Healthy eating advice may lead to unintended consequences

By Tim Hess, Professor of Water and Food Systems at the Cranfield Water Science Institute, Cranfield University and Dr Chloe Sutcliffe, Research Fellow in Water and Food System Resilience, Cranfield University.

The Global Food Security Programme has been established to fund research that will ensure the UK’s future food security. We are currently researching water-related risks and sustainability in the UK’s food system.

The UK’s food system is vulnerable to disruption by a number of internal and external factors - not least because the UK imports around half of its food and consumers expect a wide range of foods to be available all year round. 

Eating more fruit and vegetables

It is now a well-established fact that eating fresh fruit and vegetables is highly beneficial for human health. Increasing consumption of fruit and vegetables reduces the incidence of many of the diet-related diseases such as stroke, heart disease and cancers that afflict populations eating diets rich in fats and sugars.

For more than fifteen years the UK Department of Health has encouraged us to eat five pieces of fruit and veg a day (at least 400g). However, a recent meta-analysis (Aune et al. 2017) has shown that even consuming 400g of fruit and vegetables daily is not enough to achieve the highest levels of protection against cardiovascular disease and cancer. The risk could be further reduced with a daily consumption of up to 800g.

Given that The National Diet and Nutrition Survey 2013 estimated that 70% of adults and 90% of teenagers fail to reach the 400g guidelines, this would result in a significant increase in consumption of fruit and vegetables in the UK.

Increased consumption means increased waste…

From 2011 to 2015 our analysis shows that the UK supply of fresh fruit and vegetables (excluding potatoes) was equivalent to 333g per person per day. However, the UK wasted the equivalent of 36g of fresh fruit and vegetables per person per day in the home, with further waste occurring through the supply chain (Quested and Johnson, 2012). 

To meet the recommended 800g per day while continuing the same level of wastage, the UK would need to increase supplies by more than an additional 550g per person per day. 

…and increased water consumption

Keeping the sourcing and composition of the UK’s fruit and vegetable supply the same but increasing the amount, would mean increasing the quantity of water used to produce it by more than two-and-a-half times.

In the UK, fresh fruit and vegetables are mainly grown in the driest regions, such as East Anglia or the South East, where water resources are already under stress due to population increase and other factors.

The major exporters of fruit and vegetables to the UK including Spain, South Africa, Egypt and Morocco, also suffer similar pressures as their water resources are even scarcer.

Reliance on irrigation

Much of our domestic and imported fruit and vegetable production is heavily reliant on irrigation water. 

It is estimated that on average, from 2011 to 2015, 462 million m³ was required each year to produce the UK’s fruit and vegetables (excluding potatoes). More than 87% of this water was consumed in production overseas, largely in highly water-stressed countries including Spain (32%), South Africa (16%) and Egypt (7%).

Unlike rain-fed agriculture, the water used in irrigated agriculture (mostly surface water from rivers or groundwater from aquifers) has an opportunity cost. If this water was not used to supply agriculture, it would be available for alternative environmental, industrial or domestic uses.

Where water is scarce, competition with alternative uses can be high. Agricultural water use in these circumstances can result in stark environmental, economic or social trade-offs to be borne by other potential users.

The fact that fresh fruit is always available in the UK might actually be detrimental to farmers or the environment in other countries – we may in effect be ‘exporting drought’ whilst ‘importing food’. 

South African water shortage crisis


Nowhere are water-related risks more clearly illustrated at the moment, than in South Africa. The UK imports 327,000 tons of fresh fruits from South Africa each year, in particular, a large proportion of the imports of grapefruit (32%), oranges (23%), ‘easy-peelers’ (18%), plums (25%), grapes (24%), apples (18%), pears (10%) and avocados (19%). 

The Western Cape Province is a major producer of export fruits but is facing its worst drought in over a century. The delayed onset of winter rainfall in 2017, the high demand for water by cities, and the fact that the province’s water resources are still recovering from drought in 2015, led the Premier to declare a drought disaster in the province. Dam levels have reached critically low levels, with only 10% usable water. The City of Cape Town, South Africa’s second-largest city, is suffering from a severe water shortage and residents have been told they will actually run out of water on July 9, 2018, known as ‘Day Zero’.

Lack of water has a major effect on produce quantity and quality. Poorly irrigated orchards usually result in reduced fruit yields and size, which may not meet the high quality-requirements of the UK market. Consequently, the fruit is exported to less discerning markets and the UK may be forced to source fresh fruits from elsewhere to meet customer demand. This increases the cost to the UK consumer and reduces the profitability of South African fruit farming.

Distant events can be close to home

Many UK retailers are working with their supply chains, producers, packers and water managers in the Western Cape to mitigate the impact of water-related risks on fruit production. But the South African drought has served to remind us how not only the African fruit farmer, but also the UK food system, is vulnerable to extreme weather events in distant countries.

Health campaigns that drive us to increase our fruit and vegetable intake may achieve better health outcomes for the UK population, but this is not without implications for populations and the environment elsewhere. Looking to the future, to achieve better health AND a more sustainable food system it is clear we will no longer be able to have our fruit and eat it without reassessing the sourcing and composition of our national food supply.

Partnership is the key

It will require a concerted effort and a strong partnership between the agrifood industry and academic researchers to produce innovative approaches to sustainability issues within the UK’s food system.

The Agrifood Training Partnership is leading cooperation between industry and academia to offer access to the latest technology, knowledge and skills essential for UK agrifood.

The project, ‘Increasing resilience to water-related risks in the UK fresh fruit and vegetable system’, is funded through the Global Food Security’s ‘Resilience of the UK Food System Programme’, with support from BBSRC, ESRC, NERC and Scottish Government.

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