Vegetarianism


Vegetarianism is the practice of abstaining from the consumption of meat, and may also include abstention from by-products of animal slaughter.
Vegetarianism may be adopted for various reasons. Many people object to eating meat out of respect for sentient life. Such ethical motivations have been codified under various religious beliefs, as well as animal rights advocacy. Other motivations for vegetarianism are health-related, political, environmental, cultural, aesthetic, economic, or personal preference. There are variations of the diet as well: an ovo-lacto vegetarian diet includes both eggs and dairy products, an ovo-vegetarian diet includes eggs but not dairy products, and a lacto-vegetarian diet includes dairy products but not eggs. A vegan diet excludes all animal products, including eggs and dairy. Avoidance of animal products may require dietary supplements to prevent deficiencies such as vitamin B12 deficiency, which leads to pernicious anemia. Psychologically, preference for vegetarian foods can be impacted by one's own socio-economic status and evolutionary factors.
Packaged and processed foods, such as cakes, cookies, candies, chocolate, yogurt, and marshmallows, often contain unfamiliar animal ingredients, and so may be a special concern for vegetarians due to the likelihood of such additives. Feelings among vegetarians may vary concerning these ingredients. Some vegetarians scrutinize product labels for animal-derived ingredients while others do not object to consuming cheese made with animal-derived rennet or are unaware of its presence.
Semi-vegetarian diets consist largely of vegetarian foods but may include fish or poultry, or sometimes other meats, on an infrequent basis. Those with diets containing fish or poultry may define meat only as mammalian flesh and may identify with vegetarianism. A pescetarian diet has been described as "fish but no other meat".

Etymology

The first written use of the term "vegetarian" originated in the early 19th century, when authors referred to a vegetable regimen diet. Modern dictionaries explain its origin as a compound of vegetable and the suffix . The term was popularized with the foundation of the Vegetarian Society in Manchester in 1847, although it may have appeared in print before 1847. The earliest occurrences of the term seem to be related to Alcott House—a school on the north side of Ham Common, London—which was opened in July 1838 by James Pierrepont Greaves. From 1841, it was known as A Concordium, or Industry Harmony College, from which time the institution began to publish its own pamphlet entitled The Healthian, which provides some of the earliest appearances of the term "vegetarian".

History

The earliest record of vegetarianism comes from the 7th century BCE, inculcating tolerance towards all living beings. Parshwanatha and Mahavira, the 23rd & 24th tirthankaras in Jainism respectively revived and advocated ahimsa and Jain vegetarianism in 8th to 6th century BC; the most comprehensive and strictest form of vegetarianism. In Indian culture, vegetarianism has been closely connected with the attitude of nonviolence towards animals for millennia and was promoted by religious groups and philosophers. The ancient Indian work of Tirukkural explicitly and unambiguously emphasizes shunning meat and non-killing. Chapter 26 of the Tirukkural, particularly couplets 251–260, deals exclusively on vegetarianism or veganism.
Among the Hellenes, Egyptians, and others, vegetarianism had medical or ritual purification purposes. Vegetarianism was also practiced in ancient Greece and the earliest reliable evidence for vegetarian theory and practice in Greece dates from the 6th century BC. The Orphics, a religious movement spreading in Greece at that time, also practiced and promoted vegetarianism. Greek teacher Pythagoras, who promoted the altruistic doctrine of metempsychosis, may have practiced vegetarianism, but is also recorded as eating meat. A fictionalized portrayal of Pythagoras appears in Ovid's Metamorphoses, in which he advocates a form of strict vegetarianism. It was through this portrayal that Pythagoras was best known to English-speakers throughout the early modern period and, prior to the coinage of the word "vegetarianism", vegetarians were referred to in English as "Pythagoreans". Vegetarianism was also practiced about six centuries later in another instance in the northern Thracian region by the Moesi tribe, feeding themselves on honey, milk, and cheese.
began bans on killing and eating meat in 675 in Japan.
In Japan in 675, the Emperor Tenmu prohibited the killing and the eating of meat during the busy farming period between April and September but excluded the eating of wild birds and animals. These bans and several others that followed over the centuries were overturned in the nineteenth century during the Meiji Restoration. In China, during the Song Dynasty, Buddhist cuisine became popular enough that vegetarian restaurants appeared where chefs used plant-based ingredients such as beans, gluten, root vegetables and mushrooms to create meat analogues including pork, fowl, eggs and crab roe.
Following the Christianization of the Roman Empire in late antiquity, vegetarianism practically disappeared from Europe, as it did elsewhere, except in India. Several orders of monks in medieval Europe restricted or banned the consumption of meat for ascetic reasons, but none of them eschewed fish. Moreover, the medieval definition of "fish" included such animals as seals, porpoises, dolphins, barnacle geese, puffins, and beavers. Vegetarianism re-emerged during the Renaissance, becoming more widespread in the 19th and 20th centuries. In 1847, the first Vegetarian Society was founded in the United Kingdom; Germany, the Netherlands, and other countries followed. In 1886, the vegetarian colony Nueva Germania was founded in Paraguay, though its vegetarian aspect would prove short-lived. The International Vegetarian Union, an association of the national societies, was founded in 1908. In the Western world, the popularity of vegetarianism grew during the 20th century as a result of nutritional, ethical, and—more recently—environmental and economic concerns.

