Note: This webpage is for instructional purposes only and the scenario described below is fictional.

Transition from Animal-based to Plant-based Diets in the USA

UW-Madison Task Force Members:
   Md Elias Uddin, Department of Dairy Science
   John Fick, School of Business
   

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Scenario | Abstract | Introduction | Literature Review | Methods | Results and Discussion | Limitations | Conclusions | Strengths and Weaknesses Citations | Acknowledgements | About the Authors

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Scenario

Implementation cell of Dietary Guidelines for American (2015), U.S. Department of Health and Human Services and U.S. Department of Agriculture asked University of Wisconsin-Madison to form an expert group who will formulate a science-led report on implementation strategies for healthy dietary guidelines. As there is not much compiled information in the literature for people about how dietary changes are going to affect their health and the environment that they share with all, therefore our goal was to compile data from literature which might be useful for the policy maker to implement healthy dietary strategy.

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Abstract

Food habit has substantial impact on our health and the environment where we all live. Adoption of healthy diet (animal-based to plant-based diet) is considered one of the best options which might have positive impact both on our health and environment. But, implementation of healthy diet is a hurdle due to people’s perception and their tight bond with animal-derived food. Therefore, our objective was to compile the literature showing the impact of switching animal-based to plant-based diet on food production pattern, land use and resource utilization efficiency, human health and environment which might help to change the people’s perception toward healthy diet. For this purpose, we did a literature search on web of science and google scholar database with different combination of keywords that describe dietary transition (“animal to plant-based diet,” “dietary choice,” “dairy ,” “milk-derived,” “animal originated”), impact of dietary transition (“health,” “human health” “disease” “food production”, “land,” “environment,” “climate change,” “ecology,” “diversity,” “greenhouse gases,”); and perception and cultural aspects of food (“food habit,” “culture,”). We then read title and abstract of every article and selected the relevant 30 articles which were used for our study. Results showed that transition from animal-based to plant-based diet could yield more calorie and protein production per unit of land. Dietary transition could potentially increase about 50% death avoidance (depending on the extent of change) and decrease 12-20% mortality when people switched from nonvegetarian to vegetarian diet. Dietary transition also showed potentiality to reduce 29-70% (depending on degree of change) greenhouse gas emission from food production predicted for 2050. This information could be useful to bring positive changes of a particular group of consumers’ perceptions about food. The concept of nudge might also be useful to implement new dietary strategy reliant on either government policy changes or the private sector stepping up.

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Introduction

Food choice that we make to fulfill our nutritional requirement and preference not only affects our health, but it also has significant impact on both ecology and environment that we all share. Dependency on processed high calorie diet and over consumption of processed meat leads to overweight or obesity which has significant impact on increasing chronic and non-communicable diseases, and early mortality (Lim et al. 2012, Lozano et al. 2012). For more than a quarter century, about 50% US adult and 33% youth aged 2 to 19 are suffering from obesity which is more prevalent in older people (>40 years) and African-American (Table 1). The main reason causing the obesity in the US people is the food habit which is under-consumption of fruits, vegetables and dairy; and over-consumption of animal-derived proteins, sugar, fat and salts by majority of the US population (Figure 1). On contrary, almost a billion people in developing world is malnourished. Food production itself contributes more than 25 % of total greenhouse gases (GHG) emissions (Vermeulen et al. 2012) and 80 % of this emission is coming directly or indirectly from livestock farming (Steinfeld et al. 2006). The situation is getting worse as rich people from many developing countries following the same steps. Therefore, changing dietary choice or switching from animal-derived diet to plant-based diet as shown in different research have substantial positive impact on human health, food production, land use and resource utilization efficiency and environment (Bajzelj et al. 2014, Stehfest et al. 2009, Tilman and Clark 2014, Hedenus et al. 2014, Popp et al. 2010). Dietary shift might be better option than technological development for mitigation of GHG emissions and food security (Popp et al. 2010, Godfray et al. 2010). Switching toward more plant-based diet could potentially reduce 6-10% mortality globally and 29-70% GHG emissions in 2050 (Springmann 2015). Moreover, Dietary Guidelines Advisory Committee (2015) pointed implicitly that plant-originated diet would be better to promote human health and sustainability of long term food production in the US (USDA 2015). Therefore, it is a complex problem to be solved. Partial transition from animal to plant-based diet i.e. cutting animal-derived food from the diet to a certain level might be a potential option to proceed aiming to solve this complex problem in a balanced manner.

