Ovolactovegetarians, who are also known as lacto-ovovegetarians, are vegetarians who do not eat fish, poultry, or red meat but accept eggs, milk, and honey as part of their diet on the grounds that these foods can be obtained without killing the animals or insects who produce them. The ovo part of the name comes from the Latin word for egg, and lacto is derived from the Latin word for milk. In the West, ovolactovegetarians are the largest subgroup of vegetarians. As a result, most restaurants, institutional food services, cookbooks, and prepared foods that identify themselves as “vegetarian” without further qualification are ovolactovegetarian. Similarly, travelers who order vegetarian meals from an airline before departure will be given ovolactovegetarian food unless they are more specific.
Vegetarianism in general has existed for thousands of years, although the anatomical and archaeological evidence indicates that prehistoric humans were not vegetarians. The pattern of human dentition (teeth adapted for tearing meat as well as grinding plant matter), the length of the human digestive tract, and the secretion of pepsin (an enzyme necessary for digesting meat) by the human stomach are all indications that humans evolved as omnivores, or animals that consume both plant and animal matter.
Religious faith is the oldest known motive for consuming a vegetarian diet. Hinduism is the earliest of the world's major religions known to have encouraged a vegetarian lifestyle. As of the early twenty-first century, Hinduism accounts for more of the world's practicing vegetarians (70%) than any other faith or political conviction. The Hindu religion does not, however, endorse ovolactovegetarianism, as conservative observant Hindus may not eat eggs. Christians and Jews who are vegetarians for religious reasons, however, are usually either ovolactovegetarians or vegans.
Ovolactovegetarianism as it is currently practiced by most Westerners is largely a by-product of the animal rights movement that began in the midnineteenth century with the formation of the first societies for the prevention of cruelty to animals. The vegetarian groups of the late nineteenth century began by excluding meat, poultry, and fish from the diet on the grounds that these foods require the slaughter of animals, whereas the use of cow's milk and hen's eggs does not. These groups, however, were formed before the rise of modern factory farming, which often results in inhumane living conditions for dairy cows and egg-producing hens. As a result, many contemporary ovolactovegetarians insist on purchasing their eggs or dairy products from small farmers who do not use factory-farming methods.
Ovolactovegetarianism entered the medical mainstream in 2003 when the Academy of Nutrition and Dietetics (AND; formerly the American Dietetic Association) and the Dietitians of Canada (DC) jointly issued “A New Food Guide for North American Vegetarians.” This document contained the first major revisions of the familiar U.S. Department of Agriculture (USDA) food guide pyramid (originated 1912, modified in 1942 and 1992) and Canada's Food Guide to Healthy Eating (CFGHE; originated 1942, modified in 1992) intended for vegetarians. While the 1992 food guides were the first to consider overnutrition as a serious health problem and emphasized the importance of plant foods in the diet, they did not include guidelines for planning vegetarian diets. The 2003 food guide borrowed the general concept of food groups from the older guides, but reclassified foods into five plant-based groups:
Ovolactovegetarian diets can accommodate a wide variety of regional and ethnic cuisines as well as different philosophical or religious approaches. The following are some of the possible choices:
MEDITERRANEAN DIETS. Mediterranean diets were not purely ovolactovegetarian in their origins, but they are easily adapted to ovolactovegetarian food choices. In fact, several European studies of the beneficial effects of vegetarian diets have been based on ovolactovegetarian modifications of Greek and Spanish Mediterranean diets. These diets are high in their use of whole grains, fruits, nuts, and high-fiber vegetables, and therefore appeal to many people because of their wide choice of flavorful foods. They are also attracting research interest for their benefits to the health of older adults, including mental acuity as well as physical health.
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) as of 2018 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. The church has its own professional organization for dietitians, which is affiliated with the Academy of Nutrition and Dietetics, and encourages all its members to follow the AND guidelines for vegetarians.
Ovolactovegetarian diets are adopted by people in developed countries primarily for ethical or religious reasons rather than economic necessity. Another more recent reason is the growing perception that plantbased 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. A study conducted by researchers in North Carolina reported in 2013 that those who adopt vegetarian diets for ethical reasons are more restrictive in their food choices and more likely to remain vegetarians than those who became vegetarians for health reasons.
The long-term NIH study of Seventh-day Adventists 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, especially the ovolactovegetarian regimen recommended by the church. 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 an ovolactovegetarian diet, most people lose weight, especially in the first few months; and most vegetarians have lower body mass indices (BMIs), an important diagnostic criterion of obesity, than their meat-eating counterparts.
The Academy of Nutrition and Dietetics strongly recommends that people consult a registered dietitian as well as their primary physician before starting an ovolactovegetarian diet. The reason for this precaution is the variety of dietary regimens that could be called ovolactovegetarian as well as the variations in height, weight, age, genetic inheritance, food preferences, level of activity, geographic location, and preexisting health problems among people.
