Vegetarianism; the pros and cons of a meatless diet

Kristin Higgins

As Americans become increasingly more health conscious, vegetarian diets are becoming more

and more common. Produce-aisle signs stating eat 5 a day for better health are beginning to

pay off, along with the USDA-DHHS Dietary Guidelines for Americans, which state: Many

American diets have too many calories and too much fat (especially saturated fat), cholesterol,

and sodium. They also have too little complex carbohydrates and fiber. Such diets are one cause

of America’s high rates of obesity and of certain diseases-heart disease, high blood pressure,

stroke, diabetes, and some forms of cancer http://www.childsecure.com/veggie.htm

Different types of vegetarians include the vegan, who follows a strict diet excluding eggs, dairy,

and all other animal products; the lacto-ovo-vegetarian, who eats a diet of mainly grains,

vegetables, fruits, legumes, seeds, nuts, dairy products, and eggs, and excludes meat, fish, and

poultry; the lacto-vegetarian, who excludes animal flesh and eggs; the ovo-vegetarian, who

excludes animal flesh and dairy products; and the semi-vegetarian, who abstains from only red

meat and poultry http://www.penpages.psu.edu/penpages_reference/12101/121012505.html.

Vegetarian diets have many health benefits, but can also lead to health detriments if proper

precautions are not taken. Optimal health, however, can be reached through a carefully planned

vegetarian diet.

Health benefits of plant food

The American Dietetic Association has taken the position that appropriately planned

vegetarian diets are healthful, are nutritionally adequate, and provide health benefits in the

prevention of certain diseases

http://www.penpages.psu.edu/penpages_reference/12101/121012505.html. . Quite a bit of

research has been done to back up this statement. Registered dietitian Johanna Dwyer, of Tufts

University Medical School and the New England Medical Center Hospital, summarizes the

benefits of plant food: Data are strong that vegetarians are at lesser risk for obesity,

atonic(reduced muscle tone) constipation, lung cancer, and alcoholism. Evidence is good that

risks for hypertension, coronary artery disease, type 2 diabetes, and gallstones are lower. Data

are only fair to poor that risks of breast cancer, diverticular disease of the colon, colonic cancer,

calcium kidney stones, osteoporosis, dental erosion and dental caries are lower

http://www.childsecure.com/veggie.htm. Dywer says that the life span of vegetarians to

non-vegetarians is similar to or slightly higher, but is influenced in the United States by

“adoption of many healthy lifestyle habits in addition to diet, such as not smoking, abstinence or

moderation in the use of alcohol, being physically active, resting adequately, seeking ongoing

health surveillance, and seeking guidance when health problems arise

http://www.penpages.psu.edu/penpages_reference/12101/121012505.html. .

Experimental studies also support such theories based on the benefits of plant-based diets.

Data from the Oxford Vegetarian Study was used to determine whether or not a correlation

between vegetarian diets and body mass indexes exists. One thousand nine-hundred and fourteen

male and 3378 female subjects, all non-smokers between the ages of 20 and 89 were recruited to

participate in the study. The subjects completed a diet/lifestyle questionnaire providing the

details of their diet, along with other characteristics such as height, weight, smoking and drinking

habits, amount of exercise, occupation, and reproductive status. The diet portion of the

questionnaire was used to classify subjects as meat eaters and non-meat eaters, and to estimate

consumption of dietary fiber and animal fats. The results show a lower BMI in non-meat eaters

than in meat eaters in all age groups of men and women. Age-adjusted average BMI’s in Kg/m2

were 23.18 for male meat eaters and 22.05 for male non-meat eaters (P< 0.0001). Female meat

eaters averaged a BMI of 22.32, while non-meat eaters averaged a BMI of 21.32 (P < 0.0001).

Along with meat consumption, animal fat intake, dietary finer intake, past smoking, and social

class were also independently associated with BMI in both men and women. The differences in

average BMI’s between meat and non-meat eaters, after adjusting for these factors, were 31%

lower in female non-meat eaters, and 36% lower in male non-meat eaters. Thus, the conclusion

was drawn that non-meat eaters are slimmer than meat eaters. This could be a result of higher

intakes of dietary fiber, a lower intake of animal fats, and in men a lower intake of alcohol

(Appleby, Thorogood, Mann, and Key, 1998).

