Veganism

Veganism is the practice of abstaining from the use of animal products, particularly in diet, as well as following an associated philosophy that rejects the commodity status of sentient animals. A follower of veganism is known as a vegan.

Distinctions are sometimes made between different categories of veganism. Dietary vegans (or strict vegetarians) refrain from consuming animal products, not only meat but, in contrast to ovo-lacto vegetarians, also eggs, dairy products and other animal-derived substances. The term ethical vegan is often applied to those who not only follow a vegan diet, but extend the vegan philosophy into other areas of their lives, and oppose the use of animals or animal products for any purpose. Another term used is environmental veganism, which refers to the avoidance of animal products on the premise that the harvesting or industrial farming of animals is environmentally damaging and unsustainable.

The term vegan was coined in 1944 by Donald Watson when he co-founded the British Vegan Society, at first to mean "non-dairy vegetarian" and later to refer to "the doctrine that man should live without exploiting animals." Interest in veganism increased in the 2000s; vegan food became increasingly available in supermarkets and restaurants in many countries, and several top athletes in endurance sports, such as the Ironman triathlon and the ultramarathon, began to practise veganism and raw veganism.

A 2009 review of recent research indicated that vegan diets tend to be higher in dietary fibre, magnesium, folic acid, vitamin C, vitamin E, iron and phytochemicals, and lower in calories, saturated fat, cholesterol, long-chain omega-3 fatty acids, vitamin D, calcium, zinc and vitamin B12. Well-planned vegan diets appear to offer protection against certain degenerative conditions, including heart disease, and as of 2013 were regarded as appropriate for all stages of the life-cycle by the American Dietetic Association, the Australian National Health and Medical Research Council, and Dietitians of Canada. Because uncontaminated plant foods do not provide vitamin B12 (which is produced by microorganisms such as bacteria), researchers agree that vegans should eat B12-fortified foods or take a supplement.

Coining the term vegetarian
Vegetarianism can be traced to Ancient India and Greece, but the word vegetarian came into use in English in the 19th century to refer to those who avoided meat. The Oxford English Dictionary attributes the earliest use of the word to the English actress Fanny Kemble (1809–1893), writing in Georgia in the United States in 1839. Vegetarians who also avoided eggs and dairy products, or avoided using animals for any purpose, were referred to as strict or total vegetarians.

There were several attempts in the 19th century to establish vegan/strict-vegetarian communities. In the United States in 1834 Amos Bronson Alcott (1799–1888), a transcendentalist and father of the novelist Louisa May Alcott (1832–1888), opened the Temple School in Boston, Massachusetts, on strict-vegetarian principles. In 1844 Alcott also founded Fruitlands, a community in Harvard, Massachusetts, that opposed the use of animals for any purpose, including farming, though it lasted only seven months.

In England in 1838 James Pierrepont Greaves (1777–1842) opened Alcott House in Ham, Surrey, a community that followed a strict-vegetarian diet. Members of Alcott House were involved in 1847 in forming the British Vegetarian Society, which held its first meeting in September 1847 at Northwood Villa in Ramsgate, Kent, chaired by Salford MP Joseph Brotherton (1783–1857).

Shift toward veganism
Vegetarians who were interested in the moral aspects of diet, rather than its implications for human health, began to discuss abstaining from animal use entirely. An 1851 article in the Vegetarian Society's magazine discussed alternatives to leather for shoes. In 1886 the society published A Plea for Vegetarianism by the English campaigner Henry Salt (1851–1939), which argued for vegetarianism as a moral imperative; Salt later became one of the first to make the paradigm shift from the promotion of animal welfare to the concept of animal rights. His work influenced Mahatma Gandhi (1869–1948) and the men became friends.

The first known British vegan cookbook, No Animal Food: Two Essays and 100 Recipes by Rupert H. Wheldon, appeared in London in 1910. Historian Leah Leneman (1944–1999) wrote that there was a vigorous correspondence between 1909 and 1912 among members of the Vegetarian Society about dairy products and eggs. One reader wrote: "You cannot have eggs without also having on your hands a number of male birds, which you must kill." The Vegetarian Society's position remained unresolved, but its journal noted in 1923 that the "ideal position for vegetarians is abstinence from animal products."

In November 1931 Gandhi addressed a Vegetarian Society meeting in London – attended by around 500 members, including Henry Salt – and argued in a speech called "The Moral Basis of Vegetarianism" that the society ought to promote a meat-free diet as a moral issue, not only in the interests of human health. Gandhi told the society he had found in his student days in London that vegetarians talked of nothing but food and disease:

I feel that this is the worst way of going about the business. I notice also that it is those persons who become vegetarians because they are suffering from some disease or other – that is, from purely the health point of view – it is those persons who largely fall back. I discovered that for remaining staunch to vegetarianism a man requires a moral basis.

Coining the term vegan, founding the Vegan Society
In 1935 the Vegetarian Society's journal observed that the issue of whether vegetarians ought to eat dairy products and eggs was becoming more pressing with every year. In July 1943 Leslie J. Cross, a member of the Leicester Vegetarian Society, expressed concern in its newsletter, The Vegetarian Messenger, that vegetarians were still consuming cow's milk. Cross echoed the argument about eggs, that to produce milk for human consumption the cow has to be separated from her calves soon after their birth: "in order to produce a dairy cow, heart-rending cruelty, and not merely exploitation, is a necessity."

In August 1944 some of the Vegetarian Society's members, including Donald Watson (1910–2005), asked the Vegetarian Society if they could have a section of the society's magazine to discuss non-dairy vegetarianism. They were told no, and so Watson wrote a letter to the magazine saying that he wanted to set up his own quarterly newsletter. In response, 30 readers sent him a shilling.

Watson issued the first newsletter in November 1944 and called it Vegan News (, with the stress on the first syllable); the word was composed of the first three and last two letters of vegetarian, which he said represented "the beginning and end of vegetarian." The newsletter was priced tuppence (two pennies, 2d), or one shilling (1/-) for a year's subscription. Watson asked readers if they had suggestions other than vegan to describe non-dairy vegetarian. They suggested allvega, neo-vegetarian, dairyban, vitan, benevore, sanivores and beaumangeur, but decided to stick with vegan. The new Vegan Society held its first annual meeting on 15 December 1945 at the Attic Club, High Holborn, London.

Two vegan books appeared around this time. The Leicester Vegetarian Society published Vegetarian Recipes without Dairy Produce, a booklet by Margaret B. Rawls, and in the summer of 1946 the Vegan Society published Vegan Recipes by Fay K. Henderson. In 1951 the Vegan Society broadened its definition of veganism to "the doctrine that man should live without exploiting animals," and pledged to seek an end to the use of animals "for food, commodities, work, hunting, vivisection and all other uses involving exploitation of animal life by man." In 1956 Leslie Cross founded the Plantmilk Society to explore how to produce a commercial soy milk, and as Plamil Foods Ltd it began production in 1965 of one of the first widely distributed soy milks in the Western world.

