Understanding a Plant-Based Diet and Why It's Not Always Vegan


Prathyusha Dasari
ACP Council of Student Members

University of California
Riverside School of Medicine


The copious number of articles, papers, and publications that have emphasized the importance of plant-based nutrition cannot be measured. There is a misconception that equates plant-based nutrition to veganism. This is similar to all squares are rectangles, but not all rectangles are squares (I apologize for the math reference). Similarly, all vegans follow a plant-based diet, but not all who eat a plant-based diet are vegans. Now, why is that? Plant-based nutrition refers to a diet that consists mostly or entirely of plant-based foods (1). This means that any person who eats a diet that consists of anywhere from 60% to 90% plants follows a plant-based diet. Because of this myth, however, we do not have current statistics on how many people follow a plant-based diet. Based on a 2018 Gallup poll (n = 1033) referenced in multiple articles, 5% of adults self-identified as vegetarian and 3% of adults self-identified as vegan (2). In this article, I want to answer a few questions that I am curious about and that might aid current students and practicing physicians in providing better proactive care management to patients and their community.

Question 1: What is plant-based nutrition?

As mentioned, plant-based nutrition refers to a diet that consists mostly or entirely of plant-based foods. Mostly refers to anywhere between 60% and 90% of the diet consisting of fruits and vegetables in addition to nuts, seeds, whole grains, and legumes (1).

Question 2: How do you know that plant-based nutrition works?

The various physiologic and psychological effects of plant-based nutrition cannot be summarized in one paragraph: it would require at least a 20-page research document. However, to show the impact, a systemic review in January 2020 showed that those following a vegan diet were less likely to be overweight and had lower BMIs (3). It was also found that vegetarians had a 24% decrease in mortality from ischemic cardiac death (4), and switching to a plant-based diet can remodel the heart (5). Participants with diabetes who switched to a plant-based diet experienced a 35% drop in glucose levels (6). The average LDL level (“bad” cholesterol level) in the omnivorous group was found to be 34.75 points higher than the mean of the vegetarian group (7). Although the impacts on cancer are not as well characterized, it was found that women who ate diets higher in proportion of meat had a greater likelihood of developing colorectal cancer (8). Additionally, the World Health Organization (WHO) classifies meats as a group 1 carcinogen and red meats as a group 2 carcinogen (9).

Question 3: Will it hurt me?

When making a change in our lives, it is fair to fear the unknown. Many people are raised with an omnivorous or primarily carnivorous diet because of the proteins and taste that those diets provide. Additionally, some might be wary of switching to a diet that is primarily plant-based because of the medical consequences. However, in a study of 73,426 participants who were vegan, it was found that there was no increase in the risk of cardiovascular outcomes (10).

Question 4: If it works, then why are more people not following it?

This is a perplexing question. But there is a two-fold answer here—how long it takes to reach the community and how long it takes an individual to make a change. According to many researchers like Balas and Boren (11), Grant et al (12), and Wratschko (13), it takes around 17 years from research to clinical practice. This means that research that was conducted in the late 1990s and early 2000s about the benefits of a plant-based diet are only now reaching clinical practice. And, from there, it depends on the individual. In a study conducted by Lally, it was found that it took anywhere from 18 to 254 days to form a habit or change behavior (14). This lag time from compelling research to change in human behavior might not be due to people not caring about their health, but rather just the systemic lag time it takes for any change to happen.

Question 5: What simple steps can be taken to transition from other diets to a plant-based diet to make that lag time shorter?

The important question we can ask ourselves after being hit with a firehose of knowledge is how can we shorten that lag time? This is once again a two-fold answer—empower ourselves and empower our patients. By gaining the knowledge, asking questions from the patient's perspective, digging for those answers, and taking time in each patient encounter to talk about a plant-based diet, we are shortening that lag time. Additionally, we need to empower patients. And to do that we need to provide them with resources. That can be in the form of behavioral health, diet and nutrition, physical therapy, life coaching, etc. A great recourse for both physicians and patients is Doctors for Nutrition, a nonprofit organization working to introduce a whole food plant-based diet as a tool in disease prevention and care (15). Each patient varies in their needs and that is where the challenge lies.


  1. Columbia University Irving Medical Center. What is a plant-based diet, and is it healthy? 15 April 2022. Accessed at www.cuimc.columbia.edu/news/what-plant-based-diet-and-it-healthy on 9 December 2022.
  2. Reinhart RJ. Snapshot: few Americans vegetarian or vegan. Gallup. 1 August 2018. Accessed at https://news.gallup.com/poll/238328/snapshot-few-americans-vegetarian-vegan.aspx on 9 December 2022.
  3. Bakaloudi DR, Halloran A, Rippin HL, et al. Intake and adequacy of the vegan diet. A systematic review of the evidence. Clin Nutr. 2021;40:3503-21. [PMID: 33341313] doi:10.1016/j.clnu.2020.11.035
  4. Key TJ, Fraser GE, Thorogood M, et al. Mortality in vegetarians and nonvegetarians: detailed findings from a collaborative analysis of 5 prospective studies. Am J Clin Nutr. 1999;70:516S-24S. [PMID: 10479225] doi:10.1093/ajcn/70.3.516s
  5. Król W, Price S, Śliż D, et al. A vegan athlete's heart-is it different? Morphology and function in echocardiography. Diagnostics (Basel). 2020;10. [PMID: 32674452] doi:10.3390/diagnostics10070477
  6. Crane MG, Sample C. Regression of diabetic neuropathy with total vegetarian (vegan) diet. J Nutr Med. 1994;4:431-9. doi:10.3109/13590849409003592
  7. Oussalah A, Levy J, Berthezène C, et al. Health outcomes associated with vegetarian diets: an umbrella review of systematic reviews and meta-analyses. Clin Nutr. 2020;39:3283-307. [PMID: 32204974] doi:10.1016/j.clnu.2020.02.037
  8. Kesse E, Clavel-Chapelon F, Boutron-Ruault MC. Dietary patterns and risk of colorectal tumors: a cohort of French women of the National Education System (E3N). Am J Epidemiol. 2006;164:1085-93. [PMID: 16990408] doi:10.1093/aje/kwj324
  9. World Health Organization International Agency for Research on Cancer. IARC monographs evaluate consumption of red meat and processed meat. 26 October 2015. Accessed at www.iarc.who.int/wp-content/uploads/2018/07/pr240_E.pdf on 9 December 2022.
  10. Kaiser J, van Daalen KR, Thayyil A, et al. A systematic review of the association between vegan diets and risk of cardiovascular disease. J Nutr. 2021;151:1539-52. [PMID: 33831953] doi:10.1093/jn/nxab037
  11. Balas EA, Boren SA. Managing clinical knowledge for health care improvement. Yearb Med Inform. 2000:65-70. [PMID: 27699347]
  12. Grant J, Green L, Mason B. Basic research and health: a reassessment of the scientific basis for the support of biomedical science. Res Eval. 2003;12:217-24. doi:10.3152/147154403781776618
  13. Wratschko K. Strategic Orientation and Alliance Portfolio Configuration: The Interdependence of Strategy and Alliance Portfolio Management. Gabler Verlag Wiesbaden; 2009. doi:10.1007/978-3-8349-9459-2
  14. Lally P, van Jaarsveld CHM, Potts HWW, et al. How are habits formed: modelling habit formation in the real world. Eur J Soc Psychol. 2010;40:998-1009. doi:10.1002/ejsp.674
  15. Doctors for Nutrition. Revolutionizing health through whole food plant-based nutrition. Accessed at www.doctorsfornutrition.org on 9 December 2022.

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