Information on Vegan Diets
Vegetarian Foods: Powerful for Health
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 remarkable.
“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 overall.
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 atherosclerosis.
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 vegetarian diets.
Preventing and Reversing Diabetes
Non-insulin-dependent (adult-onset) 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 Osteoporosis
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 fruits.
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 B12.
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.
For 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) 1975;35:3513-22.
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 1989;2:66-71.
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 1975;292:1148-52.
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 Klin 1930;26:929-31.
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 1979;51:427-31.
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.