Vegetarianism
Description	A vegetarian diet is derived from plants, with or without eggs or dairy.[1]
Origins	Ancient India, ancient Greece; 6th century BCE and earlier
Varieties	Ovo, lacto, ovo-lacto, veganism, raw veganism, fruitarianism, Buddhist vegetarianism

Vegetarianism encompasses the practice of following plant-based diets (fruits, vegetables, etc.), with or without the inclusion of dairy products or eggs, and with the exclusion of meat (red meat, poultry, and seafood). Abstention from by-products of animal slaughter, such as animal-derived rennet and gelatin, may also be practiced.^[2][3]

Vegetarianism can be adopted for different reasons. Many object to eating meat out of respect for sentient life. Such ethical motivations have been codified under various religious beliefs, along with the concept of animal rights. Other motivations for vegetarianism include health, political, environmental, cultural, aesthetic or economic. There are varieties of the diet as well: an ovo-vegetarian diet includes eggs but not dairy products, a lacto-vegetarian diet includes dairy products but not eggs, and an ovo-lacto vegetarian diet includes both eggs and dairy products. A vegan diet excludes all animal products, including eggs, dairy, and honey.

Various packaged or processed foods, including cake, cookies, chocolate and marshmallows, often contain unfamiliar animal ingredients, and may be a special concern for vegetarians due to the likelihood of such additions.^[4] Often, products are scrutinized by vegetarians for animal-derived ingredients prior to purchase or consumption.^[4] Vegetarians vary in their feelings regarding these ingredients, however. For example, while some vegetarians may be unaware of animal-derived rennet's role in the usual production of cheese and may therefore unknowingly consume the product,^[5][6] other vegetarians may not be bothered by its consumption.^[3] The results of a 2009 International survey suggest the standard definition of vegetarianism is different in different nations. Vegetarians in some nations consume more animal products than those in others.^[7]

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.^[8][9][10] A pescetarian diet, for example, includes "fish but no meat".^[11] The common use association between such diets and vegetarianism has led vegetarian groups such as the Vegetarian Society to state that diets containing these ingredients are not vegetarian, due to fish and birds being animals.^[12]

Etymology[link]

The Vegetarian Society, founded in 1847, says that the word "vegetarian" is derived from the Latin word vegetus meaning lively or vigorous.^[13] Despite this, the Oxford English Dictionary (OED) and other standard dictionaries state that the word was formed from the term "vegetable" and the suffix "-arian".^[14] The OED writes that the word came into general use after the formation of the Vegetarian Society at Ramsgate in 1847, though it offers two examples of usage from 1839 and 1842.^[15]

History[link]

The earliest records of (lacto) vegetarianism come from ancient India and ancient Greece in the 6th century BCE.^[16] In the Asian instance the diet was closely connected with the idea of nonviolence towards animals (called ahimsa in India) and was promoted by religious groups and philosophers.^[17] Among the Hellenes, Egyptians and others, it had medical or Ritual purification purposes.

Indian emperor Ashoka asserted protection to fauna:

Vegetarian label used in India on packed foodstuff

Following the Christianisation of the Roman Empire in late antiquity, vegetarianism practically disappeared from Europe as it was in other Continents, except India.^[18] Several orders of monks in medieval Europe restricted or banned the consumption of meat for ascetic reasons, but none of them eschewed fish.^[19] (The medieval definition of "fish" included such animals as seals, porpoises, dolphins, barnacle geese, puffins, and beavers.)^[20]

It re-emerged during the Renaissance,^[21] becoming more widespread in the 19th and 20th centuries. In 1847, the first Vegetarian Society was founded in the United Kingdom;^[22] Germany, the Netherlands, and other countries followed. The International Vegetarian Union, a union 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 of vegetarianism[link]

Roadside café near Kullu, India.

There are a number of types of vegetarianism, which exclude or include various foods.

