Sewell z5052418 final research report linking health and sustainable food production
Environment Internship S1 2018
Student Name: Christopher Sewell
Student ID: z5052418
An investigation into the link between human diet and an
ecologically sustainable food supply chain.
It could be argued that both endemic negative human health outcomes and the start of large
scale environmental impacts can be traced back to the first agricultural revolution
(Neolithic Revolution), when human societies transformed from hunting and gathering to
farming at around 10, 000 BCE. (Chegg 2018).
The need for hunters and gathers to forage for food, by necessity meant a varied human
diet consisting of multiple food sources that included meat when the hunting was
successful (Harari 2017). Agricultural practices began to limit the dietary variations
leading the human anatomy evolving to cope with a less nutrient choice diet that is also
protein rich. As a consequence the current human diet is creating adverse environmental
and health impacts. The environmental degradation caused by having to sustain this
modern diet is at a tipping point. This report will look at the underlining evidence
surrounding the environmental impacts created by people’s dietary choices.
In 1945, the economist George Stigler published a diet that was both low cost and met the
minimal nutritional dietary requirements of a war ravaged population. Most people where
on nutrient deprived rationing after the end of the Second World War. According to Stigler
(1945) the optimal diet consisted of wheat flour, evaporated milk, cabbage, spinach, &
dried navy beans (Gephart et al. 2016). Stigler proposed that a person could have sufficient
nutritional intake using this diet for US $39.93 per year (in 1939 prices). Stigler’s method
was reaffirmed in 1947 with a newly developed simplex algorithm where they tested
Stigler’s ‘diet problem’ and found that it was only US 24c under his original calculation
(Gephart et al. 2016).
I would argue that while these historical milestones i.e. setting a nutrient based diet and
using an algorithm to test the assumptions, were relevant when feeding the masses during
that post war period, today we face an equally large, if not bigger threat to humanity and
the world we live on. This is the negative environmental consequences of humans having
to maintain an adequate nutrient intake as the population dramatically increases to 9.8
billion (United Nations Department of Social and Economic Affairs 2017) by 2050 within
the confines of a finite planet.
The nature of the challenge
There is growing urgency for policy makers and influencers to focus their attention on the
unsustainability of the global food chain. Overfishing, desertification of arable land and a
growing population are just three of the many issues that mean we have exceeded the
carrying capacity of the planet we inhabit.
The food production industry is a rapidly growing multi billion-dollar economic
powerhouse. This growth will need to be maintained as populations continue to move
from rural self-sufficient lifestyles into major population centres, not only in search of a
‘better’ lifestyle, but in many cases they are begin driven by climate impacts & population
pressures that are making many areas of traditional land non-arable. Coupled with the size
of the food industry we also have the numerous diet and lifestyle advice bodies that offer
guidelines on human health or environmentally sustainable ‘current best practice’. As a
consequence we see many environmental guides and labels appearing on the products that
adorn the supermarket shelves. This does not make the pathway to sustainable living for
consumers at all clear. There is an abundance of scholarly research, covering both the
environmental impact of the supply side of food production, as well as the consumption or
demand side. Academic research abounds on the subject of how food choices directly
relate to human health outcomes.
This paper sets out to understand the detrimental effect that the modern food supply chain
has on ecological health while at the same time looking for markers and research that
attempts to simplify and quantify the ‘perfect’ diet for both human and planetary survival.
Questions to be explored include; what work has been done to update Stigler’s diet to
include not only modern nutrient requirements but also how this blends with
environmentally sustainable measures; what environmental factors are being used, and
could be used, to measure and understand risk and how do they relate to nutritional intake;
and how is this information being translated from the world of academia to influence
The Intergovernmental Panel on Climate Change (IPCC) presents compelling evidence that
climate change is real and mitigation is needed today (Smith et al. 2014) although there are
a number of other important environmental impact factors that are affected by the global
food chain. I have explored a broad cross section of peer-reviewed studies that provides
environmental impact information about the food supply chain.
An indication of the depth and breadth of this subject can be seen in a study on reducing
environmental impacts of food production and consumption by Sala et al. (2017) where
they use the illustration in figure 1 to show some of the keywords that are applicable to this
Figure 1. Taken from Sala et al. (2017) shows keywords that cover the issue of food environmental impacts
One of the many challenges when reviewing the available studies on environmental
impacts caused by the global food chain is the development of appropriate footprint
indicators. Early studies focused on a single impact i.e. carbon, water, nitrogen or land
footprints. These headline impacts are then further segmented into more detailed studies
e.g. water consists of footprints showing the usage of freshwater resources to irrigate crops
through to acidification of waterways caused by nitrogen run off and greenhouse gas
Ecological studies have also attempted to combine these multiple impacts and have been
challenged by the complexity of weighting one impact against another therefore leaving
findings open to interpretation. This has resulted in varying approaches and methodologies.
