TWO-YEAR-OLD Calder Lorenz doesn't know much about food, but he knows what he likes. When he carries his lunch to "mother's day out" co-op group, he packs a tofu patty, a few carrots, maybe some raisins and cottage cheese. But the tofu patties are his favorite, because they taste better the second day so they're perfect for brown bags.

Actually, Calder's mother packs his lunch for him. Arlington artist Carol Gigliotti is raising her son according to her own vegetarian proclivities. An ovo-lacto vegetarian, Gigliotti opposes killing animals for food. "Ovo-lacto" means she -- and Calder -- will eat eggs and dairy foods, but no meat, fish or poultry.

As ovo-lacto vegetarians, they represent the majority of American non-meat eaters who embrace vegetarianism for a variety of reasons. Some -- many of them baby-boom adults -- concur with Gigliotti's philosophy. Others are motivated by the lower cost of the diet.

The growing trend, however, seems to center around health. Studies done on Seventh-Day Adventists (who usually abstain from alcohol, caffeine and smoking) hint that this diet enhances the quality of and prolongs life. As a result, many parents turn to vegetarianism to promise better health for their children.

But raising children is a tricky business, even without limitations. Start putting restrictions on what they can eat, and it may provoke images of wide-eyed children with bellies extended for want of proper nutrition. (Kwashiorkor, or severe protein malnutrition sometimes found in underdeveloped countries, causes an edema that leaves the inflicted with abnormally rounded stomachs.)

There are obstacles, to be sure. But for the most part, raising vegetarian children presents no greater problems than raising carnivores. The controversy over placing children on a meatless regime probably arose when studies on preschoolers revealed that the vegetarian children weighed slightly less than meat eaters. Researchers deemed the difference "insignificant," however, and reaffirmed the diet as a healthy one.

"There's no reason for a vegetarian diet to be anything but a good diet as long as it's a planned diet," says Johanna Dwyer, director of the Frances Stern Nutrition Center at Tufts Northeast Medical Center Hospital in Boston. Dwyer has studied vegetarians for the last 10 years and says, "The people we see in Boston who are running into trouble don't give thought to dietary patterns."

To plan adequately, one must anticipate potential problems. Children achieve maximum growth when they are about 18 years old. For those 18 years, they all experience growth spurts that mark the different stages of development. Parents realize quickly that each child has a unique pattern of growth spurts; a child who was tall at 6 might be the shortest in her class at 9, but may grow several inches by the time she reaches her 10th birthday. Some mature faster than others.

Further, if the growth spurt never comes, it's too late to do anything about it. The vegetarian child like Calder--any child, for that matter--must be well-nourished before a growth spurt begins, so that he grows and develops normally.

One way to monitor a child's growth is through height and weight charting in cooperation with the pediatrician. These, along with hemoglobin count (checking iron content in the blood), should reflect abnormalities in growth patterns before irreversible damage occurs, says Cheri Jones, assistant professor of nutrition at Loma Linda University, a Seventh-Day Adventist institution in southern California.

Frequently when parents address the problem of feeding the vegetarian child, they worry about two things: protein and starch. They worry about getting enough of the former and too much of the latter. "Both are fallacies," Jones says.

Accordingly, vegetarians stress the need to combine vegetable-protein foods. The traditional combinations have been beans and nuts (legumes) with grains, or supplementing a serving of grains or legumes with a dairy food. Traditionally, nutritionists advised combining these foods in the same meal, although they don't stress that so much any more, Jones says.

In fact, she says, "most Americans eat at least twice as much protein as they need. As long as you get enough calories from mostly unrefined sources, you're going to be getting adequate protein. It's not very hard to get a variety of protein unless you are a very picky eater."

"Mostly unrefined sources" means one should forgo the milkshakes and cupcakes and turn to less-processed food. She refers to the Basic Four food groups (meat substitutes, milk products, fruits and vegetables and grains) as "a pretty good source" of dietary guidance, supported by the recent U.S dietary guidelines (which encourage cutting down on fat, sugar and salt consumption).

Another fallacy, she says, is believing that infants warrant some kind of special diet. "A lot of people feel that infants need special food." Whatever the family eats is appropriate for the weaned infant. The younger the infant, the more finely textured the food, perhaps, but it may be just a matter of blending or sieving the food to the proper consistency.

Gigliotti follows this advice when feeding Calder. "He just sort of eats what I eat," she says, adding that although they keep very little "junk food" in the house, they are "not that strict" about what they eat--Calder had carob cake for his birthday.