• Ovo vegetarianism includes eggs but not dairy products.
• Lacto vegetarianism includes dairy products but not eggs.
• Ovo-lacto vegetarianism (or lacto-ovo vegetarianism) includes animal/dairy products such as eggs, milk, and honey.
• Veganism excludes all animal flesh and animal products, including milk, honey, and eggs, and may also exclude any products tested on animals, or any clothing from animals.^[23]
• Raw veganism includes only fresh and uncooked fruit, nuts, seeds, and vegetables. Vegetables can only be cooked up to a certain temperature.^[24]
• Fruitarianism permits only fruit, nuts, seeds, and other plant matter that can be gathered without harming the plant.^[25]
• Buddhist vegetarianism (also known as su vegetarianism) excludes all animal products as well as vegetables in the allium family (which have the characteristic aroma of onion and garlic): onion, garlic, scallions, leeks, or shallots.
• Jain vegetarianism includes dairy but excludes eggs and honey, as well as root vegetables.
• Macrobiotic diets consist mostly of whole grains and beans.

Within the 'ovo-' groups, there are many who refuse to consume fertilized eggs (with balut being an extreme example), 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 (enzymes from animal stomach lining), gelatin (derived from the collagen inside animals' skin, bones and connective tissue), some cane sugar (but not beet sugar) and apple juice/alcohol clarified with gelatin or crushed shellfish and sturgeon, while other vegetarians are unaware of such ingredients.^[4][5][6]

Individuals may describe themselves as "vegetarian" while practicing a semi-vegetarian diet,^[10][26][27] as some dictionary definitions pertaining to vegetarianism vary and include the consumption of fish,^[9] while other definitions exclude fish and all animal flesh.^[12] In other cases, individuals may describe themselves as "flexitarian".^[26] 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, environmental, or other reasons. Semi-vegetarian diets include:

• pescetarianism, which includes fish and some other forms of seafood;
• pollotarianism, which includes poultry;
• "pollo-pescetarian", which includes poultry and fish, or "white meat" only;
• macrobiotic diets consisting mostly of whole grains and beans, but may sometimes include fish.

Semi-vegetarianism is contested by vegetarian groups who state that vegetarianism excludes all animal flesh.^[12]

Health benefits and concerns[link]

Scientific endeavors in the area of vegetarianism have shifted from concerns about nutritional adequacy to investigating health benefits and disease prevention.^[28] The American Dietetic Association and Dietitians of Canada have stated that at all stages of life, a properly planned vegetarian diet is "healthful, nutritionally adequate, and provides health benefits in the prevention and treatment of certain diseases." Large-scale studies have shown that mortality from ischaemic heart disease was 30% lower among vegetarian men and 20% lower among vegetarian women than in non-vegetarians.^[29][30][31] Necessary nutrients, proteins, and amino acids for the body's sustenance can be found in vegetables, grains, nuts, soymilk, eggs and dairy.^[32] 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.^[33][34]

Vegetarians tend to have lower body mass index,^[35] lower levels of cholesterol, lower blood pressure, and less incidence of heart disease, hypertension, type 2 diabetes, renal disease, metabolic syndrome,^[36] dementias such as Alzheimer’s disease and other disorders.^[37] Non-lean red meat, in particular, has been found to be directly associated with increased risk of cancers of the esophagus, liver, colon, and the lungs.^[38] Other studies have shown no significant differences between vegetarians and non-vegetarians in mortality from cerebrovascular disease, stomach cancer, colorectal cancer, breast cancer, or prostate cancer.^[30] A 2010 study compared a group of vegetarian and meat-eating Seventh Day Adventists in which vegetarians scored lower on depression tests and had better mood profiles.^[39] However, vegetarians are more likely to be deficient in vitamin B12, leading to increased incidence of osteoporosis^[40] and depression.^[41]

The 2010 version of Dietary Guidelines for Americans, a report issued by the U.S. Department of Agriculture and the U.S. Department of Health and Human Services every five years states:

In prospective studies of adults, compared to non-vegetarian eating patterns, vegetarian-style eating patterns have been associated with improved health outcomes—lower levels of obesity, a reduced risk of cardiovascular disease, and lower total mortality. Several clinical trials have documented that vegetarian eating patterns lower blood pressure.

