Aidan Gildea
Executive Summary
Achieving a nutritious diet is difficult for many Americans, particularly those who are low income. The USDA’s Thrifty Food Plan provides a recommended low-cost diet but faces criticism for ignoring the realities of low-income consumers. Through exploratory analysis and data analysis, we find that eating more plant-based protein decreases the financial burden of eating a nutritious diet as well as provides extensive health and environmental benefits. The USDA should recognize this finding by updating the current TFP and expanding nutritional education to help Americans shift towards a more plant-based future.

Background

Consuming a quality diet is a vital step in maintaining a healthy lifestyle, regardless of age. In the United States, poor nutrition is a leading cause of chronic diseases such as Type II diabetes, heart disease, stroke, and various cancers (1). The rise in obesity among Americans is also attributed to suboptimal diets and contributes to poorer health outcomes (2). Curbing these unhealthy trends is necessary not only for improving people’s well-being, but also preventing additional strain on the nation’s healthcare and economic systems. Therefore, food and nutritional policy are pressing areas that must be addressed.

The current reality is that Americans of all income-levels can improve their diet (3). Oftentimes, researchers attribute poor nutritional choices to financial constraints that prevent individuals and families from purchasing quality foods; however, healthier foods are not necessarily more expensive (4). Misleading price metrics and a lack in nutritional education perpetuate the belief that eating healthy is more expensive, in turn, leading to poorer diet choices (5). This issue is further compounded by the general indifference many consumers have towards nutritional foods (6). It is suggested that expanding nutritional education will help more Americans – regardless of income – achieve a more nutritious diet.

While the financial realities of achieving a high quality and nutritious diet are argued by researchers, several other constraints make the task less manageable. Low-income families and individuals face other lifestyle limitations such as time, resources, and skill to properly meet all dietary guidelines within an affordable budget. The United States Department of Agriculture (USDA) offers the Thrifty Food Plan (TFP) as a recommended low-cost diet; however, it largely fails to account for these tangential factors (7). The TFP is criticized for its diversion from current consumption habits, poor variety, and low palatability; all of which make it more difficult for low-income consumers to meet recommended dietary guidelines (8). This issue has far-reaching implications as the TFP determines the maximum allotment for Supplemental Nutrition Assistance Program (SNAP) benefits, or commonly known as food stamps (9). SNAP is America’s largest anti-hunger program, and in turn, a critical component in the country’s efforts to combat poverty (10). Therefore, reforming the TFP is of pressing policy concern.

Project Relevance

Led by researchers from Duke University, Tufts University and Penn State University, our project “From Scarcity to Prosperity: Nutrition and Food Spending Goals and Constraints for Low-Income Americans” strives to make a nutritional diet more accessible to all families and individuals. To achieve this goal, the project largely focuses on analyzing and refining the TFP, as the policy ramifications of improving its design are far-reaching. By utilizing a mixed-methods approach, our research aims to reconcile previous criticisms of the TFP and more appropriately capture the feasibility of achieving a nutritional diet.

Beyond the financial constraints of healthy eating, it must be noted that time, skill, resources, and other subjective constraints play a substantial role in achieving a quality diet (11). Our project’s quantitative model seeks to partially capture these constraints by optimizing the relationship between dietary guidelines and Americans’ common consumption habits. By developing a diet that does not substantially stray from familiar foods, consumers will not have to completely re-orient their habits and abilities. However, these accompanying constraints cannot be fully understood via quantitative analysis, requiring our project’s qualitative component. Research on poverty demonstrates that self-assessments by low-income individuals of their financial circumstances and food adequacy offer the best evaluation of their needs (12). Our project takes this best practice into account by interviewing food-pantry users and staff about their food aspirations and struggles. The perspective of these individuals will provide a greater understanding of what foods low-income consumers hope to eat and what challenges prevent them from accessing them – and when integrated with our optimization model – allow us to construct a more effective TFP.

