Psychology Department

Health Psychology Home Page

Papers written by students providing scientific reviews of topics related to health and well being

Search HomeWeight LossAlternative Therapy | Supplements | Eating Disorders | Fitness | Links | Self-Assessment | About this Page |

Aspects of Vegetarianism


Tatiana Yepes


> Intro

            Many would argue Americans have never been as health conscious as they are now. Americans are hungry for ways leading to a better life-style.  One of the best marketing tools is to create low-fat, low-calorie products. Moreover, there seem to be a record number of weight-loss methods out right now, whether they are pills or dietary plans. One of the increasingly popular plans is vegetarianism. Over 2 million Americans attest to having adopted this route. (

Reasons for its popularity may vary from ethical, religious, economical, or health; however, regardless of someone’s primary reason for choosing vegetarianism, the overwhelming amounts of scientific evidence supporting the health benefits should not be overlooked.   


> What is a “Vegetarian Diet” (the treatment)

            There are four main types of vegetarians. First, there are lacto-ovovegetarians, who are vegetarians who include milk and eggs in their diets. Lacto-vegetarians are similar, for they include milk but they do not consume eggs. Vegans refrain from all animal product consumption. Finally, there are semi-vegetarians, who are vegetarians who refuse red meant but eat fish and chicken. (


> Why become one? What does it supposedly do?

            There are several reasons why people are choosing to adopt a vegetarian diet. Some argue they do it for humane reasons; they avoid “slaughterhouse by-products” out of concern for animal-welfare. In the UK alone, it is estimated that 800 million animals are slaughtered for food each year. This is about 15 animals per person per year. ( It is also important to realize that American culture is much more inclined to “meatier meals” compared to the typical UK platter, so the statistic would expectedly be higher for the United States. Many are also sympathetic towards the long, stressful, and hazardous haul to markets abroad and feel these animals are deprived of any real quality of life. (

            Environmental concerns are other contributing factors to peoples’ decisions. Many are aware that a quarter of the methane that contributes to global warming comes from livestock. Ammonia, present in animal feces, is the leading contributor to acid rain, which not only destroys plant life but also acts a corrosive agent on limestone, granite, etc. Many environmentalists are also concerned about rain forest destruction which is rapidly occurring partially to make room for grazing pastures. Subsequently, this also poses a great threat to endangered species.  (  


            But aside from humane and ecological concerns, the incentive of having better health and a longer life is suffice for many. A well-balanced, low-fat, high-fiber vegetarian diet is said to be a very healthy alternative to a high-protein diet. A low-fat and low cholesterol diet is supposed to cut your risk of heart disease. Eating lots of fruits, vegetables, and whole grains supposedly lowers the risk of obesity, diabetes, cancers of the stomach, pancreas, bladder, and lung, and reduces high blood pressures, which is a huge risk factor for heart disease and stroke. Low-protein diets are also thought to reduce the risk of renal failure. Broccoli, brussel sprouts, and other cabbages may offer special protection against breast and colon cancer. The consumption of dark leafy greens is supposed to reduce the risk of macular degeneration, a common cause of blindness in people over 65. ( Vegetarians are also supposed to have more endurance. (


> What evidence is offered in support of the claims?

            Many feel that a vegetarian diet would decrease a person’s strength and endurance. Dr. Richard Austin, Ph.D, documents the results of an experiment testing the strength of gorillas. Their diets are mainly composed of fruits and green leafy vegetables. The male gorilla can bench press 4000 lbs. Because gorillas are the closest animal to humans from the standpoint of digestion, he uses the results from this experiment to disprove the idea that vegetarians suffer from a weakening of the muscles. ( A more direct and probably more reliable comparison to human strength can be found in a study published in 1995 by the International Journal of Sports Nutrition on the physical fitness level of vegetarians. They found that concentration of intramuscular creatine, a source of energy in high-intensity exercise, is typically less in vegetarians. An omnivore usually gets 1 gram of creatine per day from muscle meat; however, vegetarians can take creatine supplements to account for this difference and overcome the lower level of performance. It may be easier to obtain from animal products, but a simple supplement and a bit of planning puts vegetarians at the same level of sports performance and strength (Maughan, 1995). Paul Williams, Ph.D., conducted a study at Lawrence Berkeley National Laboratory in California in which he compared 351 vegetarian runners to 8,891 omnivorous runners. While the two experimental groups vary quite a bit in size, the ratio shows that the vegetarian runners ran an average of 13-14% more miles per week than, inferring a higher level of stamina. ( An acclaimed study highlights the effects of vegetarianism on sports performance by comparing the nutrient intake between non-vegetarians to lacto-ovovegetarians. Both groups took part in a 1000-km race over 20 days and had their food provided. The vegetarian runners had a higher intake of dietary fiber and unsaturated fat and a lower intake of cholesterol. Everybody did not complete the race; however, neither diet was favored amongst those that did complete the race.  Through this study, it can be induced that a well-planned vegetarian diet does not necessarily lead to reduced endurance levels.  (Eisinger, Plath, Jung, & Leitzmann, 1994).