On average, vegetarians consume a lower proportion of calories from fat (particularly saturated fatty acids); fewer overall calories; and more fiber, potassium, and vitamin C than do non-vegetarians. Vegetarians generally have a lower body mass index. These characteristics and other lifestyle factors associated with a vegetarian diet may contribute to the positive health outcomes that have been identified among vegetarians.^[42]

Nutrition[link]

A fruit stall in Barcelona

Western vegetarian diets are typically high in carotenoids, but relatively low in long-chain n-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 (soy). 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.^[43][44]

Protein[link]

Protein intake in vegetarian diets is only slightly lower than in meat diets and can meet daily requirements for any person, including athletes and bodybuilders.^[45] 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.^[46] Proteins are composed of amino acids, and a common concern with protein acquired from vegetable sources is an adequate intake of the essential amino acids, which cannot be synthesised by the human body. While dairy and egg products provide complete sources for ovo-lacto vegetarians, the only vegetable sources with significant amounts of all eight types of essential amino acids are lupin beans, soy, hempseed, chia seed, amaranth, buckwheat, peanut butter, and quinoa. However, the essential amino acids can also be obtained by eating a variety of complementary plant sources that, in combination, provide all eight essential amino acids (e.g. brown rice and beans, or hummus and whole wheat pita, though protein combining in the same meal is not necessary). A 1994 study found a varied intake of such sources can be adequate.^[47]

Iron[link]

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.^{[citation needed]} Vegetarian foods rich in iron include black beans, cashews, hempseed, kidney beans, lentils, oatmeal, raisins, spinach, black-eyed peas, soybeans, many breakfast cereals, sunflower seeds, chickpeas, tomato juice, tempeh, molasses, thyme, and whole-wheat bread.^[48] The related vegan diets can often be higher in iron than vegetarian diets, because dairy products are low in iron.^[44] Iron stores often tend to be lower in vegetarians than non-vegetarians, and a few small studies report very high rates of iron deficiency (up to 40%,^[49] and 58%^[50] of the respective vegetarian or vegan groups). However, the American Dietetic Association states that iron deficiency is no more common in vegetarians than non-vegetarians (adult males are rarely iron deficient); iron deficiency anaemia is rare no matter the diet.^[51]

[edit] Vitamin B₁₂

Plants are not sources of vitamin B₁₂. According to the United States National Institutes of Health, natural food sources of vitamin B₁₂ are limited to foods that come from animals.^[52] Lacto-ovo vegetarians can obtain B₁₂ from dairy products and eggs, and vegans can obtain it from fortified foods (including some soy products and some breakfast cereals) and dietary supplements.^{[53][54][55][56]} Vitamin B₁₂ can also be obtained from yeast extract products.^[57] The research on vitamin B₁₂ sources has increased in recent years.^[58]

The recommended dietary allowance of B₁₂ in the United States is, per day, 0.4 mcg (0–6 months), rising to 1.8 mcg (9–13 years), 2.4 mcg (14+ years), and 2.8 mcg (lactating female).^[52] The body can preserve stores of B₁₂ for up to 30 years,^[59] and reuses the vitamin without destroying the substance. Clinical evidence has shown a deficiency of B₁₂ in vegans and, to lesser degree, vegetarians.^[40][60]

Fatty acids[link]

Plant-based, or vegetarian, sources of Omega 3 fatty acids include soy, walnuts, pumpkin seeds, canola oil, kiwifruit and especially hempseed, algae, chia seed, flaxseed, echium seed and purslane. Purslane contains more Omega 3 than any other known leafy green. Plant foods can provide alpha-linolenic acid but not the long-chain n-3 fatty acids EPA and DHA, which are found in low levels in eggs and dairy products. 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.^{[61][clarification needed]} Recently, some companies have begun to market vegetarian DHA supplements containing seaweed extracts. Similar supplements providing both DHA and EPA have also begun to appear.^[62] 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 (GLA), alpha-linolenic acid (ALA), linoleic acid (LA), stearidonic acid (SDA), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and arachidonic acid (AA).^[63][64]

