A plant-based diet is a diet consisting mostly or entirely of foods derived from plants (including vegetables, grains, nuts, seeds, legumes, and fruits) and with few or no animal-source foods. A plant-based diet is not necessarily vegetarian. The use of the phrase "plant-based" has changed over time and examples can be found of the phrase "plant-based diet" being used to refer to vegan diets, which contain no food from animal sources, and vegetarian diets, which may include dairy or eggs but no meat, as well as diets with varying amounts of animal-based foods, such as semi-vegetarian diets. The Academy of Nutrition and Dietetics states that well-planned plant-based diets support health and are appropriate throughout all life stages, including pregnancy, lactation, childhood, and adulthood, as well as for athletes.
As of the early 21st century, it was estimated that 4 billion people live primarily on a plant-based diet, some because of limits caused by shortages of crops, fresh water, and energy resources. In Europe, consumption of plant-based meat substitutes made up 40% of the world market in 2019 and is forecast to grow by 60% through 2025, due mainly to concerns for health, food security, and animal welfare. In the U.S. during 2019, the retail market for plant-based foods grew eight times faster than the general retail food market.
Vegan author Ellen Jaffe Jones wrote about the origins of the term in a 2011 interview:
"I taught cooking classes for the national non-profit, Physicians Committee for Responsible Medicine, and during that time, the phrase 'plant-based diet' came to be used as a euphemism for vegan eating, or "the 'v' word. It was developed to take the emphasis off the word 'vegan', because some associated it with being too extreme a position, sometimes based exclusively in animal rights versus a health rationale."
Some sources use the phrase "plant-based diet" to refer to diets including varying degrees of animal products, for example defining "plant-based diets" as diets that "include generous amounts of plant foods and limited amounts of animal foods" and stating that "The American Institute for Cancer Research and the World Cancer Research Fund call for choosing predominantly plant-based diets rich in a variety of vegetables and fruits, legumes, and minimally processed starchy staple foods and limiting red meat consumption, if red meat is eaten at all". Others draw a distinction between "plant-based" and "plant-only".
In various sources, "plant-based diet" has been used to refer to:
- Veganism: diet of vegetables, legumes, fruit, grains, nuts, and seeds, but no food from animal sources.
- Vegetarianism: diet of vegetables, legumes, fruit, nuts, and grains, that may include eggs and dairy, but no meat.
- Semi-vegetarianism: mostly vegetarian diet with occasional inclusion of meat or poultry.
Although herbivory (a diet entirely of plants) was long thought to be a Mesozoic phenomenon, evidence of it is found as soon as the fossils which could show it. Within less than 20 million years after the first land plants evolved, plants were being consumed by arthropods. Herbivory among four-limbed terrestrial vertebrates, the tetrapods developed in the Late Carboniferous (307 - 299 million years ago). Early tetrapods were large amphibious piscivores. While amphibians continued to feed on fish and insects, some reptiles began exploring two new food types: the tetrapods (carnivory) and plants (herbivory).
Carnivory was a natural transition from insectivory for medium and large tetrapods, requiring minimal adaptation. In contrast, a complex set of adaptations was necessary for feeding on highly fibrous plant materials.
Modern herbivores and mild omnivory
Quite often, mainly herbivorous creatures will eat small quantities of animal-based food when it becomes available. Although this is trivial most of the time, omnivorous or herbivorous birds, such as sparrows, often will feed their chicks insects while food is most needed for growth.
On close inspection it appears that nectar-feeding birds such as sunbirds rely on the ants and other insects that they find in flowers, not for a richer supply of protein, but for essential nutrients such as Vitamin B12 that are absent from nectar. Similarly, monkeys of many species eat maggoty fruit, sometimes in clear preference to sound fruit. When to refer to such animals as omnivorous or otherwise, is a question of context and emphasis, rather than of definition.
