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.
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.
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.
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 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
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.
- Whole grain and enriched breads and cereals. 6 servings. Supplies iron and several B vitamins.
- Fruits and vegetables. 7+ servings. Supplies vitamins A and C and iron. Include 1? 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.
- Fats as vegetable oil or margarine. 1 to 2 tablespoons daily. Supplies essential fatty acids and vitamin E.
Pat Beck, Nutrition Specialist
North Dakota State University
NDSU Extension Service