What Does "Plant-based" Actually Mean?
By Casey Brown, Julia Mathew, Ilana Wolf, and Ashley Kerckhoff
Imagine that you are vegan and are excited to see that a new plant-based café recently opened in your town. You decide to head over for the weekend brunch and you order the veggie pizza bake, assuming that the cheese they mention on the menu is non-dairy since you believe that plant-based equates to vegan. When your meal arrives, however, you realize that the café thinks differently — your pizza bake is topped with dairy cheese!
"Plant-based" evokes varying ideas and images to different people. While some assume this term equates to veganism, others believe that it can include limited amounts of meat or other animal products. Recently, this term has been increasingly used by both the media and scientific researchers in a variety of contexts.
How Does the General Public Define a Plant-based Diet?
A recent One Poll Survey asked respondents how they interpret a plant-based diet. The poll read "I think a plant-based diet means ___," and a range of answers were given in response to this survey. The survey found that 20% of respondents thought this term referred to a vegetarian diet, 17% thought it referred to a vegan diet, and 18% thought that it referred to a vegetarian or vegan diet that is composed of whole foods. An additional 13% of respondents thought that "plant-based" referred to a whole foods diet, but can include animal products, while 24% selected that they did not know what a plant-based diet was.1 The results from this One Poll Survey cannot be extrapolated to the U.S. population since they do not reflect an accurate makeup of this population. However, these results demonstrate the general confusion and inconsistent use of the term "plant-based."
How Do Researchers Define a Plant-based Diet?
The Vegetarian Resource Group decided to evaluate exactly how "plant-based" was being defined in reports of scientific research studies, as it lacks an explicit definition. We found a total of 893 research studies published within the past 10 years that use the term "plant-based." We further narrowed down the list to a total of 80 articles after excluding studies that did not use "plant-based" in reference to diet or that were a summary of a number of other studies. Additionally, we included only studies published in English that were conducted on human subjects. The 80 studies were reviewed to determine how they were using the term "plant-based."
The research studies were categorized based on nine definitions of how the term "plant-based" was used. The nine categories and results from our research are summarized in the chart on the next page.
After reviewing the 80 studies, we found that 74% of them did not explicitly define "plant-based." The majority of the studies (61%) took place in the United States, while others were conducted in Canada, Italy, Japan, and Nigeria, among other places. This demonstrates that there seems to be an inconsistent use of the term "plant-based" globally in scientific literature.
Of the studies we reviewed, 5% explicitly defined plant-based as the avoidance of all animal products, or a vegan diet. For example, researcher John McDougall, MD, and his coworkers stated that "the hotel's kitchen staff prepared foods according to prescribed guidelines. No animal-derived ingredients (e.g., meat, fish, eggs, or dairy products)... were used."2 The plant-based diet was thoroughly described in this study as a vegan dietary pattern. One of the studies defined plant-based as the avoidance of meat, fish, and poultry. Some (8%) of the studies defined plant-based as a diet that excludes red meat but can include fish and/or poultry. A total of 13% of the studies were found to define plant-based as any type of "vegetarian" diet. This ranged from vegan to pescetarian to semi-vegetarian.
There was a total of 10% of the studies that described plant-based as low-meat consumption. An example of this is an article by Akinyemiju, et al., which stated "the 'plant-based' pattern [was characterized] by fruits, vegetables, cereal, beans, poultry, and fish."3 Plant-based was used to describe diets with increased plant-food consumption in 16% of the studies. These studies did not specifically prohibit any foods. For example, Saxe, et al., stated that participants in their study were placed on a plant-based diet and taught to "increase [their] intake of whole grains, vegetables, fruit, and legumes, and to decrease meat, dairy, and refined carbohydrates."4 While this pattern did not prohibit any foods, it encouraged an increased consumption of plant foods and a decreased intake of animal foods.