According to Joanne Stepaniak, the word vegan was independently published for the first time in 1962, in the Oxford Illustrated Dictionary, defined as "a vegetarian who eats no butter, eggs, cheese or milk." World Vegan Day, held every 1 November, was established in 1994 to mark the society's founding date.

Founding the American Vegan Society
The first vegan society in the United States was founded in 1948 by nurse and chiropractor Catherine Nimmo (1887–1985) of Oceano, California, and Rubin Abramowitz of Los Angeles. Originally from the Netherlands, Nimmo had been a vegan since 1931, and when the British Vegan Society was founded she began distributing its newsletter, The Vegan News, to her mailing list within the United States. In 1957 H. Jay Dinshah (1933–2000), the son of a Parsi from Mumbai, visited a slaughterhouse and read some of Watson's literature. He gave up all animal products, and on 8 February 1960 founded the American Vegan Society (AVS) in Malaga, New Jersey. He incorporated Nimmo's society and linked veganism to the concept of ahimsa, a Sanskrit word meaning "non-harming." The AVS called this "dynamic harmlessness" and named its magazine Ahimsa.

Achieving mainstream acceptance (2000s–2010s)
From the late 1970s, a group of scientists in the United States – physicians John A. McDougall, Caldwell Esselstyn, Neal D. Barnard, Dean Ornish and Michael Greger, and biochemist T. Colin Campbell – began to argue that diets based on animal fat and animal protein, such as the standard American diet, were detrimental to health. They proposed that a low-fat, plant-based diet would prevent, and might reverse, certain chronic diseases, such as coronary heart disease, diabetes and certain cancers. For Ornish, Campbell, Esselstyn and Barnard informally discussing veganism and health, see Freston, Kathy. Veganist: Lose Weight, Get Healthy, Change the World, Weinstein Publishing, 2011:
 * Dean Ornish on weight loss and reversing heart disease, p. 21ff.
 * T. Colin Campbell on cancer, heart disease and diabetes, p. 41ff.
 * Caldwell Esselstyn on heart disease, p. 57ff.
 * Neal D. Barnard on diabetes, p. 73ff.


 * Selection of articles:
 * Ventegodt, Soren and Merrick, Joav. "The Nobel Prize in Medicine should go to Dean Ornish", British Medical Journal, 29 December 2010.
 * Trapp, C.B. and Barnard, Neal D. "Usefulness of vegetarian and vegan diets for treating type 2 diabetes", Current Diabetes Reports, 10(2), April 2010.
 * Segelken, Roger. "China Study II: Switch to Western diet may bring Western-type diseases", Cornell Chronicle, 28 June 2001.
 * , Division of Nutritional Sciences, Cornell University, archived December 2002.
 * Campbell, T. Colin; Parpia B.; and Chen J. "Diet, lifestyle, and the etiology of coronary artery disease: the Cornell China study", American Journal of Cardiology, 82(10B), November 1998, pp. 18T-21T.
 * Campbell, T. Colin et al. "Medically supervised water-only fasting in the treatment of borderline hypertension", Journal of Alternative and Complementary Medicine, 8(5), October 2002, pp. 643–650.
 * Barnard, N.D. et al. "Vegetarian and vegan diets in type 2 diabetes management", Nutrition Reviews, 67(5), May 2009, pp. 255–263.
 * Ornish, Dean; Brown, S.E.; Scherwitz L.W. et al. "Can lifestyle changes reverse coronary heart disease? The Lifestyle Heart Trial", The Lancet, 336(8708), July 1990, pp. 129–133.
 * Ornish, Dean et al. "Effects of a vegetarian diet and selected yoga techniques in the treatment of coronary heart disease," Clinical Research, 27, 1979.
 * Esselstyn, Caldwell. "Updating a 12-year experience with arrest and reversal therapy for coronary heart disease (an overdue requiem for palliative cardiology)", American Journal of Cardiology, 84(3), August 1999, pp. 339–341.
 * McDougall, J. et al. "Effects of a Very Low-Fat, Vegan Diet in Subjects with Rheumatoid Arthritis", Journal of Alternative and Complementary Medicine, 8(1), February 2002, pp. 71–75.


 * Some of their books:
 * Ornish, Dean. Dean Ornish's Program for Reversing Heart Disease, Random House, 1990.
 * Campbell, T. Colin and Campbell, Thomas M. The China Study, BenBella Books, 2005.
 * Esselstyn, Caldwell. Prevent and Reverse Heart Disease: The Revolutionary, Scientifically Proven, Nutrition-Based Cure, Avery, 2007.
 * Barnard, Neal. Dr. Neal Barnard's Program for Reversing Diabetes, Random House, 2007. Dr. Sanjay Gupta, CNN's chief medical correspondent, said in his documentary The Last Heart Attack (2011) that T. Colin Campbell's The China Study (2005) had changed the way people all over the world eat, including Gupta himself.

In 2011 the Associated Press reported that in the United States the vegan diet was "moving from marginal to mainstream," with vegan books such as Skinny Bitch (2005) becoming best sellers. In a 2011 poll over half the 1,500 chefs polled said vegan entrees were becoming popular, and chain restaurants began to mark vegan items on their menus.

The interest in veganism in the 2010s was reflected in increased page views on Wikipedia. The English Wikipedia article on veganism was viewed 73,000 times in August 2009 but 145,000 times in August 2013; articles on veganism were viewed more during this period than articles on vegetarianism in the English, French, German, Portuguese, Russian and Spanish Wikipedias.

In 2010 the European Parliament adopted a food-labelling guideline that defined "vegan" (in force as of 2015): "The term 'vegan' shall not be applied to foods that are, or are made from or with the aid of, animals or animal products, including products from living animals." The first known vegetarian butcher shop, De Vegetarische Slager, opened in the Netherlands in 2010, selling "mock meats"; as of September 2011 there were 30 branches in the Netherlands and Belgium. Europe's first vegan supermarkets appeared in Germany in 2011. Vegilicious opened in Dortmund, and the first chain, Veganz, opened in Berlin and other locations; the latter planned to have 21 stores in Europe by the end of 2015. In 2013 the Oktoberfest in Munich – traditionally a meat-heavy affair – offered vegan dishes for the first time in its 200-year history.

Celebrities, athletes and politicians began to adopt vegan diets, some seriously, some part-time. Former US president Bill Clinton and vice-president Al Gore turned to veganism, Clinton in 2010 (part-time by 2013), and Gore in 2013. Oprah Winfrey tried it for 21 days and Dr. Mehmet Oz, a vegetarian, recommended it. The boxer Mike Tyson and businessmen William Clay Ford, Jr., Joi Ito, John Mackey, Russell Simmons, Biz Stone, Steve Wynn and Mortimer Zuckerman were all reported to have become dietary vegans in 2010. The idea of the "flexi-vegan" gained currency, to the irritation of ethical vegans; in his book VB6 (2013), New York Times food columnist Mark Bittman recommended sticking to a vegan diet before 6 pm.