Table 1. Facts About Nutrition- and Physical Activity-Related Health Conditions in the United States (Adapted from 2015 – 2020 Dietary Guidelines for Americans)

Figure 1. Dietary Intakes Compared to Recommendations. Percent of the U.S. Population Ages 1 Year and Older Who Are Below, At, or Above Each Dietary Goal or Limit (Adapted from 2015 – 2020 Dietary Guidelines for Americans)

Promoting health has been the overall best way to push the sustainable diet agenda onto the masses (Graca 2015). They also found that people are more likely to act in their own best interest, so promoting plant-based diets as a benefit to their health will resonate more so than promoting sustainability. We hypothesized that by better understanding how human health, environment, and cultural perceptions influence dietary transition, we can apply implementation techniques that will lead to healthier life styles and greater environmental sustainability. The objective of our study was to evaluate the impact of switching animal-based to plant-based diet on food production pattern, land use and resource utilization efficiency, human health, and environment.

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Literature Review

Current dietary trends in the United States (US)

The current Western diet leads to debilitating effects to human health as well as to the environment. For the purposes of our research, we are focusing on the dietary trend known as the Western diet. The Western diet is rich in high fat, high sugar processed foods and weak in fruit and vegetable intake (Alles et al. 2017). A key component to the Western diet is the consumption of meat and dairy, both of which have been categorized as high energy-consuming sectors. In the current US diet, about 24% of total energy, 48% of total protein, 23-100 % essential fatty acids, and 34-67% available amino acids are coming from animal-derived food source (White and Hall, 2017).

Perception and perspective about current diets

Ferretti and Mariani (2017) found that there is a large consumer base that has a strong attachment to meat. They believe meat consumption is integral to their identity as a person. This characteristic is more prominent in males than females, though the affinity spans both genders. The study also found that animal-based diets are deeply embedded in perceptions of cultural tradition and societal roles.

Why should we care about dietary change?

On top of harming the environment, the Western Diet has also been linked to obesity and many non-communicable diseases such as heart disease and cancer. World Health Organization believes obesity in the world has doubled since 1980 and that most of the world’s populations live in countries where obesity kills more people than being underweight (Eshel et al. 2014). In a technical analysis, Eshel et al. (2014) reported that a 1.0% countrywide increase in consumption of sugars can increase a country’s obesity by 0.5% while alternatively a 1.0% increase in consumption of cereals can drop the rate by 0.4%. These numbers can become significant in wealthier nations, where fatty foods and sugars become increasingly in demand.

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Methods

A literature search was performed on google scholar and web of science databases to accumulate all the published studies that are relevant to our project. We selected search terms that describe dietary transition (“animal to plant-based diet,” “dietary choice,” “dairy ,” “milk-derived,” “animal originated”), impact of dietary transition (“health,” “human health” “disease” “food production”, “land,” “environment,” “climate change,” “ecology,” “diversity,” “greenhouse gases,”); and perception and cultural aspects of food (“food habit,” “culture,”). It was also required to include search terms of “US,” or “USA,” or “North America,” or “Western Country*”.

We reviewed title and abstract of all the articles individually followed by initial search looking at relevancy to our project. If an article was not relevant for our project, we removed it from our list. Then, we thoroughly and critically analyzed relevant articles to support our statement both in qualitative and quantitative ways.

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Results and Discussion

Impact of dietary change on food production, land utilization and efficiency

Transition from animal-based diet to plant-based diet will help to increase food production. White and Hall (2017) showed that complete elimination of animals from food production system will result in increment of energy, fiber, protein and other nutrients production except micro-nutrients. This transition will also make farming more efficient as livestock farming itself is an inefficient system compared to crop farming. Furthermore, within livestock, different species has different feed conversion efficiencies (Figure 2, Shepon et al. 2016). In the study of Shepon et al. (2016), poultry was the most efficient and beef was least efficient in terms of feed to edible protein or calorie conversion efficiency. Shepon et al (2016) also showed that reallocating land from beef to poultry feed production could yield additional calorie and protein which will meet dietary need of additional 120-140 million people (roughly 40% of US population).

Figure 2. The US feed-to-food protein flux from the three feed classes (left) into edible animal products (right). On the right, parenthetical percentages are the food-protein-out/feed-protein-in conversion efficiencies of individual livestock categories. Protein values are in Mt (109 kg). Overall, 63 Mt of feed protein yield edible animal products containing 4.7 Mt protein, an 8% weighted mean protein conversion effichancy.

