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Vegetarian Diet
Basics
Pat Beck, Nutrition
Specialist
Vegetarianism is generally
defined as the practice of living on a diet made up of vegetables, fruits,
grains, nuts and sometimes certain animal products. Vegetarian diets encompass a
wide variety of eating patterns.
A Vegan (strict or
total vegetarian) diet is made up exclusively of plant foods, that is, of
vegetables, fruits, legumes, grains, nuts and seeds. Foods of animal origin,
including all meat, fish, fowl, eggs and dairy products, are completely
excluded.
A Lacto-vegetarian
diet includes milk and other dairy products in addition to plant foods.
A Lacto-ovo-vegetarian
diet includes eggs, milk and dairy products in addition to plant foods. Foods
obtained by slaughtering an animal are avoided.
Semivegetarian diets
may be of several types. An ovolactopollovegetarian diet includes poultry
in addition to milk and eggs. For a pescovegetarian diet fish is an
acceptable food.
A part-time vegetarian
diet is followed by those who rely mainly on plant foods, but who occasionally
eat red meat and other animal foods. The 1980s saw a rise in this group.
Reasons for
Vegetarianism
Vegetarianism has existed
for centuries, often as a result of cultural and social forces, geographical
availability of foods and personal values. Today, with the increased focus on
decreasing fat and possibly calories in the diet, there is an increased
interest in vegetarian diets. Besides nutrition, current reasons for adhering
to vegetarianism may be religion, health, ethics, ecology or economics.
Potential Benefits
Most vegetarian diets in
the United States are high in fiber and low in total fat, saturated fat,
cholesterol and calories. If oils, nuts, whole milk, cheese and eggs are used
in a diet, dietary fat (both saturated and unsaturated) and cholesterol will
increase.
Studies have suggested a
positive relationship between vegetarian lifestyles and risk reduction for
several chronic degenerative diseases, such as obesity, heart disease,
hypertension, diabetes mellitus, breast and colon cancer and others.
It costs less to meet
protein needs using grains, legumes, milk and eggs rather than meat.
Vegetarian diets may be economical in terms of fuel and land use as well as
personal food costs.
Nutritional
Concerns
Vegans -- This group
must ensure that caloric intakes are adequate to maintain desirable body
weight, particularly throughout childhood. If there is not enough carbohydrate
or fat to supply energy, the body will use protein as an energy source.
Also Vegans need to be
certain to include an appropriate source of B12. Lack of vitamin B12 can
eventually cause anemia and damage the nervous system. Soybean milk and
vegetarian meat substitutes may be fortified with vitamin B12 or a supplement
may be taken.
Riboflavin and vitamin D
are concerns in a diet that does not contain milk or milk products. Vitamin D
will be synthesized by the body if the skin is exposed to sunlight. If
exposure to sun-light is limited, a vitamin D supplement may be necessary.
Calcium absorption appears
to be inhibited by such plant constituents as phytic acid, oxalic acid and
fiber but this effect may not be significant. There is little evidence to show
that low intakes of calcium give rise to major health problems among the
vegetarian population. One recent study has shown that vegetarians absorb and
retain more calcium from food than do non-vegetarians.
Iron and zinc intake may be
marginal and phytates may interfere with the availability of these minerals.
Tea and fiber may also inhibit the absorption of iron. Absorption of iron is
enhanced when consumed with ascorbic acid (vitamin C) or meats.
Food Sources
Calcium -- dairy
products; dark green vegetables such as broccoli, collards, kale, mustard, and
turnip greens; legumes; fortified soy milk; almonds and sesame seeds
Iron -- legumes;
raisins; whole and enriched grains; leafy green vegetables
Zinc -- the same as
iron except raisins
Vitamin C -- citrus
fruits; broccoli; cabbage; green peppers; tomatoes
Riboflavin -- dairy
products; dark green leafy vegetables; legumes; grains
Vitamin D --
fortified milk
Children -- The
vegan diet is not recommended for children without the guidance of nutrition
experts. It is possible to put together a diet for a young child composed
entirely of foods of vegetable origin that will supply nutrient needs except
for calcium, vitamin B12 and vitamin D. Such a diet, however, is so bulky that
it is unlikely that enough food would be consumed to meet the energy needs of
a young child and normal growth would not occur. Including milk and eggs in
the diets of children is highly recommended.
Pregnant or Lactating
Women -- These women have increased nutrient needs which can be met by a
well-planned vegetarian diet that includes an iron and folate supplement.
Vitamin D and calcium requirements may be difficult to meet without the
inclusion of milk or a supplement.
Protein
Protein is the nutrient
that seems to be of greatest concern to most new vegetarians. Although plant
foods contain less of the essential amino acids than do similar quantities of
animal food, a plant-based diet provides adequate amounts of amino acids when
a varied diet is consumed on a daily basis.