Calcium[link]

Calcium intake in vegetarians is similar to non-vegetarians. Some impaired bone mineralisation has been found among vegans who do not consume enough leafy greens, which are sources of abundant calcium.^[65] However, this is not found in lacto-ovo vegetarians.^[66] Some sources of calcium include collard greens, bok choy, kale, and turnip greens.^[67] Spinach, swiss chard and beet greens are high in calcium, but the calcium is bound to oxalate and therefore it is poorly absorbed.^[68]

Vitamin D[link]

Vitamin D needs can be met via the human body's own generation upon sufficient and sensible exposure to ultraviolet (UV) light in sunlight.^{[citation needed]} Products including milk, soy milk and cereal grains may be fortified to provide a source of Vitamin D^[69] For those who do not get adequate sun exposure and/or food sources, Vitamin D supplementation may be necessary.

[edit] Vitamin D₂

• Plantae
  • Alfalfa (Medicago sativa subsp. sativa), shoot: 4.8 mcg (192 IU) vitamin D₂, 0.1 mcg (4 IU) vitamin D₃^[70]
• Fungus, from USDA nutrient database^[71]:
  • Mushrooms, portabella, exposed to ultraviolet light, raw: Vitamin D (D₂ + D₃): 11.2 mcg (446 IU)
  • Mushrooms, portabella, exposed to ultraviolet light, grilled: Vitamin D (D₂ + D₃): 13.1 mcg (524 IU)
  • Mushrooms, shiitake, dried: Vitamin D (D₂ + D₃): 3.9 mcg (154 IU)
  • Mushrooms, shiitake, raw: Vitamin D (D₂ + D₃): 0.4 mcg (18 IU)
  • Mushrooms, portabella, raw: Vitamin D (D₂ + D₃): 0.3 mcg (10 IU)

Vitamin D₂, or ergocalciferol is found in fungus (except alfalfa which is a plantae) and created from viosterol, which in turn is created when ultraviolet light activates ergosterol (which is found in fungi and named as a sterol from ergot). Any UV-irradiated fungus including yeast form vitamin D₂.^[72] 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 to a vitamin D₂ supplement according to study.^[73] For example, Vitamin D₂ from UV-irradiated yeast baked into bread is bioavailable.^[74] By visual assessment or using a chromometer, no significant discoloration of irradiated mushrooms, as measured by the degree of "whiteness", was observed^[75] making it hard to discover if they have been treated without labeling. Claims have been made that a normal serving (approx. 3 oz or 1/2 cup, or 60 grams) of mushrooms treated with ultraviolet light increase their vitamin D content to levels up to 80 micrograms,^[76] or 2700 IU if exposed to just 5 minutes of UV light after being harvested.^[77]

Longevity[link]

A 1999 metastudy combined data from five studies from western countries.^[78] 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 (eat meat less than once per week) to be 0.84. Regular meat eaters and vegans shared the highest mortality ratio of 1.00. 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 [vegetarian] 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."^[78]

In "Mortality in British vegetarians",^[79] 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."^[80]

The Adventist Health Study is an ongoing study of 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.^[81]

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 (less than once per week) and other lifestyle choices significantly increase life expectancy, relative to a group with high meat intake.^[82] The study concluded that "The findings from one cohort of healthy adults raises the possibility that long-term (≥ 2 decades) 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.^[83]

A study by the Institute of Preventive and Clinical Medicine, and Institute of Physiological Chemistry looked at a group of 19 vegetarians (lacto-ovo) and used as a comparison a group of 19 omnivorous subjects recruited from the same region. The study found that this group of vegetarians (lacto-ovo) have a significantly higher amount of plasma carboxymethyllysine and advanced glycation endproducts (AGEs) compared to this group of non-vegetarians.^[84] Carboxymethyllysine is a glycation product which represents "a general marker of oxidative stress and long-term damage of proteins in aging, atherosclerosis and diabetes." "Advanced glycation end products (AGEs) may play an important adverse role in process of atherosclerosis, diabetes, aging and chronic renal failure."

