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- Workforce Libretexts - Vegetarianism (Oct. 24, 2026)
vegetarianism
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What is vegetarianism?
Vegetarianism is the practice of eating only vegetables, fruits, grains, legumes, and nuts, with or without milk products and eggs, for ethical, ascetic, environmental, or nutritional reasons. All forms of animal flesh are excluded from a vegetarian diet.
Those who avoid animal products altogether are known as vegans. Lacto-vegetarians consume milk products, while lacto-ovo vegetarians consume eggs as well. Pescatarians exclude land-based meats but consume fish and seafood.
A vegetarian diet can provide all essential amino acids, vitamins, fats, and minerals. Studies have linked vegetarian diets to increased lifespan and reduced risk of heart disease, high blood pressure, stroke, type 2 diabetes, and cancer.
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What foods do vegetarians eat and avoid?
Vegetarianism is a dietary practice of eating primarily vegetables, fruits, grains, legumes, and nuts. Many vegetarians consume milk products and eggs, but all forms of animal flesh are excluded.
Different types of vegetarians include:
* Lacto-ovo vegetarians eat milk products and eggs.
* Lacto-vegetarians consume milk products.
* Vegans avoid all animal-based products.
* Pescatarians exclude land-based meats but consume fish and shellfish.A well-balanced vegetarian diet can provide essential nutrients. The American Dietetic Association states vegetarian diets can meet protein requirements, supply essential amino acids, and provide necessary vitamins, fats, and minerals.
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Why do some people choose to follow a vegetarian diet?
People choose a vegetarian diet for various reasons, including health, ethics, and environmental concerns. A vegetarian diet can provide essential nutrients and reduce the risk of diseases, aligning with the views of the American Dietetic Association. Philosophers like Peter Singer have argued against modern animal farming, influencing ethical considerations. Environmental motivations include reducing methane emissions and promoting sustainable land use, as livestock farming impacts climate change. Some religious groups also advocate vegetarianism.
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What are the different types of vegetarian diets?
Vegetarianism is a dietary practice of abstaining from the consumption of animal flesh. There are several types of vegetarian diets:
* Lacto-ovo vegetarians eat vegetables, fruits, grains, legumes, nuts, dairy products, and eggs.
* Lacto-vegetarians consume dairy products, vegetables, fruits, grains, and nuts.
* Vegans exclude all animal products from their diets.
* Pescatarians follow a vegetarian diet but also consume fish and seafood.
* Flexitarians primarily follow a vegetarian diet, but occasionally eat meat or fish.4 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
How do vegetarians get important nutrients like protein and iron?
Vegetarian diets can provide all essential amino acids, vitamins, fats, and minerals. A study in 2025 showed vegan diets have the same muscle-building potential as omnivore diets.
Vegetarian sources of iron include leafy greens and beans, which contain non-heme iron. Absorption of iron from plants is enhanced when vitamin C is present. Healthy vegetarian sources of calcium include tofu, dark leafy greens like kale, spinach, and collard greens, as well as fortified cereals.
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What are some benefits and possible challenges of being a vegetarian?
Vegetarianism is a dietary practice of avoiding all flesh (meat, fowl, and seafood) and living on vegetables, fruits, grains, legumes, and nuts, with or without eggs and milk products.
Benefits of Vegetarianism
- A vegetarian diet can provide all essential amino acids, vitamins, fats, and minerals.
- Vegetarian diets can lower the risk of high blood pressure, stroke, heart disease, type 2 diabetes, and cancer.
- Abstaining from meat helps restore land and conserves water.
Challenges of Vegetarianism
- Vegans are at risk of vitamin B12 deficiency and must obtain it through supplements or fortified foods.
- It was once believed that humans cannot get enough protein from plant-based foods. However, nutritional studies have cast doubt on this claim.
- Overgrazing livestock hurts the environment through soil compaction, erosion, and harm to native plants and animals.
