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FDA Consumer October 1995
More People Trying Vegetarian Diets
by Dixie Farley
Perceiving plant foods as beneficial because they are high in dietary fiber
and, generally, lower in saturated fat than animal foods, many people turn
to vegetarian diets.
Grain products, for instance, form the base of the U.S. Department of
Agriculture and Department of Health and Human Services' Food Guide
Pyramid, which recommends 6 to 11 daily servings of bread, cereal, rice,
and pasta. Daily intakes advised for other foods are: 3 to 5 servings of
vegetables; 2 to 4 servings of fruits; 2 to 3 servings of milk, yogurt and
cheese; and 2 to 3 servings of meat, poultry, fish, dry beans, eggs, and
nuts. The guide advises using fats, oils and sweets sparingly.
And, who hasn't seen signs in their grocer's produce section urging
consumers to eat "5 a day for better health"? This slogan reflects a major
government-industry campaign to help people eat more fruits and vegetables
as part of a high-fiber, low-fat diet that emphasizes variety.
The campaign is consistent with the USDA-DHHS Dietary Guidelines for
Americans, which states: "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."
But health benefits are not the only reason vegetarian diets attract
followers.
Certain people, such as Seventh-Day Adventists, choose a vegetarian diet
because of religious beliefs. Others give up meat because they feel eating
animals is unethical. Some believe it's a better use of the Earth's
resources to eat low on the food chain--that is, to eat plant foods, rather
than the animals that eat the plant foods. And many people eat plant foods
simply because they are less expensive than animal foods.
It's wise to take precautions, however, when adopting a diet that entirely
excludes animal flesh and dairy products, called a vegan diet. (See
ƒ%"Vegetarian Varieties."ƒ`)
"The more you restrict your diet, the more difficult it is to get the
nutrients you need," says John Vanderveen, Ph.D., director of the Food and
Drug Administration's Office of Plant and Dairy Foods and Beverages. "To
be healthful, vegetarian diets require very careful, proper planning.
Nutrition counseling can help you get started on a diet that is
nutritionally adequate."
If appropriately planned, vegan diets, though restrictive, can provide
adequate nutrition even for children, according to the American Dietetic
Association and the Institute of Food Technologists.
ƒ^Plant Food Benefitsƒ`
Registered dietitian Johanna Dwyer, of Tufts University Medical School and
the New England Medical Center Hospital, Boston, summarizes these plant
food benefits:
"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 II
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 among vegetarians."
According to Dwyer, vegetarians' longevity is similar to or greater than
that of non-vegetarians, but is influenced in Western countries by
vegetarians' "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."
ƒ^Can Veggies Prevent Cancer?ƒ`
The National Cancer Institute, in its booklet Diet, Nutrition, & Cancer
Prevention: A Guide to Food Choices, states that 35 percent of cancer
deaths may be related to diet. The booklet states:
- Diets rich in beta-carotene (the plant form of vitamin A) and vitamin
C may reduce the risk of certain cancers.
- Reducing fat in the diet may reduce cancer risk and, in helping weight
control, may reduce the risk of heart attacks and strokes.
- Diets high in fiber-rich foods may reduce the risk of cancers of the
colon and rectum.
- Vegetables from the cabbage family (cruciferous vegetables) may reduce
the risk of colon cancer.
FDA, in fact, authorized several health claims on food labels relating
low-fat diets high in some plant-derived foods with a possibly reduced risk
of cancer.
While FDA acknowledges that high intakes of fruits and vegetables rich in
beta-carotene or vitamin C have been associated with reduced cancer risk,
it believes the data are not sufficiently convincing that either nutrient
by itself is responsible for the association. Nevertheless, since most
fruits and vegetables are low-fat foods and may contain vitamin A (as
beta-carotene) and vitamin C, the agency authorized a health claim relating
diets low in fat and rich in these foods to a possibly reduced risk of some
cancers.
Another claim may relate low-fat diets high in fiber-containing vegetables,
fruits and grains to a possible reduction in cancer risk. (The National
Cancer Institute recommends 20 to 30 grams of fiber a day.) Although the
exact role of total dietary fiber, fiber components, and other nutrients
and substances in these foods is not fully understood, many studies have
shown such diets to be associated with reduced risk of some cancers.
ƒ^Lowering Heart Disease Riskƒ`
FDA also notes that diets high in saturated fats and cholesterol increase
blood levels of total cholesterol and LDL cholesterol, and thus the risk
for coronary heart disease. (The National Cholesterol Education Program
recommends a diet with no more than 30 percent fat, of which no more than
10 percent comes from saturated fat.) For this reason, the agency
authorized a health claim relating diets low in saturated fat and
cholesterol to a possibly reduced risk of coronary heart disease.
Another claim may relate diets low in fat and high in fruits, vegetables,
and grain products that contain fiber, particularly soluble fiber, to a
possibly reduced risk of coronary heart disease. However, the agency
recognizes that it is impossible to adequately distinguish the effects of
fiber, including soluble fiber, from those of other food components.
With respect to increasing fiber in the diet, Joanne Slavin, Ph.D., R.D.,
of the University of Minnesota, in 1990 in Nutrition Today, gives this
advice: "The current interest in dietary fiber has allowed recommendations
for fiber supplementation to outdistance the scientific research base.
Until we have a better understanding of how fiber works its magic, we
should recommend to American consumers only a gradual increase in dietary
fiber from a variety of sources."
ƒ^Precautionsƒ`
The American Dietetic Association's position paper on vegetarian diets
states, "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." Dwyer and Suzanne Havala, also
a registered dietitian, updated the paper in the 1993 issue of the
association's journal.
