Table of Contents


Vegetarianism refers to the practice of excluding meat, poultry, and fish from the diet. The word was coined in 1847, when the Vegetarian Society of the United Kingdom—the oldest organized vegetarian group in the world—was founded in Ramsgate, Kent. The Society, which has included George Bernard Shaw and Mahatma Gandhi among its members, chose the word vegetarian for its name because it is derived from

Vegetarian diet

ServingsFoodsCalcium-rich foods
Fats (2 servings)1 tsp. oil, mayonnaise, soft margarine 
Fruits (2 servings)1 med. piece of fruit
½ cooked or cut-up fruit
½ cup fruit juice
¼ cup dried fruit
½ cup fortified fruit juice
Vegetables (4 servings)½ cup cooked vegetables
1 cup of raw vegetables
½ cup vegetable juice
1 cup cooked or 2 cups raw bok choy, broccoli, collards,
Chinese cabbage, kale, mustard greens or okra
½ cup fortified tomato juice
Legumes, nuts, and other protein-rich foods (5 servings)½ cup cooked beans, peas or lentils
½ cup tofu or tempeh
2 tbsp. nut or seed butter
1 egg
½ cup cow's milk or yogurt or fortified soy milk
¾ oz. cheese
½ cup tempeh or calcium-set tofu
½ cup cooked soybeans
¼ cup soynuts
Grains (6 servings)1 slice bread
½ cup cooked grain or cereal
1 oz. ready to eat cereal
1 oz. calcium-fortified cereal

Based on the 2003 American Dietetic Association pyramid and the Dietitians of Canada rainbow. The recommended servings and foods are intended to accommodate the needs of vegans as well as those of less strict vegetarians. (Illustration by GGS Information Services/Thomson Gale.)

the Latin vegetus, which means “lively” or “vigorous,” and because it suggests the English word vegetable. Vegetarianism is better understood as a lifestyle rather than a diet in the strict sense, as there are many specific plant-based diets that could be called vegetarian.

There are several distinctive subgroups of vegetarians:

  • Vegans: Sometimes called strict vegetarians, vegans are people who exclude all animal products from their diet or clothing, whether or not they involve the death of an animal. Vegans will not use honey or dairy products, for example, and will not wear clothing made of wool, silk, fur, or leather, or use bedding stuffed with down.
  • Ovolactovegetarians: Vegetarians in this category will use eggs, milk, and other dairy products on the grounds that these foods are not obtained by killing animals.
  • Ovovegetarians: Vegetarians who will include eggs in the diet but not milk or milk products.
  • Lactovegetarians: Vegetarians who will use milk and milk products but not eggs.
  • Semivegetarians or pesce/pollo vegetarians: People who include fish or chicken in the diet but also seek to minimize their consumption of animal protein.
  • Fruitarians: Vegetarians who eat only fruits, nuts, seeds, and other plant matter that can be harvested without harming the plant.
  • Flexitarians: Persons who prefer a vegetarian diet but are willing to eat meat, fish, or chicken on exceptional occasions.
  • Freegans: Anti-consumerist vegans who seek to avoid participating in any practices they regard as exploitative of other people or the environment, in addition to excluding meat and animal products from their diet. Freegans obtain their food by growing it themselves, by barter, or by foraging in refuse bins and restaurant trash receptacles for discarded food. This practice is called “dumpster diving” in the United States and “skipping” in the United Kingdom.

Religious vegetarianism

Religious belief is the oldest historical motive for vegetarianism. Hinduism is the earliest of the world's major religions known to have encouraged a vegetarian lifestyle. As of the early 2000s, Hinduism accounts for more of the world's practicing vegetarians—70 percent— than any other faith or political conviction. Different Hindus, however, explain their commitment to vegetarianism in different ways. Some associate vegetarianism with the doctrine of ahimsa, or nonviolence, which forbids the shedding of animal as well as human blood. Others believe that animals have souls, and that those who kill them will acquire bad karma and suffer in their next reincarnation. Last, some Hindus believe that their gods will not accept nonvegetarian offerings.

The Jain religion, which is an ascetic offshoot of Hinduism that began in the sixth century BC, requires followers to adopt a vegan diet; they may also not eat roots because to do so kills the plant. Most Jains fast on holy days and at other times throughout the year, as they believe that fasting strengthens self-control as well as protecting the believer from accumulating bad karma.