Varieties

MeatEggsDairy
Ovo-lacto vegetarianism
Ovo vegetarianism
Lacto vegetarianism
Vegan diet

There are a number of vegetarian diets that exclude or include various foods:
Within the "" groups, there are many who refuse to consume fertilized eggs ; however, such distinction is typically not specifically addressed.
Some vegetarians also avoid products that may use animal ingredients not included in their labels or which use animal products in their manufacturing. For example, sugars that are whitened with bone char, cheeses that use animal rennet, gelatin, some cane sugar and beverages clarified with gelatin or crushed shellfish and sturgeon, while other vegetarians are unaware of, or do not mind, such ingredients. In the 21st century, 90% of rennet and chymosin used in cheesemaking are derived from industrial fermentation processes, which satisfy both kosher and halal requirements.
Individuals sometimes label themselves "vegetarian" while practicing a semi-vegetarian diet, as some dictionary definitions describe vegetarianism as sometimes including the consumption of fish, or only include mammalian flesh as part of their definition of meat, while other definitions exclude fish and all animal flesh. In other cases, individuals may describe themselves as "flexitarian".
These diets may be followed by those who reduce animal flesh consumed as a way of transitioning to a complete vegetarian diet or for health, ethical, environmental, or other reasons. Semi-vegetarian diets include:
Semi-vegetarianism is contested by vegetarian groups, such as the Vegetarian Society, which states that vegetarianism excludes all animal flesh.

Health effects

Studies on the health effects of vegetarian diets observe mixed effects on mortality. One review found a decreased overall risk of all cause mortality, cancer and cardiovascular disease; however, a meta-analysis found lower risk for ischemic heart disease and cancer but no effect on overall mortality or cerebrovascular disease. Possible limitations include varying definitions used of vegetarianism, and the observation of increased risk of lung cancer mortality in those on a vegetarian diet for less than five years. An analysis pooling two large studies found vegetarians in the UK have similar all cause mortality as meat eaters.
The American Dietetic Association has stated that at all stages of life, a properly planned vegetarian diet can be "healthful, nutritionally adequate, and may be beneficial in the prevention and treatment of certain diseases." Vegetarian diets offer lower levels of saturated fat, cholesterol and animal protein, and higher levels of carbohydrates, fibre, magnesium, potassium, folate, and antioxidants such as vitamins C and E and phytochemicals.

Arthritis

Vegetarian diets have been studied to see whether they are of benefit in treating arthritis, but no good supporting evidence has been found.

Bone health

According to some studies, a vegetarian lifestyle can be associated with vitamin B 12 deficiency and low bone mineral density. A 2019 review found that vegetarians have lower bone mineral density at the femoral neck and lumbar spine compared to omnivores.

Dental health

A 2019 review found that a vegetarian diet may be associated with greater risk of dental erosion.

Diabetes

Vegetarian diets might reduce the risk of developing diabetes. There is evidence that a vegetarian diet may help people with type 2 diabetes achieve glycemic control.

Eating disorders

The American Dietetic Association discussed that vegetarian diets may be more common among adolescents with eating disorders, indicating that vegetarian diets do not cause eating disorders, but rather "vegetarian diets may be selected to camouflage an existing eating disorder".

Heart health

A 2015 review found that vegetarian diets "effectively lower blood concentrations of total cholesterol, low‐density lipoprotein cholesterol, high‐density lipoprotein cholesterol, and non–high‐density lipoprotein cholesterol."

Longevity

There have been many comparative and statistical studies of the relationship between diet and longevity, including vegetarianism and longevity.
A 1999 metastudy combined data from five studies from western countries. The metastudy reported mortality ratios, where lower numbers indicated fewer deaths, for fish eaters to be 0.82, vegetarians to be 0.84, occasional meat eaters to be 0.84. Regular meat eaters had the base mortality rate of 1.0, while the number for vegans was very uncertain due to too few data points. The study reported the numbers of deaths in each category, and expected error ranges for each ratio, and adjustments made to the data. However, the "lower mortality was due largely to the relatively low prevalence of smoking in these cohorts". Out of the major causes of death studied, only one difference in mortality rate was attributed to the difference in diet, as the conclusion states: "...vegetarians had a 24% lower mortality from ischaemic heart disease than non-vegetarians, but no associations of a vegetarian diet with other major causes of death were established".
In Mortality in British vegetarians, a similar conclusion is drawn:
British vegetarians have low mortality compared with the general population. Their death rates are similar to those of comparable non-vegetarians, suggesting that much of this benefit may be attributed to non-dietary lifestyle factors such as a low prevalence of smoking and a generally high socio-economic status, or to aspects of the diet other than the avoidance of meat and fish."

