Many people are attracted to vegetarian diets. It's no wonder. Health experts for years have been telling us to eat more plant foods and less fat, especially saturated fat, which is found in larger amounts in animal foods than plant foods.
C. Everett Koop, M.D., former surgeon general of the Public Health Service, in his 1988 Report on Nutrition and Health, expressed "major concern ... [about Americans'] disproportionate consumption of foods high in fats, often at the expense of foods high in complex carbohydrates and fiber--such as vegetables, fruits, and whole-grain products--that may be more conducive to health."
And, while guidelines from the U.S. departments of Agriculture and Health and Human Services advise 2 to 3 daily servings of milk and the same of foods such as dried peas and beans, eggs, meat, poultry and fish, they recommend 3 to 5 servings of vegetables, 2 to 4 of fruits, and 6 to 11 servings of bread, cereal, rice, and pasta--in other words, 11 to 20 plant foods, but only 4 to 6 animal foods.
It's wise to take precautions, however, when adopting diets that entirely exclude animal flesh or dairy products.
The more an individual restricts his or her diet, the more difficult it is to get all the nutrients that are needed. Vegetarian diets require very careful, proper planning.
Vegetarians who abstain totally from dairy products or animal flesh face the greatest nutritional risks because some nutrients naturally occur mainly or almost exclusively in animal foods.
Vegans, who eat no animal foods (and, rarely, vegetarians who eat no animal flesh but do eat eggs or dairy products), risk vitamin B12 deficiency, which can result in irreversible nerve deterioration.
The need for vitamin B12 may increase during pregnancy, breast-feeding, and periods of growth., according to Johanna Dwyer, D.Sc., R.D.
Published in 1988 in the American Journal of Clinical Nutrition, studies of the previous five years were reviewed and it was concluded that elderly people also should be especially cautious about adopting vegetarian diets because their bodies may absorb vitamin B12 poorly.
Ovo-vegetarians, who eat eggs but no dairy foods or animal flesh, and vegans may have inadequate vitamin D and calcium. Inadequate vitamin D may cause rickets in children, while inadequate calcium can contribute to risk of osteoporosis in later years.
These vegetarians are susceptible to iron deficiency anemia because they are not only missing the more readily absorbed iron from animal flesh, they are also likely to be eating many foods with constituents that inhibit iron absorption -- soy protein, bran, and fiber, for instance.
Vegans must guard against inadequate calorie intake, which during pregnancy can lead to low birth weight, and against protein deficiency, which in children can impair growth and in adults can cause loss of hair and muscle mass and abnormal accumulation of fluid.
According to the Institute of Food Technologists and the American Dietetic Association, if appropriately planned, vegan diets can provide adequate nutrition even for children. Some experts disagree.
Some experts believe that it is unhealthy for children to eat no red meat, and that those individuals may have health problems later in life because of imbalances with micronutrients (nutrients required only in small amounts), particularly iron, zinc and copper.
While meat is well-known as an important source of iron, it may be even more valuable for copper and zinc. Copper not only helps build the body's immunity, it builds red blood cells and strengthens blood vessels.
Some experts believe that many Americans are more susceptible to disease because of a deficiency in micronutrients, and that children "can't meet their zinc needs without eating meat."
Also, vegetarian women of childbearing age have an increased chance of menstrual irregularities, Ann Pederson and others reported in the American Journal of Clinical Nutrition.
Nine of the study's 34 vegetarians (who ate eggs or dairy foods) missed menstrual periods, but only 2 of the 41 non-vegetarians did. The groups were indistinguishable when it came to height, weight and age at the beginning of menstruation.
The National Cancer Institute states in its booklet "Diet, Nutrition & Cancer Prevention: The Good News" that a third of cancer deaths may be related to diet.
The booklet's "Good News" is: Vegetables from the cabbage family (cruciferous vegetables) may reduce cancer risk, diets low in fat and high in fiber-rich foods may reduce the risk of cancers of the colon and rectum, and diets rich in foods containing vitamin A, vitamin C, and beta-carotene may reduce the risk of certain cancers.
Part of FDA's proposed food labeling regulations, published in the Nov. 27, 1991, Federal Register, states, "The scientific evidence shows that diets high in whole grains, fruits, and vegetables, which are low in fat and rich sources of fiber and certain other nutrients, are associated with a reduced risk of some types of cancer.
The available evidence does not, however, demonstrate that it is total fiber, or a specific fiber component, that is related to the reduction of risk of cancer.
However, the FDA acknowledges that high intakes of fruits and vegetables rich in beta-carotene or in vitamin C have been associated with reduced cancer risk.
But the agency believes the data are not sufficiently convincing that either nutrient by itself is responsible for this association.