Nutrient Dashboard and Data Analysis
While the quantitative model outputs an optimal diet, exploring its composition is not entirely intuitive. Examining the relationship between different food categories and their relative affordability necessitates the ability to compare food items, thus prompting the creation of the nutrient dashboard. This interactive tool [see Figure 1], allows for the visual exploration of hundreds of food items and how they compare both nutritionally and financially. By constructing scatterplots that spatially exhibit different foods’ nutrient density and price relationships, users can identify quality sources of protein, fiber, added sugar, and sodium that are more affordable. The nutrient dashboard sources its data from the 2013/2014 National Health and Nutrition Examination Survey (NHANES) and the USDA/ERS Purchase-To-Plate Price Tool, which together offer a comprehensive summary of American consumption behavior (13). The dashboard more specifically represents data for women between 20-50 years old in the US; however, dashboard insights can be applied to the general population.


Figure 1: Home page of the nutrient dashboard.


The nutrient dashboard also includes simple linear regression models plotting the y-axis variable, nutrient density, versus the x-axis variable, price. Analyzing these regression lines, protein density and price exhibit a strong positive relationship [see Figure 2], as well as a relatively high R-squared value compared to the other models. In most simple terms, this positive relationship indicates that in order to achieve higher levels of protein in our diet, it requires more money. This conclusion is unsurprising, as protein foods are the most expensive out of all What We Eat in America (WWEIA) food groups (14). However, this does not necessarily mean that meeting recommended protein levels must be costly. Comparing food items on the protein scatterplot, it is noticeable that Plant Protein sources may offer a similarly nutritious yet less expensive option than traditional Animal Protein sources [see Figure 3].

Figure 2: Protein and price display a strong positive relationship, meaning it is more expensive to achieve a diet higher in protein.

Figure 3: Circled are plant protein foods that offer similarly nutritious but more affordable protein sources than animal protein.


To confirm the hypothesized affordability of Plant Protein, a linear model was constructed using price as the y-variable, protein density as the x-variable, and broad food category as a categorical variable. The model output [see Figure 4] includes coefficients for each food category, allowing us to compare their relative expenses. Animal Protein is the baseline category for the model; therefore, it is included in the intercept. As expected, for every additional unit increase in protein density (gm/1000kcal), we can expect a 0.037 unit increase ($/1000kcal) in the price of a food item. Interestingly, the coefficient for Plant Protein is -0.34, meaning that Plant Protein items are expected to be $0.34/1000kcal less expensive than Animal Protein items, on average. The coefficient has a p-value of 0.057, which is less than an alpha level of 0.10, making it statistically significant. This data analysis reveals that Plant Protein is a more affordable source of protein than Animal Protein – a conclusion that has far-reaching implications on how we understand a low-cost diet.

Figure 4: Based on the model output, plant protein is more affordable than animal protein, on average.



Implications of Switching to Plant Protein

By integrating plant-based protein sources into recommended diets, low-income Americans will have more financial agency to invest in other resources and opportunities. For example, low-income consumers often fail to eat enough fruit and vegetables due to their perceived strain on a budget (15). In reality, fruit and vegetable guidelines can be satisfied with a variety of produce by allocating more spending to these items rather than on protein (16). This budgetary shift can be achieved by investing in more affordable plant-based protein sources, all while not sparing the actual degree of protein consumption (17). Supplementing animal protein sources with plant proteins has been found to make the TFP budget attainable, and in turn, SNAP benefits effective at alleviating the financial constraints families face (18). Instead of compensating for the insufficiencies of SNAP, low-income Americans can use these funds to invest in other advantageous financial opportunities. Therefore, incorporating more plant-based protein into the recommended low-cost diet could be critical to ensuring SNAP effectively combats poverty in the U.S.