The Adventist Health Studies is ongoing research that documents the life expectancy in Seventh-day Adventists. This is the only study among others with similar methodology which had favourable indication for vegetarianism. The researchers found that a combination of different lifestyle choices could influence life expectancy by as much as 10 years. Among the lifestyle choices investigated, a vegetarian diet was estimated to confer an extra 1–1/2 to 2 years of life. The researchers concluded that "the life expectancies of California Adventist men and women are higher than those of any other well-described natural population" at 78.5 years for men and 82.3 years for women. The life expectancy of California Adventists surviving to age 30 was 83.3 years for men and 85.7 years for women.
The Adventist health study is again incorporated into a metastudy titled "Does low meat consumption increase life expectancy in humans?" published in American Journal of Clinical Nutrition, which concluded that low meat eating and other lifestyle choices significantly increase life expectancy, relative to a group with high meat intake. The study concluded that "The findings from one cohort of healthy adults raises the possibility that long-term adherence to a vegetarian diet can further produce a significant 3.6-y increase in life expectancy." However, the study also concluded that "Some of the variation in the survival advantage in vegetarians may have been due to marked differences between studies in adjustment for confounders, the definition of vegetarian, measurement error, age distribution, the healthy volunteer effect, and intake of specific plant foods by the vegetarians." It further states that "This raises the possibility that a low-meat, high plant-food dietary pattern may be the true causal protective factor rather than simply elimination of meat from the diet." In a recent review of studies relating low-meat diet patterns to all-cause mortality, Singh noted that "5 out of 5 studies indicated that adults who followed a low meat, high plant-food diet pattern experienced significant or marginally significant decreases in mortality risk relative to other patterns of intake."
Statistical studies, such as comparing life expectancy with regional areas and local diets in Europe also have found life expectancy considerably greater in southern France, where a low meat, high plant Mediterranean diet is common, than northern France, where a diet with high meat content is more common.
A study by the Institute of Preventive and Clinical Medicine, and Institute of Physiological Chemistry looked at a group of 19 vegetarians and used as a comparison a group of 19 omnivorous subjects recruited from the same region. The study found that this group of vegetarians have a significantly higher amount of plasma carboxymethyllysine and advanced glycation endproducts compared to this group of non-vegetarians. Carboxymethyllysine is a glycation product which represents "a general marker of oxidative stress and long-term damage of proteins in aging, atherosclerosis and diabetes" and "dvanced glycation end products may play an important adverse role in process of atherosclerosis, diabetes, aging and chronic renal failure".

Diet composition and nutrition

Western vegetarian diets are typically high in carotenoids, but relatively low in omega-3 fatty acids and vitamin B12. Vegans can have particularly low intake of vitamin B and calcium if they do not eat enough items such as collard greens, leafy greens, tempeh and tofu. High levels of dietary fiber, folic acid, vitamins C and E, and magnesium, and low consumption of saturated fat are all considered to be beneficial aspects of a vegetarian diet. A well planned vegetarian diet will provide all nutrients in a meat-eater's diet to the same level for all stages of life.

Protein

Protein intake in vegetarian diets is lower than in meat diets but can meet the daily requirements for most people. Studies at Harvard University as well as other studies conducted in the United States, United Kingdom, Canada, Australia, New Zealand, and various European countries,
confirmed vegetarian diets provide sufficient protein intake as long as a variety of plant sources are available and consumed.

Iron

Vegetarian diets typically contain similar levels of iron to non-vegetarian diets, but this has lower bioavailability than iron from meat sources, and its absorption can sometimes be inhibited by other dietary constituents. According to the Vegetarian Resource Group, consuming food that contains vitamin C, such as citrus fruit or juices, tomatoes, or broccoli, is a good way to increase the amount of iron absorbed at a meal. Vegetarian foods rich in iron include black beans, cashews, hempseed, kidney beans, broccoli, lentils, oatmeal, raisins, spinach, cabbage, lettuce, black-eyed peas, soybeans, many breakfast cereals, sunflower seeds, chickpeas, tomato juice, tempeh, molasses, thyme, and whole-wheat bread. The related vegan diets can often be higher in iron than vegetarian diets, because dairy products are low in iron. Iron stores often tend to be lower in vegetarians than non-vegetarians, and a few small studies report very high rates of iron deficiency. However, the American Dietetic Association states that iron deficiency is no more common in vegetarians than non-vegetarians ; iron deficiency anaemia is rare no matter the diet.