Dietary transition and human health

Health benefits of dietary pattern change is complicated due to multiple confounding factors. However, Springmann et al. (2016) study clearly showed the health benefits of dietary transition in 2050 and the extent of positive health impact is even more prominent for aged people (Figure 3 and Figure 4). This study compared four dietary scenarios which include a FAO reference diet (REF), healthy global diet (HGD), vegetarian diet (VGT) and vegan diet (VGN). Compared to REF diet, all three diets (HGD, VGT, VGN) reduced death per year (5.1-8.1 millions per year) and saved 79-129 million years life. More than 50% death avoidance were due to reduction of red meat consumption. Other factors which also contributed to death avoidance were increment of fruits and vegetable in the diet and reduction of obesity due to lower calorie intake. Death avoidance benefits were mainly from the heart disease, stroke, cancer and type 2 diabetes. Most of the health benefits (64-71% reduction in death) in developed countries came from decreased red meat consumption and reduction of energy intake. Tilman and Clark (2014) study also reported the reduction of 0-18% mortality due to adoption of vegetarian, pescatarian or Mediterranean diet. Le and Sabaté (2014) showed a reduction of 12-20% mortality for vegetarian in comparison to nonvegetarian diets in the US. Therefore, dietary transition could be a potential optional to reduce health risk and increase life span.

Figure 3. Total number of avoided deaths (left axis) and years of life saved (right axis) in 2050 compared to 2005/07 by risk factor (Δweight: change in prevalence of overweight and obesity combined, ΔC(fruit&veg): change in fruit and vegetable consumption; ΔC(red meat): change in red meat consumption; Total: all risk factors combined; Total YLS: all risk factors combined for the measure of years of life saved).

Figure 4. Total number of avoided deaths in 2050 compared to 2005/07 by age group.

Dietary transition and environment

Compared to plant production, livestock production is less efficient and livestock production also contributes greater portion of the agricultural GHG. Therefore, dietary transition from animal derived diet to plant derived diet is surprising. White and Hall (2017) showed that in extreme case scenario (elimination of animals from system) would reduce 28% of total agricultural GHG. But, a scenario without animals is not feasible in terms of implementations which might have different reason. Reasons might include overall ecological balance, trade-off between system, consumer adoption, cultural perception and attitude related with food habits, adaptation of human physiology to new dietary situation and so on. Therefore, we are interested in partial transition which is feasible to be implemented. This partial transition means that we could switch from current US diet to either US healthy diet or vegetarian diet (2015 – 2020 Dietary Guidelines for Americans). As per Springmann et al. (2016) study, GHG emissions associated with consumption of food could be reduced between 29-70% in 2050 depending on dietary situations (HGD or VGT or VGN) compared to REF diet (Figure 5). This reduction is mainly due to inclusion of decreased animal-derived foods (e.g. meat, milk, eggs and dairy products) in human diet. Reduction of GHG from developed country is attributable to reduced consumption of red meat in all three nonreference scenario in this study. Few other studies conducted previously also reported the reduction of GHG emissions ranging between 3.4-8.4 Gt CO2-euivalent due to dietary transition from current nonvegetarian diet toward vegetarian diet (Tilman and Clark 2014, Hedenus et al. 2014, Bajzelj et al. 2014).

Figure 5. Food-related GHG emissions (GtCO2-eq) in 2005/07 and projected to 2050 for each dietary scenarios by commodity. The percentages within the bars refer to the percentage of food-related GHG emissions to total GHG emissions, using historical emissions data for 2005/07 and an emissions pathway that would limit global temperature increase to below 2°C (32).

Dietary transition implementation strategies and alternatives

Nudge

An implementation strategy currently being researched deals with the idea of aiding in the decision making process of individuals. This concept is known as a nudge, an asymmetric intervention in the environment. The gist of asymmetric interventions is that judgmental heuristics can be exploited to yield positive, desirable outcomes; in other words, the environment in which people make choices can be engineered such that when judgmental heuristics are applied, the resulting choice reflects the most positive outcome across a set of agreed-upon objectives (Arvai et al. 2012). An example of where a nudge may be helpful in the dissuasion of meat-consumption (Ferretti and Mariani 2017). Ferretti and Mariani (2017) found that by calling on consumers to reflect on their animal’s own mental attributes subsequently increases thoughts of disgust about eating other animals. United States and European governments alike have seen many positive, cost-effective results from using nudges. The UK created a nudge unit to its government in 2010 and in 2015, the Obama administration created one as well (Benartzi et al. 2017). An example of government policy that has benefited from nudges is vaccinations. The US government found that simply asking people to privately plan a vaccination date lead to a 1.5 times increase in vaccinations per government dollar spent. Nudges can also be used to reinforce positive behavior through different reward and recognition systems. A recent article in the New York Times, written by Richard Conniff, suggests a carbon tax could be one of the options used to reduce meat consumption and GHG emissions. Research shows that tax on meat and dairy products could have potentiality to reduce about 12 % of GHG emissions (Säll and Gren, 2015).

