ADA Position on Vegetarianism
POSITION OF THE AMERICAN DIETETIC ASSOCIATION: VEGETARIAN DIETS
A considerable body of scientific data suggests positive relationships between
vegetarian diets and risk reduction for several chronic degenerative diseases
and conditions, including obesity, coronary artery disease, hypertension,
diabetes mellitus, and some types of cancer.
POSITION STATEMENT
It is the position of The American Dietetic Association that vegetarian
diets are healthful and nutritionally adequate when appropriately planned.
VEGETARIANISM IN PERSPECTIVE
There is no single vegetarian eating pattern. The vegetarian diet is mainly
plant foods: fruits, vegetables, legumes, grains, seeds, and nuts. Eggs,
dairy products, or both may be included as well. The lacto vegetarian diet
is fruits, vegetables, grains, dairy foods, and their products whereas the
lacto-ovo vegetarian diet also adds eggs. The vegan, or total vegetarian,
diet completely excludes meat, fish, fowl,eggs, and dairy products. Even
within specific classifications of the diet, considerable variation may
exist in the extent to which animal products are avoided. Therefore, individual
assessment is required in order to accurately evaluate the nutritional quality
of a given diet.
Studies of vegetarians indicate that they often have lower mortality rates
from several chronic degenerative diseases than do non vegetarians(1,2).
These effects may be attributable to diet as well as to other lifestyle
characteristics such as maintaining desirable weight, regular physical activity,
and abstinence from smoking, alcohol, and illicit drugs.
In addition to possible health advantages, other considerations that may
lead to the adoption of a vegetarian diet include environmental or ecological
concerns, world hunger issues, economic reasons,philosophical or ethical
reasons, and religious beliefs.
IMPLICATIONS FOR HEALTH PROMOTION
Mortality from coronary artery disease is lower in vegetarians than in non
vegetarians (1,2). Total serum cholesterol and low-density lipoprotein cholesterol
levels are usually lower, whereas high density lipoprotein cholesterol and
triglyceride levels vary, depending on the type of vegetarian diet followed
(3,4). Low-fat, low-cholesterol vegetarian diets may decrease levels of
apoprotein A, B, and E; alter platelet composition and platelet function;
and decrease plasma viscosity. One study demonstrated reversal of even severe
coronary artery disease without the use of lipid lowering drugs by using
a combination of a vegetarian diet deriving less than 10% of its energy
from fat, smoking cessation, stress management, and moderate exercise(3).
Vegetarians have lower rates of hypertension (5) and non-insulin-dependent
diabetes mellitus than do non vegetarians;lessening these risk factors may
also decrease the risk of cardiovascular and coronary artery disease in
the vegetarian population.
Seventh-Day Adventist vegetarians have lower rates of mortality from colon
cancer than the general population (6). This may be attributable to dietary
differences that include increased fiber intake; decreased intake of total
fat, saturated fat, cholesterol, and caffeine; increased intake of fruits
and vegetables; and, in lacto vegetarians, increased intakes of calcium.
The dietary differences, especially in vegans, may produce physiologic changes
that may inhibit the causal chain for colon cancer (7). Reduced consumption
of meat and animal protein has also been associated with decreased colon
cancer in some, but not all, studies of omnivores. Lung cancer rates are
lower in vegetarians, chiefly because they usually do not smoke, but possibly
also because of diet (8).Research suggests that vegetarians are also at
decreased risk for breast cancer (9).
Obesity, a major public health problem in the United States, exacerbates
or complicates many diseases. Vegetarians, especially vegans, often have
weights that are closer to desirable weights than do non vegetarians(10).
Vegetarians may be at lower risk for non-insulin-dependent diabetes because
they are leaner than non vegetarians. Also, vegetarians' high intake of
complex carbohydrates, which are often relatively high in fiber content,
improves carbohydrate metabolism and may lower basal blood glucose levels
(11).
NUTRITION CONSIDERATIONS
Plant sources of protein alone can provide adequate amounts of the essential
and nonessential amino adds, assuming that dietary protein sources from
plants are reasonably varied and that caloric intake is sufficient to meet
energy needs. Whole grains, legumes, vegetables,seeds, and nuts all contain
essential and nonessential amino adds.Conscious combining of these foods
within a given meal, as the complementary protein dictum suggests, is unnecessary.
Additionally, soy protein has been shown to be nutritionally equivalent
in protein value to proteins of animal origin and, thus, can serve as the
sole source of protein intake if desired (12).