Vitamin B12

is not generally present in plants but is naturally found in foods of animal origin. Lacto-ovo vegetarians can obtain B12 from dairy products and eggs, and vegans can obtain it from manufactured fortified foods and dietary supplements. A strict vegetarian diet avoiding consumption of all animal products risks vitamin B12 deficiency, which can lead to hyperhomocysteinemia, a risk factor for several health disorders, including anemia, neurological deficits, gastrointestinal problems, platelet disorders, and increased risk for cardiovascular diseases. The recommended daily dietary intake of B12 in the United States and Canada is 0.4 mcg, rising to 1.8 mcg, 2.4 mcg, and 2.8 mcg. While the body's daily requirement for vitamin B12 is in microgram amounts, deficiency of the vitamin through strict practice of a vegetarian diet without supplementation can increase the risk of several chronic diseases.

Fatty acids

Plant-based, or vegetarian, sources of Omega 3 fatty acids include soy, walnuts, pumpkin seeds, canola oil, kiwifruit, hempseed, algae, chia seed, flaxseed, echium seed and leafy vegetables such as lettuce, spinach, cabbage and purslane. Purslane contains more Omega 3 than any other known leafy green. Olives are another important plant source of unsaturated fatty acids. Plant foods can provide alpha-linolenic acid which the human body uses to synthesize the long-chain n-3 fatty acids EPA and DHA. EPA and DHA can be obtained directly in high amounts from oily fish or fish oils. Vegetarians, and particularly vegans, have lower levels of EPA and DHA than meat-eaters. While the health effects of low levels of EPA and DHA are unknown, it is unlikely that supplementation with alpha-linolenic acid will significantly increase levels. Recently, some companies have begun to market vegetarian DHA supplements containing seaweed extracts. Whole seaweeds are not suitable for supplementation because their high iodine content limits the amount that may be safely consumed. However, certain algae such as spirulina are good sources of gamma-linolenic acid, alpha-linolenic acid, linoleic acid, stearidonic acid, eicosapentaenoic acid, docosahexaenoic acid, and arachidonic acid.

Calcium

intake in vegetarians and vegans can be similar to non-vegetarians, as long as the diet is properly planned. Lacto-ovo vegetarians that include dairy products can still obtain calcium from dairy sources like milk, yogurt, and cheese.
Non-dairy milks that are fortified with calcium, such as soymilk and almond milk can also contribute a significant amount of calcium in the diet. The calcium found in broccoli, bok choy, and kale have also been found to have calcium that is well absorbed in the body. Though the calcium content per serving is lower in these vegetables than a glass of milk, the absorption of the calcium into the body is higher. Other foods that contain calcium include calcium-set tofu, blackstrap molasses, turnip greens, mustard greens, soybeans, tempeh, almonds, okra, dried figs, and tahini. Though calcium can be found in Spinach, swiss chard, beans and beet greens, they are generally not considered to be a good source since the calcium binds to oxalic acid and is poorly absorbed into the body. Phytic acid found in nuts, seeds, and beans may also impact calcium absorption rates. See the National Institutes of Health Office of Dietary Supplements for calcium needs for various ages, the Vegetarian Resource Group and the Vegetarian Nutrition Calcium Fact Sheet from the Academy of Nutrition and Dietetics for more specifics on how to obtain adequate calcium intake on a vegetarian or vegan diet.

Vitamin D

Vitamin D needs can be met via the human body's own generation upon sufficient and sensible exposure to ultraviolet light in sunlight. Products including milk, soy milk and cereal grains may be fortified to provide a source of Vitamin D. For those who do not get adequate sun exposure or food sources, Vitamin D supplementation may be necessary.

Vitamin D2

Vitamin D2, or ergocalciferol is found in fungus and created from viosterol, which in turn is created when ultraviolet light activates ergosterol. Any UV-irradiated fungus including yeast form vitamin D2. Human bioavailability of vitamin D2 from vitamin D2-enhanced button mushrooms via UV-B irradiation is effective in improving vitamin D status and not different from a vitamin D2 supplement according to study. For example, Vitamin D2 from UV-irradiated yeast baked into bread is bioavailable.
By visual assessment or using a chromometer, no significant discoloration of irradiated mushrooms, as measured by the degree of "whiteness", was observed making it hard to discover if they have been treated without labeling. Claims have been made that a normal serving of mushrooms treated with ultraviolet light increase their vitamin D content to levels up to 80 micrograms, or 2700 IU if exposed to just 5 minutes of UV light after being harvested.