It's generally agreed that to avoid intestinal discomfort from increased
bulk, a person shouldn't switch to foods with large amounts of fiber all at
once. A sensible approach is to slowly increase consumption of grains,
legumes, seeds, and nuts. "Some may choose to eliminate red meat but
continue to eat fish and poultry occasionally, and such a diet is also to
be encouraged," Jack Zeev Yetiv, M.D., Ph.D., in his book Popular
Nutritional Practices: A Scientific Appraisal.
As with any diet, it's important for the vegetarian diet to include many
different foods, since no one food contains all the nutrients required for
good health. "The wider the variety, the greater the chance of getting the
nutrients you need," says FDA's Vanderveen.
In its position paper on vegetarian diets, the American Dietetic
Association states that, with a plant-based daily diet, eating a variety of
foods and sufficient calories for energy needs will help ensure adequate
intakes of calcium, iron and zinc. (Seeƒ%"Replacing Animal Sources of
ƒ^Nutrients."ƒ`)
The mixture of proteins from grains, legumes, seeds, nuts, and vegetables
provides a complement of amino acids so that deficits in one food are made
up by another. Not all types of plant foods need to be eaten at the same
meal, since the amino acids are combined in the body's protein pool.
"Soy protein," the paper states, "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."
The Institute of Food Technologists also recommends careful diet planning
for vegetarians. This is especially important when the diet excludes dairy
foods, to ensure adequate intake of calcium, iron, riboflavin, and vitamin
D. For these vegetarians, the institute recommends calcium supplements
during pregnancy, when breast-feeding, and for infants and children.
The institute and the American Dietetic Association say a vitamin D
supplement may be needed if sunlight exposure is limited. (Sunlight
activates a substance in the skin and converts it into vitamin D.)
They also point out that vegan diets should include a reliable source of
vitamin B12 (see "Replacing Animal Sources of Nutrients"), because this
nutrient occurs only in animal foods. Vitamin B12 deficiency can result in
irreversible nerve deterioration.
The need for vitamin B12 increases during pregnancy, breast-feeding, and
periods of growth, Dwyer says. In a recent issue of Annual Review of
Public Health, she writes that elderly people also should be especially
cautious about adopting vegetarian diets because their bodies may absorb
vitamin B12 poorly.
Unless advised otherwise by a doctor, those taking dietary supplements
should limit the dose to 100 percent of the U.S. Recommended Daily
Allowances.
With the array of fruits, vegetables, grains, and spices available in U.S.
grocery stores and the availability of vegetarian cookbooks, it's easy to
devise tasty vegetarian dishes that even non-vegetarians can enjoy.
However, the key to any healthful diet--vegetarian or non-vegetarian--is
adherence to sound nutrition principles.
_Dixie Farley is a staff writer for FDA Consumer._
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ƒ^Vegetarian Varietiesƒ`
The American Dietetic Association describes three types of vegetarians.
They are listed here by the extent to which the diet includes animal foods:
- lacto-ovo-vegetarian--dairy foods and eggs
- lacto-vegetarian--dairy foods, but no eggs
- vegan--no animal foods of any type
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ƒ^Replacing Animal Sources of Nutrientsƒ`
Vegetarians who eat no animal products need to be more aware of nutrient
sources. Nutrients most likely to be lacking and some non-animal sources
are:
- vitamin B12--fortified soy beverages and cereals
- vitamin D--fortified soy beverages and sunshine
- calcium--tofu processed with calcium, broccoli, seeds, nuts, kale, bok
choy, legumes (peas and beans), greens, lime-processed tortillas, and
soy beverages, grain products, and orange juice enriched with calcium
- iron--legumes, tofu, green leafy vegetables, dried fruit, whole
grains, and iron-fortified cereals and breads, especially whole-wheat.
(Absorption is improved by vitamin C, found in citrus fruits and
juices, tomatoes, strawberries, broccoli, peppers, dark-green leafy
vegetables, and potatoes with skins.)
- zinc--whole grains (especially the germ and bran), whole-wheat bread,
legumes, nuts, and tofu
- protein--tofu and other soy-based products, legumes, seeds, nuts,
grains, and vegetables
_--D.F._
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ƒ^American Dietetic Association Recommendationsƒ`
For people who follow vegetarian diets, the American Dietetic Association
has these recommendations:
- Consult a registered dietitian or other qualified nutrition
professional, especially during periods of growth, breast-feeding,
pregnancy, or recovery from illness.
- Minimize intake of less nutritious foods such as sweets and fatty
foods.
- Choose whole or unrefined grain products instead of refined products.
- Choose a variety of nuts, seeds, legumes, fruits, and vegetables,
including good sources of vitamin C to improve iron absorption.
- Choose low-fat or nonfat varieties of dairy products, if they are
included in the diet.
- Avoid excessive cholesterol intake by limiting eggs, if they are
included in the diet, to three or four egg yolks per week.
- For infants, children and teenagers, ensure adequate intakes of
calories, vitamin D, calcium, iron, and zinc. (Intakes of vitamin D,
calcium, iron, and zinc are usually adequate when a variety of foods
and sufficient calories are consumed.)
- If exclusively breast-feeding premature infants or babies beyond 4 to
6 months of age, give vitamin D and iron supplements to the child from
birth or at least by 4 to 6 months, as your doctor suggests.
- Usually, take iron and folate (folic acid) supplements during
pregnancy.
- In addition, for vegans:
- Use properly fortified food sources of vitamin B12, such as fortified
soy beverages or cereals, or take a supplement.
- If sunlight is inadequate, take a vitamin D supplement during
pregnancy or while breast-feeding.
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FDA Consumer magazine (October 1995)