            One of the most attractive benefits to the vegetarian diet is the supposed decrease in risk of heart disease. Many studies have supported the association between animal fat consumption and risk of dying from heart disease. Also in the Oxford Vegetarian Study, heart disease was found to be 57% less frequent in the vegetarians. (  Also, the mortality rate from the heart disease in vegetarians is 30% less than that of nonvegetarians. (  The American Dietetic Association says that comprehensive health programs in which utilized vegetarian diets low in saturated fat were able to successfully reverse severe coronary artery disease. ( Some specific reasons for a lower risk in heart disease for vegetarians may be because of a lowered LDL cholesterol level amongst vegetarians.

            Paul Williams, Ph.D, also used his study on vegetarian runners to support the claim that a vegetarian diet promotes a lower LDL cholesterol level. In his study, vegetarian runners had about 3-5% lower levels of LDL cholesterol. ( The Oxford Vegetarian Study, which was published in the American Journal of Clinical Nutrition, selected 6000 vegetarians and a control group of 5000 non-vegetarians and followed them for 12 years. In this prospective cohort study, they found that the vegetarians had a lower cholesterol level and a lower mortality rate. ( Laurie Barclay, MD conducted a study this year on the effects of dietary soy on lipid profile. The study used 23 men and 18 postmenopausal women, all with elevated cholesterol levels. The control diet contained protein from low-fat dairy products and egg substitute and the soy-protein containing diets contained low-fat soymilk and various soy based meat substitutes. The subjects in the soy-protein diet resulted in a lower LDL cholesterol and a lower blood pressure, both contributing to a lower risk of heart disease (2002).  

            There has been considerable scientific evidence supporting the idea that certain foods can either enhance or restrain the immune system which would in turn affect a persons’ ability to fight against cancer. In Germany, a recent study showed that the natural killer cell activity in vegetarians was more than double that of non-vegetarians (Malter, 1989). Natural killer cells are white blood cells that attack cancer cells. This added strength to the immune system only supports the evidence of a reduced risk of cancer in vegetarians. Research has shown that a vegetarian diet could reduce the risks from certain cancers by 40%. ( It has been noted that high fiber diets, an inherent trait of vegetarian diets, reduce the risk of diseases of the digestive tract. Colon cancer is more prevalent in countries where their diets are based upon animal products. It is not perfectly understood how fiber prevents digestive tract disorders, but it is believed that the fiber helps retain water which helps the fecal matter in carrying carcinogens out of the body. Fiber is also thought to reduce the risk of breast cancer. Estrogen is typically secreted into the intestine, where fiber would then bind to the hormone and carry it out of the body. However, without adequate fiber, the estrogen can be reabsorbed through the intestine.  (

            There is also evidence supporting the claim that low-protein diets reduce risk for renal failure. The Cochrane Library published a study done by Fouque Wang and Laville Boissel  concerning this issue. The study consisted of randomized trials comparing two groups of people: those consuming high-protein diets and those consuming low-protein diets. The number of subjects that needed to start dialysis or have a kidney transplant or die from renal failure was recorded. It was found the undesired effects favored the high-protein diet (2002). Although the study didn’t directly compare vegetarians and non-vegetarians, it is likely that the same holds true for the vegetarian as for the low-protein intake consumers.  

