Waste and losses in the global food system

This Thought for Food article examines the loss of nutrients as a result of food waste. Not all foods are wasted to the same extent, and thus neither are all nutrients. Aggregate numbers for global waste or waste reduction targets mask these important variations.

When considering the impact of changes in the food system, we need to consider the supply of nutrients, as well as the supply of foods. The primary role of the food system is to provide nutrients – in the form of foods – to meet the needs of the global population.

Distinction should be made between food losses and food waste. Losses are the decrease in edible mass along the supply chain prior to retail, and waste the decrease that occurs at the retail and consumer end of the chain. Read More

When demonstrating the impact of food loss and food waste, we should consider the decreases in available nutrients.

When we lose or waste foods containing nutrients that are in abundant supply, this is less critical from a human wellbeing point of view than the loss or waste of foods rich in undersupplied nutrients.

Ways of improving the future food system could include:

  • reducing loss and waste (and potentially lowering production) where we have excess nutrient supply
  • reducing loss and waste (and potentially increasing production) where there are nutrient shortages

So where are the nutrient shortages?

From a macronutrient perspective, current estimates are that nearly 690 million people have insufficient protein and/or energy intakes. However, micro-nutrient deficiencies (hidden hunger) are also an enormous problem: globally, anaemia (iron deficiency) is estimated to impact 43% of 0-5 year olds and 38% of pregnant women; up to 1.8 billion people may have insufficient iodine intake; and 17% of the global population is at risk of zinc deficiency.

The DELTA Model has been created to help people explore future food production scenarios. It uses data on food production, losses, wastes and end uses, coupled with food composition, nutrient bioavailability, population forecasts and nutrient requirements to determine whether a future food system scenario can meet the nutrient needs of the global population. Modelling the food system shows that globally, with equal distribution, we have enough macro-nutrients for all, even carrying current production levels through to feed the 2030 population.

For protein – often cited as a nutrient we need to produce more of to satisfy a growing global demand – there is already enough protein available globally to provide the target intake for the expected 2050 population based on current nutritional guidelines, if it were equitably distributed.

This may seem surprising, but a challenge in discussing the future of food is in separating the nutrition we need, and the nutrition we might want or prefer. Protein is a good example of this. Statements that we “need to expand production by 70%” by 2050 are based on consumer demand rather than requirement. The DELTA Model exposes the differences between demand for specific nutrients such as protein and population requirements.

However, the global story differs for the micronutrients. We are already limited on total supply of Calcium and Vitamin E and will also be limited on Iron, Potassium, Vitamin A and Zinc by 2030 unless changes to the food system are made. That is, even if distributed equally, there is not enough of these nutrients to meet everyone’s needs.

When we look at the distribution of nutrient supply at a country level the picture is worse. The variation in nutrient supply in 2015 shows that a significant proportion of the global population had insufficient access to Calcium, Vitamin E, Iron, Potassium, Zinc, Vitamin A, Riboflavin, Vitamin B12, Fibre, Folate, and Vitamin C.

Relative nutrient supply distribution at a country level in 2015.  All values are normalised to the target intake with the coloured bar showing the global average supply and the error bars showing the range in country level supply from the 10th to the 90th percentile of the global population.

Waste varies with food type, which affects the supply of nutrients in different ways.

Let’s consider a simplified food supply chain: On Farm -> Supply Chain -> Retail -> Consumer

  • On Farm losses are challenging to quantify, as these may include crops or parts of crops not harvested or not used for human food. These quantities are often not recorded either. In many farming systems, waste materials on farm are used to provide food for animals with almost 30% of the global livestock ration coming from crop residues, by-products and coproducts.
  • Once food commodities leave the farm, losses occur along the supply chains that connect farms with retail, including as part of processing into other products. With more expensive commodities there are strong economic drivers to reduce losses through supply chain infrastructure. For less valuable commodities this may not be the case. Well-developed supply chains seek to recover valuable nutrients from by-products and “wastes” by processing into additional foods, animal feeds, or for other uses.
  • At the consumer end of the supply chain, food may be discarded at retail or in-home for its appearance, age, or various other reasons. Consumer waste is generally greater in high income nations where there is the luxury of choice. Individual consumers or households often lack the resources and the incentives to repurpose food waste and inedible material.
Per-capita food waste by country income bracket expressed as Wasted Daily Diets – the number of additional person days of nutrition wasted based on the first limiting nutrient. Data from Chen et al. 2020. 

Across the supply chain economic drivers mean we waste less of what is expensive, which – combined with the perishability of many fruits and vegetables – means food loss and waste is dominated by plant material. Over 20% of fruits, nuts, and vegetables, and their associated nutrients are lost or wasted after leaving the farm gate. Losses of animal products are 7-10%, and losses of more stable plant commodities (e.g. pulses and sugar) are up to 8%. This means that there is less potential to increase the supply of nutrients that are mainly found in animal sourced foods by reducing loss and waste, compared with nutrients common in plant foods. For example, an 50% reduction in all food loss and waste would result in a 16% increase in Vitamin C supply, but only a 6% increase in Vitamin B12.

Overconsumption is a form of waste

The other aspect of waste that needs to be considered is overconsumption. Nutrients consumed in excess of requirements are either excreted in bodily wastes, or in some cases – as with excess food energy intake – accumulated within the body. Once a certain level of supply has been achieved, further intake gives no further benefit to the individual and is thus a form of nutrient or food waste. When we look to the future, reducing overconsumption waste may have a significant impact on global nutrition.

Taking the previous example of Vitamin C, the range in 2015 nutrient supply at a country level was from around 66% of the daily requirement, to more than 2.8 times the target. For Vitamin B12 – sourced almost exclusively from animal foods – the 2015 availability varied from 40% to 1.75 times the target. Reduced waste and more equitable distribution of foods would increase the availability of nutrients to the populations currently below the target.

When considering the question of what to do about food waste, we should also think about the nutrient waste that occurs as part of this. Waste of nutrient rich foods has a greater impact on our ability to nourish populations that waste of nutrient poor foods. Waste occurs at all stages of the supply chain, and there are many forms of consumer waste – including excess intake. Quantifying and addressing how and where we waste important nutrients is a promising route to reducing nutrient deficiencies.

This Thought for Food was written by the SNi team in collaboration with Prof Thom Huppertz and Prof Wayne Martindale.


Photo by Joshua Hoehne on Unsplash