Information on Vegan Diets
A vegetarian diet has been
advocated by everyone from philosophers such as Plato and
Nietzsche, to political leaders such as Benjamin Franklin and
Gandhi, to modern pop icons such as Paul McCartney and Bob Marley.
Science is also on the side of vegetarianism. A multitude of
studies have proven the health benefits of a vegetarian diet to be
“Vegetarian” is defined as avoiding
all animal flesh, including fish and poultry. Vegetarians who
avoid flesh, but do eat animal products such as cheese, milk, and
eggs, are ovo-lacto-vegetarians (ovo = egg; lacto = milk, cheese,
etc.). The ranks of those who eschew all animal products are
rapidly growing; these people are referred to as pure vegetarians
or vegans. Scientific research shows that ovo-lacto-vegetarians
are healthier than meat-eaters, and vegans are the healthiest
A vegetarian diet helps to prevent
cancer. Numerous epidemiological and clinical studies have shown
that vegetarians are nearly 50 percent less likely to die from
cancer than non-vegetarians.1 Similarly, breast cancer rates are
dramatically lower in nations, such as China, that follow
plant-based diets. Interestingly, Japanese women who follow
Western-style, meat-based diets are eight times more likely to
develop breast cancer than women who follow a more traditional
plant-based diet.2 Vegetarians also have lower rates of colon
cancer than meat-eaters.1 Animal products are usually high in fat
and always devoid of fiber. Meat and dairy products contribute to
many forms of cancer, including cancer of the colon, breast, and
prostate. Colon cancer has been directly linked to meat
consumption. High-fat diets also encourage the body’s production
of estrogens, in particular, estradiol. Increased levels of this
sex hormone have been linked to breast cancer. One recent study
linked dairy products to an increased risk of ovarian cancer. The
process of breaking down the lactose (milk sugar) into galactose
evidently damages the ovaries.3
Vegetarians avoid the animal fat
linked to cancer and get abundant fiber and vitamins that help to
prevent cancer. In addition, blood analysis of vegetarians reveals
a higher level of Natural Killer Cells, specialized white blood
cells that attack cancer cells.4
Beating Heart Disease
Vegetarian diets also help prevent
heart disease. Animal products are the main source of saturated
fat and the only source of cholesterol in the diet. Vegetarians
avoid these risky products. Additionally, fiber helps reduce
cholesterol levels,5 and animal products contain no fiber. One
study even demonstrated that a low-fat, high-fiber, vegetarian
diet combined with stress reduction techniques, smoking cessation,
and exercise could actually reverse atherosclerosis—hardening of
the arteries.6 Heart diets that include animal products are much
less effective, usually only slowing the process of
Lowering Blood Pressure
Back in the early 1900s,
nutritionists noted that people who ate no meat had lower blood
pressure.7 It was also discovered that vegetarian diets could,
within two weeks, significantly reduce a person’s blood pressure.8
These results were evident regardless of the sodium levels in the
Preventing and Reversing
diabetes can be better controlled and sometimes even eliminated
through a low-fat, vegetarian diet along with regular exercise.
Because such a diet is low in fat and high in fiber and complex
carbohydrates, it allows insulin to work more effectively. The
diabetic person can more easily regulate glucose levels. While a
vegetarian diet cannot eliminate the need for insulin in people
with insulin-dependent (childhood-onset) diabetes, it can often
reduce the amounts of insulin used. Some scientists believe that
insulin dependent diabetes may be caused by an auto-immune
reaction to dairy proteins.
Gallstones, Kidney Stones, and
Vegetarian diets have been shown to
reduce one’s chances of forming kidney stones and gallstones.
Diets that are high in protein, especially animal protein, tend to
cause the body to excrete more calcium, oxalate, and uric acid.
These three substances are the main components of urinary tract
stones. British researchers have advised that persons with a
tendency to form kidney stones should follow a vegetarian diet.9
Similarly, high-cholesterol, high-fat diets—the typical meat-based
diet—are implicated in the formation of gallstones.
For many of the same reasons,
vegetarians are at a lower risk for osteoporosis. Since animal
products force calcium out of the body, eating meat can promote
bone loss. In nations with mainly vegetable diets (and without
dairy product consumption), osteoporosis is less common than in
the U.S.—even when calcium intake is also less than in the U.S.10
Calcium is important, but there is no need to get calcium from
dairy products. For more information on protecting your bones,
contact PCRM for additional reference materials and fact sheets.
A 1985 Swedish study demonstrated
that asthmatics who practice a vegan diet for a full year have a
marked decrease in their need for medications, and in their
frequency and severity of asthma attacks. Twenty-two of the 24
subjects reported improvement by the end of the year.11 Dairy
allergies may be part of the reason.