In ancient Greece, the followers of the philosopher and mathematician Pythagoras (c. 582–507 BC) practiced an ascetic lifestyle that included a vegetarian diet and abstaining from animal bloodshed, including sacrifices to the Greek gods. Neoplatonist philosophers of the third and fourth centuries AD revived the Pythagorean notion that vegetarianism helps to purify the soul. As a result of the association of a plant-based diet with Pythagoras, European Christians in the sixteenth and seventeenth centuries who practiced vegetarianism were often called Pythagoreans.

Mainstream Christianity in both its Eastern and Western forms has never made year-round vegetarianism mandatory for laypeople; however, there is a long tradition of monastic vegetarianism going back at least as far as the Desert Fathers in the third and fourth centuries AD. In addition, many Christians abstain from meat during certain seasons of the church year (Lent and Advent). One reason for vegetarian diets in some of the monastic orders is the belief that eating meat increases temptations to anger and violence. Another reason, found more commonly among evangelical Protestants, is the interpretation of Genesis 1:29 and other Bible passages as meaning that God originally intended humans to be vegetarians, and that God wants his present-day followers to be responsible stewards of the earth. The Christian Vegetarian Association (CVA), which welcomes Roman Catholics as well as mainstream and evangelical Protestants, was founded in 1999.

One Christian denomination that was formed in the United States in the nineteenth century, namely the Seventh-day Adventist Church, has expected its members to be vegetarians since its beginning. Members of the church have been studied by the National Institutes of Health (NIH) and the National Cancer Institute (NCI) since 1960. NIH findings indicate that Adventist men live on average seven years longer than men in the general population, and Adventist women eight years longer than their non-Adventist counterparts.

Many members of New Age groups, as well as some atheists and agnostics, practice vegetarian or vegan lifestyles out of respect for nature or for the earth, even though they would not consider themselves religious in the conventional sense.

Environmental vegetarianism

The application of scientific methods to agriculture in the eighteenth and nineteenth centuries also allowed people to calculate for the first time the cost to the environment of raising animals for meat. As early as the 1770s, the English clergyman William Paley had already urged a vegetarian lifestyle on the grounds that an acre of land used to raise fruits and vegetables could support twice the number of people as an acre used to graze animals. A common ethical argument for vegetarianism in the early 2000s is that 40% of the world's grain goes to feed animals raised for meat rather than to feed people, and that world hunger could be eliminated if even half this grain could be redistributed to undernourished populations. According to the North American Vegetarian Society (NAVS), 15 vegans can be fed on the same amount of land needed to feed one person consuming a meat-based diet.

Animal rights vegetarianism

Commitment to a vegetarian diet as a way to reduce the suffering of animals—sometimes called compassion-based vegetarianism—emerged during the mid-nineteenth century, a period that also witnessed the foundation of the first groups devoted to animal welfare. The Royal Society for the Prevention of Cruelty to Animals (RSPCA) was given its charter by


Carnivore—An animal whose diet consists mostly or entirely of meat. Cats, wolves, snakes, birds of prey, frogs, sharks, spiders, seals, and penguins are all carnivores.

Dietitian—A health care professional who specializes in individual or group nutritional planning, public education in nutrition, or research in food science. To be licensed as a registered dietitian (RD) in the United States, a person must complete a bachelor's degree in a nutrition-related field and pass a state licensing examination. Dietitians are also called nutritionists.

Factory farming—A term that refers to the application of techniques of mass production borrowed from industry to the raising of livestock, poultry, fish, and crops. It is also known as industrial agriculture.

Freegan—A vegan who obtains food outside the mainstream economic system, most often by growing it, bartering for it, or scavenging for it in restaurant or supermarket trash bins.

Fruitarian—A vegetarian who eats only plant-based products, as fruits, seeds, and nuts, that can be obtained without killing the plant.

Herbivore—An animal whose diet consists primarily or entirely of plant matter. Herbivorous animals include deer, sheep, cows, horses, elephants, giraffes, and bison.

Lactovegetarian—A vegetarian who uses milk and cheese in addition to plant-based foods.