Humans are omnivorous, capable of consuming diverse plant and animal foods. Fossil evidence from wear patterns on teeth indicates the possibility that early hominids like robust australopithecines and Homo habilis were opportunistic omnivores, generally subsisting on a plant-based diet, but supplementing with meat when possible.
The Food and Agriculture Organization defined a sustainable diet as one with "low environmental impacts which contribute to food and nutrition security, and to healthy life for present and future generations" and one that is affordable for all while optimizing both natural and human resources. A sustainable diet can be measured by its level of nutritional adequacy, environmental sustainability, cultural acceptability and affordability. Environmental sustainability can be measured by indicators of efficiency and environmental protection. Efficiency measures the ratio of inputs and outputs required to produce a given level of foods. Input energy refers to processing, transporting, storing and serving food, compared with the output of physical human energy. Conversely, environmental protection refers to the level of preservation of ecological systems.
Plant-based diets can contribute to reducing greenhouse gas emissions and the amount of land, water, and fertilizers used for agriculture. As a significant percentage of crops around the world are used to feed livestock rather than humans, evidence shows that increasing the practice of a plant-based diet may contribute toward minimizing climate change and biodiversity loss. While soy cultivation is a "major driver of deforestation in the Amazon basin", the vast majority of soy crops are used for livestock consumption rather than human consumption.
A 2020 study found that the climate change mitigation effects of shifting worldwide food production and consumption to plant-based diets, which are mainly composed of foods that require only a small fraction of the land and CO2 emissions required for meat and dairy, could offset CO2 emissions equal to those of past 9 to 16 years of fossil fuel emissions in nations that they grouped into 4 types. The researchers also provided a map of approximate regional opportunities.
Plant-based diets are under preliminary research to assess whether they may improve metabolic measures in health and disease, and if there are long-term effects on diabetes. Cognitive and mental effects of a plant-based diet are inconclusive.
When the focus was whole foods, an improvement of diabetes biomarkers occurred, including reduced obesity. In diabetic people, plant-based diets were also associated with improved emotional and physical well-being, relief of depression, higher quality of life, and better general health.
Commerce of plant-based foods
In 2019, Europeans consumed 40% of the world total of plant-based meat alternatives out of concern for health, food security, and animal welfare. During 2019, the total retail market for plant-based foods in the U.S. was $4.5 billion, growing at 31% over the previous two years, compared to 4% for the entire retail food market. Growth of plant-based food consumption in the U.S. occurred among flexitarian consumers seeking alternative protein sources to meat, fortification with micronutrients, whole grains, and dietary fiber ingredients, meat flavor and comfort food innovations, and "clean" food product labels. In 2019, the European Union launched a program called "Smart Protein" to reuse large-scale, plant-based residues such as pasta, bread, and yeast byproducts together with whole grains, as new high protein, flavorful substitutes for meat, seafood, and dairy products.
- "Plant-based diet". British Dietetic Association. September 2017.
- Taylor Wolfram (1 October 2018). "Vegetarianism: The basic facts". Academy of Nutrition and Dietetics. Retrieved 21 April 2019.
- Summerfield, Liane M. (2012-08-08). Nutrition, Exercise, and Behavior: An Integrated Approach to Weight Management (2nd ed.). Cengage Learning. pp. 181–182. ISBN 9780840069245.
A plant-based diet is not necessarily a vegetarian diet. Many people on plant-based diets continue to use meat products and/or fish but in smaller quantities.
- Tuso, Philip J.; Ismail, Mohamed H.; Ha, Benjamin P.; Bartolotto, Carole (Spring 2013). "Nutritional Update for Physicians: Plant-Based Diets". The Permanente Journal. Kaiser Permanente. 17 (2): 61–66. doi:10.7812/TPP/12-085. PMC 3662288. PMID 23704846.
... a plant-based diet, which we define as a regimen that encourages whole, plant-based foods and discourages meats, dairy products, and eggs as well as all refined and processed foods.