An example of how combining multiple impacts can presented under the grouping
‘Footprint Family’ was reviewed in Galli et al. (2012).
An important factor that also needs consideration when aggregating multiple impact
factors is the potential risk of trade offs. Ridoutt et al. (2017) identifies problems that arise
from the unintended nutritional and environmental consequences of food substitution that
occur in practice often differ from those that are prescribed in the literature. This becomes
an issue if the studies are subsequently used to shape policy in environmental protection or
setting sustainable dietary guidelines. Incentivising a decrease in one impact group may
have negative impacts in another and therefore leads to adverse overall outcomes.
Beef consumption is an example that is often cited where negative environmental
outcomes can be evidenced across each of the four main impact categories (carbon, water,
nitrogen and land degradation). Here we also see a complex calculation used to weigh the
optimal footprint for consideration but the obvious mitigation strategy is just to consume
Further adding to the complexity in understanding various impacts can be found in an
evidenced based review by Ridoutt et al. (2017). They state that there us a disconnect
between the science that informs the agricultural industry on climate change, and how the
science that informs public health nutritional stakeholders on lowering GHG emissions
view dietary guidance. Within this context we must now look at the methods used to
understand the various environmental impacts and the rules or guidelines that help us gain
a better understanding of the cross over between the food chain and an adequate nutrient
Guiding principles of measuring impacts - The Life Cycle Assessment (LCA)
Regardless of the questions around the correct approach to presenting information on
environmental impacts, the LCA technique can be used to both measure the impact across
the production and consumption of individual food products as well as how these relate to
diet patterns (Hellweg et al. 2014).
LCA’s have international standards and as such are comprehensive and consider all
relevant environmental impacts when applied correctly. According to the International
Organization for Standardization (2017) this means LCA’s can therefore be used to focus
efforts to address the most critical environmental impacts while at the same time help
avoid polices and decisions that could cause ‘Problem Shifting’ between different life
cycles or from one geographic location to another. LCA’s are therefore currently the best
method to compare impacts on food production, consumption and the diet strategies that
attempt to address these impacts without shifting the environmental burden to another area.
Wiedmann & Minx (2007) help define LCA’s when applied to the term carbon footprint
(CF) as the GHG emissions caused by an activity or product during its lifecycle including
both the direct and indirect emissions. In the case of carbon emissions as they relate to the
food chain, direct emissions would be defined as being within the complete control of the
producer e.g. the practice of farming the land, and indirect emissions being from external
areas like the electricity or fuel supply for running farm equipment. This definition can
also be used for other environmental impacts.
We see this definition and further explanation of the way LCA’s can be applied used in a
study from China that compares CF in agriculture from Jianyi et al (2015) titled “Carbon
footprints of food production in China (1979-2009).” The work outlines three possible
approaches: bottom up based process analysis; top down based environmental input-output
analysis; and a hybrid, which combines both components. Jianyi et al. (2015) used this
third approach EIO (environmental input-output) – LCA (life cycle assessment) for their
study because the combination gives a wider coverage of the important elements of the
lifecycle. One of the key findings that relate to this report from the Jianyi et al. (2015)
study is, while using some sample data that is now nearly forty years old, the high level of
indirect carbon emissions from agriculture inputs are 28-35% of the total CF from food
production in China. We see the focus on CF where we will explore later in this report that
the environmental impacts arising from land degradation and water usage in Chinese
agriculture would far exceed these CF measures.
The environmental impact we are addressing when using LCA’s in the food chain
As stated previously, even with the considerations listed earlier, LCA’s are currently the
best method for understanding and measuring impacts across the numerous environmental
areas of concern. The question we need to address now is what targets should all
participants be aiming to meet using this standardized LCA approach for food production
and consumption as it relates to diet.
The 17 United Nations sustainable development goals (SDG) do help us here by forming
the basis for both social and environmental targets. Ridoutt et al. (2017) compiled a list,
shown in table 1 below, which is the result of a major literature review across 169 separate
targets of the 17 SDG’s which found 93 relevant journal articles that reported on
environmental assessment and impacts of the human diet. Unfortunately Ridoutt et al.
(2017) also found a weak alignment of environmental areas of concern covered within the
literature with those outlined in the 17 SDG’s.
• Water scarcity
UNSW Masters research by Christopher Sewell on finding a ecologically sustainable diet.