Demographics (1996–present)
Surveys in the United States between 1996 and 2012 suggested that between 0.5 and three percent (1.5 to over nine million people) in that country were vegan. In 1996 three percent said they did not use animals for any purpose. A 2006 Harris Interactive poll suggested that 1.4 percent were dietary vegans; a 2008 survey for the Vegetarian Resource Group (VRG) reported 0.5 percent; a 2009 VRG survey said that it was one percent (two million out of a population of 313 million, or one in 150); and a 2012 Gallup poll reported two percent.

In Europe the Times of London estimated in 2005 that there were 250,000 vegans in the UK (out of a population of 60 million), in 2006 The Independent estimated 600,000, and in 2007 two percent of respondents in a British government survey self-identified as vegan. The British market for tofu and mock meats was £786.5 million a year in 2012. The Netherlands Association for Veganism estimated that there were 16,000 vegans in the Netherlands as of 2007, around 0.1 percent of the population. The German Vegetarian Society said in 2013 that there were 800,000 vegans in Germany (out of a population of nearly 82 million).

Avoidance
The issue that divided the 19th- and early 20th-century vegetarians – whether to avoid animal products for reasons of ethics or health – persists. Dietary vegans avoid consuming any animal products (no meat, fish, eggs or dairy products), but may use them in clothing and toiletries. Against this, ethical vegans see veganism as a philosophy. They reject the commodification of animals and will not use them for food, clothing, entertainment or any other purpose. The British Vegan Society will only certify a product if it is free of animal involvement as far as possible and practical, including animal testing.

Animal products include meat, poultry, seafood, eggs, dairy products, honey, fur, leather, wool and silk. Less well-known animal products are beeswax, bone char, bone china, carmine, casein, cochineal, gelatin, isinglass, lanolin, lard, rennet, shellac, tallow, whey and yellow grease. Many of these may not be identified in the list of ingredients in the finished product.

Ethical vegans will not use these products and will try to avoid anything tested on animals. They will not buy fur coats, leather shoes, cars with leather seats, woollen jumpers, silk scarves, camera film, bedding that contains goose down or duck feathers, and will not use certain vaccines; the production of the flu vaccine, for example, involves the use of chicken eggs. Depending on their circumstances, vegans may donate non-vegan items to charity or use them until they wear out. Alternatives to wool include acrylic, cotton, hemp, rayon and polyester. Some vegan clothes, in particular shoes and leather alternatives, are made of petroleum-based products, which has triggered criticism because of the environmental damage associated with production.

Milk, eggs, honey and silk
The main difference between a vegan and vegetarian diet is that vegans exclude eggs and dairy products; ethical vegans state that the production of eggs and dairy causes animal suffering and premature death. In both battery cage and free-range egg production, most male chicks are culled because they will not lay eggs and there is no financial incentive for a producer to keep them.

To obtain milk from dairy cattle, cows are kept pregnant through artificial insemination to prolong lactation. Male calves are slaughtered at birth, sent for veal production or reared for beef. Female calves are separated from their mothers within 24–48 hours of birth and fed milk replacer, so that the cow's milk is retained for human consumption. After about five years they are slaughtered to be made into ground-meat products, although they might otherwise live for 20 years. The situation is similar with goats and their kids.

There is disagreement among vegan groups about the extent to which products from insects should be avoided. Ethical vegans will not use silk, a protein obtained from silkworms. Most vegans also regard modern beekeeping as cruel and exploitative; once the honey (the bees' natural food store) is harvested, it is sometimes substituted with sugar or corn syrup to maintain the colony. Neither the Vegan Society nor the American Vegan Society considers the use of honey, silk or other insect products to be suitable for vegans, while Vegan Action and Vegan Outreach regard it as a matter of personal choice. Agave nectar is a popular vegan alternative to honey.

Common dishes and ingredients

 * Further information: Vegan recipes

Common vegan dishes include chilis and soups, ratatouille, falafel, hummus, veggie burritos, rice and beans, veggie stir-fry, veggie burgers, and various pasta dishes like pasta primavera.

Ingredients made from soybeans are a staple of vegan diets because soybeans are a complete protein. They are consumed most often in the form of soy milk and tofu (bean curd), which is soy milk mixed with a coagulant; tofu comes in a variety of textures, depending on water content, from firm, medium firm and extra firm for stews and stir-fries, to soft or silken for salad dressings, desserts and shakes. Soy is also eaten in the form of tempeh and texturized vegetable protein (TVP) (also known as textured soy protein, TSP); the latter is often used in pasta sauces.

The wheat-based seitan/gluten is another common source of plant protein. Meat analogues, or mock meats, also based on soy or gluten, come in the form of vegetarian sausage, vegetarian mince and veggie burgers, and are usually free of animal products.

Plant milk, ice-cream and cheese
Plant cream and plant milk – such as soy milk, almond milk, grain milk (oat milk and rice milk) and coconut milk – are used instead of cows' or goats' milk. The most widely available are soy and almond milk. Soy milk provides around 7 g of protein per cup (250 ml or 8 fluid ounces), compared with 8 g of protein per cup of cow's milk. Almond milk has fewer calories but less protein.

Like animal milk and meat, soy milk is a complete protein, meaning that it contains all the essential amino acids and can be relied upon entirely for protein intake. Soy milk alone should not be used as a replacement for breast milk for babies; babies who are not breastfed need commercial infant formula, which is normally based on cow's milk or soy (the latter is known as soy-based infant formula or SBIF).

Cheese analogues are made from soy, nuts and tapioca. Vegan cheeses like Chreese, Daiya, Sheese, Teese and Tofutti can replace both the taste and meltability of dairy cheese. Nutritional yeast is a common cheese substitute in vegan recipes. Cheese substitutes can be made at home, using recipes from Joanne Stepaniak's Vegan Vittles (1996), The Nutritional Yeast Cookbook (1997), and The Uncheese Cookbook (2003), and Mikoyo Schinner's Artisan Vegan Cheese (2012). One recipe for vegan brie involves combining cashews, soy yogurt and coconut oil. Butter can be replaced with a vegan margarine such as Earth Balance.

Egg replacements
Vegan (egg-free) mayonnaise brands include Vegenaise, Nayonaise, Miso Mayo, and Plamil's Egg-Free Mayo. Eggs are used in recipes as thickeners and binders; the protein in eggs thickens when heated and binds the other ingredients together. This effect can be achieved in vegan recipes with ground flax seeds; replace each egg in a recipe with one tablespoon of flaxseed meal mixed with three tablespoons of water. Commercial egg substitutes, such as Bob's Red Mill egg replacer and Ener-G egg replacer, are also available.