Although most vegetarian diets meet or exceed the Recommended Dietary Allowances
(13) for protein, they often provide less protein than nonvegetarian diets.
This lower protein intake may be associated with better calcium retention
in vegetarians and improved kidney function in individuals with prior kidney
damage. Further, lower protein intakes may result in a lower fat intake
with its inherent advantages, because foods high in protein are frequently
high in fat also.
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Suggested Food group daily servings Serving sizes ---------- --------------
-------------
Breads, cereals, 6 or more 1 slice bread
rice, and pasta 1/2 bun, bagel, or English muffin
1/2 cup cooked cereal, rice, or
pasta 1 oz dry cereal
Vegetables 4 or more 1/2 cup cooked or 1 cup raw
Legumes and other 2 to 3 1/2 cup cooked beans
meat substitutes 4 oz tofu or tempeh
8 oz soy milk
2 Tbsp nuts or seeds (these tend to
be high in fat, so use sparingly if you are following a low-fat diet)
Fruits 3 or more 1 piece fresh fruit
3/4 cup fruit juice
1/2 cup canned or cooked fruit
Dairy products Optional- up 1 cup low-fat or skim milk
to 3 servings 1 cup low-fat or nonfat yogurt
daily 1 1/2 oz low-fat cheese
Eggs Optional -- 1 egg or 2 egg whites
limit to 3 to
4 yolks per week
Fats, sweets, Go easy on Oil, margarine, and mayonnaise
and alcohol these foods Cakes, cookies, pies, pastries,
and beverages and candies
Beer, wine, and distilled spirits
Daily food guide for vegetarians. Source: Eating Well--The Vegetarian Way.
Chicago, Ill: American Dietetic Association; 1992._____________________________________________
Plant carbohydrates are usually accompanied by liberal amounts of dietary
fiber. This is in contrast to animal products, which are devoid of fiber.
Fiber has been shown to be important in the prevention and treatment of
certain conditions and diseases.
Vegetarian diets that are low in animal products are typically lower than
non vegetarian diets in total fat, saturated fat, and cholesterol,factors
associated with reduced risk of coronary artery disease and some forms of
cancer.
Adequate iron nutriture depends on both the amount of dietary iron consumed
and the amount absorbed. Inhibitors and enhancers affect the absorption
of nonheme iron, the form of iron found in plants. However,inhibitors and
enhancers can offset each other when a variety of foods is consumed. Vegetarians
are not at greater risk of iron deficiency than nonvegetarians, but Western
vegetarians generally have better iron status than those in developing countries.
Western vegetarians generally have an adequate intake of iron from plant
products. They also consume greater amounts of ascorbic acid, an important
enhancer of nonheme iron absorption. In contrast, vegetarians in developing
countries rely on food staples that are low in iron; consume less ascorbic
acid; and consume more tea, which contains tannin, an inhibitor of iron
absorption.
The Recommended Dietary Allowance (13) for vitamin B-12 is minute.Vitamin
B-12 is produced by microorganisms present in the guts or gastrointestinal
tracts of animals and human beings, as well as in dirt on the surface of
unwashed plants. Vitamin B-12 is found in all animal products; hence, a
pattern that includes animal products such as milk and milk products is
unlikely to be deficient in vitamin B-12. Bacteria produce vitamin B-12
in the human gut, but it appears to be produced beyond the ilium, the site
of vitamin B-12 absorption in the intestine(14).
Lack of intrinsic factor in the stomach, rather than diet, however, is the
most common cause of vitamin B-12 deficiency. Atrophic gastritis,with the
consequent bacterial overgrowth of the upper gut, may also contribute to
vitamin B-12 deficiency, especially in the elderly. Plants provide no vitamin
B-12. In countries where sanitation is poor, vegans may derive vitamin B-12
from foods that are contaminated with microbes and organisms that produce
the vitamin, such as on the surfaces of unwashed fruits or vegetables. In
Western countries, however, where sanitary practices are better, the risk
of vitamin B-12 deficiency for vegans may be greater.
Vegans should include a reliable source of the vitamin in their diets.Spirulina,
seaweed, tempeh, and other fermented foods are not reliable sources of vitamin
B-12. As much as 80% to 94% of the so-called vitamin B-12 in these foods,
as measured by microbiological assay, may be inactive analogs. Cyanocobalamin,
the form of vitamin B-12 that is physiologically active for human beings,
is available from vitamin supplements or fortified foods such as some commercial
breakfast cereals, soy beverages, some brands of nutritional yeast, and
other products.
