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Is Being a Vegetarian Healthy?
All words that end in ‘-ism’ including vegetarianism and veganism denote ideology and express an underlying belief system. Abstention from meat and animal foods has been a religious practice for both Eastern and Western religions since ancient times. Eastern groups that have practiced meat avoidance include Buddhists, Zoroastrians, and some Hindu sects. In Western classical times, numerous Greek and Roman philosophers adhered to a meatless diet and promoted plant foods. Pythagorus, Plato, Theophrastus, Ovid, Seneca, Plutarch, Porphyry, and others advocated abstention from meat for spiritual, health, humanitarian, and ethical reasons (Roe, 1986). The emergence of vegetarian practices in recent times had its roots in the health and social reform movements and religious revivalism of the nineteenth century.
The term ‘vegetarian’ was first coined and the first Vegetarian Society founded in England in 1847 by followers of the Reverend William Cowherd of the Bible Christian Church. In 1850, the American Vegetarian Society was organized in New York by clerics and health reformers such as William Metcalfe, Sylvester Graham, and William Andrus Alcott, and others. Revival of vegetarianism in the twentieth century came in 1971 with the publication of Diet for a Small Planet by Frances Moore Lappe. It launched a humanistic and secular vegetarian movement especially among the young and ‘hippies.’ ‘The Farm’ a vegetarian commune was started in Summertown, Tennessee. The writings of the Australian ethic professor Peter Singer in Animal Liberation provided the spark for the birth of the US animal rights movement and the founding of the group People for Ethical treatment of Animals (PETA), strong proponents of not eating animals or experimenting on them. The publication of John Robbins Diet for a New America exposed the horrors of factory farming in the production of meat, dairy and poultry, and the environmental consequences of animal agriculture. It helped introduce the term ‘vegan’ into the vocabulary and provided the impetus for the establishing of the first Vegan Society. Recently efforts by the various vegetarian groups have focused on policy changes to improve the health of individuals and the environment ( Whorton, 1994).
Vegetarian diets are those which do not include any meat, poultry, or fish. These types of diets are further subclassified as: lacto-ovo-vegetarians consume dairy products and eggs; lactovegetarians consume dairy product but no eggs; ovo-vegetarians consume eggs but not dairy; while vegans do not eat any animal products. Some vegans refrain from eating honey or wearing leather (Key et al., 2006). Pescatarian diets include fish or other seafood but not poultry or red meat. The term ‘flexitarians’ is used to describe individuals who reduce their meat consumption without becoming vegetarian. They are described as vegetarians who occasionally eat meat. In contrast, ‘vegivores’ are individuals who prefer vegetables and choose vegetable or nonmeat dishes for flavor, rather than for ideological reasons.
Vegetarian diets are gaining popularity all over the world, however, the number of vegetarians is not known. In 2008, the Vegetarian Resource Group commissioned the Harris Interactive Service Bureau to conduct a national poll of US vegetarians. The poll surveyed over 5000 respondents, a statistically representative sample of the total US population. The survey found that approximately 3.4% of US adults never eat meat, poultry, and fish/seafood. This is equivalent to approximately 7.3 million adult vegetarians in the United States. About one-third to one-fourth of those vegetarians (1% of the US population) do not consume dairy, eggs, and honey, meaning they are vegan (Stahler, 2009). Of the vegetarians surveyed, 59% were female and 82% were younger than 55 years of age. The study also found that over half of vegetarians eat a vegetarian diet to improve their overall health. Environmental concerns were cited by 47%; 39% cited ‘natural approaches to wellness’; 31% food safety concerns; 54% animal welfare; and approximately 25% indicated they followed the diet for weight loss or weight maintenance.
While in places like the US, most individuals are vegetarian due to principles or preference, in some countries like India, it is a cultural decision. It has been estimated that one-third of Indians are vegetarians. In emerging countries, poverty may be the underlying impetus for diets low in animal foods. In industrialized countries, the rates of vegetarianism vary but are likely lower than those in the US. Adolescents tend to choose vegetarian diets for different reasons than adults, and may include reasons like being raised in a vegetarian family, ethical issues of animal rights, disliking the taste or texture of animal products, and possible eating disorders due to body image issues. Adults tend to be motivated by religious or health reasons (Fessler et al., 2003; Greene-Finestone et al., 2005).
Health Benefits of Vegetarian Diets
Numerous prospective epidemiological studies have indicated that individuals who follow a vegetarian dietary pattern typically have lower cholesterol levels, blood pressure, and body mass index (BMI) when compared with their nonvegetarian counterparts. These indicators are associated with a lower risk of developing chronic diseases like heart disease, diabetes, cancer, and hypertension. Many of these associations were derived from large-scale cohort studies on vegetarians. Studies that involved more than 1000 participants are listed and the major outcomes are summarized.