For vegan pancakes a tablespoon of baking powder can be used instead of eggs. Other ingredients include, to replace one egg, one tablespoon of soy flour and one tablespoon of water; a quarter cup of mashed bananas, mashed prunes or apple sauce; or in batter two tablespoons of white flour, half a tablespoon of vegetable oil, two tablespoons of water and half a tablespoon of baking powder. Silken (soft) tofu and mashed potato can also be used.

Vegan food groups
Since 1991 the Physicians Committee for Responsible Medicine (PCRM) has recommended a no-cholesterol, low-fat vegan diet based on what they call the Four New Food Groups: fruit, legumes, grains, and vegetables. Legumes include peas, beans, lentils and peanuts. PCRM recommends three or more servings a day of fruit (at least one of which is high in vitamin C, such as citrus fruit, melon or strawberries), two or more of protein-rich legumes (such as soybeans, which can be consumed as soy milk, tofu or tempeh), five or more of whole grains (such as corn, barley, rice and wheat, in products such as bread and tortillas), and four or more of vegetables (dark-green leafy vegetables such as broccoli, and dark-yellow and orange such as carrots or sweet potatoes).

The PCRM vegan food group was intended to replace the Four Food Groups – meat, milk, vegetables and fruit, and cereal and breads – recommended by the United States Department of Agriculture (USDA) from 1956 until 1992. In 1992 the USDA replaced its model with the food guide pyramid, and in 2011 with MyPlate, which is divided into five food groups: grains, vegetables, fruits, dairy, and protein (meat, poultry, seafood, beans and peas, eggs, processed soy products, nuts and seeds). In the UK the government recommends the eatwell plate, also with five food groups, which are consistent with veganism: fruits and vegetables; potatoes, bread and other starchy foods; dairy products (which can be swapped for vegan alternatives); meat, fish, eggs or beans for protein; and fat and sugar.

Protein
Proteins are composed of amino acids. Nutritionist Reed Mangels writes that omnivores generally obtain a third of their protein from plant foods, and ovo-lacto vegetarians a half. Vegans obtain all their protein from plant sources. A common question is whether plant protein supplies an adequate amount of the essential amino acids, which cannot be synthesized by the human body.

Sources of plant protein include legumes, such as soy beans (consumed as tofu, tempeh, texturized vegetable protein, soy milk and edamame), peas, peanuts, black beans and chickpeas (the latter often eaten as hummus); grains such as quinoa (pronounced keenwa), brown rice, corn, barley, bulgur and wheat (often eaten as whole-wheat bread and seitan); and nuts and seeds, such as almonds, hemp and sunflower seeds.

Soy beans and quinoa are known as complete proteins because they each contain all the essential amino acids. Mangels et al. write that consuming the recommended dietary allowance (RDA) of protein (0.8 g/kg body weight) in the form of soy will meet the biologic requirement for amino acids. They add that the United States Department of Agriculture has ruled that soy protein may replace meat protein in the Federal School Lunch Program.

Traditional combinations that contain high amounts of all the essential amino acids are rice and beans, corn and beans, and hummus and whole-wheat pita. The American Dietetic Association said in 2009 that a variety of plant foods consumed over the course of a day can provide all the essential amino acids for healthy adults, which means that protein combining in the same meal may not be necessary. Mangels et al. write that there is little reason to advise vegans to increase their protein intake, but erring on the side of caution (taking into account the lower digestibility and poorer amino acid pattern of plant protein), they would recommend a 25 percent increase over the RDA for adults, to 1.0 gram of protein per kilogram of body weight.

Vitamin B12
Vitamin B12 is a bacterial product needed for cell division, the formation and maturation of red blood cells, the synthesis of DNA, and normal nerve function. A deficiency can lead to several health problems, including megaloblastic anemia and nerve damage. The consensus among nutritionists is that vegans and even vegetarians should eat foods fortified with B12 or use supplements.Pawlak, R, et al. "How prevalent is vitamin B(12) deficiency among vegetarians?", Nutrition Reviews, 71(2), February 2013, pp. 110–117 (review article): "The main finding of this review is that vegetarians develop B12 depletion or deficiency regardless of demographic characteristics, place of residency, age, or type of vegetarian diet. Vegetarians should thus take preventive measures to ensure adequate intake of this vitamin, including regular consumption of supplements containing B12."
 * Mangels, Reed; Messina, Virginia; and Messina, Mark. The Dietitian's Guide to Vegetarian Diets. Jones & Bartlett Learning, 2011 (hereafter Mangels, Messina and Messina 2011), pp. 181–192.
 * Mangels, Reed. "Vitamin B12 in the Vegan Diet", Vegetarian Resource Group, accessed 17 December 2012: "Vitamin B12 is needed for cell division and blood formation. Neither plants nor animals make vitamin B12. Bacteria are responsible for producing vitamin B12. Animals get their vitamin B12 from eating foods contaminated with vitamin B12 and then the animal becomes a source of vitamin B12. Plant foods do not contain vitamin B12 except when they are contaminated by microorganisms or have vitamin B12 added to them. Thus, vegans need to look to fortified foods or supplements to get vitamin B12 in their diet."
 * "Vitamin B12", Office of Dietary Supplements, National Institutes of Health, accessed 17 December 2012.
 * Norris, Jack. "Vitamin B12: Are you getting it?", Vegan Outreach, 26 July 2006: "Contrary to the many rumors, there are no reliable, unfortified plant sources of vitamin B12 ... [There is an] overwhelming consensus in the mainstream nutrition community, as well as among vegan health professionals, that vitamin B12 fortified foods or supplements are necessary for the optimal health of vegans, and even vegetarians in many cases. Luckily, vitamin B12 is made by bacteria such that it does not need to be obtained from animal products."
 * Herbert, Victor. "Vitamin B12: plant sources, requirements and assay", American Journal of Clinical Nutrition, 48(3), September 1988, pp. 852–858. That vegans are unable in most cases, at least in the West, to obtain B12 from a plant-based diet is often used as an argument against veganism.

Neither plants nor animals make B12; it is produced by microorganisms, such as bacteria, fungi and algae. Herbivorous animals obtain it from bacteria in their rumens, either by absorbing it or by eating their own cecotrope faeces; rabbits, for example, produce and eat cecal pellets. When those animals are eaten, they become sources of B12. Plants from the ground that are not washed properly may contain B12 from bacteria in the soil, often from faeces; drinking water may also be contaminated with B12-producing bacteria, particularly in the developing world. Mangels et al. write that bacteria in the human digestive tract produce B12, but most of it is not absorbed and is expelled in the faeces, with tiny amounts also expelled in the urine. James Halsted, a medical researcher, reported in the 1960s that a group of villagers in Iran eating very little or no animal protein were found to have normal B12 levels because they were living with animal manure near their homes, and were eating vegetables grown in human manure (known as night soil) and not thoroughly washed. The human mouth is another source of B12, but in small amounts and possibly analogue (not biologically active).

