FunctionVegetarian diets are adopted by people in devel-
oped countries primarily for ethical or religious rea-
sons rather than economic necessity—although some
nutritionists do point out that plant-based foods are
usually easier on the household food budget than
meat. Another more recent reason is the growing per-
ception that plant-based diets are a form of preventive
health care for people at increased risk of such diseases
as heart disease, type 2 diabetes and some forms of
cancer. Adolescents, however, are more likely to adopt
vegetarian diets as a weight reduction regimen.
BenefitsThe long-term NIH study of Seventh-day Adven-
tists began to report in the 1970s and 1980s that lowered
blood pressure, lower rates of cardiovascular disease
and stroke, lower blood cholesterol levels, and lowered
risks of colon andprostatecancer are associated with a
vegetarian diet. In particular, SDAs were only half as
likely to develop type 2 (adult-onset) diabetes as were
nonvegetarian Caucasians. Although it is possible to
gain weight on a vegetarian diet, most people lose
weight, especially in the first few months; and most
vegetarians have lower body mass indices (an impor-
tant diagnostic criterion ofobesity) than their meat-
eating counterparts.
Several studies carried out in Germany and Aus-
tria reported in 2006 that vegetarian diets appear to be
effective in lowering the risk of rheumatoid arthritis,
osteoporosis, kidney disease,gallstones, diverticulitis,
and dementia as well as heart attacks, stroke, and
diabetes.
In addition to lowering the risk of chronic degen-
erative diseases, vegetarian diets have also been shown
to be useful in treatingconstipationin adults and
children, and dysmenorrhea (painful menstrual peri-
ods) in women of childbearing age.
PrecautionsThe ADA strongly recommends that people consult
a registered dietitian as well as their primary physician
before starting a vegetariandiet.Thereasonforthis
precaution is the variety of vegetarian regimens as well
as the variations in height, weight, age, genetic inheri-
tance, food preferences, level of activity, geographic
location, and preexisting health problems among people.
A nutritionist can also help design a diet that a new
vegetarian will enjoy eating as well as getting adequate
nourishment and other health benefits.
Risks
The longstanding concern about vegetarian diets is
the risk of nutritional deficiencies, particularly for such
important nutrients asprotein,minerals(iron,calcium,
andzinc),vitamins(vitamin D,riboflavin,vitamin B 12 ,
andvitamin A),iodine, and n-3 fatty acids. The 2003
vegetarian food guide recommends that vegetarians
over 50 years of age as well as vegans in all age groups
should take supplements of vitamin B 12 and vitamin D,
or use foods fortified with these nutrients. Vitamin D
supplements are particularly important for vegans living
in northern latitudes or other situations in which they
receive little sun exposure.
In addition to nutritional concerns, there is some
evidence that vegetarian diets may actually increase the
risk of breast cancer in women, particularly in those who
use large amounts of soy-based products. Soybeans con-
tain phytoestrogens, or plant estrogens, which have been
implicated in breast cancer. The plant estrogens in soy-
based products may also explain why vegetarians have a
disproportionate number offemale babies, and why
these girls have a higher rate of precocious puberty
than girls born to nonvegetarian mothers.Research and general acceptance
General acceptance
Vegetarianism is accepted by all mainstream med-
ical associations and professional nutritionists’ soci-
eties, and positively recommended by some. The
position statement jointly adopted by the ADA and
DC in 2003 states: ‘‘It is the position of the American
Dietetic Association and Dietitians of Canada that
appropriately planned vegetarian diets are healthful,QUESTIONS TO ASK YOUR
DOCTOR What are the potential benefits for a person of
my age, sex, and lifestyle in adopting a
vegetarian diet? A semivegetarian diet?
What are the potential health risks, if any, for me
as an individual?
Have you treated other patients who are
vegetarians?
What specific types of vegetarian diets would
you recommend? Have you tried any of them
yourself?
Will I need any dietary supplements if I adopt a
vegetarian diet?Vegetarianism