Vegetarian diets have been proven to reduce the risk of coronary artery disease. This is

largely due to their lower saturated fat, cholesterol, and animal protein content, along with

increased concentrations of folate (which reduces homocysteine levels), and antioxidants such as

vitamin C and E. In addition to lower coronary artery disease mortality rates in vegetarians,

plant food diets have been found to have an arresting effect on coronary artery disease. Soluble

fiber, an ingredient found in many fruits and vegetables, has been linked to reduced risk of

coronary artery disease. However, the Food and Drug Administration (FDA) recognizes that it

is impossible to adequately distinguish the effects of fiber, including soluble fiber, from those of

other food components Well-planned vegetarian diets may also be effective in the treatment and

prevention of renal disease. Studies show that certain plant proteins may increase survival rates

and decrease proteinuria, glomerular filtration rate, renal blood flow, and histologic renal damage

compared with a non-vegetarian diet.

With high levels of animal fat intake being a risk factor for coronary artery disease, many

research studies have been done analyzing the levels of these fats in meat eaters versus non-meat

eaters. 13C magnetic resonance spectroscopy (MRS) has been used to study lipids. Thomas,

Frost, Barnard, Bryant, Taylor-Robinson, Simnrunner, Coutts, Burl, Bloom, Sales, and Bell

(1996) applied 13C MRS to determine the fatty acid composition of adipose tissue in 88 healthy

subjects with varying diets (39 omnivores, 38 vegans, 11 vegetarians) assessed through dietary

record analysis. Results showed more unsaturated and fewer saturated fatty acids (P < 0.01) in

the adipose tissue of vegans.

Krajcovicova-Kudlackova, Simoncic, Klvanova, Bedevora, Babinska, and Grancicova

(1997) analyzed the fatty acid levels in plasma of 27 vegetarian adults(13 males, 14 females)

ages 20 to 63, with the average period of vegetarianism being 8.8 years. Half of the women and

a third of the men were lacto-vegetarians, and the rest were lacto-ovo vegetarians. Results

showed the levels of saturated and monounsaturated fatty acids in vegetarians decreased

significantly as compared to levels in non-vegetarians. Higher levels of lonoliec acid C 18:2, and

a significantly higher ratio of linoliec /leic acids C 18:2/C18:1, along with decreased levels of

poly-unsaturated fatty acids C 20:4 (arachidonic acid) and C 22:6 (n3; docosahexaenoic acid) are

seen as positive factors in the prevention of atherosclerosis in vegetarians.

Incidence of cancer has also been linked to diet. The National Cancer Institute states that

A third of cancer deaths may be related to diet. Vegetables from the cabbage family

(cruciferous vegetables) may reduce cancer, along with along with diets low in saturated fat and

high in fiber, may reduce the risk of cancers of the colon and rectum. Plant food diets rich in

vitamin A, vitamin C, and beta-carotene may also reduce the risk of certain cancers

http://www.fda.gov./bbs/topics/CONSUMER/CON00138.html. Diets high in fiber-containing

vegetables have also been associated with reduced risks of cancer

http://www.childsecure.com/veggie.htm.

According to Erhardy, Lim, and Bode (1997), Production of reactive oxygen species in

the lumen of the colen, a process influenced by nutrition, may be a factor in the development of

colon cancer. Little research on humans supporting this hypothesis exists, so the objective of

Erhardy, Lim, and Bode’s study was to measure the effect of varying nutrition on in vitro

oxygen radical production in human feces. Seven healthy subjects received a diet high in fat

(50%) and meat and low in dietary fiber for. After one week, they received a vegetarian diet low

in fat (20%) and high in high in dietary fiber. At the end of each period, feces were collected and

analyzed with dimethylsulfoxide for in vitro oxygen radical production. Average hydroxl radical

production was 13 times greater when the subjects consumed the diet high in fat and low in

dietary fiber. The difference of hydroxol radical production was associated with a 42% higher

fecal iron concentration when the subjects consumed the first diet than when the subjects

consumed the second diet. The conclusion can be drawn that diets high in fat and low in fiber

increase the hydroxol radical formation in human feces, which may to lead an increased risk of

colorectal cancer.

