Background/objectives: Improved global data allow for a new understanding of what impact the food we produce, eat and dispose of has on the environment, human health and Nature's resources. The overall goal is to guide decision-makers and individuals by providing in-depth knowledge about the effects of their dietary preferences on human and environmental health.

Methods: The method is to investigate ways to reduce environmental degradation and to secure healthy food supplies in an urbanizing world, and to quantify the options.

Results: Reviewed articles show that by eating less meat-based food and more plant-based and soilless food, as well as reducing food waste and recycling urban-disposed nutrients as fertilizers, we could reduce agriculture's land requirement by 50% to 70% while still securing a healthy food supply. Less land under cultivation and pasture would reduce global emissions to air and water to a similar extent, and allow Nature to reclaim freed areas in order to catch more carbon and rejuvenate biodiversity. Thus, we could avoid further environmental degradation such as the current clearing of new fields needed under a business-as-usual regime. Presently, some 17 million people die each year due to poor diets, which is more than double the 7 million deaths since the onset of the COVID-19 pandemic. A return to more plant-based diets with unchanged intake of proteins but less calories, sugar, salt and fat combined with less red meat and ultra-processed food would reduce foremost non-communicable diseases by up to 20% and prolong life. The article suggests that the international focus has gradually turned to the food sector's big contribution to climate change, biodiversity loss and harmful chemicals as well as to poor human health. It argues that this century's rapid population growth and urbanization give urban residents a pivotal role in food's impact on agricultural areas, which today cover half of the globe's inhabitable areas. Their food demand, rather than the activities of farmers, fishermen or loggers, will guide remedial measures to be taken by individuals, industry and the public sector. A tool to calculate the potential environmental footprints of individual or societal measures is presented.

Conclusions: Measures to make the agrifood sector more sustainable are still pending full recognition in international fora such as the UN COP Summits. Smart cities fitted with infrastructures to recycle macro- and micro-nutrients and organic matter have the potential to ameliorate human-induced impacts such as emissions to air and water bodies, crossing planetary boundaries, and polluting extraction of N (nitrogen), P (phosphorus) and K (potassium). Rapid results are within reach since dietary change and the turn-around time of nutrients in food is short compared to decades or centuries for recycled materials in cars or buildings.

Community-led total sanitation (CLTS) is increasingly promoted globally as an innovative approach to addressing the sanitation challenge in developing countries, especially in the rural areas where access to sanitation remains poor. However, a significant challenge in CLTS is poor management of faecal sludge when pits are full. In this regard, composting toilets offer a potentially viable and ecologically sound method for effective and efficient faecal sludge management, by providing fertilisers that act as soil conditioners, and ultimately contribute to clean environment, food security, good health, and poverty alleviation. Despite these advantages, there is limited knowledge on why and how composting toilets can be successfully integrated into CLTS initiatives. In this paper, we use the case of Ghana to demonstrate that integrating composting toilets into the CLTS approach is a feasible option for sustainable and environmentally friendly faecal sludge management in rural areas where agriculture is the predominant livelihood activity.

With growing urbanization cities become hotspots for nutrients. Food items are imported, and food residues, including excreta and not-eaten food, are often exported to landfill sites and water bodies. However, urban sanitation systems can be designed to achieve a high degree of nutrient recovery and food security while counteracting current nutrient resources depletion, environmental degradation, and wasteful energy use. This article illustrates how an extended solid waste hierarchy also including human excreta and wastewater can guide actions to save and recover phosphorus (P) by the three sectors: food industry, households, and waste utilities. P use in diets and agricultural production is not part of the analysis, despite the potential to save P. Novel systems thinking and material flow analysis show that waste prevention can replace over 40% of mined P presently used for making fertilizers. Reuse and recycling of P in excreta and food waste can replace another 15–30%, depending on P efficiency from mine to plate. Keeping excreta separated from other wastewater facilitates such measure. Incineration and land filling are deemed the least appropriate measures since mainly P is recovered in the ashes. The European Union (EU) waste management policy is analyzed for real barriers and opportunities for this approach. The EU Parliament policy guidelines were watered down in the EU Commission’s Directives, and today most biowastes are still being landfilled or incinerated instead of recovered. An anticipated overcapacity of incineration plants in Europe threatens to attract all combustible materials and therefore, irrevocably, reduce nutrient recovery. On the other hand, reduced generation and enhanced recovery can delay exhaustion of P resources by several centuries and simultaneously reduce environmental degradation.