- McManus, Katherine D. (September 26, 2018). "What is a plant-based diet and why should you try it?". Harvard Medical School.
It doesn't mean that you are vegetarian or vegan and never eat meat or dairy. Rather, you are proportionately choosing more of your foods from plant sources.
- "Position of the Academy of Nutrition and Dietetics: Vegetarian Diets". Academy of Nutrition and Dietetics. 2016. Retrieved 21 April 2019.
- Pimentel, David; Pimentel, Marcia (1 September 2003). "Sustainability of meat-based and plant-based diets and the environment". The American Journal of Clinical Nutrition. 78 (3): 660S–663S. doi:10.1093/ajcn/78.3.660S. PMID 12936963.
Worldwide, an estimated 2 billion people live primarily on a meat-based diet, while an estimated 4 billion live primarily on a plant-based diet. The shortages of cropland, fresh water, and energy resources require most of the 4 billion people to live on a plant-based diet
- Gorissen, Stefan H. M.; Witard, Oliver C. (29 August 2017). "Characterising the muscle anabolic potential of dairy, meat and plant-based protein sources in older adults". Proceedings of the Nutrition Society. 77 (1): 20–31. doi:10.1017/S002966511700194X. PMID 28847314.
- Flora Southey (25 October 2019). "'Plant-based', 'vegan', or 'vegetarian'? Consumers reveal attitudes to diet descriptions". FoodNavigator.com, William Reed Business Media Ltd. Retrieved 23 January 2020.
- Mary Ellen Shoup (23 January 2020). "Where next for plant-based in 2020? ADM shares top trend predictions for the category". FoodNavigator.com-USA, William Reed Business Media Ltd. Retrieved 23 January 2020.
- Stark, Michelle (May 25, 2015). "Wellness experts weigh in on the vegan diet". Tampa Bay Times. Archived from the original on 2015-06-11. Retrieved 20 June 2019.
- See American Dietetic Association and Dietitians of Canada, "Position of the American Dietetic Association and Dietitians of Canada: Vegetarian diets" (February 16, 2014): " ... plant-based diets, defined as diets that include generous amounts of plant foods and limited amounts of animal foods", and listing the views of other groups.
- Dwyer, J (2003). "Vegetarian Diets". In Caballero, Benjamin; Trugo, Luiz C.; Finglas., Paul M. (eds.). Encyclopedia of Food Sciences and Nutrition (Second ed.). Academic Press/Elsevier. pp. 5974–5979. ISBN 978-0-12-227055-0.
- "Plant Based | Vegetarian Journal | Vegetarian Resource Group". www.vrg.org. Retrieved 2020-10-29.
- Labandeira, C. (2007). "The origin of herbivory on land: Initial patterns of plant tissue consumption by arthropods". Insect Science. 14 (4): 259–275. doi:10.1111/j.1744-7917.2007.00152.x. S2CID 221813576.
- Sahney S, Benton MJ, Falcon-Lang HJ (2010). "Rainforest collapse triggered Pennsylvanian tetrapod diversification in Euramerica". Geology. 38 (12): 1079–1082. doi:10.1130/G31182.1.
- Capinera, John (2010). Insects and Wildlife. Publisher: Wiley-Blackwell. ISBN 978-1-4443-3300-8.
- Ewing, Jack (2005). Monkeys Are Made of Chocolate. Publisher: Pixyjack Press. ISBN 978-0-9658098-1-8.
- Haenel H (1989). "Phylogenesis and nutrition". Nahrung. 33 (9): 867–87. PMID 2697806.
- Cordain, Loren (2007). "Implications of Plio-pleistocene diets for modern humans". In Peter S. Ungar (ed.). Evolution of the human diet: the known, the unknown and the unknowable. pp. 264–5.
- Ungar, P. S; Sponheimer, M (2011). "The diets of early hominins". Science. 334 (6053): 190–3. doi:10.1126/science.1207701. PMID 21998380. S2CID 206534879.