Specific studies have been done on the effects of vegetable proteins, which constitute

large part of vegetarian diets. One in particular, the soya protein, has been linked to lower

incidence of breast, prostate, and colon cancer in Asian countries. Stephen Holt, M.D., actively

studies the soya protein, and has found that in these Asian countries where there has been more

of a shift to a Western type diet, particularly in urban areas, there are notable increases in cancer

and cardiovascular related deaths http://www.sholtmd.com/soyafor.htm. Holt believes that

differences in disease profiles in many Eastern versus Western communities is attributable to a

major degree to the presence of soya in the diet. According to Holt, soya protein lowers blood

cholesterol. It also promotes the balance of internal milieu of the body, especially by virtue of

its efficient handling by the human kidney . Holt also believes that soybeans provide a unique

combination of isoflavones, including genistein daidzein, and glycetin. These isoflavones have

amazing biopharmaceutical properties, including anticarcinogenic, antiangiogenic, and

estrogenic effects. Holt also supports in vitro and in vivo studies involving isoflavones which

confirm the medical benefit of these substances for a variety of chronic diseases. Holt believes

that the soyabean is the nutrient of the future, as people began to change their eating habits to a

more vegetarian style diet.

Vegetarian diets also tend to lead to a lower incidence of hypertension than

non-vegetarian diets. Type 2 diabetes mellitus is less likely to be a cause of death in vegetarians,

most likely because of a higher intakes of complex carbohydrates and lower body mass indexes.

Studies also show that vegetarians have lower morbidity and mortality rates from many chronic

degenerative diseases. Nondietary factors may play a role also, but diet is a significant factor

http://www.penpages.psu.edu/penpages_reference/12101/121012505.html..

Health detriments of plant food

According to John Vanderveen, PH.D., director of the FDA’s office of Plant and Dairy

Foods and Beverages, "the more you restrict your diet, the more difficult it is to get the nutrients

you need" http://www.childsecure.com/veggie.htm. Vegetarians who exclude all dairy and

animal flesh products face the greatest nutritional risks, because some essential nutrients exist

only in animal products http://www.glyphmedia.com/host/darklight/Vege.htm.

Vegans face the risk of inadequate vitamin and mineral levels. Vitamin B12 deficiencies

are found in vegans, and this deficiency can lead to irreversible nerve deterioration (5). The

American Journal of Clinical Nutrition concluded in 1988 that elderly people should be

especially careful when adapting vegetarian diets, because their bodies may absorb vitamin B12

poorly http://www.fda.gov./bbs/topics/CONSUMER/CON00138.html.

Vegans and ovo-vegetarians (those who eat eggs but no meat or dairy products) may have

low vitamin D and calcium intake. Lack of vitamin D can cause rickets in children, and lack of

calcium can lead to osteoporosis later in life. These vegetarians are also at risk for

iron-deficiency anemia, not only from exclusion of animal products, but also because of the high

dietary fiber content of foods such as soy protein, bran, and fiber. The dietary fiber in these

foods actually inhibits iron absorption. Protein deficiency must also be guarded against, which

can lead to loss of hair and muscle mass, along with abnormal accumulation of fluid. Care must

be taken to ensure proper caloric intake for all vegetarians

http://www.fda.gov./bbs/topics/CONSUMER/CON00138.html.