Pointing out that plant foods' low fat content also confers health benefits, FDA states in its proposed rule that diets low in fat give protection against coronary heart disease and that it has tentatively determined, "Diets low in fat are associated with the reduced risk of cancer."
FDA notes that diets high in saturated fats and cholesterol increase levels of both total and LDL cholesterol, and thus the risk for coronary heart disease, and that high-fat foods contribute to obesity, a further risk factor for 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 those reasons, the agency would allow some foods to be labeled with health claims relating diets low in saturated fat and cholesterol to decreased risk of coronary heart disease, and relating diets low in fat to reduced risk of breast, colon and prostate cancer.
"Examples of foods qualifying for a health claim include most fruits and vegetables; skim milk products; sherbets; most flours, grains, meals, and pastas (except for egg pastas); and many breakfast cereals," the proposed rule stated.
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.
Death rates for vegetarians are similar or lower than for non-vegetarians, but are 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.
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 to beginning a vegetarian diet is to first cut down on the fattiest meats, replacing them with cereals, fruits and vegetables, recommends Jack Zeev Yetiv, M.D., Ph.D., in his book Popular Nutritional Practices: A Scientific Appraisal.
"Some may choose to eliminate red meat but continue to eat fish and poultry occasionally, and such a diet is also to be encouraged."
Changing to the vegetarian kitchen slowly also may increase the chances of success. It's sometimes difficult to change habits, and sometimes discouraging to think there's nothing to eat.
Build meals around starchy carbohydrates such as pasta or potatoes. And experiment with recipes. Shifting from a meat-centered meal to plant-centered one is easier once you've found recipes you like.
Because vegans and ovo-vegetarians face the greatest potential nutritional risk, the Institute of Food Technologists recommends careful diet planning to include enough calcium, riboflavin, iron, and vitamin D, perhaps with a vitamin D supplement if sunlight exposure is low. (Sunlight activates a substance in the skin and converts it into vitamin D.)
For these two vegetarian groups, the institute recommends calcium supplements during pregnancy, infancy, childhood, and breast-feeding.
Vegans may need to take a vitamin B12 supplement because that vitamin is found only in animal food sources. Unless advised otherwise by a doctor, the National Academy of Sciences' Recommended Dietary Allowances is a good guide to use for taking supplements.
Vegans, and especially children, also must be sure to consume adequate calories and protein.
For other vegetarians, it is not difficult to get adequate protein, although care is needed in small children's diets.
Nearly every animal food, including egg whites and milk, provides all eight of the essential amino acids in the balance needed by humans and therefore constitutes "complete" protein.
Plant foods contain fewer of these amino acids than animal foods.
The American Dietetic Association's position paper on vegetarian diets, published in its journal in 1988, states that a plant-based diet provides adequate amounts of amino acids when a varied diet is eaten on a daily basis.
The mixture of proteins from grains, legumes, seeds, and vegetables provide 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. Frances Lappe, in Diet for a Small Planet, writes that to gain the greatest use of all the amino acids, it's best to consume complementary proteins within three to four hours.
High amounts of complete proteins can be gained by combining legumes with grains, seeds or nuts.
Also available are various protein analogs. These substitute "meats"--usually made from soybeans--are formed to look like meat foods such as hot dogs, ground beef, or bacon. Many are fortified with vitamin B12.
Listed at the end of this article are sources of the nutrients of greatest concern for vegetarians who don't eat animal foods. 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.
The American Dietetic Association recommends:
With the array of fruits, vegetables, grains, and herbs available in U.S. grocery stores and the availability of vegetarian cookbooks, it's easy to devise tasty vegetarian dishes.
People who like their entrees on the hoof also can benefit from adding more plant foods to their diets. You don't have to be a vegetarian to enjoy dishes from a vegetarian menu.
The Institute of Food Technologists, in the July 1991 issue of its journal, Food Technology, describes six types of vegetarians. They are listed here by degree of exclusion of animal foods and by the foods included in the diet:
Vegetarians who eat no meat, fish, poultry, or dairy foods face the greatest risk of nutritional deficiency. Nutrients most likely to be lacking and some non-animal sources are:
As all plant foods -- including fruit -- contain some protein, by eating a variety of fruits, vegetables and grains, even vegans probably can get enough of this nutrient.
To improve the quality of protein and ensure getting enough:
Combine legumes such as black-eyed peas, chickpeas, peas, peanuts, lentils, sprouts, and beans (black, broad, kidney, lima, mung, navy, pea, and soy) with grains such as rice, wheat, corn, rye, bulgur, oats, millet, barley, and buckwheat. There are also foods made to look like meats (protein analogs) such as hot dogs, sausage, and bacon.Source: FDA Consumer