The process by which humans take in and use food in their bodies; also the study of diet as it relates to health.
Good nutrition in childhood lays the foundation for good health throughout a person's lifetime. With the proliferation of fast food restaurants, the number of junk food commercials on television, and the increased trend toward eating out, it is more difficult than ever for parents to ensure that their children maintain a nutritious diet. Across the last decades of the twentieth century, increasing affluence and the widespread availability of vitamin-enriched foods have shifted the focus of nutritional concerns in the United States from obtaining minimum requirements to cutting down on harmful elements in one's diet. Parents need to be as concerned about high levels of fat, cholesterol, sugar, and salt, as well as adequate intake of vitamins , minerals , and other nutrients.
The American Academy of Pediatrics, the National Academy of Sciences, the American Heart Association, and other health-care organizations agree that fat should not account for more than 30 percent of the calorie intake of children over the age of two, and saturated fat should account for under 10 percent. The main dietary sources in children's diets of saturated fat are whole milk, cheese, hot dogs, and luncheon meats. Recommendations for dietary change include switching to 1 percent or skim milk, low-fat cheese, and meats from which the fat can be trimmed. Since fat is important for growth, experts also caution that fat intake should not be under 25 percent of daily calorie intake and that parents of children under age two should not restrict fat in their diets.
The amount of refined sugar in children's diets—typically accounting for 14 percent of calorie intake by adolescence—is another cause for concern. Although sugar is known to cause tooth decay and also may be associated with behavior problems, the greatest danger in consuming foods high in added sugar is that these "empty calories" may replace the more nutritious foods that children need in order to maintain good health. (Soft drinks, perhaps the single greatest source of refined sugar in the diet of children and teenagers, get virtually all their calories from sugar and offer no nutrients.) This high intake of fat can lead to excess weight and, potentially, obesity .
Another element that needs to be restricted in children's diets is the intake of sodium through salted foods. Sodium has been closely linked to hypertension (high blood pressure), which increases a person's risk of heart disease and stroke . It has been determined that 18-year-olds need only 500 milligrams of sodium daily. In addition to limiting the amounts of fat, cholesterol, salt, and sugar in their children's diets, health authorities also recommend that parents concerned about nutrition ensure that children obtain a generous supply of complex carbohydrates (found in such foods as beans, potatoes, whole-grain products, and pasta) and have at least five servings of fresh fruits and vegetables daily.
The first nutritional decision that must be made for a child by a parent or primary caregiver is whether to breastfeed or bottle feed. Breast milk is generally considered the best food for an infant up to the age of six to nine months. It has virtually all the nutrients that babies need and in the right balance. In addition, it contains important antibodies that help protect infants from infection at a time when their own immune systems are not yet fully developed.
The composition of breast milk actually changes during the first two weeks after a baby is born. Initially, it consists largely of colostrum, a substance that has more protein than complete breast milk and lower amounts of fat and sugar. It is also rich in the antibody immunoglobin A, which helps protect against infections. By the tenth day after birth, the regular breast milk, containing more carbohydrates and fat and less protein, is produced. The amounts of carbohydrates and fat gradually continue to increase, as will the quantity of the milk itself, to match the needs of the growing baby. Although most full-term infants get all the necessary nutrients from breastfeeding, some may need supplements of vitamins D and K.
Women who are either unable to breastfeed or who choose not to do so usually feed their babies formula made from processed cow's milk, generally reconstituted skim milk with vegetable oils added to substitute for the missing butterfat, which is difficult for infants to digest. Lactose (milk sugar) is also added, and some formulas contain whey protein as well. For infants who demonstrate sensitivity to cow's milk, formulas based on soy protein are available.
Breast milk or formula provides all the nutrients an infant needs up to the age of four to six months. Contrary to past beliefs, it has been found that not only do babies not need solid foods before then, introducing solids too early may lead to food allergies or overfeeding. Regular grocery-store cow's milk, which cannot be adequately digested by infants and can cause gastrointestinal bleeding, should not be introduced until a child is a year old. As the first solid food, pediatricians often recommend cereal made from a grain other than wheat, such as rice. The first solid foods may be either commercial baby food or strained foods prepared at home. Once solid foods have been introduced, infants still need to receive most of their nourishment from either breast milk or formula during their first year.
During children's second year, their growth rate slows dramatically compared to the prior period. In the first year, their birth weight triples, their length increases by 50 percent, and the size of their brain doubles. After that first year, it takes several years for their weight to even double. They will grow in spurts, with each spurt followed by a period of weight gain. This decreased
Preschoolers are still growing relatively slowly. Their weight increases about 12 percent between the ages of three and five, although their appearance changes considerably as they lose the baby fat of infancy and toddlerhood. They are still picky eaters, generally eating less—and less consistently—than their parents would like. Although their fat requirement is not as high as that of infants, preschoolers still require more fat and fewer carbohydrates than adults. Fat is needed both for growth and for regulation of body temperature. Also, preschoolers need more than twice as much protein as adults. If the nutritional recommendations of the National Academy of Sciences are followed, a preschooler's diet will consist of 40 percent carbohydrates, 35 percent fats, 20 percent protein, and 5 percent fiber.
Between the ages of three and five, children's tastes expand considerably, and they are willing to consider foods they would have refused as toddlers. Four-year-olds can generally eat whatever foods the rest of the family is having. Preschoolers still cannot eat enough at three meals to meet their nutritional needs, and nutritious snacks are important. By this age, children's food choices can be strongly influenced by others. They will imitate good eating habits they see practiced by their parents, but they can also be easily swayed by television commercials for junk food.