Barr, Prior, Janelle, and Lentle (1998) have examined the association of vegetarian diets

with spinal bone mineral density. The study used a cross-sectional comparison method of bone

mineral density of 23 vegetarians and 22 non-vegetarians, all premenopausal. The subjects were

between the ages of 20 and 40, and had normal body weights and menstrual cycles. Twenty of

the women participated in repeat measurements 13 months later. Methods used to make

comparisons include descriptive statistics, independent samples and paired tests, 1-way analysis

of variance, correlation analysis, and stepwise multiple regression. Results showed vegetarians

having a lower mean bone mineral density, 1.148 versus 1.216 for non-vegetarians. Vitamin

B-12 and body fat were factors used in predicting baseline bone mineral density. Participants in

the follow-up study differed only by being slightly older. In one year, mean bone mineral

density increased by 1.1% in the diet group, non-vegetarian’s bone mineral density increased,

while vegetarians stayed the same. No other monitered variables affected bone mineral density.

Conclusions from the study state that vegetarian women should be aware of the association of

low bone mineral density with a vegetarian diet.

Children with vegetarian diets face additional risks and health concerns. Gretchen Hill,

Ph.D., associate professor of food science and human nutrition at the University of Missouri,

Columbia, believes that many health problems arise among child vegetarians. My bet is those

kids will have health problems when they reach 40, 50, or 60 years of age, she says, mostly

because of imbalances with micronutrients [nutrients required only in small amounts],

particularly iron, zinc, and copper. Hill believes that while vegetarian children will be missing

iron from animal products, the most valuable vitamins may be copper and zinc. Copper is

essential to the human body in that it builds the bodies immune system, and strengthens and

builds red blood cells. A lot of Americans are marginal in this micronutrient, and as a result,

are more susceptible to diseases. Children can’t meet their zinc needs without eating meat.

Children are also at risk of developing protein defeciency, which can lead to stunted growth

http://www.fda.gov./bbs/topics/CONSUMER/CON00138.html.

Scientific evidence in support of Hill’s claims does exist. Nathan, Hackett, and Kirby

(1997) assessed the growth of vegetarian children as compared to non-vegetarian children. Fifty

vegetarian children ages 7 to 11, were compared to a control group of 50 omnivores of similar

age, sex, and ethnic group. Main outcome measurements include height, weight, upper arm

skinfold thickness, and mid-upper arm circumference measurements, and were taken at baseline

and one year later. The results show that only the height increment of non-vegetarians was

slightly greater, .47 cm, than that of the omnivores. The difference, however, was only apparent

after allowing for father’s height, maternal smoking habit and number of siblings. The tendency

for vegetarians to be leaner than the omnivores was not significant. It was concluded that

vegetarian children grow at least as well as non-vegetarian children.

Women of childbearing age, especially pregnant women, also face additional risks. Ann

Pederson of the American Journal of Clinical Nutrition reported that vegetarian women have an

increase chance of irregular menstruation. Nine of the study’s 34 vegetarians missed periods, as

compared to 2 of the 41 non-vegetarians. The groups were indistinguishable in regards to height,

weight, and age at the beginning of menstruation. Pregnant vegetarians must take precautions

against inadequate caloric intake, which can lead to low birth weight

http://www.fda.gov./bbs/topics/CONSUMER/CON00138.html. In addition, low Vitamin B12

levels in many vegetarians can become very dangerous during pregnancy

http://www.fda.gov./bbs/topics/CONSUMER/CON00138.html.

How to benefit from a vegetarian diet while avoiding the health risks

The Institute of Food Technologists recommends careful diet planning to ensure that

vegetarians get adequate amounts of essential vitamins and minerals

http://www.childsecure.com/veggie.htm. It is especially important for vegans, to ensure

proper intake of calcium, vitamin D , riboflavin, and iron. Calcium supplements are

recommended by the Institute of Food Technologists for pregnant women, breast-feeding

women, infants, and children. Calcium needs can also be met by calcium fortified foods

including tofu processed with calcium, broccoli, seeds, nuts, kale, bok choy, legumes,, greens,

and orange juice enriched with calcium. Vitamin D supplements may be needed if one does not

receive adequate sun exposure, as sunlight is essential in the body’s production of vitamin D

http://www.childsecure.com/veggie.htm. Five to 15 minutes of sun exposure a day is the

recommended amount needed to ensure this production. Older people need to take special care,

as their bodies synthesize vitamin D less efficiently and their sun exposure is usually limited.