Choline

is a nutrient that helps transfer signals between nerve cells and is involved in liver function. It is highest in dairy foods and meat but it is possible to be obtained through a vegan diet.

Ethics and diet

General

Various ethical reasons have been suggested for choosing vegetarianism, usually predicated on the interests of non-human animals. In many societies, controversy and debate have arisen over the ethics of eating animals. Some people, while not vegetarians, refuse to eat the flesh of certain animals due to cultural taboo, such as cats, dogs, horses or rabbits. Others support meat eating for scientific, nutritional and cultural reasons, including religious ones. Some meat eaters abstain from the meat of animals reared in particular ways, such as factory farms, or avoid certain meats, such as veal or foie gras. Some people follow vegetarian or vegan diets not because of moral concerns involving the raising or consumption of animals in general, but because of concerns about the specific treatment and practices involved in the processing of animals for food. Others still avoid meat because meat production is claimed to place a greater burden on the environment than production of an equivalent amount of plant protein. Ethical objections based on consideration for animals are generally divided into opposition to the act of killing in general, and opposition to certain agricultural practices surrounding the production of meat.

Ethics of killing for food

Ethical vegetarians believe that killing an animal, like killing a human, especially one who has equal or lesser cognitive abilities than the animals in question, can only be justified in extreme circumstances and that consuming a living creature for its enjoyable taste, convenience, or nutrition value is not a sufficient cause. Another common view is that humans are morally conscious of their behavior in a way other animals are not, and therefore subject to higher standards. Jeff McMahan proposes that denying the right to life and humane treatment to animals with equal or greater cognitive abilities than mentally disabled humans is an arbitrary and discriminatory practice based on habit instead of logic. Opponents of ethical vegetarianism argue that animals are not moral equals to humans and so consider the comparison of eating livestock with killing people to be fallacious. This view does not excuse cruelty, but maintains that animals do not possess the rights a human has.

Dairy and eggs

One of the main differences between a vegan and a typical vegetarian diet is the avoidance of both eggs and dairy products such as milk, cheese, butter and yogurt. Ethical vegans do not consume dairy or eggs because they state that their production causes the animal suffering or a premature death.
To produce milk from dairy cattle, farmers separate calves from their mothers soon after birth or fed milk replacer to retain cow milk for human consumption. To prolong lactation, dairy cows are almost permanently kept pregnant through artificial insemination. After about five years, once the cow's milk production has dropped, it is considered "spent" and processed for beef and hide. A dairy cow's natural life expectancy is about twenty years.
In battery cage and free-range egg production, unwanted male chicks are culled or discarded at birth during the process of securing a further generation of egg-laying hens.

Treatment of animals

has become popular in developed countries particularly because of the spread of factory farming, faster communications, and environmental consciousness. Some believe that the current mass-demand for meat cannot be satisfied without a mass-production system that disregards the welfare of animals, while others believe that practices like well-managed free-range farming or the consumption of game could substantially alleviate consumer demand for mass-produced meat.

Religion and diet

teaches vegetarianism as moral conduct as do some major sects of Hinduism. Buddhism in general does not prohibit meat eating, while Mahayana Buddhism encourages vegetarianism as beneficial for developing compassion. Other denominations that advocate a vegetarian diet include the Seventh-day Adventists, the Rastafari movement, the Ananda Marga movement and the Hare Krishnas. Sikhism does not equate spirituality with diet and does not specify a vegetarian or meat diet.

Bahá'í faith

While there are no dietary restrictions in the Bahá'í faith, `Abdu'l-Bahá, the son of the religion's founder, noted that a vegetarian diet consisting of fruits and grains was desirable, except for people with a weak constitution or those that are sick. He stated that there are no requirements that Bahá'ís become vegetarian, but that a future society should gradually become vegetarian. `Abdu'l-Bahá also stated that killing animals was contrary to compassion. While Shoghi Effendi, the head of the Bahá'í Faith in the first half of the 20th century, stated that a purely vegetarian diet would be preferable since it avoided killing animals, both he and the Universal House of Justice, the governing body of the Bahá'ís have stated that these teachings do not constitute a Bahá'í practice and that Bahá'ís can choose to eat whatever they wish but should be respectful of others' beliefs.

Buddhism

Theravadins in general eat meat. If Buddhist monks "see, hear or know" a living animal was killed specifically for them to eat, they must refuse it or else incur an offense. However, this does not include eating meat which was given as alms or commercially purchased. In the Theravada canon, Buddha did not make any comment discouraging them from eating meat but he specifically refused to institute vegetarianism in his monastic code when a suggestion had been made.
In several Sanskrit texts of Mahayana Buddhism, Buddha instructs his followers to avoid meat. However, each branch of Mahayana Buddhism selects which sutra to follow, and some branches, including the majority of Tibetan and Japanese Buddhists, do eat meat, while many Chinese Buddhist branches do not.

