Many people become vegetarians for health, environmental, or spiritual reasons, and there's growing evidence that a plant-based diet may be the healthiest choice for almost everyone. In fact, thousands of years before Nathan Pritikin, John McDougall and Dean Ornish ever started preaching the low-fat gospel, the ancient yogis were extolling the virtues of vegetarianism.

It appears that the practice of yoga does increase sensitivity to the effect of diet on our physical, mental, and spiritual well being. Since an important pillar of yoga philosophy is that of nonviolence, many yoga practitioners turn to complete vegetarianism to avoid supporting the slaughtering and eating of animals. Some want to reduce the health hazards of a meat-based diet, while others are experimenting with modified vegetarian diets which may include minimal amounts of animal products. For the total vegetarian or vegan, good intentions may outweigh solid nutrition information. This can lead to nutrient deficiencies or health problems down the road. There may be a tendency to follow rigid, unbalanced diets or to consume supplemental products of unproven value or questionable safety.

A well-balanced vegetarian diet is safe, healthy, cost effective, and can help in the prevention of cancer, diabetes, heart disease and arthritis. It is higher in complex carbohydrates, fiber, and antioxidants, and lower in saturated fat and cholesterol than a meat-based diet. Many vegetarians weigh less, have lower blood cholesterol, and live longer than their meat eating counterparts. However, a vegetarian diet can still be as high or higher in fat, cholesterol and calories as a meat-based diet if excess cheese, oil or nut butter is consumed. To reduce potential risks and maximize the benefits, it's important to know how to design a healthy vegetarian meal plan.

Over 14 million Americans consider themselves to be vegetarians, of which there are at least four types: semi-vegetarians, who eat a primarily plant-based diet, but include some fish or poultry; lacto-ovo-vegetarians, who exclude meat, poultry, and fish, but include dairy products and eggs; lacto-vegetarians, who exclude meat, poultry, fish and eggs, but include dairy products; vegans or strict vegetarians, who exclude all animal products including meat, poultry, fish, eggs, milk, and cheese. Semi-vegetarians can gain valuable health benefits without having to adhere to strict diets that make it harder to eat out, and they are less likely to have nutrient deficiencies. Vegans have a harder time meeting their dietary needs and must know more about nutrition to make consistently healthy choices.

A total vegetarian (vegan) diet must be carefully planned to insure adequacy of protein and certain other nutrients. A vegan diet does not provide sufficient vitamin B12 unless fortified soy milk and meat analogs are consumed. Iron, calcium, and riboflavin may be lacking as well, so dark green, leafy vegetables should be consumed in abundance. Fortified soy milk can replace the key nutrients found in cow's milk and this is especially important for children.

Plant proteins have a lower biologic value than proteins of animal origin. The ability of dietary protein to support growth and maintain body structure depends on the number and proportion of the amino acids it carries. The proteins in beans, grains, nuts, and vegetables have all of the essential amino acids, but at lower levels and in different proportions than do animal proteins. However, choosing a variety of plant proteins and combining them properly on a daily basis (but not necessarily at each meal) provides complete, usable protein.

To combine more complementary proteins, combine the following foods: rice with beans, nuts, dairy, eggs, wheat germ; beans: with corn, rice, grains, nuts, eggs, and dairy; pasta: with dairy, wheat germ, eggs, nuts, and spinach; vegetables: with rice, eggs, wheat germ, nuts and seeds.

Iron intake can be increased by using whole grain and fortified grains, cereals and legumes; cooking in cast iron skillets, which "leak" a healthy amount of absorbable iron into the food; or by including a vitamin C rich food, such as broccoli or citrus juice with each meal. Serum iron levels can be checked periodically and if anemia is found, supplemental doses of iron in the form of ferrous sulfate may be needed.

To plan healthy vegetarian diets, choose at least the minimum daily servings from the following food groups: fruits and vegetables: 5-9 servings (1 piece of fruit, ½ cup chopped vegetables or fruit, 1 cup leafy greens); breads, cereals, grains: 6-11 servings (1 slice bread, ½ bagel; 1 oz. dry cereal; ½ cup cooked cereal or 1/3 cup rice or pasta); milk or soy milk products: 2-3 servings (8oz. Milk or yogurt, 1 ½ oz. Cheese); legumes, meat analogs: 2-4 servings (½ cup tofu, temeph or seitan (wheat meat); 2tbsp. peanut butter, ½ cup cooked beans; ¼ cup nuts or seeds).

It has never been easier to be a vegetarian than it is today. The new "health food department stores" offer a huge variety of vegetarian convenience foods of excellent taste and quality. Even traditional supermarket chains have expanded their selection of alternative foods in response to growing competition. Explore ways of preparing vegetarian meals, you may find it can be fast, healthy, and delicious.

Susan Witz, RD, LD, Registered Dietitian, Private Practice; E-mail: srwitz@cs.com. Nutrition Consultant to Northwestern University Athletic Club, Chicago, Il.  E-mail: s-witz@northwestern.edu. (312)503-8508.