Beyond the financial savings associated with eating more plant-protein, the dietary switch also has well-established health benefits. Higher consumption of plant-based protein sources is associated with lower blood pressure, lower LDL (“bad” cholesterol), lower obesity rates, and a lower risk of all-causes mortality (19). This is a stark contrast to the effects of diets high in animal protein, which are linked to an increased risk of Type II diabetes, cardiovascular disease, and mortality (20). The advantages of plant-based protein diets are also evident in measures of nutritional and diet quality, as they display significantly higher Healthy Eating Index (HEI) scores and nutrient densities than animal-based protein diets (21). These extensive benefits are often countered with arguments describing plant-based proteins as unsatisfying and ultra-processed (ie. imitation meats) in comparison to meats (22). While these arguments may have shock-value, they are largely refutable. In a study comparing higher protein diets that are beef and soy-based, researchers found little difference in their effect on appetite control, satiety, and subsequent eating behavior (23). And even though ultra-processed plant-based proteins are deemed safe, traditional options like tofu, tempeh, beans, and lentils offer high protein without the processing (24).

Transitioning from animal-based protein diets to plant-based proteins has enormous implications on sustainability and human impact on the environment. The production of meats is incredibly “resource intensive” – particularly beef and pork – and requires approximately ten times the resources and emissions than plant-based protein to produce (25). This extensive carbon emission and resource consumption – in tandem with additional pollution from waste – solidify meat production as a principal polluter in the food industry (26). Each decision to eat plant-based protein over animal-based protein is not only a beneficial choice for your body and budget, but one that limits the damaging effects of the meat sector on the planet. Widespread adoption of plant-protein production by farmers would exponentiate these climate benefits, all while producing enough food to feed 350 million additional people (27).

For all the benefits plant-based proteins present, it must be noted that certain barriers prevent consumers from simply transitioning away from animal-based protein. Education is a key component in protein selection. Higher education is significantly correlated with plant-based protein diets while lower education is associated with animal-based protein diets (28). A lack in information about plant-based protein is preventing many Americans from making the switch. In fact, 51% of Americans say they are open to incorporating more plant-based foods in their diet if provided more information on the environmental impacts of their choices (29). This is a significant portion of the population and presents a consequential opportunity to educate Americans on the positive changes their dietary choices can make. Even among those who understand the benefits of plant-based proteins, a general enjoyment of eating meat still prevents them from transitioning away from animal protein (30). Meat has been engrained in the American diet for centuries, so much so that we consume more meat per capita than almost any other country (31). To effectively convince consumers to eat more plant-based proteins, it requires a cultural shift where plant-based diets are not outside of the norm.

Recommendations

The extensive benefits of a plant-based protein diet as presented by the nutrient dashboard, data analysis, and relevant research merit policy action on this issue. The following recommendations should be taken into consideration to help low-income Americans achieve a nutritional and affordable diet via plant-based protein:

Emphasize Plant Protein in the TFP

Transitioning from animal-based protein to plant-based protein allows low-income consumers to successfully meet dietary guidelines within the recommended TFP budget (32). The USDA should update the TFP to reflect this conclusion and advise low-income Americans to eat more plant-based protein. With the next revision of the TFP expected in late 2021, this policy recommendation could reasonably be implemented in the near future.

Expand Nutritional Education

More than half of Americans are open to incorporating more plant-based proteins into their diet; however, they lack the educational information to make the shift (33). By expanding public education about the health, budgetary, and environment benefits of plant-based protein diet – particularly for low-income families and individuals – the USDA can help Americans achieve a more nutritious and affordable diet.

Shift Dietary Norms and Perceptions

The U.S. population consumes among the most meat per capita largely due to the perception that it should be at the center of the plate (34). The USDA and other governmental agencies should provide information on accessible and attractive replacements for meat in our meals. By demonstrating that plant-based protein diets can be convenient and delicious, we can shift dietary norms away from excessive meat consumption.

Conclusion

A nutritious diet is an essential step towards leading a more healthful life. In the United States, the widespread misconception that eating healthy is more expensive prevents many from meeting recommended dietary guidelines – particularly those who face significant financial constraints. Replacing animal-based protein with plant-based protein offers a viable path towards achieving a quality diet that is affordable within a low-income budget. By updating the TFP to reflect the benefits of a plant-based protein diet, the USDA can help Americans not only stay within a budget, but also improve their health and the environment.