Christianity

Early Christians disagreed as to whether they should eat meat, and later Christian historians have disagreed over whether Jesus was a vegetarian. Various groups within Christianity have practiced specific dietary restrictions for various reasons. The Council of Jerusalem in around 50 AD, recommended Christians keep following some of the Jewish food laws concerning meat. The early sect known as the Ebionites are considered to have practiced vegetarianism. Surviving fragments from their Gospel indicate their belief that – as Christ is the Passover sacrifice and eating the Passover lamb is no longer required – a vegetarian diet may be observed. However, orthodox Christianity does not accept their teaching as authentic. Indeed, their specific injunction to strict vegetarianism was cited as one of the Ebionites' "errors".
At a much later time, the Bible Christian Church founded by Reverend William Cowherd in 1809 followed a vegetarian diet. Cowherd was one of the philosophical forerunners of the Vegetarian Society. Cowherd encouraged members to abstain from eating of meat as a form of temperance.
Seventh-day Adventists are encouraged to engage in healthy eating practices, and ova-lacto-vegetarian diets are recommended by the General Conference of Seventh-day Adventists Nutrition Council. They have also sponsored and participated in many scientific studies exploring the impact of dietary decisions upon health outcomes. The GCNC has in addition adapted the USDA's food pyramid for a vegetarian dietary approach. However, the only kinds of meat specifically frowned upon by the SDA health message are unclean meats, or those forbidden in scripture.
Additionally, some monastic orders follow a vegetarian diet, and members of the Orthodox Church follow a vegan diet during fasts. There is also a strong association between the Quakers and vegetarianism dating back at least to the 18th century. The association grew in prominence during the 19th century, coupled with growing Quaker concerns in connection with alcohol consumption, anti-vivisection and social purity. The association between the Quaker tradition and vegetarianism, however, becomes most significant with the founding of the Friends' Vegetarian Society in 1902 "to spread a kindlier way of living amongst the Society of Friends."
According to Canon Law, Roman Catholics ages 14 and older are required to abstain from meat on Ash Wednesday and all Fridays of Lent including Good Friday. Canon Law also obliges Catholics to abstain from meat on the Fridays of the year outside of Lent unless, with the permission of the local conference of bishops, another penitential act is substituted. The restrictions on eating meat on these days is solely as an act of penance and not because of a religious objection to eating meat.

Seventh-day Adventist

Since the formation of the Seventh-day Adventist Church in the 1860s when the church began, wholeness and health have been an emphasis of the Adventist church, and has been known as the "health message" belief of the church. Adventists are well known for presenting a health message that recommends vegetarianism and expects adherence to the kosher laws in Leviticus 11. Obedience to these laws means abstinence from pork, shellfish, and other animals proscribed as "unclean". The church discourages its members from consuming alcoholic beverages, tobacco or illegal drugs. In addition, some Adventists avoid coffee, tea, cola, and other beverages containing caffeine.
The pioneers of the Adventist Church had much to do with the common acceptance of breakfast cereals into the Western diet, and the "modern commercial concept of cereal food" originated among Adventists. John Harvey Kellogg was one of the early founders of Adventist health work. His development of breakfast cereals as a health food led to the founding of Kellogg's by his brother William. In both Australia and New Zealand, the church-owned Sanitarium Health and Wellbeing Company is a leading manufacturer of health and vegetarian-related products, most prominently Weet-Bix.
Research funded by the U.S. National Institutes of Health has shown that the average Adventist in California lives 4 to 10 years longer than the average Californian. The research, as cited by the cover story of the November 2005 issue of National Geographic, asserts that Adventists live longer because they do not smoke or drink alcohol, have a day of rest every week, and maintain a healthy, low-fat vegetarian diet that is rich in nuts and beans. The cohesiveness of Adventists' social networks has also been put forward as an explanation for their extended lifespan.
Since Dan Buettner's 2005 National Geographic story about Adventist longevity, his book, The Blue Zones: Lessons for Living Longer From the People Who've Lived the Longest, named Loma Linda, California a "blue zone" because of the large concentration of Seventh-day Adventists. He cites the Adventist emphasis on health, diet, and Sabbath-keeping as primary factors for Adventist longevity.
An estimated 35% of Adventists practice vegetarianism or veganism, according to a 2002 worldwide survey of local church leaders.

Hinduism

Though there is no strict rule on what to consume and what not to, paths of Hinduism hold vegetarianism as an ideal. Some reasons are: the principle of nonviolence applied to animals; the intention to offer only "pure" food to a deity and then to receive it back as prasad; and the conviction that a sattvic diet is beneficial for a healthy body and mind and that non-vegetarian food is not recommended for a better mind and for spiritual development.
However, the food habits of Hindus vary according to their community, location, custom and varying traditions. Historically and currently, those Hindus who eat meat prescribe Jhatka meat, Hindus believe that the cow is a holy animal whose processing for meat is forbidden.