Some people still worry about the
ease with which a vegetarian diet can provide all essential
nutrients. The fact is, it is very easy to have a well-balanced
diet with vegetarian foods. Vegetarian foods provide plenty of
protein. Careful combining of foods is not necessary. Any normal
variety of plant foods provides more than enough protein for the
body’s needs. Although there is somewhat less protein in a
vegetarian diet than a meat-eater’s diet, this is actually an
advantage. Excess protein has been linked to kidney stones,
osteoporosis, and possibly heart disease and some cancers. A diet
focused on beans, whole grains, and vegetables contains adequate
amounts of protein without the “overdose” most meat-eaters get.
Calcium is easy to find in a
vegetarian diet. Many dark green leafy vegetables and beans are
loaded with calcium, and some orange juices and cereals are
calcium-fortified. Iron is plentiful in whole grains, beans, and
Vitamin B12 is a genuine issue for
vegans, although very easy to deal with. Traditionally, getting
this vitamin has not been difficult. In cultures with plant-based
diets, the microorganisms that produce B12 grow in the soil and
cling to root vegetables, and traditional Asian miso and tempeh
contain large amounts of the vitamin. But with industrialized
production and improved hygiene, this source of B12 has been
eliminated. Meat-eaters get B12 through microorganisms living in
the animals they eat.
Although cases of B12 deficiency
are very uncommon, it is important to make sure that one has a
reliable source of the vitamin. Good sources include all common
multiple vitamins (including vegetarian vitamins), fortified
cereals, and fortified soymilk. It is especially important for
pregnant women and breast-feeding mothers to get enough vitamin
Special Concerns: Pregnancy,
Infants, and Children
During pregnancy, nutritional needs
increase. The American Dietetic Association has found vegan diets
adequate for fulfilling nutritional needs during pregnancy, but
pregnant women and nursing mothers should supplement their diets
with vitamins B12 and D. Most doctors also recommend that pregnant
women supplement their diet with iron and folic acid, although
vegetarians normally consume more folic acid than meat-eaters.
Vegetarian women have a lower
incidence of pre-eclampsia in pregnancy, and significantly more
pure breast milk. Analyses of vegetarians’ breast milk show that
the levels of environmental contaminants in their milk are much
lower than in non-vegetarians.12 Studies have also shown that in
families with a history of food allergies, when women abstain from
allergenic foods, including milk, meat, and fish, during
pregnancy, they are less likely to pass allergies onto the
infant.13 Mothers who drink milk pass cow antibodies along to
their nursing infants through their breast milk. These antibodies
can cause colic.
Vegetarian children also have high
nutritional needs, but these, too, are met within a vegetarian
diet. A vegetarian menu is life-extending. As young children,
vegetarians may grow more gradually, reach puberty somewhat later,
and live substantially longer than do meat-eaters. Do be sure to
include a reliable source of vitamin B12.
more information on vegetarian diets, PCRM recommends:
Foods That Fight Pain,
by Neal Barnard, M.D.
Eat Right, Live Longer,
by Neal Barnard, M.D.
Food for Life,
by Neal Barnard, M.D.
The McDougall Plan, by
John McDougall, M.D.
Dr. Dean Ornish’s Program for Reversing Heart
Disease, by Dean Ornish, M.D.
1. Phillips RL. Role of lifestyle and dietary habits in risk
of cancer among Seventh-Day Adventists. Cancer Res (Suppl)
2. Trichopoulos D, Yen S, Brown J, Cole P, MacMahon B. The effect
of westernization on urine estrogens, frequency of ovulation, and
breast cancer risks: a study in ethnic Chinese women in the Orient
and in the U.S.A. Cancer 1984;53:187-92.
3. Cramer DW, Harlow BL, Willett WC. Galactose consumption and
metabolism in relation to the risk of ovarian cancer. Lancet
4. Malter M, Schriever G, Eilber U. Natural killer cells,
vitamins, and other blood components of vegetarian and omnivorous
men. Nutr Cancer 1989; 12:271-8.
5. Sacks FM, Castelli WP, Donner A, Kass EH. Plasma lipids and
lipoproteins in vegetarians and controls. N Engl J Med
6. Ornish D, Brown SE, Scherwitz LW. Can lifestyle changes reverse
coronary heart disease? Lancet 1990;336:129-33.
7. Salie F. Influence of vegetarian food on blood pressure. Med
8. Donaldson AN. The relation of protein foods to hypertension.
Calif West Med 1926;24:328-31.
9. Robertson WG, Peacock M, Heyburn PJ. Should recurrent calcium
oxalate stone formers become vegetarians? Br J Urol
10. Hegsted DM. Calcium and osteoporosis. J Nutr 1986;116:2316-9.
11. Lindahl O, Lindwall L, Spangberg A, Stenram A, Ockerman PA.
Vegan regimen with reduced medication in the treatment of
bronchial asthma. J Asthma 1985;22:45-55.
12. Hergenrather J, Hlady G, Wallace B, Savage E. Pollutants in
breast milk of vegetarians (letter). N Engl J Med 1981;304:792.
13. Allergies in infants are linked to mother’s diets. New York
Times, 30 August 1990.