Aidan Gildea is a rising junior at Duke University studying Statistics and Public Policy. He can be contacted at .

References

  1. Poor Nutrition | CDC. (2021, January 12). https://www.cdc.gov/chronicdisease/resources/publications/factsheets/nutrition.htm

  2. Unhealthy Diets and Obesity. (2010, May 24). NCD Alliance. https://ncdalliance.org/unhealthy-diets-and-obesity

  3. Carlson, A., & Frazão, E. (2014). Food costs, diet quality and energy balance in the United States. Physiology & Behavior, 134, 20–31. https://doi.org/10.1016/j.physbeh.2014.03.001

  4. Carlson, A. (2017, February 21). Healthy Foods Not Necessarily More Expensive Than Less Healthy Ones. https://www.usda.gov/media/blog/2012/05/16/healthy-foods-not-necessarily-more-expensive-less-healthy-ones

  5. Carlson, A., & Frazão, E. (2014). Food costs, diet quality and energy balance in the United States. Physiology & Behavior, 134, 20–31. https://doi.org/10.1016/j.physbeh.2014.03.001

  6. Ibid

  7. United States Department of Agriculture. (2007, November). The Low-Cost, Moderate-Cost, and Liberal Food Plans: 2007 Administrative Report | USDA-FNS. https://www.fns.usda.gov/low-cost-moderate-cost-and-liberal-food-plans-2007-administrative-report

  8. Drewnowski, A., & Eichelsdoerfer, P. (2010). Can Low-Income Americans Afford a Healthy Diet? Nutrition Today, 44(6), 246–249. https://doi.org/10.1097/NT.0b013e3181c29f79

  9. United States Department of Agriculture. (2007, November). The Low-Cost, Moderate-Cost, and Liberal Food Plans: 2007 Administrative Report | USDA-FNS. https://www.fns.usda.gov/low-cost-moderate-cost-and-liberal-food-plans-2007-administrative-report

  10. Hunger Programs. (2015, April 16). Bread for the World. https://www.bread.org/hunger-programs

  11. Gundersen, C., & Ribar, D. (2011). Food Insecurity and Insufficiency at Low Levels of Food Expenditures. Review of Income and Wealth, 57(4), 704–726. https://doi.org/10.1111/j.1475-4991.2011.00471.x

  12. Blaylock, J. R., & Smallwood, D. M. (1986). An Alternative Approach to Defining and Assessing Poverty Thresholds. Western Journal of Agricultural Economics, 11(1), 100–105.

  13. Carlson, A., Kuczynski, K., Pannucci, T., Koegel, K., Page, E. T., Tornow, C. E., & Zimmerman, T. P. (n.d.). Estimating Prices for Foods in the National Health and Nutrition Examination Survey: The Purchase to Plate Price Tool. Retrieved July 12, 2021, from http://www.ers.usda.gov/publications/pub-details/?pubid=99294

  14. Greenberg, J. A., Luick, B., Alfred, J. M., Barber, L. R., Bersamin, A., Coleman, P., Esquivel, M., Fleming, T., Leon Guerrero, R. T., Hollyer, J., Johnson, E. L., Novotny, R., deBlair Remengesau, S., & Yamanaka, A. (2020). The Affordability of a Thrifty Food Plan-based Market Basket in the United States-affiliated Pacific Region. Hawai’i Journal of Health & Social Welfare, 79(7), 217–223.