- Timothy Clack, Ancestral Roots: Modern Living and Human Evolution (2008), p. 324.
- Robert Foley, "The Evolutionary Consequences of Increased Carnivory in Hominids", in Meat-Eating and Human Evolution (2001), p. 321.
- Burlingame, B; Dernini, S (2012). Sustainable diets and biodiversity: directions and solutions for policy, research and action. Proceedings of the International Scientific Symposium. Biodiversity and sustainable diets united against hunger (PDF). Rome, Italy: Food and Agriculture Organization. Retrieved 26 August 2019.
- Fanzo, J; Cogill, B; Mattei, F (2012). Technical brief: metrics of sustainable diets and food systems. Maccarese, Italy: Bioversity International. pp. 1–8.
- Sabate, J; Soret, S (4 June 2014). "Sustainability of plant-based diets: back to the future". American Journal of Clinical Nutrition. 10 (1): 476S–482S. doi:10.3945/ajcn.113.071522. PMID 24898222.
- Nemecek, T.; Poore, J. (2018-06-01). "Reducing food's environmental impacts through producers and consumers". Science. 360 (6392): 987–992. doi:10.1126/science.aaq0216. ISSN 0036-8075. PMID 29853680.
- "Sustainability pathways: Livestock and landscapes" (PDF). Food and Agriculture Organization, United Nations. 2012. Retrieved 2019-06-05.
- "Soy agriculture in the Amazon Basin". Yale University. 2019. Retrieved 2019-06-05.
- Rowland, Michael Pellman. "The most effective way to save the planet". Forbes. Retrieved 2019-06-05.
meat and dairy provide only 18% of our calories and 37% of our protein, yet use up 83% of our farmland.
- "Changing what we eat could offset years of climate-warming emissions, new analysis finds". phys.org. Retrieved 9 October 2020.
- Hayek, Matthew N.; Harwatt, Helen; Ripple, William J.; Mueller, Nathaniel D. (7 September 2020). "The carbon opportunity cost of animal-sourced food production on land". Nature Sustainability: 1–4. doi:10.1038/s41893-020-00603-4. ISSN 2398-9629. Retrieved 9 October 2020.
- Medawar, Evelyn; Huhn, Sebastian; Villringer, Arno; Veronica Witte, A. (12 September 2019). "The effects of plant-based diets on the body and the brain: a systematic review". Translational Psychiatry. 9 (1): 226. doi:10.1038/s41398-019-0552-0. ISSN 2158-3188. PMC 6742661. PMID 31515473.
- Qian, Frank; Liu, Gang; Hu, Frank B.; Bhupathiraju, Shilpa N.; Sun, Qi (1 September 2019). "Association between plant-based dietary patterns and risk of type 2 diabetes". JAMA Internal Medicine. 179 (10): 1335. doi:10.1001/jamainternmed.2019.2195. ISSN 2168-6106. PMC 6646993. PMID 31329220.
- Toumpanakis, Anastasios; Turnbull, Triece; Alba-Barba, Isaura (2018). "Effectiveness of plant-based diets in promoting well-being in the management of type 2 diabetes: a systematic review". BMJ Open Diabetes Research & Care. 6 (1): e000534. doi:10.1136/bmjdrc-2018-000534. ISSN 2052-4897. PMC 6235058. PMID 30487971.
- Dinu, M; Abbate, R; Gensini, GF; Casini, A; Sofi, F (2017). "Vegetarian, vegan diets and multiple health outcomes: a systematic review with meta-analysis of observational studies". Critical Reviews in Food Science and Nutrition. 57 (3): 3640–3649. doi:10.1080/10408398.2016.1138447. hdl:2158/1079985. PMID 26853923. S2CID 10073754.
- Flora Southey (8 October 2019). "Smart Protein: Barilla, AB InBev, Thai Union et al. collaborate on EU-funded novel protein project". FoodNavigator.com, William Reed Business Media Ltd. Retrieved 23 January 2020.