An excerpt from Conniff's article reads:

“Chatham House, the influential British think tank, attributes 14.5 percent of global emissions to livestock — “more than the emissions produced from powering all the world’s road vehicles, trains, ships and airplanes combined.” Livestock consume the yield from a quarter of all cropland worldwide. Add in grazing, and the business of making meat occupies about three-quarters of the agricultural land on the planet. Beef and dairy cattle together account for an outsize share of agriculture and its attendant problems, including almost two-thirds of all livestock emissions, according to the United Nations Food and Agriculture Organization. That’s partly because there are so many of them — 1 billion to 1.4 billion head of cattle worldwide. They don’t outnumber humanity, but with cattle in this country topping out at about 1,300 pounds apiece, their footprint on the planet easily outweighs ours. A new study in the journal Carbon Balance and Management puts the global gas output of cattle at 120 million tons per year. Methane doesn’t hang around in the atmosphere as long as carbon dioxide. But in the first 20 years after its release, it’s 80 to 100 times more potent at trapping the heat of the sun and warming the planet.”

With these numbers in mind, Conniff believes are carbon tax would increase the price of beef up to 40%. This would align it with taxes the American people are used to such as a sugar tax or a tobacco tax. He goes on further to say the tax would also reduce the substantial contribution of beef and dairy cattle to water pollution, deforestation, biodiversity loss and human mortality (Harvard School of Public Health, 2012). The carbon tax on beef’s ultimate goal is to nudge people towards poultry and pork-based meat options.

Potentially the most realistic nudge that can be implemented is a default. Defaults are simply the option (or options) that people automatically receive or see if they do not explicitly specify otherwise (Brown & Krishna, 2004). They are thought to work because they exploit predictable decision-making biases like loss aversion and the endowment effect (Kahneman, Knetsch, & Thaler, 1991; Knetsch, 1996), which result in people automatically imbuing default or status quo options with greater value when compared with non-defaults. Likewise, defaults are effective because they eliminate the need for people to confront trade-offs that, under even the best of circumstances, people tend to find difficult (Lichtenstein, Gregory, & Irwin, 2007). Arvai (2012) found that in a busy restaurant setting, both males and females that were given menus with non-meat healthy options as the default were much more likely to choose those options than comparable people who were given menus that had meat options as the default. This finding can be applied to restaurants and supermarkets through the implementation of a restructuring of food display. By showcasing healthy-options and hiding the less-healthy options, the restaurants and supermarkets can help make a positive dietary change for people who otherwise might just settle for the most convenient, less-healthy option. If they implement this strategy to try to wane beef consumption, they will most likely also bring upon a positive impact on the environment.

Alternative Options: Reducing over-consumption and food waste

As it is well established that changing consumer perception and ties with meat consumption is a hurdle. Strategies that can reduce GHG emissions from food consumption without elimination of meat from our diet might be one of the alternative. Over consumption of food leads to GHG emissions and it is known that average US people consume more than their requirements and waste 25 % of the food purchased. Therefore, avoiding over-consumption and reduction of food waste could potentially help to reduce GHG emission in USA (Hyland et al. 2017) and this could also have substantial contributions to food security. Education, awareness and promotion of new strategies could be useful in this case. For example, Government policy could focus on making people aware about harmfulness of over-consumption, reduction of red-meat and extra calorie from the diet.

Every year, global food waste is more than one billion tons (FAO, 2011). In developed countries, around 40% food waste occurs before reaching to consumer (on-farm or during, transportation and processing, Buttriss, 2011; FAO, 2011)). Therefore, reduction of food waste could be one of the potential way to save food as well as reducing GHG emission.

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Limitations

      Limitation 1This is a major topic and much of the research for consumer preference and ideologies is done through surveys which can be misleading and biased.

      Limitation 2 This is mainly an environmental play. The economic and social aspects of sustainability are much more difficult to address given our topic.

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Conclusions

The current food production system in the United States is unsustainable and a lot of the problem stems from beef production creating GHG emissions at an alarming and environmentally destructive rate. We have found in our studies that most Americans are willing to make a change in line with a healthier, more sustainable plant-based diet, yet the lack the knowledge or resources to act on their intentions. An implementation strategy we looked at in-depth was the nudge. A nudge creates an asymmetric decision-making process in the environment that leads people to more likely make positive decisions for themselves and the environment.

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