Certain plant constituents appear to inhibit the absorption of dietary calcium,
but within the context of the total diet, this effect does not appear to
be significant. Calcium from low-oxalate vegetable greens,such as kale,
has been shown to be absorbed as well or better than calcium from cow's
milk (15). Calcium deficiency in vegetarians is rare,and there is little
evidence to show that calcium intakes below the Recommended Dietary Allowance
(13) cause major health problems in the vegetarian population. The relatively
high US recommendations for calcium intake, compared with those for populations
consuming a more plant based diet, are designed to compensate for the calciuric
effect of high intakes of animal protein, which are customary in the United
States. Studies have shown that vegetarians, on the other hand, absorb and
retain more calcium from foods than do non vegetarians (16,17).
Zinc is necessary for proper growth and development. Good plant sources
include grains, nuts and legumes. Western vegetarians usually have satisfactory
zinc status (18).
GROUPS WITH SPECIAL NEEDS
Infants, children, and adolescents who consume well-planned vegetarian diets
can generally meet all of their nutritional requirements for growth (19,20).
Those who follow vegan or vegan like diets should consume a reliable source
of vitamin B-12 and should have a reliable source of vitamin D. Calcium,
iron, and zinc intakes may also deserve special attention, although intakes
are usually adequate when reasonable variety and adequate energy are consumed.
If exposure to sunlight is limited, the need for vitamin D supplementation
should be assessed. Because vegan diets tend to be high in bulk, care should
be taken to ensure that caloric intakes are sufficient to meet energy needs,
particularly in infancy and during weaning. Both vegetarians and non vegetarians
whose infants are premature or solely breast fed beyond 4 to 6 months of
age should provide supplements of vitamin D, if exposure to sunlight is
inadequate, andiron from birth or at least by 4 to 6 months of age (21).
Well-planned vegetarian diets can be adequate for pregnant and lactating
women. Vegetarians and non vegetarians alike are generally advised to take
iron and folic acid supplements during pregnancy, although vegetarians frequently
have greater intakes of those nutrients than do nonvegetarians. A regular
source of vitamin B-12 is recommended for vegans during pregnancy and lactation
(21,22). A vitamin D supplement should be taken by pregnant and lactating
vegans if exposure to sunlight is inadequate. Consumption of a variety of
foods and adequate energy will help ensure adequate intakes of calcium,
iron, and zinc.
MEAL PLANNING
In planning vegetarian diets of any type, one should choose a wide variety
of foods and ensure that the caloric intake is adequate to meet energy needs
(23). (See the Figure.) Additionally, the following recommendations are
in order.
* Keep the intake of low nutrient-dense foods, such as sweets and fatty
foods, to a minimum. -- Choose whole or unrefined grain products,
instead of refined products, whenever possible, or use fortified or
enriched cereal products.
* Use a variety of fruits and vegetables, including a good food source of
vitamin C.
* If milk or dairy products are consumed, use low-fat or nonfat varieties.
* Limit egg intake to 3 to 4 yolks per week.
* Vegans should have a reliable source of vitamin B-12, such as some
fortified commercial breakfast cereals, fortified soy beverages, or a
cyanocobalamin supplement. A vitamin D supplement may be indicated if
exposure to sunlight is limited.
* Vegetarian and non vegetarian infants who are solely breast fed beyond
4 to 6 months of age should receive supplements of iron and vitamin D
if exposure to sunlight is limited.
The Dietary Guidelines for Americans (24) recommend a reduction in fat intake
and an increased consumption of fruits, vegetables, and whole grains. Well-planned
vegetarian diets can effectively meet these guidelines and can be a health-supporting
dietary alternative.
References
1. Burr ML, Butland BK. Heart disease in British vegetarians. Am J ClinNutr.
1988; 48:830-832.
2. Fraser GE. Determinants of ischemic heart disease in Seventh-Day Adventists:
a review. Am J Clin Nutr. 1988;48:833-836.
3. Ornish D, Brown S, Scherwitz L, Billings J, Armstrong W, Ports T,McLanahan
S, Kirkeeide R, Brand R, Gould KL. Can lifestyle changes reverse coronary
heart disease? Lancet. 1990;336:129-133.
4. Kestin M, Rouse I, Correll R, Nestel P. Cardiovascular disease risk factors
in free-living men: comparison of two prudent diets, one based on lacto
ovo vegetarianism and the other allowing lean meat. Am J ClinNutr. 1989;50:280-287.