Western vegan diets are likely to be deficient in B12 because of increased hygiene. Vegans can obtain B12 by taking a supplement or by eating fortified foods, such as fortified soy milk or cereal, where it may be listed as cobalamin or cyanocobalamin. B12 supplements are produced industrially through bacterial fermentation-synthesis; no animal products are involved in that process. The RDA for adults (14+ years) is 2.4 mcg (or µg) a day, rising to 2.4 and 2.6 mcg for pregnancy and lactation respectively; 0.4 mcg for 0–6 months, 0.5 mcg for 7–12 months, 0.9 mcg for 1–3 years, 1.2 mcg for 4–8 years, and 1.8 mcg for 9–13 years.

There is some disagreement within the vegan community as to whether supplementation is needed; several studies of vegans who did not take supplements or eat fortified food, including in Western countries, have found no sign of B12 deficiency. According to Mangels et al., the disagreement is caused in part by the lack of a gold standard for assessing B12 status, and also because there are very few studies of long-term vegans who have not used supplements or fortified foods. There are reports that certain plant foods are sources of B12; fermented foods such as tempeh and miso, as well as edible seaweed (such as arame, wakame, nori, and kombo), spirulina, and certain greens, grains and legumes, have been cited as B12 sources, as has rainwater. According to Mangels et al., tiny amounts have been found in barley malt syrup, shiitake mushrooms, parsley and sourdough bread, and higher amounts in spirulina and nori, but these products may be sources of inactive B12. They write that all Western vegans not using supplements or eating fortified foods will probably develop a B12 deficiency, although it may take decades to appear.

Calcium
Calcium is needed to maintain bone health, and for a number of metabolic functions, including muscle function, vascular contraction and vasodilation, nerve transmission, intracellular signalling and hormonal secretion. Ninety-nine percent of the body's calcium is stored in the bones and teeth. The RDA is 200 mg for 0–6 months, 260 mg for 7–12 months, 700 mg for 1–3 years, 1,000 mg for 4–8 years, 1,300 mg for 9–18 years, 1,000 mg for 19–50 years, 1,000 mg for 51–70 years (men) and 1,200 mg (women), and 1,200 mg for 71+ years.

Vegans are advised to eat three servings per day of a high-calcium food, such as fortified soy milk, fortified tofu, almonds or hazelnuts, and to take a supplement as necessary. Plant sources include broccoli, turnip and cabbage, such as Chinese cabbage (bok choi) and kale; the bioavailability of calcium in spinach is poor. Whole-wheat bread contains calcium; grains contain small amounts. Because vitamin D is needed for calcium absorption, vegans should make sure they also consume enough vitamin D (see below).

The EPIC-Oxford study suggested that vegans have an increased risk of bone fractures over meat eaters and vegetarians, likely because of lower dietary calcium intake, but that vegans consuming more than 525 mg/day have a risk of fractures similar to that of other groups. A 2009 study of bone density found the bone mineral density (BMD) of vegans was 94 percent that of omnivores, but deemed the difference clinically insignificant. Another study in 2009 by the same researchers examined over 100 vegan post-menopausal women, and found that their diet had no adverse effect on BMD and no alteration in body composition. Biochemist T. Colin Campbell suggested in The China Study (2005) that osteoporosis is linked to the consumption of animal protein; he argued that, unlike plant protein, animal protein increases the acidity of blood and tissues, which is then neutralized by calcium pulled from the bones.

Vitamin D
Vitamin D (calciferol) is needed for a number of functions, including calcium absorption, enabling mineralization of bone, and bone growth. Without it bones can become thin and brittle; together with calcium it offers protection against osteoporosis. Mangels writes that it may also play a role in protecting against heart disease, diabetes, colon cancer, multiple sclerosis and dementia. Vitamin D is produced in the body when ultraviolet rays from the sun hit the skin; outdoor exposure is needed because UVB radiation does not penetrate glass. It is present in very few foods (mostly salmon, tuna, mackerel, cod liver oil, with small amounts in cheese, egg yolks and beef liver, and in some mushrooms).

Most vegan diets contain little or no vitamin D, unless the food is fortified (such as fortified soy milk), so supplements may be needed depending on exposure to sunlight. Vitamin D comes in two forms. Cholecalciferol (D3) is synthesized in the skin after exposure to the sun and may be consumed in the form of animal products; when produced industrially it is taken from lanolin in sheep's wool. Ergocalciferol (D2) is suitable for vegans; it is mostly human-made and is derived from ergosterol from yeast. Several conflicting studies have suggested that the two forms may or may not be bioequivalent. According to a 2011 report by the Food and Nutrition Board of the National Academy of Sciences, the differences between D2 and D3 do not affect metabolism, both function as prohormones, and when activated exhibit identical responses in the body.

Supplements should be used with caution because vitamin D can be toxic, especially in children. The RDA is 10 mcg for 0–12 months, 15 mcg for 1–70 years, and 20 mcg for 70+. People with little or no sun exposure may need more, perhaps up to 25 mcg daily. The daily tolerable upper intake level (daily) for 9 years to adulthood is 100 mcg, according to the National Institutes of Health; for children it is 25 mcg for 0–6 months, 38 mcg for 7–12 months, 63 mcg for 1–3 years, and 75 mcg for 4–8 years.

The extent to which sun exposure is sufficient to meet the body's needs will depend on the time of day, cloud and smog cover, skin melanin content, whether sunscreen is worn, and the season. According to the US National Institutes of Health, most people can obtain and store sufficient vitamin D from sunlight in the spring, summer and fall months, even in the far north. They report that some researchers recommend 5–30 minutes of sun exposure without sunscreen between ten in the morning and three o'clock in the afternoon, at least twice a week. They also report that tanning beds emitting 2–6 per cent UVB radiation will have a similar effect, though tanning may be inadvisable for other reasons.

Iron
Vegetarian and vegan diets usually contain as much iron as animal-based diets, or more; vegan diets generally contain more iron than vegetarian ones because dairy products contain very little. There are concerns about the bioavailability of iron from plant foods, assumed by some researchers to be around 5–15 percent compared to 18 percent from a nonvegetarian diet. Iron deficiency anaemia is found as often in nonvegetarians as in vegetarians, though studies have shown vegetarians' iron stores to be lower.

The RDA for nonvegetarians is 11 mg for 7–12 months, 7 mg for 1–3 years, 10 mg for 4–8 years, and 8 mg for 9–13 years. The RDA then changes for men and women to 11 mg for 14–18 years (men) and 15 mg for 14–18 years (women), 8 mg for 19–50 years (men) and 18 mg for 19–50 years (women). It returns to 8 mg for 51+ years (men and women). Mangels writes that because of the lower bioavailability of iron from plant sources, the Food and Nutrition Board of the National Academy of Sciences established a separate RDA for vegetarians and vegans of 14 mg for vegetarian men and postmenopausal women, and 33 mg for premenopausal women not using oral contraceptives. Supplements should be used only with caution after consulting a physician, because iron can accumulate within the body and cause damage to organs; this is particularly true of anyone suffering from hemochromatosis, a relatively common condition that can remain undiagnosed. The daily tolerable upper intake level, according to the National Institutes of Health, is 40 mg for 7 months to 13 years, and 45 mg for 14+.