Obligate carnivore—An animal that must have meat in its diet to maintain health. Cats are obligate carnivores, although humans and most breeds of dogs are not.

Omnivore—An animal whose teeth and digestive tract are adapted to consume either plant or animal matter. The term does not mean, however, that a given species consumes equal amounts of plant and animal products. Omnivores include bears, squirrels, opossums, rats, pigs, foxes, chickens, crows, monkeys, most dogs, and humans.

Ovolactovegetarian—A vegetarian who consumes eggs and dairy products as well as plant-based foods. The official diet recommended to Seventh-day Adventists is ovolactovegetarian.

Ovovegetarian—A vegetarian who eats eggs in addition to plant-based foods.

Pepsin—A protease enzyme in the gastric juices of carnivorous and omnivorous animals that breaks down the proteins found in meat. Its existence in humans is considered evidence that humans evolved as omnivores.

Pesce/pollo vegetarian—A term used to describe semivegetarians; that is, people who avoid the use of red meat but will include fish (pesce in Italian) or chicken (pollo in Italian) in the diet. Other terms for semivegetarians include piscitarian or fishetarian for those who eat only fish but not chicken, and pollove-getarian or pollotarian for those who add chicken but not fish to their vegetarian diet.

Textured vegetable protein (TVP)—A meat substitute made from defatted soybean flour formed into a dough and cooked by steam while being forced through an extruder. It resembles ground beef in texture and can replace it in most recipes. TVP is also known as textured soy protein or TSP.

Tofu—Bean curd; a soft food made by coagulating soy milk with an enzyme, calcium sulfate, or an organic acid, and pressing the resulting curds into blocks or chunks. Tofu is frequently used in vegetarian dishes as a meat or cheese substitute.

Vegan—A vegetarian who excludes all animal products from the diet, including those that can be obtained without killing the animal. Vegans are also known as strict vegetarians.

Queen Victoria in 1840, seven years before the organization of the Vegetarian Society. The American Society for the Prevention of Cruelty to Animals (ASPCA) was founded in New York City by Henry Bergh in 1866. In addition to ongoing concern about maltreatment of household pets and working animals, the advent of so-called factory farming in the twentieth century has intensified the revulsion many people feel regarding the use of animals for human dietary consumption and clothing.

The 2003 vegetarian food guide

  • Grains: The foundation of the vegetarian diet. Whole grains are best, but enriched refined grains are also acceptable.
  • Vegetables and fruits: The ADA and DC recommend that vegetarians choose both vegetables and fruits rather than using only one or the other.
  • Legumes, nuts, and other protein-rich foods: Legumes include soy milk and tofu. Dairy products used by ovo-and lactovegetarians also fall into this category, as do meat substitutes.
  • Fats: Vegetarians who do not eat fish require plant-based sources of n-3 fats.
  • Calcium-rich foods: Adult vegetarians require eight servings from this category each day. Each serving, however, counts toward one of the other food choices, as calcium-rich foods can be found across the other food groups.

The minimum number of servings per food group in this diet would provide about 1400 or 1500 calories per day. Nonsedentary adults can meet higher energy needs by choosing more servings from any of the basic five groups. Sweets and alcohol should be used only sparingly.

Dietary supplements are recommended for vegetarians over 50 and for vegans, based on studies conducted by the Institute of Medicine (IOM). These guidelines are described more fully under Risks below.

Some specific vegetarian diets

Vegetarian diets can accommodate a wide variety of regional and ethnic cuisines as well as different philosophical or religious approaches. The following are only a few of the possible choices:

MEDITERRANEAN DIET. In its origin, the Mediterranean diet was not a purely vegetarian diet. It is, however, sparing in its use of red meat and eggs, and low in its use of fish and poultry. It can thus be easily adapted to a vegetarian or pesce/pollo vegetarian diet. The Mediterranean diet is high in its use of whole grains, fruits, nuts, and high-fiber vegetables; it appeals to many people because of its wide choice of flavorful foods.

MACROBIOTIC DIET. The macrobiotic diet, which was brought to Europe and North America from Japan in the 1960s, is associated with the Eastern concepts of yin and yang as well as with the elimination of animal products from the diet. This diet also involves such changes in eating habits as chewing each mouthful of food at least 50 times, drinking liquids only when thirsty, avoiding the use of aluminum cook-ware, and cooking foods on a wood stove rather than using electrical appliances.