The Health Food Shoppers Study (Key et al., 1996)
Subjects for this study (∼11 000) were from the United Kingdom and were recruited between 1973 and 1979 from shoppers at health food shops and from magazine advertisements. Approximately 40% were vegetarian and overall the cohort has a mortality about half that of the general population.
The Heidelberg Vegetarian Study (Chang-Claude et al., 2005)
This was a cohort of vegetarians (n = 1225) and health-conscious persons (n = 679) in the Federal Republic of Germany which was followed-up for 21 years. Both vegetarian and nonvegetarian health-conscious groups had reduced mortality compared with the general population. The vegetarian diet was associated with a nonsignificant reduction in relative risk for ischemic heart disease.
The Oxford Vegetarian Study (Appleby et al., 1999)
Subjects for this study were approximately 6000 vegetarians and 5000 nonvegetarians from the United Kingdom. After 12 years of follow-up, death rated for ischemic heart disease and malignant neoplasms were significantly lower in vegetarians than in nonvegetarians.
As a branch of a European-wide investigation, EPIC-Oxford in the United Kingdom oversamples for vegetarians. Of the approximately 65 000 participants, more than half are vegetarian.
The Adventist Health Studies (AHS)
Seventh-day Adventists are a Christian denomination established in 1863 that from its beginnings was distinguished by an emphasis on health. To date, there have been three separate cohorts of Adventists whose dietary practices and health outcomes have been tracked in the US. The first cohort was called the Adventist Mortality Study, recruited about 23 000 non-Hispanic white members in California. A 21-year follow-up of participants showed a positive association between meat consumption and all-cause mortality (Kahn et al., 1984).
The next cohort called AHS-1 was approximately 34 000 individuals and again included only non-Hispanic white California participants. Major findings from this study was that risk of fatal heart disease was significantly related to beef intake in men, and men who consumed beef three times or more per week had a 2.3 times greater risk of dying than vegetarian men (Fraser, 1999). The study also showed that eating nuts and whole-grain breads and cereals were associated with lower risk of coronary heart disease (Fraser, 2009).
The more recent AHS-2 begun in 2002 includes approximately 96 000 participants from all 50 states and Canada, of which 72% are non-Hispanic white, 26% are blacks and the rest are from other ethnic groups. Participants exhibit a wide range but stable dietary patterns with about 8% of the cohort vegan, 28% lacto-ovo-vegetarian, 16% pescatarian and semivegetarian and, 48% nonvegetarian.
Numerous studies of vegetarian diets have indicated that vegetarians have a lower BMI than their nonvegetarian counterparts and the proportion of vegetarians who are obese is correspondingly lower than that among nonvegetarians. While there are various suggested mechanisms for this difference, the composition of the diet (such as a higher fiber intake and lower protein intake) plays an important role (Key et al., 2006). In the EPIC-Oxford study, vegans showed a significantly lower weight gain over time than meat-eaters (Rosell et al., 2006; Thedford and Raj, 2011).
With the increased prevalence of obesity throughout the life cycle and in children, weight control interventions that will help reduce and prevent weight gain at an early age is extremely important. As mentioned earlier, epidemiologic studies have indicated lower BMI for those on vegetarian diets. Similarly, vegetarian children are leaner than their nonvegetarian counterparts. With plant-based diets low in energy density and high in complex carbohydrates, fiber, and nutrients, individuals may have increased satiety and resting energy expenditure (Sabate and Wien, 2010).
Metabolic syndrome is a cluster of disorders that are associated with an increased risk of diabetes and cardiovascular disease. Vegetarian diets have been linked to more favorable metabolic outcomes and a lower risk for metabolic syndrome, according to a cross-sectional analysis from the AHS-2. The results indicated that all metabolic risk factors were significantly lower, except for HDL cholesterol, in association with a vegetarian diet versus a nonvegetarian diet (Rizzo et al., 2011).
This excerpt was taken from the article Vegetarianism and Veganism by E.H. Haddad, P. Faed included in the innovative Reference Module in Biomedical Sciences. Hosted on ScienceDirect, this visionary resource contains thousands of comprehensive and encyclopedic articles into one interdisciplinary product. Every Month the content is reviewed, updated and new articles are commissioned where needed to ensure the latest developments and discoveries are included. Achieve more with this empowering resource, learn more here or take a look at this article from the Reference Module on Human Nutrition for free!
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