According to the Vegetarian Resource Group, high-iron foods suitable for vegans include black-strap molasses, lentils, tofu, quinoa, kidney beans and chickpeas. Tom Sanders, a nutritionist at King's College London, writes that iron absorption can be enhanced by eating a source of vitamin C along with a plant source of iron, and by avoiding coingesting anything that would inhibit absorption, such as tannin in tea. Sources of vitamin C might be half a cup of cauliflower, or five fluid ounces of orange juice, consumed with a plant source of iron such as soybeans, tofu, tempeh, or black beans. Some herbal teas and coffee can also inhibit iron absorption, as can spices that contain tannins (turmeric, coriander, chillies, and tamarind).

Omega-3 fatty acids
Alpha-linolenic acid (ALA), an omega-3 fatty acid, is found in leafy green vegetables and nuts, and in vegetable oils such as canola and flaxseed oil. The Adequate Intake for ALA is 1.1–1.6 g/day. Vegan Outreach suggests vegans take 1/4 teaspoon of flaxseed oil (also known as linseed oil) daily, and use oils containing low amounts of omega-6 fatty acids, such as olive, canola, avocado or peanut oil.

Iodine
Iodine supplementation may be necessary for vegans in countries where salt is not typically iodized, where it is iodized at low levels, or where, as in Britain and Ireland, dairy products are relied upon for iodine delivery because of low levels in the soil. Iodine can be obtained from most vegan multivitamins or from regular consumption of seaweeds, such as kelp. The RDA is 110 mcg (0–six months), 130 mcg (7–12 months), 90 mcg (1–8 years), 120 mcg (9–13 years), 150 mcg (14+). The RDA for pregnancy and lactation is 220 and 290 mcg respectively.

Health arguments
As of the 2000s, there was growing scientific consensus that a plant-based diet reduces the risk of a number of degenerative diseases, including coronary artery disease, diabetes, cancer, osteoporosis, kidney disease and dementia. Note that several sources use the word vegetarian to refer to an entirely plant-based diet:
 * Leitzmann, Claus. "Vegetarian diets: what are the advantages?", Forum of Nutrition, 57, 2005, pp. 147–156 (review article): "A growing body of scientific evidence indicates that wholesome vegetarian diets offer distinct advantages compared to diets containing meat and other foods of animal origin. The benefits arise from lower intakes of saturated fat, cholesterol and animal protein as well as higher intakes of complex carbohydrates, dietary fiber, magnesium, folic acid, vitamin C and E, carotenoids and other phytochemicals. ... In most cases, vegetarian diets are beneficial in the prevention and treatment of certain diseases, such as cardiovascular disease, hypertension, diabetes, cancer, osteoporosis, renal disease and dementia, as well as diverticular disease, gallstones and rheumatoid arthritis."
 * Craig, Winston J. "Health effects of vegan diets", The American Journal of Clinical Nutrition, 89(5), May 2009, pp. 1627S–1633S (review): "Vegans tend to be thinner, have lower serum cholesterol, and lower blood pressure, reducing their risk of heart disease ... A vegan diet appears to be useful for increasing the intake of protective nutrients and phytochemicals and for minimizing the intake of dietary factors implicated in several chronic diseases."
 * Sabaté, J. "The contribution of vegetarian diets to health and disease: a paradigm shift?", American Journal of Clinical Nutrition, 78(3 Suppl), September 2003, pp. 502S–507S (review): "Diets largely based on plant foods, such as well-balanced vegetarian diets, could best prevent nutrient deficiencies as well as diet-related chronic diseases."
 * Nestle, M. "Animal v. plant foods in human diets and health: is the historical record unequivocal?", Proceedings of the Nutrition Society, 58(2), May 1999, pp. 211–218 (review): "This shift has led to increasing scientific consensus that eating more plant foods but fewer animal foods would best promote health. This consensus is based on research relating dietary factors to chronic disease risks, and to observations of exceptionally low chronic disease rates among people consuming vegetarian, Mediterranean and Asian diets. ... Most evidence suggests that a shift to largely plant-based diets would reduce chronic disease risks among industrialized and rapidly-industrializing populations."
 * Key, Timothy J., Appleby, Paul N., and Rosell, M.S. "Health effects of vegetarian and vegan diets", Proceedings of the Nutrition Society, 65(1), February 2006, pp. 35–41 (review).
 * Ströhle, A. et al. "Vegetarian nutrition: Preventive potential and possible risks. Part 1: Plant foods", Wien Klin Wochenschr, 118(19–20), October 2006, pp. 580–593 (review).
 * Van Horn, L. et al. "The evidence for dietary prevention and treatment of cardiovascular disease", Journal of the American Dietetic Association, 108(2), February 2008, pp. 287–331 (systematic review).
 * "Building healthy eating patterns", Dietary Guidelines for Americans, United States Department of Agriculture, 2010, p. 45: "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 (in particular, saturated fatty acids); fewer overall calories; and more fiber, potassium, and vitamin C than do non-vegetarians. In general, vegetarians 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." According to nutritionist Winston Craig, writing in 2009, vegan diets tend to be higher in dietary fibre, magnesium, folic acid, vitamin C, vitamin E, iron and phytochemicals, and lower in calories, saturated fat, cholesterol, long-chain omega-3 fatty acids, vitamin D, calcium, zinc and vitamin B12. He wrote that vegans tend to be thinner, with lower serum cholesterol and lower blood pressure. Craig added that eliminating all animal products increases the risk of nutritional deficiencies; of particular concern are vitamins B12 and D, calcium and omega-3 fatty acids. He advised vegans to eat foods fortified with these nutrients or to take supplements, and warned that iron and zinc may also be problematic because of limited bioavailability.

The American Dietetic Association and Dietitians of Canada said in 2003 that properly planned vegan diets were nutritionally adequate for all stages of life, including pregnancy and lactation. People avoiding meat are reported to have lower body mass index; from this follows lower death rates from ischemic heart disease, lower blood cholesterol levels, lower blood pressure, and fewer incidences of type 2 diabetes, prostate and colon cancers. In 2013 the Australian National Health and Medical Research Council also recognized a well-planned vegan diet as a viable option for people of any age; they recommended that vegans eat B12-fortified foods or take supplements. As of 2006 and 2011 respectively, the Swiss Federal Nutrition Commission and the German Society for Nutrition did not recommend a vegan diet, and cautioned against it for children, the pregnant and the elderly.