  15. Stewart, H., Hyman, J., Carlson, R., & Frazão, E. (2016, February). The Cost of Satisfying Fruit and Vegetable Recommendations in the Dietary Guidelines. http://www.ers.usda.gov/publications/pub-details/?pubid=42904

  16. Ibid

  17. Consuming Beef vs. Soy Protein Has Little Effect on Appetite, Satiety, and Food Intake in Healthy Adults | The Journal of Nutrition | Oxford Academic. (n.d.). Retrieved August 13, 2021, from https://academic-oup-com.proxy.lib.duke.edu/jn/article/145/5/1010/4589966

  18. Wilde, P. E., & Llobrera, J. (2009). Using the Thrifty Food Plan to Assess the Cost of a Nutritious Diet. Journal of Consumer Affairs, 43(2), 274–304. https://doi.org/10.1111/j.1745-6606.2009.01140.x

  19. Aggarwal, A., & Drewnowski, A. (2019). Plant- and animal-protein diets in relation to sociodemographic drivers, quality, and cost: Findings from the Seattle Obesity Study. The American Journal of Clinical Nutrition, 110(2), 451–460. https://doi.org/10.1093/ajcn/nqz064

  20. Ibid

  21. Ibid

  22. Reiley, L. (2019, November 4). Inside the little-known world of flavorists, who are trying to make plant-based meat taste like the real thing. Washington Post. https://www.washingtonpost.com/business/2019/11/04/inside-little-known-world-flavorists-who-are-trying-make-plant-based-meat-taste-like-real-thing/

  23. Consuming Beef vs. Soy Protein Has Little Effect on Appetite, Satiety, and Food Intake in Healthy Adults | The Journal of Nutrition | Oxford Academic. (n.d.). Retrieved August 13, 2021, from https://academic-oup-com.proxy.lib.duke.edu/jn/article/145/5/1010/4589966

  24. Are Meat Substitutes Healthy? – Cleveland Clinic. (n.d.). Retrieved August 13, 2021, from https://health.clevelandclinic.org/are-meat-substitutes-healthy/

  25. Smith, C. (2014, November 15). New Research Says Plant-based Diet Best for Planet and People—Our World. https://ourworld.unu.edu/en/new-research-says-plant-based-diet-best-for-planet-and-people

  26. Djekic, I. (2015). Environmental Impact of Meat Industry – Current Status and Future Perspectives. Procedia Food Science, 5, 61–64. https://doi.org/10.1016/j.profoo.2015.09.025

  27. Smith, C. (2014, November 15). New Research Says Plant-based Diet Best for Planet and People—Our World. https://ourworld.unu.edu/en/new-research-says-plant-based-diet-best-for-planet-and-people

  28. Aggarwal, A., & Drewnowski, A. (2019). Plant- and animal-protein diets in relation to sociodemographic drivers, quality, and cost: Findings from the Seattle Obesity Study. The American Journal of Clinical Nutrition, 110(2), 451–460. https://doi.org/10.1093/ajcn/nqz064

  29. Climate Change and the American Diet. (n.d.). Earth Day. Retrieved August 15, 2021, from https://www.earthday.org/foodprintsreport/

  30. Fehér, A., Gazdecki, M., Véha, M., Szakály, M., & Szakály, Z. (2020). A Comprehensive Review of the Benefits of and the Barriers to the Switch to a Plant-Based Diet. Sustainability, 12(10), 4136. https://doi.org/10.3390/su12104136

  31. Barclay, E. (2012, June 27). A Nation Of Meat Eaters: See How It All Adds Up. NPR. https://www.npr.org/sections/thesalt/2012/06/27/155527365/visualizing-a-nation-of-meat-eaters

  32. Wilde, P. E., & Llobrera, J. (2009). Using the Thrifty Food Plan to Assess the Cost of a Nutritious Diet. Journal of Consumer Affairs, 43(2), 274–304. https://doi.org/10.1111/j.1745-6606.2009.01140.x

  33. Climate Change and the American Diet. (n.d.). Earth Day. Retrieved August 15, 2021, from https://www.earthday.org/foodprintsreport/

  34. Barclay, E. (2012, June 27). A Nation Of Meat Eaters: See How It All Adds Up. NPR. https://www.npr.org/sections/thesalt/2012/06/27/155527365/visualizing-a-nation-of-meat-eaters

Published August 15th, 2021.