ORNISH DIET. Developed by a medical doctor to reverse the signs of heart disease, the Ornish diet has also been popularized as a weight-loss program. It is a strict low-fat, high-fiber diet that excludes red meat, poultry, and fish, although persons following this diet may use limited amounts of egg whites, fat-free milk, and other fat-free dairy products.

SEVENTH-DAY ADVENTIST DIET. Seventh-day Adventists (SDAs) have followed vegetarian dietary regimens since the denomination was first organized in 1863. The diet recommended by the church's General Conference Nutrition Council (GCNC) in the early 2000s is an ovolactovegetarian diet high in whole-grain breads and pastas, fresh vegetables and fruits; moderate use of nuts, seeds, and low-fat dairy products; and limited use of eggs. Some SDAs prefer a vegan diet. The church has its own professional organization for dietitians, which is affiliated with the ADA, and encourages all its members to follow the ADA guidelines for vegetarians.

Tips for starting a vegetarian diet

The ADA offers the following suggestions for persons considering vegetarianism:

  • List all the meatless dishes that you already like to eat. Pizza, chili, vegetable soups, salads, bean casseroles, Oriental stir-fried vegetables, and pasta dishes are common favorites.
  • Look through some vegetarian cookbooks and copy the recipes that appeal to you.
  • Check out natural food stores and try some of their products.
  • Visit ethnic restaurants—Chinese, Japanese, Thai, Indian, Vietnamese, or Middle Eastern are good choices—and sample some of their meatless dishes.
  • Try meat substitutes (sometimes called meat analogues or “mock meat”) made from textured vegetable protein (TVP) or tofu (bean curd). Veggie burgers, veggie hot dogs, and imitation sausage are popular items of this type.


Vegetarian diets are adopted by people in developed countries primarily for ethical or religious reasons rather than economic necessity—although some nutritionists do point out that plant-based foods are usually easier on the household food budget than meat. Another more recent reason is the growing perception that plant-based diets are a form of preventive health care for people at increased risk of such diseases as heart disease, type 2 diabetes and some forms of cancer. Adolescents, however, are more likely to adopt vegetarian diets as a weight reduction regimen.


The long-term NIH study of Seventh-day Adven-tists began to report in the 1970s and 1980s that lowered blood pressure, lower rates of cardiovascular disease and stroke, lower blood cholesterol levels, and lowered risks of colon and prostate cancer are associated with a vegetarian diet. In particular, SDAs were only half as likely to develop type 2 (adult-onset) diabetes as were nonvegetarian Caucasians. Although it is possible to gain weight on a vegetarian diet, most people lose weight, especially in the first few months; and most vegetarians have lower body mass indices (an important diagnostic criterion of obesity) than their meat-eating counterparts.

Several studies carried out in Germany and Austria reported in 2006 that vegetarian diets appear to be effective in lowering the risk of rheumatoid arthritis, osteoporosis, kidney disease, gallstones, diverticulitis, and dementia as well as heart attacks, stroke, and diabetes.

In addition to lowering the risk of chronic degenerative diseases, vegetarian diets have also been shown to be useful in treating constipation in adults and children, and dysmenorrhea (painful menstrual periods) in women of childbearing age.


The ADA strongly recommends that people consult a registered dietitian as well as their primary physician before starting a vegetarian diet. The reason for this precaution is the variety of vegetarian regimens as well as the variations in height, weight, age, genetic inheritance, food preferences, level of activity, geographic location, and preexisting health problems among people. A nutritionist can also help design a diet that a new vegetarian will enjoy eating as well as getting adequate nourishment and other health benefits.


  • What are the potential benefits for a person of my age, sex, and lifestyle in adopting a vegetarian diet? A semi vegetarian diet?
  • What are the potential health risks, if any, for me as an individual?
  • Have you treated other patients who are vegetarians?
  • What specific types of vegetarian diets would you recommend? Have you tried any of them yourself?
  • Will I need any dietary supplements if I adopt a vegetarian diet?


