natural resources (especially wild fish stocks), to capture important environmental trade-offs. If more indicators can be handled in the assessment, indicators to capture impacts related to land use quantity and quality and green water consumption should be used. For ambitious assessments, indicators related to biogeochemical flows, stratospheric ozone depletion, and energy use can be added.

Water Footprint as a Tool for Selection of Alternatives (Comments on “Food Recommendations for Reducing Water Footprint”)

Water footprint is a new tool for assessing sustainability in terms of water use. Researchers are devising new applications that use water footprint, one of which is focused on comparing the water requirements of individual diets. Systems have been proposed to suggest tailor-made recipes that use a lower water quantity in production. This system proposes alternative recipes with lower demands for water resources based on their water footprint. The water footprint consists of three components—blue, green, and grey water footprints. However, focusing only on a reduction in the total water footprint may lead to an increase in some of its parts, such as the blue water footprint, and subsequently to water scarcity in some river basins. Therefore, it is recommended to extend the food recommendations system with sustainability criteria in order to avoid the unsustainable management of water resources. The same criteria can be used in any system for selecting alternatives based on the water footprint.

National water shortage for low to high environmental flow protection

Global freshwater biodiversity has been decreasing rapidly, requiring the restoration and maintenance of environmental flows (EFs) in streams and rivers. EFs provide many ecosystem services that benefit humans. Reserving such EFs for aquatic ecosystems, implies less renewable water availability for direct human water use such as agriculture, industry, cities and energy. Here we show that, depending on the level of EF protection, global annual renewable water availability for humans decreases between 41 and 80% compared to when not reserving EFs. With low EF protection, currently 53 countries experience different levels of water shortage, which increases to 101 countries for high EF protection. Countries will carefully have to balance the amount of water allocated to humans and the environment.

Sustainable Diet Optimization Targeting Dietary Water Footprint Reduction—A Country-Specific Study

Food production creates 70% of the total anthropogenic water footprint, and it is the main cause of water pollution. Thus, more sustainable diets could contribute to the achievement of the Sustainable Development Goals. A linear programming-based stepwise optimization was designed to create dietary water footprint-reduced, culturally acceptable, and healthier diets in the case of Hungary based on a representative dietary survey. Optimization resulted in a considerable total dietary water footprint reduction (women: 18%; men: 28%) with a moderate dietary shift (~32%). Milk and dairies (observed: ~31.5%, optimized: ~20.5%) and meats and meat products (observed: ~28.0%, optimized: 28.9%) contributed the most to the dietary water footprint. In the water footprint–healthiness synergy, the vegetables, eggs, poultries, and fermented dairies were the most beneficial, increasing in amount, while fatty dairies, foods high in added sugar, and meat products were the most non-beneficial food sub-groups, decreasing in amount in the optimized diets. The problematic nutrients to fulfill in the optimized diets were energy, dietary fibers, sodium, vitamin D, zinc, vitamin B12, calcium, iron, and potassium at the maximum water footprint reduction. The study provides supporting evidence about the dietary water footprint–healthiness synergy for the further improvement of the national food-based dietary guideline.

Arjen Y. Hoekstra: A Water Management Researcher to Be Remembered

On 18 November 2019, the life of Arjen Y [...]

Integrative analysis of dietary water footprint and dietary quality – Towards the practical application of sustainable nutrition

The contribution of food production to the environmental burden is considerable, therefore, numerous countries have been trying to create a sustainable food supply chain to ensure food and nutrition security. The scope of this study was to analyse the association between water footprint and healthiness based on dietary records. Furthermore, it was aimed to create a classification of integrative dietary indicators of sustainable nutrition. With these methodological aims, the dietary records of 25 healthy adults were assessed. The dietary quality scores and dietary water footprint were calculated and Spearman's rank correlation was tested between them. The indicator nutrients were classified based on their advantageous or disadvantageous health impact and association with water footprint. There was a significant positive correlation between the meat consumption and water footprint, while significant negative correlations were found between the dietary quality score and water footprint and dietary quality score and meat consumption (P < 0.05). Protein, energy, sodium, and saturated fatty acids as integrated indicator nutrients could be identified for both dietary quality and water footprint. The improvement in dietary quality could simultaneously decrease the dietary water footprint. The integration of environmental impact into the analysis of diets could be the future direction in the counseling practice of nutritionists.