5. Beilin, LJ, Rouse IL, Armstrong BK, Margetts BM, Vandongen R.Vegetarian
diet and blood pressure levels: incidental or causal association? Am J Clin
Nutr. 1988;48:806-810.
6. Phillips R, Snowdon D. Association of meat and coffee use with cancers
of the large bowel, breast, and prostate among Seventh-Day Adventists: preliminary
results. Cancer Res. 1983;45 (suppl):2403-2408.
7. Turjiman N, Goodman GT, Jaeger B, Nair PP. Diet, nutrition intake and
metabolism in populations at high and low risk for colon cancer:metabolism
of bile acids. Am J Clin Nutr. 1984;4:937.
8. Colditz G, Stampfer M, Willet W. Diet and lung cancer: a review of the
epidemiological evidence in humans. Arch Intern Med. 1987;147:157.
9. Chen J, Campbell TC, Li J, Peto R. In: Diet, Life-style and Mortality
in China. A study of the characteristics of 65 Counties. OxfordUniversity
Press, Cornell University Press, and the China People's Medical Publishing
House; 1990.
10. Bergan JC, Brown PT. Nutritional status of "new" vegetarians.
J AmDiet Assoc. 1980;76:151-155.
11. Nieman DC, Underwood BC, Sherman KM, Arabatzis K, Barbosa JC,Johnson
M, Shultz TD. Dietary status of Seventh-Day Adventist vegetarian and non-vegetarian
elderly women. J Am Diet Assoc. 1989;89:1763-1769.
12. Young VR. Soy protein in relation to human protein and amino acid nutrition.
J Am Diet Assoc. 1991;91:828-835.
13. Food and Nutrition Board. Recommended Dietary Allowances. 10th ed.Washington,
DC: National Academy Press; 1989.
14. Herbert V. Vitamin B-12: plant sources, requirements, assay. In:Mutch
PB, Johnston PK, eds. First International Congress on Vegetarian Nutrition.
Am J Clin Nutr. 1988; 48:452.
15. Heaney R, Weaver C. Calcium absorption from kale. Am J Clin Nutr.1990;51:656.
16. Zemel M. Calcium utilization: effect of varying level and source of
dietary protein. Am J Clin Nutr. 1988;48:880.
17. Marsh A, Sanchez T, Michelsen O, Chaffee F, Fagal S. Vegetarian lifestyle
and bone mineral density. Am J Clin Nutr. 1988;48:837-841.
18. Hambige K, Casey C, Krebs N. Zinc. In: Mertz W, ed. Trace Elementsin
Human and Animal Nutrition. Vol 2. 5th ed. Orlando, Fla: Academic Press;
1986.
19. Sabate J, Lindsted K, Harris R. Sanchez A. Attained height of lacto-ovo
vegetarian children and adolescents. Eur J Clin Nutr.1991;45:51-58.
20. O'Connell J, Dibley M, Sierra J, Wallace B, Marks J, Yip R. Growth of
vegetarian children: the Farm study. Pediatrics. 1989;84:475-480.
21. Food and Nutrition Board, Institute of Medicine. Nutrition During Lactation.
Washington, DC: National Academy Press; 1991.
22. Food and Nutrition Board, Institute of Medicine. Nutrition During Pregnancy.
Washington, DC: National Academy Press; 1991.
23. Eating Well--The Vegetarian Way. Chicago, Ill: American Dietetic Association;
1992.
24. Nutrition and Your Health: Dietary Guidelines for Americans. 3rd ed.Washington,
DC: US Dept of Agriculture and US Dept of Health and Human Services; 1990.
* ADA Position adopted by the House of Delegates on October 18, 1987,
and reaffirmed on September 12, 1992. The update will be in effect until
October 1997.
* Recognition is given to the following for their contributions:
Authors: Suzanne Havala, MS, RD; Johanna Dwyer, DSc, RD
Reviewers: Phyllis Acosta, RD; Patricia Johnston, DrPH, RD; Mary Clifford,
RD; Vegetarian Nutrition dietetic practice group: Winston Craig, PhD, RD,
and Virginia Messina, MPH, RD; Pediatric Nutrition dietetic practice group
___________________________________________________________
This position paper was "reprinted" from Journal of the American
Dietetic Association, November 1993, Volume 93, Number 11.
For more information on vegetarianism, write to :
The Vegetarian Resource Group P.O. Box 1463 Baltimore, MD 21203
(410) 366-VEGE, (410) 366-8343
email: brad@clark.net