Protein is a nutrient that
provides the framework for all living cells. It is made up of building blocks
called amino acids which are necessary for building, maintaining and repairing
of body tissues.
About half of the known
amino acids can be synthesized in the human body. The nine amino acids that
cannot be synthesized must be provided by the foods eaten, and these are
called essential amino acids. During digestion proteins are broken down and
the resulting amino acids are stored in a common amino acid pool. The body
draws on this pool 24 hours a day to get the amino acids it needs to make new
protein for growth and repair of body tissue. In order to make any new
protein, all the necessary amino acids must be present at the same time in the
pool.
Thus, it follows that
intakes of different types of protein which complement one another should be
eaten over the course of the day. However, it is not necessary that all of the
amino acids be eaten at exactly the same meal as the recently popular
"combined proteins theory" suggested. This theory urged conscious
combining of proteins at every meal.
A protein which contains
all the essential amino acids in proper proportions is called a complete
protein. Foods from animal sources, except gelatin, contain complete proteins.
Most plant foods contain incomplete protein because they are short one or more
of the essential amino acids. By combining plant foods that have complementary
essential amino acid mixtures, incomplete plant proteins form complete
proteins that supply all of the essential amino acids found in animal
products.
Proteins from the same
plant family, such as grains, are generally low in the same amino acids.
Proteins from another plant family, such as legumes, are low in different
amino acids. If proteins from these two plant families are eaten together, one
plant protein provides the amino acids that are low in the other plant
protein. Since each protein makes up for the other's shortcomings, they can be
said to be "complementary" to each other, and so they are known as
complementary proteins. For example, beans and rice, when eaten together,
result in a good balance of amino acids.
Some foods which may be
combined to provide a good balance of amino acids are:
-
cereal + milk as
breakfast cereal and milk
-
pasta + cheese
as macaroni and cheese
-
rice + milk as
rice pudding
-
wheat + peanuts
as peanut butter sandwich
-
beans + wheat as
baked beans and brown bread
-
peas + rye as
split pea soup and rye bread
-
beans + corn as
refried beans and tortillas
-
soybeans +
seeds/nuts as trail mix
Planning
Adequacy of any diet is
defined in terms of the nutrients it provides. No food in itself is essential
if the nutrients it offers can be secured from other foods or supplements. If
a diet provides what the body needs to ensure well-being, the diet is adequate
even if it does not include conventional foods.
The American Dietetics
Association notes that "vegetarian diets are healthful and nutritionally
adequate when appropriately planned." Both vegetarian and nonvegetarian
diets have the potential to be either beneficial or detrimental to health.
Careful planning of either type of diet to meet the Dietary Guidelines for
Americans may result in the reduction of some risk factors for some
diet-related diseases and conditions.
Choose a wide variety of
foods, including fruits, vegetables, whole grain food products, nuts, legumes,
low-fat dairy products or fortified soy substitutes and a limited number of
eggs. Additionally, the following recommendations are made:
-
Keep the intake of low
nutrient-dense foods, such as sweets and fatty foods, to a minimum.
-
Choose whole or
unrefined grain products whenever possible, instead of refined products.
-
Use a variety of fruits
and vegetables, including a good food source of vitamin C to enhance iron
absorption.
-
If milk products are
consumed, use low-fat varieties.
-
Limit intake of eggs to
2 to 4 yolks per week to ensure that cholesterol intakes are not
excessive.
-
For vegans, use a
fortified food source of vitamin B12, such as fortified soy milks or
breakfast cereals, or take a vitamin B12 supplement.
-
For infants and
children, ensure adequate intakes of iron, vitamin D, calcium and energy.
-
Consult a registered
dietitian or other qualified nutrition professional.
The following are
guidelines, based on food groups, for selecting daily vegetarian menus:
-
Milk, milk products,
and fortified soy milk
4 servings for adults. Additional servings for teens, children, and
pregnant or lactating women.
Supplies calcium, riboflavin and protein.
-
Protein-rich foods,
includes legumes, nuts and seeds, as well as milk and eggs.
2 servings legumes and 1 serving nuts for adults. Additional servings of
nuts for pregnant or lactating women.
Supplies protein, iron, thiamin, riboflavin and niacin.
-
Fruits and
vegetables.
7+ servings.
Supplies vitamins A and C and iron. Include 1½ servings of a dark green;
3 of vitamin C rich; and 3 others. Dark greens include romaine lettuce,
loose leaf lettuce, broccoli, kale, beet, collard, mustard or dandelion
greens. Vitamin C rich foods include citrus, potato, melon, tomato, raw
cabbage, strawberries, broccoli, sweet peppers and spinach.
North Dakota State University
NDSU Extension Service
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Diet Basics
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