A total of 28% of the studies appeared to be using the term "plant-based" interchangeably with "vegetarian" or "vegan." They did not provide an explicit definition for the term, but we were able to infer these meanings. Many studies (20%) used the term "plant-based" throughout the article without providing a clear definition. These studies prevented us from understanding what was meant by a plant-based diet, which also limits our interpretation of their results.
| Category # | Definition of the term "plant-based" | Percentage |
| 1 | Plant-based was defined as the avoidance of all animal products. | 5% |
| 2 | Plant-based was defined specifically as the avoidance of meat, fish, and poultry. | 1% |
| 3 | Plant-based was defined as the avoidance of meat, but could include fish and/or poultry. | 8% |
| 4 | Plant-based was defined as any type of vegetarian or near-vegetarian diet (including vegan, vegetarian, pescetarian, semi-vegetarian). | 13% |
| 5 | Plant-based was described as low meat consumption or semi-vegetarian. This can include limited amounts of meat and other animal products. | 10% |
| 6 | Plant-based was used to describe diets with an increased consumption of plant foods (fruits, vegetables, legumes, etc.). | 16% |
| 7 | Plant-based was used as a synonym for a vegan diet, but it was not clearly defined. | 20% |
| 8 | Plant-based was used as a synonym for a vegetarian diet, but it was not clearly defined. "Vegetarian" could include semi-vegetarian. | 8% |
| 9 | Plant-based was used but was not defined. | 20% |
How is a Plant-based Diet Defined by the Media?
In addition to reviewing scientific studies that used the term "plant-based," we reviewed articles found in the media that were using this term. We selected articles from Runner's World, CBS News, CNN, The Washington Post, and other sources, to determine how "plant-based" was being used in these contexts. The same categories were used to group the media articles. None of the articles reviewed fit into categories 2, 3 or 5.
Category 1: Defined as avoidance of all animal products.
While many articles and restaurants seem to be using the term "plant-based" synonymously with vegan, others explicitly define "plant-based" as the avoidance of all animal products.
ABC News published a story titled "Teacher who had heart attack inspires 1300 colleagues to try a 10-day plant-based diet." This article explicitly defined plant-based as "a diet that consists of whole grains, legumes, nuts and seeds, herbs, and spices and excludes all animal products including red meat, poultry, fish, eggs, and dairy products."5
Additionally, Cornell University offers a plant-based nutrition certification program. This program encourages a whole-foods plant-based diet, which groups foods into three categories: animal foods, whole foods, and refined plant fragments. The specific definition provided by Cornell states that a whole-foods, plant-based diet includes only unrefined plant foods and excludes all animal foods and refined plant fragments.6
Category 4: Defined as any type of vegetarian diet.
The article "Plant-Based Diet for Heart Health" explains that there are multiple kinds of plant-based diets, most commonly including vegan, lacto-vegetarian, and lacto-ovo-vegetarian. It states that pescetarian "means they eat a plant-based diet plus fish."7 In this article, they appear to be defining plant-based as any type of vegetarian diet excluding those that allow for meat or fish. The definition used in this article is more specific, allowing a reader a better understanding of what is meant by the term "plant-based."
Category 6: Used to describe diets with an increased consumption of plant-foods.
Many articles described a plant-based diet as one that increases the consumption of plant-foods without strictly limiting or prohibiting animal-based foods. In "Plant-based Diet? Sure, But First Understand What That Really Means" by Carrie Dennett, she states that "plant-based diets can take many forms, from vegan to vegetarian to flexitarian to omnivore. The common denominator is that they make plant foods the focal point of the plate."8 Similarly, in "7 Reasons To Choose a Plant-based Diet" by Laura McMullen, she states that a plant-based diet "allows for modest amounts of fish and lean meat. But more importantly, choosing a diet heavy in fruits and vegetables."9
NFL Quarterback, Tom Brady, follows a plant-based diet for peak performance. His diet consists of 80% fruits and vegetables and 20% of other foods, mainly lean meats. The CBS News article "What Does Tom Brady Eat? How the Star Stays on the Field in his 40s" states that he "sticks to a mostly plant-based diet, but allows for some lean meat and poultry."10 It is unclear from this wording whether poultry is considered to be a part of his plant-based diet or is eaten in addition to his "mostly" plant-based diet.
Category 7: Synonym for vegan diet.
Some restaurants seem to be using the term "plant-based" to describe vegan meals. Bean Vegan Cuisine is a restaurant in North Carolina with an entirely vegan menu. Their mission statement says that they "believe in the health benefits of a plant-based diet and promote a plant-based diet within their communities."11 While they do not explicitly define plant-based, it can be inferred that they are using this term synonymously with vegan. Purple Carrot is a 100% plant-based meal delivery service that ships to the contiguous 48 states. This organization does not define plant-based on their website; however, their meals appear to all be vegan, implying that they are using these terms interchangeably.