Islam

Some followers of Islam, or Muslims, chose to be vegetarian for health, ethical, or personal reasons. However, the choice to become vegetarian for non-medical reasons can sometimes be controversial due to conflicting fatwas and differing interpretations of the Quran. Though some more traditional Muslims may keep quiet about their vegetarian diet, the number of vegetarian Muslims is increasing.
Vegetarianism has been practiced by some influential Muslims including the Iraqi theologian, female mystic and poet Rabia of Basra, who died in the year 801, and the Sri Lankan Sufi master Bawa Muhaiyaddeen, who established The Bawa Muhaiyaddeen Fellowship of North America in Philadelphia. The former Indian president Dr. A. P. J. Abdul Kalam was also famously a vegetarian.
In January 1996, The International Vegetarian Union announced the formation of the Muslim Vegetarian/Vegan Society.
Many non-vegetarian Muslims will select vegetarian options when dining in non-halal restaurants. However, this is a matter of not having the right kind of meat rather than preferring not to eat meat on the whole.

Jainism

Followers of Jainism believe that all living organisms whether they are micro-organism are living and have a soul, and have one or more senses out of five senses and they go to great lengths to minimise any harm to any living organism. Most Jains are lacto-vegetarians but more devout Jains do not eat root vegetables because they believe that root vegetables contain a lot more micro-organisms as compared to other vegetables, and that, by eating them, violence of these micro-organisms is inevitable. So they focus on eating beans and fruits, whose cultivation do not involve killing of a lot of micro-organisms. No products obtained from dead animals are allowed, because when a living beings dies, a lot of micro-organisms will reproduce in the body which decomposes the body, and in eating the dead bodies, violence of decomposers is inevitable. Jain monks usually do a lot of fasting, and when they knew through spiritual powers that their life is very little, they start fasting until death. Some particularly dedicated individuals are fruitarians. Honey is forbidden, because honey is the regurgitation of nectar by bees and may also contain eggs, excreta and dead bees. Some Jains do not consume plant parts that grow underground such as roots and bulbs, because the plants themselves and tiny animals may be killed when the plants are pulled up.

Judaism

While classical Jewish law neither requires nor prohibits the consumption of meat, Jewish vegetarians often cite Jewish principles regarding animal welfare, environmental ethics, moral character, and health as reasons for adopting a vegetarian or vegan diet.
Rabbis may advocate vegetarianism or veganism primarily because of concerns about animal welfare, especially in light of the traditional prohibition on causing unnecessary "pain to living creatures". Some Jewish vegetarian groups and activists believe that the halakhic permission to eat meat is a temporary leniency for those who are not ready yet to accept the vegetarian diet.
The book of Daniel starts in its with the benefits of vegetarianism. Due to its size, its late time of origin and its revealing content, the book is of particular importance for the time of the following exile, which lasts now for 2000 years and technically still goes on until the Temple in Jerusalem is rebuilt. A diet described as “pulse and water” is presented along benefits such as accordance with the biblical dietary laws, health, beauty, wisdom and visions. Vegetarianism can be seen as a safeguard around the dietary laws or the beautification of them.
Jewish vegetarianism and veganism have become especially popular among Israeli Jews. In 2016, Israel was described as "the most vegan country on Earth", as five percent of its population eschewed all animal products. Interest in veganism has grown among both non-Orthodox and Orthodox Jews in Israel.

Rastafari

Within the Afro-Caribbean community, a minority are Rastafari and follow the dietary regulations with varying degrees of strictness. The most orthodox eat only "Ital" or natural foods, in which the matching of herbs or spices with vegetables is the result of long tradition originating from the African ancestry and cultural heritage of Rastafari. "Ital", which is derived from the word vital, means essential to human existence. Ital cooking in its strictest form prohibits the use of salt, meat, preservatives, colorings, flavorings and anything artificial. Most Rastafari are vegetarian.

