Updated: Jan 23
In the last several years, the number of people identifying as vegans has increased dramatically. According to the research firm GlobalData, the number of U.S. consumers identifying as vegans has increased from 1% to 6% between 2014 and 2021. A vegan diet is one abstaining from any form of animal products like meat, eggs, and honey. With the rising popularity of vegan documentaries such as “The Game Changers” and “What the Health”, the sales of plant-based foods in the U.S. have increased and more people are adopting a vegan diet. Although many factors like environmental concerns and animal welfare may encourage veganism, this article will primarily focus on the diet’s health effects.
There is evidence that some of the health benefits of a vegan diet are simply caused by the removal of animal products. According to various U.S. and European epidemiological studies done on the health risks associated with meat consumption, long-term consumption of red and processed meat is linked to a higher risk of cardiovascular problems, type 2 diabetes, colorectal cancer, and death in both women and men, even after considering confounding variables like age, physical activity, and blood pressure . According to Dr. Neal Barnard, adjunct professor of medicine and president of the Physicians Committee for Responsible Medicine who has extensively researched the effects of a vegan diet on several health aspects, a diet containing animal-based products can consist of harmful constituents like heme iron, which can cause Alzheimer’s disease and cancer when consumed in excess, lactose, which increases the growth of pathogenic gut bacteria, estrogens, which may contribute to breast cancer, and animal feces, which is routinely found in muscle products and can transmit pathogens . There are numerous other studies that point to the harmful effects of a diet containing specific animal products.
Much of the health benefits of a vegan diet, however, actually come from the increase in whole foods like fruits, vegetables, whole grains, legumes, nuts, and seeds. A diet rich in antioxidants, fiber, potassium, folate, vitamins, and magnesium naturally lowers blood pressure and cholesterol, protects against colorectal and breast cancers, lowers the risk of heart disease, prevents metabolic diseases like type II diabetes, and extends general lifespan . Additionally, fruits and vegetables contain phytochemicals which are potent antioxidants and have antiproliferative properties. This means that they can interfere with several cellular processes involved in cancer progression. There is emerging evidence that fiber promotes a healthy gut microbiome, which is tied to better mental health, stronger immune system, healthier weight, and better brain function. In fact, gut dysbiosis may actually be associated with issues such as allergies, Celiac disease, gastric cancer, irritable bowel disease, and autism . Data following a cohort of 12,168 middle-aged subjects from 1987 to 2016 suggests that higher adherence to a healthy plant-based diet was associated with a 19% and 11% lower risk of cardiovascular disease mortality and all cause mortality, respectively . The EPIC-Oxford study also found that fewer vegans had hypertension than meat-eaters. About 15% of male meat-eaters and 12.1% of female meat-eaters self-reported hypertension compared to only 5.8% in male vegans and 7.7% in female vegans. The results were largely due to differences in BMI. The Epic-Oxford study found that meat eaters had the highest BMI (24.41 kg/m2 in men, 23.52 kg/m2 in women). Vegans had the lowest BMI (22.49 kg/m2 in men, 21.98 kg/m2 in women) and fish eaters and vegetarians a similar, intermediate mean BMI .
While it is undeniable that a diet rich in plants is healthy, is it necessarily the case that a diet consisting of some animal products is unhealthy? There have been no conclusive answers to this question. While some epidemiological studies like the Adventist Health Studies do reveal an association between vegan diets and lower all-cause mortality and cardiovascular diseases, other studies like the EPIC-Oxford study and the “45 and Up Study” do not prove this association . Interestingly, there are only a few studies on the long-term health benefits of vegetarians and vegans that are not based on association, which means that there may be confounding variables like health-consciousness to consider. Many of the intervention studies are carried out in small sample sizes over a period of less than 2 years. In fact, a vegan diet may pose some potential health risks. Some of these risks include hormone disruptions due to an increase in soy intake, risk of anemia due to a lack of heme iron, inadequate intake of omega-3 fatty acid and vitamin B12, and an increased possibility of hemorrhagic strokes.
Ultimately, the decision to adopt a vegan diet is one that needs to be made carefully on an individual basis. In the meantime, it wouldn’t hurt to include more plants on our plates!
Battaglia Richi E, Baumer B, Conrad B, Darioli R, Schmid A, Keller U. Health Risks Associated with Meat Consumption: A Review of Epidemiological Studies. Int J Vitam Nutr Res. 2015;85(1-2):70-8. doi: 10.1024/0300-9831/a000224. PMID: 26780279.
Neal D Barnard, Frédéric Leroy, Children and adults should avoid consuming animal products to reduce risk for chronic disease: YES, The American Journal of Clinical Nutrition, Volume 112, Issue 4, October 2020, Pages 926–930, https://doi.org/10.1093/ajcn/nqaa235
Tuso PJ, Ismail MH, Ha BP, Bartolotto C. Nutritional update for physicians: plant-based diets. Perm J. 2013;17(2):61-66. doi:10.7812/TPP/12-085
Glick-Bauer M, Yeh M-C. The Health Advantage of a Vegan Diet: Exploring the Gut Microbiota Connection. Nutrients. 2014; 6(11):4822-4838. https://doi.org/10.3390/nu6114822
Kim, H., Caulfield, L. E., Garcia Larsen, V., Steffen, L. M., Coresh, J., & Rebholz, C. M. (2019). Plant-based diets are associated with a lower risk of incident cardiovascular disease, cardiovascular disease mortality, and all cause mortality in a general population of middle‐aged adults. Journal of the American Heart Association, 8(16). https://doi.org/10.1161/jaha.119.012865
Marsh, K., Zeuschner, C., & Saunders, A. (2012). Health Implications of a Vegetarian Diet: A Review. American Journal of Lifestyle Medicine, 6(3), 250–267. https://doi.org/10.1177/1559827611425762
Medawar, E., Huhn, S., Villringer, A. et al. The effects of plant-based diets on the body and the brain: a systematic review. Transl Psychiatry 9, 226 (2019). https://doi.org/10.1038/s41398-019-0552-0
University of Oxford. (2013, January 30). Vegetarianism can reduce risk of heart disease by up to a third. ScienceDaily. Retrieved November 12, 2021 from www.sciencedaily.com/releases/2013/01/130130121637.htm
Winston J Craig, Health effects of vegan diets. The American Journal of Clinical Nutrition, Volume 89, Issue 5, May 2009, Pages 1627S–1633S, https://doi.org/10.3945/ajcn.2009.26736N
Park, J. E., Miller, M., Rhyne, J., Wang, Z. & Hazen, S. L. Differential effect of short-term popular diets on TMAO and other cardio-metabolic risk markers. Nutr. Metab. Cardiovasc. Dis. 29, 513–517 (2019).