Raising environmental awareness among farmers is the key to successfully reaching environmental goals. The present study assessed the knowledge development process and the raising of environmental awareness among 30 farmers from Poland exposed to four approaches aimed to reduce phosphorus (P) and nitrogen (N) losses to water. The farmers were interviewed with open-ended questions on-farm both before and after the project intervention. As hoped, the farmers attempted to adjust their farm practices to the European Union regulations, which are in some cases supported by subsidies. As a complement, the project offered tools for system-thinking based on farm data and support from agricultural advisors: a) a survey of plant-available P, potassium (K), magnesium (Mg), and soil pH, resulting in soil maps; b) assessment of nitrogen leaching risks from individual fields; c) compilation of a farm-gate balance. Farmers were positive to soil surveys and maps, but had limited understanding of the nutrient balance concept and calculations. They generally relied on their own experiences regarding fertilization rather than on calculated farm nutrient balances and leaching risks. Farmers’ understanding and willingness to adopt new approaches to improve nutrient efficiency and reduce negative environmental impacts are discussed.

As global consumption expands, the world is increasingly facing threats to resource availability and food security. To meet future food demands, agricultural resource efficiency needs to be optimized for both water and nutrients. Policy makers should start to radically rethink nutrient management across the entire food chain. Closing the food loop by recycling nutrients in food waste and excreta is an important way of limiting the use of mineral nutrients, as well as improving national and global food security. This article presents a framework for sustainable nutrient management and discusses the responsibility of four key stakeholder groups—agriculture, the food industry, consumers, and waste management—for achieving an effective food loop. In particular, we suggest a number of criteria, policy actions, and supporting strategies based on a cross-sectoral application of the waste hierarchy.

Phosphorus is a non-substitutable component in all living plants and organisms and thus a crucial element in the food chain. The use of fertilizers derived from phosphate rock has made increases in food production possible and reduced malnourishment since the mid-20th century. Recent worries about a future shortage of phosphorus have sparked a debate over the lifespan of existing reserves. In this article, the author focuses on improved management of the phosphorus we have access to, and argue the case that halting present wastage of phosphorus and reuse/recycling nutrients in waste products can make phosphorus (almost) limitless.

The sanitation issue is entering the development discussion and the UN proclaimed 2008 the year of sanitation. The study aims to understand the cultural–spatial dimension among Muslim communities of excreting and recirculating human excreta in North West Frontier Province in Pakistan. Information on local perceptions and cultural understanding was collected through interviews, group discussions and observations in four selected villages. The study identifies a diversity of excreting practices among age groups and sexes, and varied adherence to expressed cultural norms. Interviewees express less resentment towards urine compared to faeces, however, their negative attitude subsides when faecal matter is mixed with water since this changes appearance, odour—and cultural meaning. Religious dictums about excreta and sewage accommodate contradicting routine behaviours to cater for needs of residents and farmers. For example, when mothers pray wearing soiled clothing, and in the use of wastewater as fertiliser for food production. The excreta-related practices are compatible with good hygienic behaviour as outlined by WHO Guidelines, except for children who are allowed to defecate anywhere.

Although human excreta contain the necessary nutrients for plant growth, local authorities in Ghana spend huge sums of money to dispose them as waste. Reusing excreta for agricultural purposes saves expenditure for chemical fertilizers, improves soil fertility, reduces poverty and ensures food security. People’s attitudes and perceptions about excreta vary between cultures and even within specific cultures. This study aimed to explore attitudes and perceptions among a peri-urban agricultural community towards sanitized human excreta and its use. The study adopted an exploratory design and collected data from 154 randomly selected households using questionnaires and focus group discussions. It was found that there is a general negative attitude to fresh excreta and the handling of it. However, the residents accept that excreta can be used as fertilizer, but they are not willing to use it on their own crops or consume crops fertilized with excreta. The study recommends open discussions in the community for a successful implementation of ecological sanitation.

Sustainable sanitation and food security have been issues in all human history although named differently. This study describes the evolution of sanitation arrangements in the Swedish town Linköping for the period 1870–2000. The flow of phosphorus from food consumption is estimated for the period and its output is divided into gainful reuse in agriculture and energy production and (harmful) losses to the hydrosphere and landfills. The rate of gainful reuse varies dramatically, from very high, up until the 1920s, followed by a drop to almost zero around 1950. Reuse was picking up since the introduction of a phosphorus removal unit at wastewater treatment plants and application of sludge in agriculture from the 1970s, but was followed by a sharp decline at the end of the 20th century. The results from Linköping are applied to scenarios for Sweden as a whole and extended to some anticipated implications for the world in the years to come.

Sustainable sanitation and food security have been issues in all human history although named differently. This study describes the evolution of sanitation arrangements in the Swedish town Linkoping for the period 1870-2000. The flow of phosphorus from food consumption is estimated for the period and its output is divided into gainful reuse in agriculture and energy production and (harmful) losses to the hydrosphere and landfills. The rate of gainful reuse varies dramatically, from very high, up until the 1920s, followed by a drop to almost zero around 1950. Reuse was picking up since the introduction of a phosphorus removal unit at wastewater treatment plants and application of sludge in agriculture from the 1970s, but was followed by a sharp decline at the end of the 20th century. The results from Linkoping are applied to scenarios for Sweden as a whole and extended to some anticipated implications for the world in the years to come.