These problems relate to vegetarianism in general. Specifically, Jones says, "If someone is a lacto-ovo vegetarian, his nutrient deficiencies will be the same as a meat eater." In other words, there are problem nutrients in each age group, but those concerns apply across the board, and not only to the vegetarian child.

(The exception here is with the "vegan" child, one who consumes no animal products whatsoever. The diet can be planned to meet a child's nutrient requirements, but vegans "are the only group that has a problem," Jones says. "Whether you're talking about infants or adults," she adds, "vegan diets should be planned with the help of a nutritionist."

The breast-fed or formula-fed infant usually avoids nutrient deficiency for his first six months. After that, iron poses a problem, which, according to Jones, is the "major nutrient deficiency" that will hound the infant through childhood and, if she is female, through adulthood. Iron-fortified cereals can solve the problem, and Jones recommends a multivitamin supplement as well.

Multivitamins, Jones cautions, should not be regarded as a dietary panacea absolving the parent from meal planning. The diet should be balanced, and, she adds, the multivitamin-mineral supplement should be not greater than 100 percent of the recommended allowance for the nutrients. Gigliotti, like 92 percent of the country's vegetarians who supplement their diets, sprinkles her diet liberally with brewer's yeast (high in B vitamins and a good source of iron) and wheat germ.

Geographical location may determine other deficiencies. "Infants and rapidly growing children appear to be more sensistive to dietary shortages of vitamin D," says one report, of research done with Boston children. The deficiency was found mostly among macrobiotic children who subsist on pure vegetarian diets that include no milk products. Milk is usually fortified with vitamin D, which can also be made in the body if a person is exposed to sunlight, but that may be insufficient in northern cities in the winter. Vitamin D deficiency impairs metabolism of calcium, which affects bone growth. Clearly, this an area of great concern in the growing child.

California, which produces much of this country's fresh fruits and vegetables, ironically produces children deficient in vitamins A and C. A study in San Bernadino showed that 45 percent of the children did not consume adequate quantities of these vitamins, which are prevalent in fresh produce. These deficiencies, pronounced in this instance, are common throughout the country in preschool children.

Gigliotti has no problem with fruits and vegetables. In fact, when given a choice, Calder usually goes for fruit instead of a cookie, or "fresh things over cooked things." He loves raw carrots and he loves Chinese food, says Gigliotti, so he gets plenty of fresh produce.

Reluctance to eat fresh foods may be traced to the parents' attitude, confirms Jones. "Parents pass on their food biases to kids, and traditionally vegetables have had a bad name."

Influence the child before he's two, and you're golden. Says Jones of one study, "77 percent of the kids were willing to try new foods," before age 2. From 2 to 4 years old, only 10 percent would try new foods; after age four, the numbers dropped to three percent.

Calcium deficiency may crop up among youngsters after weaning, especially if they eat very few milk products. Calder Lorenz avoids calcium deficiency because he, like many very young children, loves plain yogurt. Three servings of milk products, such as yogurt, milk (including that in "creamed" soups and quiches) and cheese, should supply a youngster's calcium needs.

As the child ages he begins to assert his independence and choose peculiar dietary regimens. Perhaps the most familiar is the weight-loss diet, which, according to one researcher, leaves teen-age girls the most malnourished population in the country. Vegetarianism can complicate the issue because it further restricts an already-limited diet.

This independence also raises new issues provoked by but not limited to a special diet. Pre-teens and teen-agers may question their dietary regimens. Seventh-Day Adventist professionals (teachers and dieticians) report that these teen-agers, many of whom have been raised vegetarian, begin to ask why they shouldn't eat meat (although vegetarianism is not a doctrine of the church, it is advocated for health reasons). Omnivore teen-agers may announce to their parents one night that they are loath to eat meat, or may return from an extended stay at camp or school and announce their newly found dietary regime.

Carol Gigliotti, now 30, says her parents are accustomed to her 5-year-old dietary habits. When they kept Calder for 10 days about six months ago, they kept him to the diet and "snuck into the kitchen" to eat their meat-oriented meals. Gigliotti's husband, Laird Lorenz, also eats meat; just recently Calder said, "What's that?"

"I've given him a background of good-tasting food," says Gigliotti, who says she can imagine worse things than having him eat meat. "I expect him to try meat at least once. I would hope that he would be that curious."

It's a common attitude. Most of the parents interviewed said they anticipated a challenge from their children and responded with something akin to, "That's his choice."

Carol Gigliotti gives Calder what most experts would call a sound diet. She emphasizes fresh foods, makes as much from scratch as possible, uses whole grains, tries to complement high-protein foods (nut, bean, grain, dairy combinations). In other words, she concentrates on what is most important in any diet -- getting a large variety of foods as close to their natural state as possible.