Between 1980 and 1984 the Oxford Vegetarian Study recruited 11,000 subjects (6,000 vegetarians and a control group of 5,000 non-vegetarians) and followed up after 12 years. The study indicated that vegans had lower total- and LDL-cholesterol concentrations than the meat-eaters, and that death rates were lower in the non-meat eaters. The authors wrote that mortality from ischemic heart disease was positively associated with higher dietary cholesterol levels and the consumption of animal fat. They also wrote that the non-meat-eaters had half the risk of the meat eaters of requiring an emergency appendectomy, and that vegans in the UK may be prone to iodine deficiency.

A 1999 meta-analysis of five studies comparing mortality rates in Western countries found that mortality from ischemic heart disease was 26 percent lower in vegans than in regular meat-eaters. This was compared to 20 percent lower in occasional meat eaters, 34 percent lower in pescetarians (those who ate fish but no other meat), and 34 percent lower in ovo-lacto vegetarians (those who ate no meat, but did consume animal milk and eggs). No significant difference in mortality from other causes was found between vegetarian/vegan and non-vegetarian diets. In 2010 a 15-year survey in the UK that examined the association between diet and age-related cataracts found that vegans had a 40 percent lower risk than the biggest meat eaters; it found a "progressive decrease in risk of cataract in high meat eaters to low meat eaters, fish eaters (participants who ate fish but not meat), vegetarians, and vegans."

The American Dietetic Association indicated in 2003 that vegetarian diets may be more common among adolescents with eating disorders, but that the adoption of a vegetarian diet may serve to camouflage an existing disorder, rather than cause one. Other studies supported that conclusion.

Pregnancy, babies and children
As of 2003 the American Dietetic Association and Dietitians of Canada considered well-planned vegan diets "appropriate for all stages of the life cycle, including during pregnancy, lactation, infancy, childhood and adolescence." The Swiss Federal Nutrition Commission and the German Society for Nutrition cautioned against a vegan diet for pregnant women and children as of 2006 and 2011 respectively. The American Dietetic Association added that a regular source of B12 is crucial for pregnant, lactating and breastfeeding women. According to Reed Mangels, maternal stores of B12 appear not to cross the placenta, and researchers have reported cases of vitamin B12 deficiency in lactating vegetarian mothers that were linked to deficiencies and neurological disorders in their children. Pregnant vegans may also need to take extra vitamin D, depending on their exposure to sunlight and whether they are eating fortified foods. Doctors may recommend iron supplements and folic acid for all pregnant women (vegan, vegetarian and non-vegetarian). A doctor or registered dietitian should be consulted about taking supplements during pregnancy.

During the 2000s, newspapers reported several cases of malnutrition in children whose parents said they were vegan. A 12-year-old girl in Scotland who had eaten no meat or dairy since birth was found in 2008 to be suffering from rickets (caused by a lack of vitamin D), and had several fractures. In 2000, in London, a nine-month-old girl died after her vegan mother fed her a fruitarian diet of raw fruit and nuts. In 2004, in Atlanta, a six-week-old boy died after his vegan parents appear to have fed him mostly apple juice and soy milk; the prosecution argued that the case was not about veganism, but that the child had simply not been fed.

Vegan toiletries
The British Vegan Society criteria for vegan certification are that the product contain no animal products, and that neither the product nor its ingredients have been tested on animals by the manufacturer, by others on behalf of the manufacturer, or by anyone over whom the manufacturer has control. The society's website contains a list of certified companies and products. Beauty Without Cruelty is well-known within the vegan community as a manufacturer of vegan toiletries and cosmetics. Animal Aid in the UK sells vegan toiletries and other products online, as does Honesty Cosmetics. Kiss My Face sells a range of vegan toiletries in the United States, Canada and the UK. Lush is based in a number of countries and sells products online; the company says that 83 percent of its products are vegan. Haut Minerals in Canada make a range of vegan products, including a vegan BB cream. In South Africa, Esse Organic Skincare is one of several companies certified by Beauty Without Cruelty. The Choose Cruelty Free website in Australia lists vegan products available there.

Because animal ingredients are cheap, they are ubiquitous in toiletries. After animals are slaughtered for meat, the leftovers (bones, brains, eyes, spines and other parts) are put through the rendering process, and some of that material, especially the fats, ends up in toiletries and cosmetics. Vegans often refer to Animal Ingredients A to Z (2004) to check which ingredients might be animal-derived. Common animal products in toiletries include tallow in soap, and glycerine (derived from collagen), which is used as a lubricant and humectant in haircare products, moisturizers, shaving foam, soap and toothpaste; there is a plant-based form but the glycerine in most products is probably animal-based. Lanolin, from sheep's wool, is another common ingredient, found in lip balm and moisturizers, as is stearic acid, used in face creams, shaving foam and shampoos; as with glycerine, there is a plant-based form of stearic acid, but most mainstream manufacturers use the animal-derived form. Lactic acid, an alpha-hydroxy acid derived from animal milk, is often found in moisturizers, as is allantoin, derived from the comfrey plant or cow's urine, and found in shampoos, moisturizers and toothpaste.

Arguments
Ethical veganism is based on opposition to speciesism, the assignment of different values to individuals on the basis of their species membership alone. Carol J. Adams, the vegan-feminist writer, has used the concept of the absent referent to describe the detachment between the consumer and the consumed:

"Behind every meal of meat is an absence: the death of the animal whose place the meat takes. The 'absent referent' is that which separates the meat eater from the animal and the animal from the end product. The function of the absent referent is to keep our 'meat' separated from any idea that she or he was once an animal, to keep the 'moo' or 'cluck' or 'baa' away from the meat, to keep something from being seen as having been someone.'"

There is a division within animal rights theory between a rights-based or deontological approach and a utilitarian one, which is reflected in the debate about the moral basis of veganism. Tom Regan, professor emeritus of philosophy at North Carolina State University, is a rights theorist who argues that animals possess inherent value as "subjects-of-a-life" – because they have beliefs and desires, an emotional life, memory, and the ability to initiate action in pursuit of goals – and must therefore be viewed as ends in themselves, not as a means to an end. He argues that the right of subjects-of-a-life not to be harmed can be overridden only when outweighed by other valid moral principles, but that the reasons cited for eating animal products – pleasure, convenience and the economic interests of farmers – are not weighty enough to override the animals' moral rights.

Gary L. Francione, professor of law at Rutgers School of Law-Newark, is also a rights theorist. He argues that "all sentient beings should have at least one right – the right not to be treated as property," and that adopting veganism must be the unequivocal baseline for anyone who sees nonhuman animals as having intrinsic moral value:

"We all believe it's wrong to inflict unnecessary suffering and death on animals. ... So now the next question becomes 'what do we mean by necessity?' Well, whatever it means, whatever abstract meaning it has, if it has any meaning whatsoever, its minimal meaning has to be that it's wrong to inflict suffering and death on animals for reasons of pleasure, amusement or convenience – because if it's all right to inflict suffering and death on animals for reasons of pleasure, amusement or convenience, then you've got a loophole that's now so large you could drive a truck through it. So if the moral notion that we all accept, if that has any meaning, then it has got to be the case that we can't inflict suffering and death on animals for reasons of pleasure, amusement or convenience. Okay. Problem is 99.9999999 percent of our animal use can only be justified by reasons of pleasure, amusement or convenience. It's gotta go. If we mean what we say ... we have no choice. Veganism is the only rational, logical response ...'"