Food safety[link]

E. coli contamination in food has been linked to industrial-scale meat and dairy farms.^[85] E. coli infections in the US during 2006 that were traced to spinach and onions were later determined to have been caused by a neighbouring cattle and wild pig farm whose feces had contaminated the water supply.^[86][87][88]

Transmission of pathogenic E. coli often occurs via fecal-oral transmission.^[89][90][91] Common routes of transmission include unhygienic food preparation^[90] and farm contamination.^[92][93][94] Dairy and beef cattle are primary reservoirs of the E. coli strain O157:H7,^[95] and they can carry it asymptomatically and shed it in their feces.^[95] Food products associated with E. coli outbreaks include raw ground beef,^[96] raw seed sprouts or spinach,^[92] raw milk, unpasteurized juice, and foods contaminated by infected food workers via fecal-oral route.^[90] In 2005, some people who had consumed triple-washed, pre-packaged lettuce were infected with E. coli.^[97] In 2007, packaged lettuce salads were recalled after they were found to be contaminated with E. coli.^[98] E. coli outbreaks have been traced to unpasteurised apples,^[99] orange juice, milk, alfalfa sprouts,^[100] and water.^[101]

Outbreaks of salmonella have been traced to peanut butter, frozen pot pies & puffed vegetable snacks.^[102] Bovine spongiform encephalopathy (BSE), also known as mad cow disease, is linked by the World Health Organization to Creutzfeldt–Jakob disease in humans.^[103]

There have been reports of fears of foot-and-mouth disease in sheep, PCBs in farmed salmon, mercury in fish, dioxin concentrations in animal products, artificial growth hormones, antibiotics, lead and mercury,^[104] pesticide contamination of vegetables and fruits, banned chemicals being used to ripen fruits.^{[105][106][107]}

Medical use[link]

In Western medicine, patients are sometimes advised to adhere to a vegetarian diet.^[108] Vegetarian diets have been used as a treatment for rheumatoid arthritis, but the evidence is inconclusive whether this is effective.^[109] Certain alternative medicines, such as Ayurveda and Siddha, prescribe a vegetarian diet as a normal procedure. Maya Tiwari notes that Ayurveda recommends small portions of meat for some people, though "the rules of hunting and killing the animal, practiced by the native peoples, were very specific and detailed". Now that such methods of hunting and killing are not observed, she does not recommend the use of "any animal meat as food, not even for the Vata types."^[110]

Physiology[link]

Humans are omnivorous, capable of consuming a wide variety of plant and animal material.^[111][112] Nutritional experts believe that early hominids evolved into eating meat as a result of huge climatic changes that took place three to four million years ago, when forests and jungles dried up and became open grasslands and opened hunting and scavenging opportunities.^[113][114]

Animal-to-human disease transmissions[link]

The consumption of meat can cause a transmission of a number of diseases from animals to humans.^[115] The connection between infected animal and human illness is well established in the case of salmonella; an estimated one-third to one-half of all chicken meat marketed in the United States is contaminated with salmonella.^[115] Only recently, however, have scientists begun to suspect that there is a similar connection between animal meat and human cancer, birth defects, mutations, and many other diseases in humans.^[115][116] The rate of disease among chickens is so high that the Department of Labor has ranked the poultry industry as one of the most hazardous occupations.^[115] 20% of all cows are afflicted with a variety of cancer known as bovine leukemia virus (BLV).^[115] Studies have increasingly linked BLV with HTLV-1, the first human retrovirus discovered to cause cancer.^[115] Scientists have found that a bovine immunodeficiency virus (BIV), the equivalent of the AIDS virus in cows, can also infect human cells.^[115] It is supposed that BIV may have a role in the development of a number of malignant or slow viruses in humans.^{[115][clarification needed]}