Sikhism

The tenets of Sikhism do not advocate a particular stance on either vegetarianism or the consumption of meat, but leave the decision of diet to the individual. The tenth guru, Guru Gobind Singh, however, prohibited "Amritdhari" Sikhs, or those that follow the Sikh Rehat Maryada from eating Kutha meat, or meat which has been obtained from animals which have been killed in a ritualistic way. This is understood to have been for the political reason of maintaining independence from the then-new Muslim hegemony, as Muslims largely adhere to the ritualistic halal diet.
"Amritdharis" that belong to some Sikh sects are vehemently against the consumption of meat and eggs. This vegetarian stance has been traced back to the times of the British Raj, with the advent of many new Vaishnava converts. In response to the varying views on diet throughout the Sikh population, Sikh Gurus have sought to clarify the Sikh view on diet, stressing their preference only for simplicity of diet. Guru Nanak said that over-consumption of food involves a drain on the Earth's resources and thus on life. Passages from the Guru Granth Sahib say that it is "foolish" to argue for the superiority of animal life, because though all life is related, only human life carries more importance: "Only fools argue whether to eat meat or not. Who can define what is meat and what is not meat? Who knows where the sin lies, being a vegetarian or a non-vegetarian?" The Sikh langar, or free temple meal, is largely lacto-vegetarian, though this is understood to be a result of efforts to present a meal that is respectful of the diets of any person who would wish to dine, rather than out of dogma.

Environment and diet

Environmental vegetarianism is based on the concern that the production of meat and animal products for mass consumption, especially through factory farming, is environmentally unsustainable. According to a 2006 United Nations initiative, the livestock industry is one of the largest contributors to environmental degradation worldwide, and modern practices of raising animals for food contribute on a "massive scale" to air and water pollution, land degradation, climate change, and loss of biodiversity. The initiative concluded that "the livestock sector emerges as one of the top two or three most significant contributors to the most serious environmental problems, at every scale from local to global."
In addition, animal agriculture is a large source of greenhouse gases. According to a 2006 report it is responsible for 18% of the world's greenhouse gas emissions as estimated in 100-year CO2 equivalents. Livestock sources account for about 3.1 percent of US anthropogenic GHG emissions expressed as carbon dioxide equivalents. This EPA estimate is based on methodologies agreed to by the Conference of Parties of the UNFCCC, with 100-year global warming potentials from the IPCC Second Assessment Report used in estimating GHG emissions as carbon dioxide equivalents.
Meat produced in a laboratory may be more environmentally sustainable than regularly produced meat. Reactions of vegetarians vary. Rearing a relatively small number of grazing animals can be beneficial, as the Food Climate Research Network at Surrey University reports: "A little bit of livestock production is probably a good thing for the environment".
In May 2009, Ghent, Belgium, was reported to be "the first in the world to go vegetarian at least once a week" for environmental reasons, when local authorities decided to implement a "weekly meatless day". Civil servants would eat vegetarian meals one day per week, in recognition of the United Nations' report. Posters were put up by local authorities to encourage the population to take part on vegetarian days, and "veggie street maps" were printed to highlight vegetarian restaurants. In September 2009, schools in Ghent are due to have a weekly veggiedag too.
Public opinion and acceptance of meat-free food is expected to be more successful if its descriptive words focus less on the health aspects and more on the flavor.

Labor conditions and diet

Some groups, such as PETA, promote vegetarianism as a way to offset poor treatment and working conditions of workers in the contemporary meat industry. These groups cite studies showing the psychological damage caused by working in the meat industry, especially in factory and industrialised settings, and argue that the meat industry violates its labourers' human rights by assigning difficult and distressing tasks without adequate counselling, training and debriefing. However, the working conditions of agricultural workers as a whole, particularly non-permanent workers, remain poor and well below conditions prevailing in other economic sectors. Accidents, including pesticide poisoning, among farmers and plantation workers contribute to increased health risks, including increased mortality. According to the International Labour Organization, agriculture is one of the three most dangerous jobs in the world.

Economics and diet

Similar to environmental vegetarianism is the concept of economic vegetarianism. An economic vegetarian is someone who practices vegetarianism from either the philosophical viewpoint concerning issues such as public health and curbing world starvation, the belief that the consumption of meat is economically unsound, part of a conscious simple living strategy or just out of necessity. According to the Worldwatch Institute, "Massive reductions in meat consumption in industrial nations will ease their health care burden while improving public health; declining livestock herds will take pressure off rangelands and grainlands, allowing the agricultural resource base to rejuvenate. As populations grow, lowering meat consumption worldwide will allow more efficient use of declining per capita land and water resources, while at the same time making grain more affordable to the world's chronically hungry." According to estimates in 2016, adoption of vegetarianism would contribute substantially to global healthcare and environmental savings.

Demographics

Prejudice researcher Gordon Hodson observes that vegetarians and vegans frequently face discrimination where eating meat is held as a cultural norm.

Gender

A 1992 market research study conducted by the Yankelovich research organisation concluded that "of the 12.4 million people who call themselves vegetarian, 68% are female, while only 32% are male".
At least one study indicates that vegetarian women are more likely to have female babies. A study of 6,000 pregnant women in 1998 "found that while the national average in Britain is 106 boys born to every 100 girls, for vegetarian mothers the ratio was just 85 boys to 100 girls".

Country-specific information