The longstanding concern about vegetarian diets is the risk of nutritional deficiencies, particularly for such important nutrients as protein, minerals (iron, calcium, and zinc), vitamins (vitamin D, riboflavin, vitamin B12, and vitamin A), iodine, and n-3 fatty acids. The 2003 vegetarian food guide recommends that vegetarians over 50 years of age as well as vegans in all age groups should take supplements of vitamin B12 and vitamin D, or use foods fortified with these nutrients. Vitamin D supplements are particularly important for vegans living in northern latitudes or other situations in which they receive little sun exposure.

In addition to nutritional concerns, there is some evidence that vegetarian diets may actually increase the risk of breast cancer in women, particularly in those who use large amounts of soy-based products. Soybeans contain phytoestrogens, or plant estrogens, which have been implicated in breast cancer. The plant estrogens in soy-based products may also explain why vegetarians have a disproportionate number of female babies, and why these girls have a higher rate of precocious puberty than girls born to nonvegetarian mothers.

General acceptance

The ADA has a professional subgroup called the Vegetarian Nutrition Dietary Practice Group, or DPG, which publishes a quarterly newsletter called Vegetarian Nutrition Update, available to nonmem-bers of the ADA for an annual subscription fee of $25. The Vegetarian Nutrition DPG also has its own website at, with articles available to the public on vegetarian diets and cancer prevention, treatment of rheumatoid arthritis, sports nutrition, pregnancy, and vegan diets for children.

Once considered an eccentricity, vegetarianism is widely accepted by the general public in developed countries as a legitimate dietary option in the early 2000s. The ADA and DC state that about 2.5% of adults (defined as people over 18 years of age) in the United States and 4% of Canadian adults follow vegetarian diets. The Vegetarian Resource Group (VRG), a nonprofit research organization, conducted a poll in 2006. It estimated that 2.3% of adults in the United States—4.7 million people—are vegetarians, with a third to a half of this group being vegans. In addition, the VRG notes that 30 to 40% of American adults choose vegetarian dishes over meat dishes at least some of the time. Other interesting details from the 2006 poll:

  • People between 45 and 54 years of age are almost twice as likely to be vegetarians as people between 18 and 24 years of age.
  • The Northeast has the highest percentage of vegetarians in the general population, with the South having the lowest.
  • People who have graduated from college are twice as likely to be vegetarians as those who did not complete high school.
  • Hispanics are more likely to be vegetarians than either Caucasians or African Americans.
  • There is no correlation between household income and a vegetarian lifestyle as of the early 2000s; people at all income levels seem to be equally likely to become vegetarians.

Most opposition to vegetarianism in developed countries is interpersonal rather than scientific or political, as some vegetarians develop a sense of moral or spiritual superiority to nonvegetarians and make themselves socially unpopular by criticizing or lecturing others for continuing to eat meat. NAVS advises new vegetarians, “Be cheerful about your choices [but] remember to let people come to their own dietary conclusions.”


As has been noted in Europe as well as the United States, the emphasis in medical research on vegetarian diets has shifted in the early 2000s from concern about nutritional deficiencies in people following these diets to the role of vegetarianism in preventing or treating chronic diseases. It was the NIH's studies of Seventh-day Adventists that first indicated that vegetarian diets lower the risk of heart disease, stroke, and type 2 diabetes. The Adventist Health Study received new funding in 2003 for its continuation. As of early 2007, the NIH is conducting five additional clinical trials to evaluate the advantages of vegetarian diets in managing uremia in the elderly, cardiovascular disease, type 2 diabetes, high blood pressure, and postmenopausal disorders in women as well as treating obesity.

One area of concern, however, is in veterinary medicine—namely, the trend among some pet owners to put dogs and cats on vegetarian diets, often with homemade foods. Cats in particular are at risk of malnutrition and eventual blindness on a vegetarian or vegan diet because they are obligate carnivores (must have meat in the diet). Their bodies cannot form taurine (an amino acid), thiamine, retinol (a form of vitamin A essential to healthy eye tissue), and vitamin B12—all micronutrients found primarily in meat. The Vegetarian Society (UK) has an information sheet warning against putting cats on a vegetarian diet, while the American Veterinary Medical Association (AVMA) strongly urges vegetarian pet owners to consult their veterinarian before offering either dogs or cats vegetarian pet food.


Colbert, Don. What Would Jesus Eat? Nashville, TN: T. Nelson Publishers, 2002. A conservative Christian attempt to prove that Jesus was a vegetarian.