The academy also notes in particular that dietary choices for athletes depend on whether the athlete is consuming a lactovegetarian, ovolactovegetarian, or vegan diet: “Athletes need to eat small amounts of protein throughout the day to ensure this important nutrient is available when their bodies need it most… not every source of protein is equal…Meat, eggs, and dairy foods are typically the most coveted protein sources because they contain all nine essential amino acids in the ratios that humans require.”
People with high blood cholesterol levels may need to limit their consumption of eggs as much as possible even though this type of vegetarian diet allows the use of eggs. A nutritionist can also help design a diet that a new ovolactovegetarian will enjoy eating as well as getting adequate nourishment and other health benefits.
The longstanding concern about vegetarian diets in general 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 omega-3 fatty acids. The 2003 vegetarian food guide recommends that ovolactovegetarians over 50 years of age should take supplements of vitamin B12 and vitamin D, or use foods fortified with these nutrients. Vitamin D supplements are particularly important for older vegetarians living in northern latitudes or other situations in which they receive little sun exposure.
Vegetarianism in general is accepted by all mainstream medical associations and professional registered dietitians' societies, and positively recommended by some. The position statement adopted by the AND in 2016 states: “It is the position of the Academy of Nutrition and Dietetics that appropriately planned vegetarian, including vegan, diets are healthful, nutritionally adequate, and may provide health benefits for the prevention and treatment of certain diseases. These diets are appropriate for all stages of the life cycle, including pregnancy, lactation, infancy, childhood, adolescence, older adulthood, and for athletes.”
The AND has a professional subgroup called the Vegetarian Nutrition Dietary Practice Group, or DPG, which publishes a quarterly newsletter called Vegetarian Nutrition Update. The newsletter is available to nonmembers of the ADA for an annual subscription fee.
Once considered an eccentricity, ovolactovegetarianism is widely accepted by the general public in developed countries as a legitimate dietary option in the early 2000s. Most restaurants, school cafeterias, airlines, and other public food services presently offer ovolactovegetarian dishes as a matter of course. The AND notes in its 2016 position paper that vegetarians now have increased technological support: “applications for mobile devices allow vegetarians to discover nutritional needs, track intake, and locate restaurants and markets.” The Vegetarian Resource Group (VRG), a nonprofit research organization, conducted a poll in 2016 that indicated that about 8 million adults in the United States are vegetarian; about 3.4 million of these are vegans. As of 2018, the Northeast has the highest percentage of adults who are vegetarians or vegans (5.4%), with the lowest percentages (2.3%) in the South and Midwest. About 3% of Hispanics and 3% of African Americans are vegetarians or vegans.
Some evidence has shown that many people find vegetarian and vegan diets difficult to maintain over the long term. A research group called Faunalytics reported in 2014 that about 10% of adult Americans are former vegetarians and vegans: “More than half of former vegetarians/vegans abandoned the diet within the first year, and a third of them abandoned it in three months or less.” The chief factor in giving up a vegan or vegetarian diet is living with a family member or roommate who eats meat.
Most of the research in nutrition and medicine that has been carried out on vegetarians in the West has been done with research subjects who are ovolactovegetarians, with a smaller number of studies done on vegans. In general, Western researchers use “vegetarians,” as a synonym for ovolactovegetarians. Most studies done in India have recruited lactovegetarian subjects, as strict Hindus do not eat eggs. As a result, it is not always easy to compare study findings from different countries unless the subjects were drawn from the same vegetarian subgroup.
Studies on the role of vegetarian diets of all types in preventing disease go back to the 1960s, when the National Institutes of Health (NIH) and the National Cancer Institute (NCI) began to study members of the Seventh-day Adventist Church. 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. The Adventist Health Study-2 (AHS-2), an ongoing study of 96,000 SDAs in the United States and Canada carried out by the Loma Linda University School of Public Health, has a website with early findings about the benefits of the Adventist diet listed under Resources below.
Research done after 2010 indicates that people choose vegetarian diets for reasons other than weight loss. A study of data from the 2012 National Health Interview Survey reported in 2017 that women are more likely than men to follow vegetarian diets “for unspecific health reasons,” usually described as illness prevention or general wellness. The vegetarians also were more likely to be single, college-educated, and using herbal products and vitamin supplements as part of their diet.
Relatively few clinical trials of specifically ovolactovegetarian diets are being conducted as of 2018. Four registered with the National Institutes of Health: three are being conducted in Europe and only one in the United States, at the University of Pittsburgh.
See also Calcium ; Cancer ; Flexitarian ; Omega-3 and omega-6 fatty acids ; Ovovegetarianism ; Veganism ; Vegetarianism .
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Rebecca J. Frey, PhD