He argues that the pursuit of improved conditions for animals, rather than the abolition of animal use, is like campaigning for "conscientious rapists" who will rape their victims without beating them. The pursuit of animal welfare does not move us away from the paradigm of animals qua property, and serves only to make people feel comfortable about using them.

Debate about the "Paris exemption"
Peter Singer, professor of bioethics at Princeton University, argues from a utilitarian perspective that there is no moral or logical justification for refusing to count animal suffering as a consequence when making ethical decisions, and that sentience is "the only defensible boundary of concern for the interests of others." He argues that killing animals should be rejected unless necessary for survival. Unlike Francione, Singer is not concerned about what he calls trivial infractions of vegan principles. He supports what is known as the "Paris exemption": if you find yourself in a fine restaurant, allow yourself to eat what you want, and if you have no access to vegan food, go vegetarian.

Singer's support for the "Paris exemption" is reflected within the animal rights movement by the divide between the protectionist side (represented by Singer and PETA), according to which incremental change can achieve reform, and the abolitionist side (represented by Regan and Francione), according to which apparent welfare reform serves only to persuade the public that animal use is morally unproblematic. Bruce Friedrich of Farm Sanctuary, a protectionist, argued in 2006 that strict adherence to veganism can become an obsession:

"[W]e all know people whose reason for not going vegan is that they 'can't' give up cheese or ice cream. ... Instead of encouraging them to stop eating all other animal products besides cheese or ice cream, we preach to them about the oppression of dairy cows. ... [W]e've preserved our personal purity, but we've hurt animals – and that's anti-vegan."

Francione writes that this is similar to arguing that, because human rights abuses can never be eliminated, we should not safeguard human rights in situations we control. By failing to ask a server whether something contains animal products, in the interest of avoiding a fuss, he argues that we reinforce the idea that the moral rights of animals are a matter of convenience. He concludes from this that the protectionist position fails even on its own consequentialist terms.

Resources and the environment
Environmental vegans focus on conservation rather than animal rights: they reject the use of animal products on the premise that practices such as farming – particularly factory farming – fishing, hunting and trapping are environmentally unsustainable. One example of an environmental vegan is Paul Watson of the Sea Shepherd Conservation Society, the marine conservation direct-action group. He told the Guardian in 2010 that all Sea Shepherd ships are vegan for environmental reasons: "Forty percent of the fish caught from the oceans is fed to livestock – pigs and chickens are becoming major aquatic predators. The livestock industry is one of the greatest contributors to greenhouse gas emissions ever. The eating of meat is an ecological disaster ... We're promoting veganism not for animal-rights reasons but for environmental conservation reasons."

In November 2006, the United Nations Food and Agriculture Organization released Livestock's Long Shadow, a report that linked animal agriculture to environmental damage. It concluded that livestock farming (primarily of cows, chickens and pigs) has an impact on almost all aspects of the environment: air, land, soil, water, biodiversity and climate change. It concluded that livestock account for 9 percent of total carbon dioxide emissions, 37 percent of methane, 65 percent of nitrous oxide, and 68 percent of ammonia; livestock waste emits 30 million tonnes of ammonia a year, which the report said is involved in the production of acid rain.

In June 2010 a report from the United Nations Environment Programme declared that a move toward a vegan diet is needed to save the world from hunger, fuel shortages and climate change. It said that agriculture, particularly the production of meat and dairy products, accounts for 19 percent of the world's greenhouse gas emissions, 38 percent of land use and 70 percent of freshwater consumption.

Greenhouse gas emissions are not limited to animal husbandry. Plant agriculture such as rice cultivation can also cause environmental problems. A 2007 Cornell University study that simulated land use for various diets for New York State concluded that, although vegetarian diets used the smallest amount of land per capita, a low-fat diet that included some meat and dairy – less than 2 oz of meat/eggs per day, significantly less than that consumed by the average American – could support slightly more people on the same available land than could be fed on some high-fat vegetarian diets, since animal food crops are grown on lower-quality land than are crops for human consumption.

Debate about animals killed in crop harvesting
Steven Davis, a professor of animal science at Oregon State University, asked Tom Regan in 2001 what the difference was between killing a field mouse while cultivating crops, and killing a pig for the same reason, namely so that human beings could eat. Regan responded with what Davis called the "Least Harm Principle," according to which we must choose the food products that, overall, cause the least harm to the least number of animals. Davis argued that a plant-based diet would kill more than one containing beef from grass-fed ruminants.

Andy Lamey, a philosopher at Monash University, calls this the "burger vegan" argument, namely that if human beings were to eat cows raised on a diet of grass, not grain, fewer animals would be killed overall, because the number of mice, rats, raccoons and other animals killed during the harvest outnumbers the deaths involved in raising cows for beef.

Based on a study finding that wood mouse populations dropped from 25 to five per hectare after harvest (attributed to migration and mortality), Davis estimated that 10 animals per hectare are killed from crop farming every year. He argued that if all 120000000 acre of cropland in the continental United States were used for a vegan diet, approximately 500 million animals would die each year. But if half the cropland were converted to ruminant pastureland, he estimated that only 900,000 animals would die each year – assuming people switched from the eight billion poultry killed each year to beef, lamb and dairy products. Therefore, he argued, according to the least-harm principle we should convert to a ruminant-based diet rather than a plant-based one.

Davis's analysis was criticized in 2003 by Gaverick Matheny in the Journal of Agricultural and Environmental Ethics. Matheny argued that Davis had miscalculated the number of animal deaths, based his figures on land area rather than per consumer, and had confined his analysis to grass-fed ruminants, rather than factory-farmed animals. He wrote that Davis had also equated lives with lives worth living, focusing on numbers rather than including in his calculations the harm done to animals raised for food, which can involve pain from branding, dehorning and castration, a life of confinement, transport without food or water to a slaughterhouse, and a frightening death. Matheny argued that vegetarianism "likely allows a greater number of animals with lives worth living to exist."

Andy Lamey further argued that Davis's calculation of harvest-related deaths was flawed based on two studies. One study included deaths from predation, which Lamey wrote are morally unobjectionable for Regan because they are not related to human action. The other study examined production of a nonstandard crop (sugarcane), which Lamey wrote has little relevance to deaths associated with typical crop production. Lamey also maintained, like Matheny, that accidental deaths are ethically distinct from intentional ones, and that if Davis includes accidental animal deaths in the moral cost of veganism, he must also include the accidental human deaths caused by his proposed diet, which, Lamey wrote, leaves "Davis, rather than Regan, with the less plausible argument."