INTRODUCTION Food is essential for life and growth(2,10). Without an adequate supply of food and nutrients, a living organism cannot grow and develop properly, and may even die(1,10). Adolescence is characterized by profound somatic, psychological and social transformations, and according to the World Health Organization (WHO), it encompasses the period between 10 and 19 years of age(11). It is a time of accelerated growth and development in which the individual acquires approximately 25% of their final height and 50% of their body mass(9,13). Important changes also occur in body composition, characterized by greater fat deposits in girls and muscle mass in boys(12). Due to these special characteristics, their involvement with nutrition assumes unique and highly important aspects(9). Currently, the social behavior of adolescents favors the development of eating habits and styles that may be nutritionally inadequate(8). Irregular and poorly balanced meals, excessive consumption of empty calories, and fad diets can contribute to poor nutrition during adolescence(14,18). As in childhood, this period can also mark the beginning of undesirable eating habits that continue into adulthood(19). NUTRITIONAL RECOMMENDATIONS Nutritional recommendations refer to the amounts of energy and nutrients that foods consumed should contain to meet the needs of almost all individuals in a healthy population. These recommendations, the recommended dietary allowance (RDA), emerged in 1941 by the US National Research Council, and were updated on several occasions until 1989. They undoubtedly serve as a useful guideline for individuals, institutions, populations, and population subgroups. Although their original purpose was to provide standards for good nutrition (12), this was hampered by the important fact that RDAs were developed based on the minimum amount indicated as necessary to prevent clinical deficiencies. This limitation became more acute and provided impetus for the establishment of new recommendations, the dietary reference intakes(DRIs), which are based on the amount of nutrients we need not only to prevent deficiencies, but also to minimize the risk of chronic diseases and improve quality of life. DRIs are expected to replace RDAs. These new recommendations began to be studied in 1994 by the Food and Nutrition Board, when committees were formed to define how RDAs should be revised. At that time, new and important concepts about nutritional recommendations were introduced(4). The most significant difference between RDAs/89 and DRIs was the provision of up to four dietary intake reference values ​​for the same nutrient, which include the RDA, diversifying and expanding the use of recommendations for individuals and population groups. The references are as follows:

• estimated average requirement (EAR) – refers to the nutrient intake that aims to meet the recommendation of 50% of healthy individuals at a particular stage of life and of the same sex. It is used to establish an RDA. It can be used to assess the adequacy of intakes for groups and to plan adequate intakes for them;
• RDA – refers to an average daily intake of nutrients sufficient to meet the recommended daily allowance for virtually all (97% to 98%) healthy individuals at a particular stage of life and sex. RDAs apply to the individual, not to groups. And EARs, in turn, serve as the basis for establishing RDAs;
• adequate intake ( AI) – refers to the daily intake of a nutrient based on estimates of observed or experimentally determined intakes in a group of healthy individuals that is considered adequate. It is used when the RDA cannot be determined;
• tolerable upper intake level (UL)-the highest average daily intake of a nutrient that is believed not to put the individual at risk of adverse health effects(4). The UL has not yet been established for all nutrients.

It is important to remember that the DRIs were established for the populations of the United States and Canada, and for their use in the Brazilian population, probable differences and, consequently, some associated errors must be considered. ENERGY The energy requirements of adolescents are defined to maintain health, promote optimal growth and allow for the practice of physical activity. The increase in energy needs in adolescence is determined by the increase in lean body mass, and not by the increase in body weight, with its variable fat content(9). The recommended range of energy intake reflects the different needs of adolescents. Growth rate and level of exercise should be considered in determining these needs(11). The energy DRIs for adolescents are based on the estimated energy requirement (EER/2002), which was calculated based on energy expenditure and growth requirements. To calculate the EER, an equation (shown below) was developed using the doubly labeled water (DLW) method to predict the total energy expenditure (TEE), based on sex, age, height, weight and physical activity level category, adding 25 kcal/day for stored energy(4). EER for boys aged 9 to 18 years EER=TEE+stored energy EER=88.5-61.9×age [years]+PAx(26.7×weight[kg]+903×height[m]+25[kcal/day for stored energy]) Where PA is the physical activity coefficient: PA=1 if sedentary; PA=1.13 if the physical activity level is light; PA=1.26 if the physical activity level is moderate; PA=1.42 if the physical activity level is intense. EER for girls aged 9 to 18 years EER=TEE energy store EER=135.3-30.8×age[years]+PA×(10xweight[kg]+934×height[m]+25[kcal/day for energy store]) Where PA is the physical activity coefficient: PA=1 if sedentary; PA=1.16 if the level of physical activity is light; PA=1.31 if the level of physical activity is moderate; PA=1.56 if the level of physical activity is intense; The estimated EER for adolescents is found in Table 1 for boys and in Table 2 for girls. PROTEIN Protein requirements for adolescents can be estimated at around 12% to 15% of total calories(4,6). During adolescence, protein utilization is more strongly linked to growth patterns than to age. Protein requirements are determined by the amount needed to support the growth of new tissues, which can represent a substantial portion during adolescence(4). Using the reference value, the body weight for girls aged 14 to 18 years is 54 kg and for boys, 61 kg; the 2002 RDA for protein should be 46 g/day for girls and 52 g/day for boys(5). RDA for boys aged 14 to 18 = 0.85 g/kg/day of protein or 52 g/day of protein RDA for girls aged 14 to 18 = 0.85 g/kg/day of protein or 46 g/day of protein CARBOHYDRATES The recommended carbohydrate intake is in the range of 55% to 60% of the total energy in the diet, with preference given to complex carbohydrates(4), which are the main sources of energy for adolescents. The American Dietetic Association (ADA) recommends, for the age group of 3 to 18 years, a daily fiber intake equal to age + 5 g. Fiber is important in the care of several nutritional conditions such as constipation, obesity, dyslipidemia and diabetes. Encouraging fiber consumption as early as possible can reduce these types of nutritional changes, as well as prevent some cancers(14). LIPIDS The American Academy of Pediatrics (AAP) Committee on Nutrition recommends that fats should provide 30% of calories in the diet during the first two decades of life, unless there is a greater susceptibility to atherosclerosis, whether due to a positive family history, smoking, hypertension, diabetes or other risk factors(4,11,14). For the general population of children and adolescents, the National Cholesterol Education Program (NCEP) (1991) recommends the adoption of dietary patterns to meet the following fat and cholesterol criteria:

• saturated fatty acids-less than 10% of total calories;
• polyunsaturated fatty acids-up to 7% of total calories;
• monounsaturated fatty acids-10% to 15% of total calories;
• total fat-an average of no more than 30% of total calories;
• dietary cholesterol-less than 300mg day.

VITAMINS AND MINERALS In general, it is known that vitamin and mineral requirements increase during adolescence. Thiamine, riboflavin and niacin are recommended in large quantities to meet high energy requirements. This increased caloric intake may be accompanied by increased and adequate levels of B vitamins(15). Folic acid, due to its role in DNA synthesis, is important during increased cell replication during this period of growth(5). The best sources are organ meats, beans and green leafy vegetables(9,11). Vitamin D is involved in maintaining calcium and phosphorus homeostasis in bone mineralization, and is essentially necessary for rapid skeletal growth(3,13). Foods considered sources of vitamin D are egg yolk, liver, fatty fish (herring and mackerel) and butter. Vitamin A, in addition to being important for growth, is essential for sexual maturation(6). Sources of vitamin A include: whole milk, liver, egg yolk, and dark green leafy vegetables (broccoli and spinach) and orange vegetables (pumpkin and carrots)(9). Vitamin C acts as a reducing agent in several hydroxylation reactions, is essential for collagen synthesis, is reflected in healing, tooth formation, and capillary integrity, making it indispensable in adequate quantities to ensure satisfactory growth(7). The best sources of vitamin C are oranges, lemons, acerola cherries, strawberries, broccoli, cabbage, and spinach. Adolescents incorporate twice the amount of calcium, iron, zinc, and magnesium into their bodies during their growth spurt compared to other stages of life(3,6,15). Calcium requirements during adolescence are based on skeletal growth, 45% of which occurs during this period(13), as well as accelerated muscle and endocrine development(9). Foods rich in calcium include: milk and dairy products. During adolescence, the need for iron is high in both sexes(6). In men, due to the construction of muscle mass, which is accompanied by greater blood volume and respiratory enzymes, and in women, iron is lost monthly with the onset of menstruation(11,17,19). Meat, grains, eggs and dark green vegetables are sources of iron(9). The bioavailability of iron should be emphasized. Foods rich in vitamin C increase iron absorption, while those rich in oxalates and phytates hinder its absorption, being a risk factor for anemia and impaired growth. Zinc is an essential element for adolescent growth and maturation(15, 17). There are reports of a zinc deficiency syndrome characterized by growth retardation(13), hypogonadism, decreased taste acuity, and hair loss(6). Sources of zinc include meat, shrimp, oysters, liver, whole grains, nuts, cereals, and tubers. The recommendations for other vitamins and minerals (DRIs) for this age group are listed in Tables 3 and 4. CONCLUSION At all stages of life—and adolescence is no different—the diet should be as varied as possible and should contain foods from all groups. The National Health and Nutrition Examination Surveys (1971-1974 and 1976-1980) revealed that, among all age groups, adolescents had the highest prevalence of unsatisfactory nutritional status. Based on anamnesis and dietary recall, the intake of calcium, vitamin A, vitamin C, and iron among adolescents tended to be lower than the DRIs, making this population segment particularly vulnerable to nutritional disorders. Therefore, health professionals should intervene, encouraging healthy habits and a diet that allows for an adequate growth process.