In addition to restaurants and meal delivery services, athletes are also getting on board with the plant-based lifestyle. Ultra-endurance athlete, Scott Jurek, chooses to follow a plant-based, or vegan, diet. In the Runner's World article "Eat Vegan & Run," Steve Friedman describes Jurek's dietary pattern as plant-based. Throughout the article, he uses "plant-based" and "vegan" interchangeably to describe Jurek's food choices. In the article, Friedman quotes Jurek saying that he "actually prefer[s] 'plant-based' to vegan" due to the negative connotation that sometimes surrounds the term "vegan."12 This negative connotation might be due to a lack of understanding of vegan diets and the positive benefits that are associated with them. CNN's article "Go Vegan, Save the Planet" by George Wang describes the relationship between our food system and climate change. He uses the terms "plant-based" and "vegan" interchangeably to describe the significant impact our food choices have on the environment.13
Category 8: Synonym for vegetarian diet.
Restaurants and food companies have started offering plant-based menus and food items. The Butcher's Daughter is a plant-based café and juice bar located in New York City and Los Angeles. They offer 100% vegetarian fare, with a majority of the options being vegan. Some of their vegetarian dishes contain animal products including dairy or eggs. Despite this, they still consider their menu to be plant-based.
Category 9: Plant-based was used but not defined.
CBS News published "Not all plant-based diets are created equal when it comes to heart health" by Amy Norton. This article discusses the health benefits that can be associated with plant-based diets, but it also mentions how there are "healthy ways to do it and not-so-healthy ways [to follow a plant-based diet]."14 While it discusses the benefits associated with this dietary pattern and exploring plant foods and animal foods, it never explicitly defines plant-based. This leaves the interpretation up to the reader, which could result in various meanings.
The use of the term "plant-based," throughout research studies, restaurants, and the media, has proven to be inconsistent. Based on our research, the definitions vary widely and cannot be assumed to be vegetarian or vegan. So if a new plant-based café opens in your town, you'll want to make sure to ask about the ingredients before ordering that veggie pizza bake.
References
1 What does plant-based mean to the public? VRG blog. www.vrg.org/blog/2017/08/11/what-does-plant-based-mean-to-the-public. August 11, 2017.
2 McDougall J, Thomas LE, McDougall C, et al. 2014. Effects of 7 days on an ad libitum low-fat vegan diet: the McDougall Program cohort. Nutr J. 13:99.
3 Akinyemiju T, Moore JX, Pisu M, et al. 2016. A prospective study of dietary patterns and cancer mortality among Blacks and Whites in the REGARDS cohort. Int J Cancer. 139(10):2221-31.
4 Saxe GA, Major JM, Westerberg L, et al. 2008. Biological mediators of effect of diet and stress reduction on prostate cancer. Integr Cancer Ther. 7(3):130-8.
5 Kindelan K. Teacher who had heart attack inspires 1,300 colleagues to try 10-day plant-based diet. ABC News. www.abcnews.go.com/Health/teacher-heart-attack-inspires-1300-colleagues-10-day/story?id=52232892. January 10, 2018.
6 T. Colin Campbell Center for Nutrition Studies. Whole food, plant-based diet guide. www.nutritionstudies.org/whole-food-plant-based-diet-guide/. Accessed February, 2018.
7 Plant-based diet for heart health. WebMD. www.webmd.com/heart-disease/guide/plant-based-diet-for-heart-health. 2016.
8 Dennett C. Plant-based diet? Sure, but first understand what that really means. The Washington Post. www.washingtonpost.com/lifestyle/wellness/plant-based-diet-sure-but-first-understand-what-it-means/2017/08/08/d6c5b674-7949-11e7-8839-ec48ec4cae25_story. August 9, 2017.
9 McMullen L. 7 reasons to choose a plant-based diet. US News. www.health.usnews.com/health-news/health-wellness/slideshows/reasons-to-choose-a-plant-based-diet. January 5, 2016.
10 What does Tom Brady eat? How the star stays on the field in his 40s. CBS News. www.cbsnews.com/news/tom-brady-football-player-diet-nutrition. September 19, 2017.
11 Mission Statement. Bean Vegan Cuisine. www.eatatbean.com/mission-statement. Accessed February, 2018.
12 Friedman S, Jurek S. Eat vegan & run. Runner's World. www.runnersworld.com/nutrition/eat-vegan-run. April 23, 2012.
13 Wang GC. Go vegan, save the planet. CNN. www.cnn.com/2017/04/08/opinions/go-vegan-save-the-planet-wang/index.html. April 9, 2017.
14 Norton A. Not all plant-based diets are created equal when it comes to heart health. CBS News. www.cbsnews.com/news/plant-based-vegetarian-diets-heart-health. July 18, 2017.