            In conjunction with the specific health benefits of vegetarian diets, there are also many claims to better general health. In 1999, the American Journal of Clinical Nutrition published a study which followed 34,192 California-based vegetarians. The subjects were found to have an overall healthier lifestyle and a lower risk of diabetes, hypertension, and arthritis compared to non-vegetarians. ( Vegetarians have higher blood levels of beta-carotene and consume more vitamin C and fiber than non-vegetarians. ( A vegetarian diet was also found to restrict the chance of suffering from kidney and gallstones, diet-related diabetes, and high blood pressure. And on a less serious note, over 90% of all food poisoning cases each year in the UK are related to the consumption of animal products. (


> Possible Health Risks Associated with a Vegetarian Diet

            Many people considering vegetarian diets are concerned about Vitamin B12 deficiencies. Vegetarian diets can provide most of the vitamin B requirements, however, B12 is of specific concern. Since the active form of B12, cobalamin, is only found in animal products, vegan consumers need to be concerned and should probably invest in B12 fortified foods. All other vegetarians shouldn’t be concerned about B12 deficiencies, for they receive plenty of cobalamin from eggs, cheese, and milk. (

            One of the big concerns with vegetarian diets is inducing a nutrient deficiency. Adopting a vegetarian diet requires careful planning. It needs to compensate for the nutrients that it excludes. A well-balanced vegetarian diet includes a mix of fruits, vegetables, whole grains, and beans.  A specific dietary deficiency that concerns people is a protein deficiency. Protein sources can be found in soy-based meat substitutes such as tofu burgers and soy beans. (Barclay, 2002). Calcium can be obtained through milk, dark green leafy vegetables, and citrus juice. Fiber, shown to significantly reduce the risk of various cancers, can be easily obtained thought while grains, beans, peas, lentils, vegetables and fruits. Foods that are unrefined and unpeeled are in their highest state of fiber content. (  Iron sources include dried beans, dried fruits, and dark green vegetables. Vitamin C is easily found in citrus fruits and several vegetables. Selenium is found in whole grains. Both of these are antioxidants which neutralize cancer-causing chemicals.  (


> Who is presenting the information and why?

            AdvancePCS (Building Better Health) claim they publish their information solely for the purpose of providing information and resources on health-related issues. (  Richard Austin, writing for the Ferro Cement group, plans to start a local Earth Save group to help educate others about the benefits to individuals and our environment through a vegetarian diet.

(  The Vegetarian Society exists not only to educate the public but also to provide business opportunities and contact links for questions and help, advertise merchandise for the online store, and to provide membership to their organization. ( The Adventists Affirm seems to be presenting the material so that the reader can objectively decide if they want to adopt this plan and if they want to recommend it to others. ( Devine Crew wants to establish a site where they can share information and acquire others’ information. ( The more acclaimed sources are the peer-reviewed articles that have been published in reliable sources such as the American Journal of Clinical Nutrition and the International Journal of Sports Nutrition. These publications are typically designed to be a source for the latest clinical studies on nutrition and human resources.



**   “Nothing will benefit health and increase the chances for survival of life on Earth as the evolution to a vegetarian diet.” (Albert Einstein quoted in Ferro Cement)



Works Cited

Barclay, Laurie MD. (2002). Dietary Soy Improves Lipid Profile, Lowers CAD Risk. American Journal of Clinical Nutrition  76, 365-372.

Eisinger M, Plath M, Jung K, Leitzmann C (1994). Nutrient Intake of endurance runners with    ovo-lacto-vegetarian diet and regular western diet. Zeitschrift fur Ernahrungswiss 33, 217-229.

Fouque D, Wang P, Laville M, Boissel JP. (2002). Low protein diets for chronic renal failure in on diabetic adults. The Cochrane Library, Issue 2. Oxford:     Update Software.

Malter M. Natural Killer cells, vitamins, and other blood components of vegetarian and omnivorous men. Nutrition and Cancer Vol. 12. 1989. 271-278.

Maughan RJ (1995). Creatine Supplementation and exercise performance. International Journal of Sports Nutrition 5, S39-S61.


Psychology Department

The Health Psychology Home Page is produced and maintained by David Schlundt, PhD.

Vanderbilt Homepage | Introduction to Vanderbilt | Admissions | Colleges & Schools | Research Centers | News & Media Information | People at Vanderbilt | Libraries | Administrative Departments | Medical 

  Return to the Health Psychology Home Page
  Send E-mail comments or questions to Dr. Schlundt


Search: Vanderbilt University
the Internet
  Help  Advanced
Tip: You can refine your last query by searching only the results by clicking on the tab above the search box
Having Trouble Reading this Page?  Download Microsoft Internet Explorer.