Harris, William, MD. The Scientific Basis of Vegetarianism. Honolulu, HI: Hawaii Health Publishers, 1995.

Pelletier, Kenneth R., MD. The Best Alternative Medicine, Chapter 3, “Food for Thought.” New York: Fireside Books, 2002. A good summary of recent studies of the health benefits of vegetarianism.

Stepaniak, Joanne. The Vegan Sourcebook, 2nd ed., with nutrition section by Virginia Messina. Los Angeles: Lowell House, 2000.

Stuart, Tristan. The Bloodless Revolution: A Cultural History of Vegetarianism from 1600 to Modern Times. New York: W. W. Norton &Co., 2006.


American Dietetic Association and Dietitians of Canada. “Position of the American Dietetic Association and Dietitians of Canada: Vegetarian Diets.” Canadian Journal of Dietetic Practice and Research 64 (Summer 2003): 62–81.

Key, T. J., P. N. Appleby, and M. S. Rosell. “Health Effects of Vegetarian and Vegan Diets.” Proceedings of the Nutrition Society 65 (February 2006): 35–41.

Leitzmann, C. “Vegetarian Diets: What Are the Advantages?” Forum of Nutrition 57 (2005): 147–156.

Michel, K. E. “Unconventional Diets for Dogs and Cats.” Veterinary Clinics of North America, Small Animal Practice 36 (November 2006): 1269–1281.

Shapin, Steven. “Vegetable Love.” New Yorker, January 22, 2007. Available online. URL: This article is a review of Stuart's book.

Stahler, Charles. “How Many Adults Are Vegetarian?”. Vegetarian Journal, no. 4 (2006). Available online at

Willett, Walter, MD. “Lessons from Dietary Studies in Adventists and Questions for the Future.” American Journal of Clinical Nutrition 78 (September 2003): 539S–543S.


Indian Vegetarian Cooking Videos, vol. 1 and vol. 2. Simple step-by-step demonstrations of vegetarian cooking in the Indian tradition by a registered dietitian. Nutritional information is provided for the recipes in the videos. To order, call (757) 464-0786 or e-mail

Mayo Clinic Staff. Vegetarian Diet: A Starter's Guide to a Plant-Based Diet. Rochester, MN: Mayo Clinic Foundation, 2006. Available online at

North American Vegetarian Society (NAVS). Vegetarianism: Answers to the Most Commonly Asked Questions. Dolgeville, NY: NAVS, 2005. Available online at

Prieur, Ran. “How to Drop Out.” Ran, April 2, 2004. URL: Personal essay explaining freeganism.

Seventh-day Adventist Dietetic Association (SDADA). A Position Statement on the Vegetarian Diet. Orlando, FL: SDADA, 2005. Available online at


American Dietetic Association (ADA). 120 South Riverside Plaza, Suite 2000, Chicago, IL 60606-6995. Telephone: (800): 877–1600. Website:

American Vegan Society (AVS). 56 Dinshah Lane, P. O. Box 369, Malaga, NJ 08328. Telephone: (856) 694–2887. Website:

Christian Vegetarian Association (CVA). P.O. Box 201791, Cleveland, OH 44120. Telephone: (216) 283–6702. Website:

Dietitians of Canada/Les diététistes du Canada (DC). 480 University Avenue, Suite 604, Toronto, Ontario, Canada M5G 1V2. Telephone: (416) 596–0857. Website:

North American Vegetarian Society (NAVS). P.O. Box 72, Dolgeville, NY 13329. Telephone: (518) 568–7970. Website:

Seventh-day Adventist Dietetic Association (SDADA). 9355 Telfer Run, Orlando, FL 32817. Website: SDADA is an official affiliate of the ADA.

Vegetarian Resource Group (VRG). P.O. Box 1463, Dept. IN, Baltimore, MD 21203. Telephone: (410) 366-VEGE. Website: Publishes Vegetarian Journal, a quarterly periodical.

Vegetarian Society of the United Kingdom. Parkdale, Dunham Road, Altrincham, Cheshire, England WA14 4QG. Telephone: 0161 925 2000. Website: The oldest organized vegetarian group, founded in 1847.

Rebecca J. Frey, PhD