Optimal virtual water flows for improved food security in water-scarce countries

The worsening water scarcity has imposed a significant stress on food production in many parts of the world. This stress becomes more critical when countries seek self-sufficiency. A literature review shows that food self-sufficiency has not been assessed as the main factor in determining the optimal cultivation patterns. However, food self-sufficiency is one of the main policies of these countries and requires the most attention and concentration. Previous works have focused on the virtual water trade to meet regional food demand and to calculate trade flows. The potential of the trade network can be exploited to improve the cropping pattern to ensure food and water security. To this end, and based on the research gaps mentioned, this study develops a method to link intra-country trade networks, food security, and total water footprints (WFs) to improve food security. The method is applied in Iran, a water-scarce country. The study shows that 781 × 10⁶ m³ of water could be saved by creating a trade network. Results of the balanced trade network are input to a multi-objective optimization model to improve cropping patterns based on the objectives of achieving food security and preventing water crises. The method provides 400 management scenarios to improve cropping patterns considering 51 main crops in Iran. Results show a range of improvements in food security (19–45%) and a decrease in WFs (2–3%). The selected scenario for Iran would reduce the blue water footprint by 1207 × 10⁶ m³, and reduce the cropland area by 19 × 10³ ha. This methodology allows decision makers to develop policies that achieve food security under limited water resources in arid and semi-arid regions.

Which diet has the lower water footprint in Mediterranean countries?

The Mediterranean region is increasingly water scarce, with the food system being the largest driver of water use. We calculate the water resources related to food consumption in nine major Mediterranean countries, by means of the water footprint (WF), for the existing situation (period 2011-2013) as well as the Mediterranean and EAT-Lancet diets. We account for different food intake requirements according to gender and six age groups. These nine countries - Spain, France, Italy, Greece, Turkey, Egypt, Tunisia, Algeria and Morocco - represent 88% of the population of all countries bordering the Mediterranean. As first major observation, we find that the EAT-Lancet diet, a scientifically optimised diet for both nutrition and certain environmental indicators, requires less water resources than the Mediterranean diet, a culturally accepted diet within the region. In terms of water resources use, adherence to the former is thus more beneficial than adherence to the latter. As second major observation, we find that the EAT-Lancet diet reduces the current WF for all nations consistently, within the range -17% to -48%, whereas the Mediterranean diet reduces the WF of the European countries, Turkey, Egypt and Morocco within the range of -4% to -35%. For the Maghreb countries Tunisia and Algeria, the Mediterranean diet WF is slightly higher compared to the current WF and the proportions of food product groups differ. Such dietary shifts would be important parts of the solution to obtain the sustainable use of water resources in Mediterranean countries.

The scarcity-weighted water footprint provides unreliable water sustainability scoring

To evaluate the environmental sustainability of blue water use or the blue water footprint (WF) of a product, organisation, geographical entity or a diet, two well-established indicators are generally applied: water efficiency and blue water stress. In recent years, the Life Cycle Assessment (LCA) community has developed, used and promoted the indicator scarcity-weighted WF, which aims to grasp both blue water use and blue water stress in one indicator. This indicator is now recommended in an ISO document on water footprinting and many scholars have used associated scarcity-weighted water use indicators. However, questions on its physical meaning and its ability to correctly evaluate water sustainability have emerged. Here, we analyse for global irrigated wheat production to what extend the scarcity-weighted WF addresses blue water stress and water efficiency. We observe inconsistent results, as a significant proportion of unsustainably produced irrigated wheat has better scarcity-weighted WF scores as compared to sustainably produced irrigated wheat. Using the scarcity-weighted WF or scarcity-weighted water use for policy-making including product labelling, punishes some farmers producing their wheat in a water-sustainable way and promotes some farmers producing wheat unsustainably. Applying the scarcity-weighted WF indicator thereby is contraproductive in reaching the Sustainable Development Goal (SDG) target 6.4 on reducing water stress. In line with the specifications of this SDG target, to evaluate the sustainability of blue water use or the blue WF, the two indicators water stress and water efficiency should be used separately, in a complementary way.