Vitamin D fortified foods such as soymilk and some cereals are also available

http://www.penpages.psu.edu/penpages_reference/12101/121012505.html..

Protein deficiency can be avoided by combining legumes with seeds, grains, and nuts,

which together provide high amounts of complete proteins. Substitute meat products such as

vegetable burgers and soy dogs provide protein and are also fortified with B12

http://www.fda.gov./bbs/topics/CONSUMER/CON00138.html.

Special care should be taken when planning the diets of for vegetarian children and

adolescents, especially those with vegan diets. Foods high in calcium, iron, and zinc make up a

large part of the daily diet. To meet energy needs, vegetarian children should eat frequent meals

and snacks, along with foods higher in fat

http://www.penpages.psu.edu/penpages_reference/12101/121012505.html..

As with any dietary change, experts recommend a gradual shift to a vegetarian diet. An

increase in dietary fiber from a vegetarian diet can cause intestinal discomfort from increased

bulk, and it is recommended to slowly increase consumption of grains, legumes, seeds, and nuts

http://www.childsecure.com/veggie.htm. To reap the greatest benefits of a vegetarian diet,

one must include many different types of foods that provide a variety of vitamins and nutrients.

The following list, compiled by the American Dietetic Association, provides vegetarians with

nutritional guidelines to follow http://www.geocities.com/Yosemite/9854/amhrt_vegdiet.html.

1.) Keep intake of sweets and fatty foods, which are low in nutrient density, to a minimum.

Choose whole or unrefined grain products when possible, or use fortified or enriched cereal

products.

2.) Use a variety of fruits and vegetables, including foods that are good sources of vitamin C.

If you use milk or dairy products, choose low-fat or nonfat varieties.

3.) Limit eggs, if eaten, to 3 to 4 yolks a week.

4.) You do not have to eat animal products to have enough protein in your diet. Plant proteins

alone can provide enough of the essential and non-essential amino acids, as long as sources

of dietary protein are fairly varied and caloric intake is high enough to meet energy needs.

Vegetarian diets are a healthy alternative to a meat-based diet. When properly planned,

plant food diets provide all the nutritional components needed for a healthy adult lifestyle. The

safety of the vegetarian diet for a child, however, should be questioned critically, as many

vitamins and minerals found in meat are essential to a child’s development. Variety is the key,

because the more restrictive the diet, the more likely it is to be nutritionally inadequate

http://pharamcy-web.com/WHP/InfoService/MedTribune/Abstract/M960708a.html.

Works Cited

Appleby PN, Thorogood M, Mann JI, Key TJ (1998). Low body mass index in non-meat eaters:

the possible roles of animal fat, dietary fiber and alcohol. International Journal of

Related Metabolism Disorders, 22, 454-60.

Barr SI, Prior JC, Janelle KC, Lentle BC (1998). Spinal bone mineral density in premenopausal

vegetarian and nonvegetarian women: cross-sectional and prospective comparisons.

Journal of American Dietetic Association, 7, 760-5.

Erhardt JG, Lim SS, Bode JC, Bode C (1997). A diet rich in fat and poor in dietary fiber

increases the in vitro formation of reactive oxygen species in human feces. Journal of

Nutrition, 127, 706-9.

Krajcovicova-Kudlackova M, Simoncic R, Klvanova J, Bederova A, Babinska K, Grancicova E

(1997). The plasma profile of fatty acids in vegetarians. Bratisl Lek Listy, 1, 23-7.

Nathan I, Hackett AF, Kirby S (1997). A longitudinal study of the growth of matched pairs of

vegetarian and omnivorous children, aged 7-11 years, in the north-west of England.

European Journal of Clinical Nutrition, 51, 20-5.

Thomas EL, Frost G, Barnard ML, Bryant DJ, Taylor-Robinson SD, Simbrunner J, Coutts GA,

Burl M, Bloom SR, Sales KD, Bell JD (1996). An in vivo 13C magnetic resonance

spectroscopic study of the relationship between diet and adipose tissue composition.

Lipids, 2, 145-51.

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