The diet of young school-age children, like that of preschoolers, should contain, in order of importance, carbohydrates, fat, and protein. A recommended proportion of these nutrients is 55 percent of the daily calorie intake from carbohydrates, 30 percent from fats, and 15 percent from protein. Once children begin spending a full day in school, a substantial, nutritious breakfast becomes more important than ever. Breakfast has been shown to affect the concentration and performance of elementary school children. Ideally, a balanced breakfast for a school-age child contains food high in protein as well as fruit and bread or another form of grain.
A major change affecting the nutrition of school-age children is the growth of opportunities to eat outside the home. The carefully packed homemade lunch may be traded for a salty snack or cupcake, and parts of it may be discarded. Vending machines and stores offer more temptations. In addition, school lunch programs differ widely in quality; even the nutritional value of a single food, such as a hamburger, can vary significantly depending on how it is prepared and what ingredients are used.
Adolescence brings its own set of nutritional needs and challenges. Beginning with the pre-teen years, children undergo their most intensive period of physical growth since infancy and need more food than at any other stage of life, particularly if they participate in sports . Teenagers, especially boys, are notorious for being able to empty the refrigerator of food, usually without gaining excess weight. Early adolescence in particular is a time of increased nutritional requirements for girls, who experience their greatest growth spurt at this time and also begin menstruating. It is difficult for weight-conscious teenage girls to eat enough to satisfy their minimum daily iron requirement of 18 milligrams, and they should try to eat either foods that are naturally rich in iron, such as turkey, beef, liver, and beans, or foods made from iron-enriched cereals. Adequate calcium intake is essential for the rapidly growing bones of teenagers, but milk has often been replaced by soft drinks as the beverage of choice among this age group. Parents should encourage adolescents, especially girls, to eat other foods rich in calcium, such as cheese, salmon, and broccoli.
As adolescents grow more independent, the number of meals and snacks eaten away from home increases as they spend more time with friends and take increased responsibility for arranging their own meals, with fast foods, soft drinks, and sweets often prominent on the menu. In addition to the natural appeal of these foods, peer pressure contributes to the choice of a diet soft drink over milk or juice, or pizza over broccoli. Although parents cannot control the eating habits of their teenagers, they can influence them by consistently making nutritious foods available at home and, at least in some cases, by discussing the benefits of good nutrition with them, especially if a relative or friend has had an illness, such as heart disease or colon cancer , that has known links to diet.
A special problem that may affect childhood nutrition is the presence of food allergies , which are more common in children than in adults. They are most likely to begin when a child is very young and the immune system is still sensitive, usually in infancy. Food allergies also tend to run in families: if one parent has food allergies, a child has a 40 percent likelihood of developing one. This figure rises to 75 percent if both parents have food allergies. Common symptoms of food allergies include hives and rashes ; swelling of the eyes, lips, and mouth; respiratory symptoms; and digestive problems. Foods that most often produce allergic reactions in infants are cow's milk, soy products, and citrus fruits. Other common childhood allergens include wheat, nuts, chocolate, strawberries, tomatoes, corn, and seafood. In time, childhood food allergies are often outgrown. Feeding a child with food allergies is a challenging but not impossible task for parents. A variety of foods can be substituted for those to which a child is allergic: soy products for milk and other dairy products; carob for chocolate; and, in the case of wheat allergies, products or flour made from grains such as rice or oats.
About 2 percent of Americans ages six to 17 (about 1 million) are vegetarian, the same percentage as among American adults, and 0.5 percent are vegan, according to a 2002 survey by the Vegetarian Resource Group (VRG). Six percent of six- to 17-year-olds do not eat meat but eat fish and/or poultry. Teens who follow a vegetarian diet are more likely to meet recommendations for total fat, saturated fat, and number of servings of fruits and vegetables as compared to non-vegetarians. They also have higher intakes of iron, vitamin A, fiber, and diet soda, and lower intakes of vitamin B12, cholesterol, and fast food. Most teens, whether they are vegetarian or not, do not meet recommendations for calcium, according to the VRG survey. The study concluded that rather than viewing adolescent vegetarianism as a phase or fad, the diet could be viewed as a healthy alternative to the traditional American meat-based diet. The study also said that vegetarian diets in adolescence could lead to lifelong health-promoting dietary practices. The study was reported in the July-August 2002 issue of the VRG publication Vegetarian Journal.
Parents should closely monitor their vegetarian child's height, weight, and general health. A child who is not getting enough vitamins and nutrients may have symptoms such as skin rashes, fatigue, a painful and swollen tongue, irritability, pale skin, mental slowness, or difficulty breathing. The diets of vegetarian adolescents should be monitored closely to make sure they include a variety of foods, including fruits, vegetables, beans, whole grains, and non-meat protein sources. For vegetarians who do not eat fish, getting enough omega-3 essential fatty acids may be an issue, and supplements such as flax-seed oil should be considered, as well as walnuts and canola oil. Another essential fatty acid, omega-6, found in fish, can be obtained from borage oil or evening primrose oil supplements.
When to call the doctor
Parents should consult their child's pediatrician or physician if they are unsure the child's diet is nutritionally adequate. A doctor should also be consulted if a child's weight or height is not appropriate for their age.
Colostrum —Milk secreted for a few days after birth and characterized by high protein and antibody content.
Essential fatty acid (EFA) —A fatty acid that the body requires but cannot make. It must be obtained from the diet. EFAs include omega-6 fatty acids found in primrose and safflower oils, and omega-3 fatty acids oils found in fatty fish and flax-seed, canola, soybean, and walnuts.
Immunoglobin A —A sugar protein with a high molecular weight that acts like an antibody and is produced by white blood cells during an immune response.
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Ken R. Wells