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vegetarianism, the theory or practice of living solely upon vegetables, fruits, grains, legumes, and nuts—with or without the addition of milk products and eggs—generally for ethical, ascetic, environmental, or nutritional reasons. All forms of flesh (meat, fowl, and seafood) are excluded from all vegetarian diets, but many vegetarians use milk and milk products; those in the West usually eat eggs also, but most vegetarians in India exclude them, as did those in the Mediterranean lands in Classical times. Vegetarians who exclude animal products altogether (and likewise avoid animal-derived products such as leather, silk, honey, and wool) are known as vegans. Those who use milk products are sometimes called lacto-vegetarians, and those who use eggs as well are called lacto-ovo vegetarians; those who exclude land-based meats, like vegetarians, but consume fish and shellfish are called pescatarians. Among some agricultural peoples, flesh eating has been infrequent except among the privileged classes; such people have rather misleadingly been called vegetarians.
Ancient origins
Deliberate avoidance of flesh eating probably first appeared sporadically in ritual connections, either as a temporary purification or as qualification for a priestly function. Advocacy of a regular fleshless diet began about the middle of the 1st millennium bce in India and the eastern Mediterranean as part of the philosophical awakening of the time. In the Mediterranean, avoidance of flesh eating is first recorded as a teaching of the philosopher Pythagoras of Samos (c. 530 bce), who alleged the kinship of all animals as one basis for human benevolence toward other creatures. From Plato onward many pagan philosophers (e.g., Epicurus and Plutarch), especially the Neoplatonists, recommended a fleshless diet; the idea carried with it condemnation of bloody sacrifices in worship and was often associated with belief in the reincarnation of souls and, more generally, with a search for principles of cosmic harmony in accord with which human beings could live. In India, followers of Buddhism and Jainism refused on ethical and ascetic grounds to kill animals for food. Human beings, they believed, should not inflict harm on any sentient creature. This principle was soon taken up in Brahmanism and, later, Hinduism and was applied especially to the cow. As in Mediterranean thought, the idea carried with it condemnation of bloody sacrifices and was often associated with principles of cosmic harmony.
In later centuries the history of vegetarianism in the Indic and Mediterranean regions diverged significantly. In India itself, though Buddhism gradually declined, the ideal of harmlessness (ahimsa), with its corollary of a fleshless diet, spread steadily in the 1st millennium ce until many of the upper castes, and even some of the lower, had adopted it. Beyond India it was carried, with Buddhism, northward and eastward as far as China and Japan. In some countries, fish were included in an otherwise fleshless diet.
West of the Indus the great monotheistic traditions were less favorable to vegetarianism. The Hebrew Bible, however, records the belief that in paradise the earliest human beings had not eaten flesh. Ascetic Jewish groups and some early Christian leaders disapproved of flesh eating as gluttonous, cruel, and expensive. Some Christian monastic orders ruled out flesh eating, and its avoidance has been a penance and a spiritual exercise even for laypersons. A number of saints, such as St. Anthony of Egypt, were noted vegetarians. Many Muslims have been hostile to vegetarianism, yet some Muslim Sufi mystics recommended a meatless diet for spiritual seekers.
The 17th through 19th centuries
The 17th and 18th centuries in Europe were characterized by a greater interest in humanitarianism and the idea of moral progress, and sensitivity to animal suffering was accordingly revived. Certain Protestant groups came to adopt a fleshless diet as part of the goal of leading a perfectly sinless life. Persons of diverse philosophical views advocated vegetarianism; for example, Voltaire praised it, and Percy Bysshe Shelley and Henry David Thoreau practiced the diet. In the late 18th century the utilitarian philosopher Jeremy Bentham asserted that the suffering of animals, like the suffering of humans, was worthy of moral consideration, and he regarded cruelty to animals as analogous to racism.
Vegetarians of the early 19th century usually condemned the use of alcohol as well as flesh and appealed as much to nutritional advantages as to ethical sensibilities. As before, vegetarianism tended to be combined with other efforts toward a humane and cosmically harmonious way of life. Although the vegetarian movement as a whole was always carried forward by ethically inclined individuals, special institutions grew up to express vegetarian concerns as such. The first vegetarian society was formed in England in 1847 by the Bible Christian sect, and the International Vegetarian Union was founded tentatively in 1889 and more enduringly in 1908.

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