Adolescent Health Care: A Practical Guide

Chapter 6

Nutrition

Michael R. Kohn

This chapter focuses on energy and nutrient requirements as well as deficiency states that develop during adolescence. Adolescent obesity is discussed in Chapter 32.

Nutrition is an essential component of total adolescent health care. Two important transformations occur during adolescence that may cause significant changes in a teenager's nutritional needs. Growth in height and weight and changes in body composition are greater and more rapid than at any other time in life, except during infancy. In general, there is also a significant change in the adolescent's eating habits and food consumption. Adolescents have been found to have the highest prevalence of any age-group for unsatisfactory nutrition. Adolescents are known to reduce regular breakfast consumption, increase consumption of prepared foods, snacks, fried foods, nutrient-poor foods, and sweetened beverages and have a significant increase in portion size at each meal. This is associated with a decrease in the consumption of dairy products, fruits, and vegetables. Furthermore, sodium intake is far in excess of recommended levels, whereas calcium and potassium intakes are below recommended levels (Gidding et al., 2005).

Health care providers should assess nutritional status and provide appropriate nutritional counseling as part of health supervision visits. The MyPyramid Food Guide (www.MyPyramid.gov) is a helpful educational tool that can be used to assist teenagers in improving their diets (Figs. 6.1 and 6.2). MyPyramid incorporates recommendations from the 2005 Dietary Guidelines for Americans that was released by the United States Department of Agriculture (USDA) and United States (U.S.) Department of Health and Human Services (HHS). The Dietary Guidelines for Americans provides authoritative advice for individuals 2 years of age and older on how proper dietary habits can promote health and reduce risk of major chronic diseases. MyPyramid was developed to promote dietary guidance and increase the awareness of the health benefits from simple and modest improvements in nutrition, physical activity, and lifestyle.

Potential Nutritional Problems

Risk Factors

  1. Increased nutritional needs during adolescence are related to several factors.
  2. Adolescents gain 20% of their adult height.
  3. Adolescents gain 50% of their adult skeletal mass.
  4. Caloric and protein requirements are maximal.
  5. Gender-specific nutrient needs.
  6. Increased physical activity of adolescents makes proper nutrition essential.
  7. Poor eating habits contribute to nutritional problems.
  8. Missed meals are common.
  9. High-sugar snacks of low nutritional value are popular. A study of 460 teenage girls (Wyshak, 2000) found that almost 80% consumed soft drinks, most of which were sugar-containing cola drinks. The same study found an association between carbonated beverage consumption and history of bone fracture.
  10. Peer pressure leads to changes in a range of eating behaviors including restrictive and overeating patterns and purging behaviors (Van den Berg et al., 2002).
  11. The adolescent's family may exhibit poor eating habits and meal preparation may be inadequate.
  12. Many meals and snacks are obtained from vending machines or fast-food restaurants. Table 6.1 lists the fat and sodium contents of popular fast foods and ice cream snacks, many of which approach or exceed 50% of their calories from fat. Open access to nutritional information on fast foods is available on the Internet at www.nutritiondata.com.
  13. Inadequate financial resources to purchase food or to prepare nutritious meals.
  14. Factors that influence nutritional needs during adolescence are as follows:
  15. Level of activity
  16. Special diets (i.e., vegetarian)
  17. Chronic illness
  18. Substance abuse
  19. Menstruation
  20. Pregnancy
  21. Lactation

All of these factors contributed to the findings of the Food and Drug Administration's (FDA) Ten State Nutritional Survey in the 1960s (U.S. Department of Health, Education and Welfare, 1972), the National Health and Nutrition Examination Survey (NHANES) during 1971–1974 (National Center for Health Statistics [NCHS], 1979), the NHANES III study in 1988–1994 (National Center for Health Statistics,

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1994), and the National Health and Nutrition Examination Survey, 1999–2002. These surveys concluded that the highest prevalence of unsatisfactory nutritional status occurs in the adolescent age-group. Of particular note were deficiencies in the intake of calcium, iron, riboflavin, thiamine, and vitamins A and C.

 

FIGURE 6.1 USDA new food pyramid. (From U.S. Department of Agriculture Center for Nutrition Policy and Promotion. www.mypyramid.gov. April 2005.)

Key Areas

  1. Overweight: On the basis of data from National Health and Nutrition Examination Survey, 1999–2002, the prevalence of adolescent overweight ranges from 12.7% to 24% depending on the race (Hedley, 2004).
  2. Iron deficiency ranges from 0.6% to 7% in adolescents between 11 and 19 years of age. Rates of iron deficiency depend on gender and socioeconomic status (iron deficiency is higher in low-income families (Donovan, 1995)). Iron deficiency is best indicated by serum ferritin (<16 µg/L).
  3. Deficiencies in protein, minerals, and vitamins during pregnancy.

Nutritional Assessment

Assessing the nutritional status of an adolescent should be part of a comprehensive health evaluation. This becomes even more important in adolescents who are identified as nutritionally at risk. Such adolescents include those with nutritionally related medical conditions, dietary deficiencies, or those with conditions that predispose them to inadequate nutrition. Nutritional assessment requires repeated measurements of nutritional status over time. Methods used in the nutritional assessment of adolescents include dietary and clinical evaluation, measurements of body composition and laboratory data.

Dietary Data

Dietary information can be obtained from a food record kept by the teenager, a dietary history obtained from a nutritionist, a 24-hour recall, or a diet questionnaire. Figure 6.3 is an example of a diet questionnaire for adolescents. Simple screening questions that are quick and easy to ask include the following:

  1. How many meals do you usually space eat in a day? Any snacks?
  2. Tell me everything you have eaten in the past 24 hours.
  3. Are there any foods that you have eliminated from your diet?
  4. Are you on a diet?
  5. Are you comfortable with your eating habits?
  6. Do you ever eat in secret? Do you ever feel you can't stop eating?

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  1. Have you recently lost or gained weight, or has your weight stayed the same?
  2. Do you feel that your weight is too much, too little, or about right?
  3. What is the most you have ever weighed, and what would you like to weigh?
 

FIGURE 6.2 USDA new food pyramid, example for 16-year-old male. (From U.S. Department of Agriculture Center for Nutrition Policy and Promotion. www.mypyramid.gov. April 2005.)

Helpful screening questions used in older adolescents and young adults (followed by the associated sensitivity and specificity for disordered eating) include the following (Anstine and Grinenko, 2000):

  1. How many diets have you been on in the past year? (Two or three diets, 88% sensitivity and 63% specificity; four or five diets, 69% sensitivity and 86% specificity).
  2. Do you feel you should be dieting? (Often, 94% sensitivity and 67% specificity; usually, 87% sensitivity and 82% specificity).
  3. Do you feel dissatisfied with your body size? (Often, 96% sensitivity and 61% specificity; usually, 88% sensitivity and 74% specificity).
  4. Does your weight affect the way you feel about yourself? (Often, 97% sensitivity and 61% specificity; usually, 91% sensitivity and 74% specificity).

Each of these questions appears to have a very high correlation with the score on the Eating Attitudes Test (EAT-26). This screening test examines attitudes and behaviors regarding food, weight, and body image and has been validated for use in adolescents.

Anthropometric Measurements

  1. Weight: Weight is a short-term measurement of nutrition. To accurately measure an adolescent's weight, the young person should remove his or her shoes and heavy clothing. Weight-for-age charts can be obtained from the Centers for Disease Control (CDC) on their website at www.cdc.gov/growthcharts (Figs. 1.21 and 1.23).
  2. Height: Height is a long-term indicator of nutrition. A wall-mounted stadiometer is the most accurate method for measuring height. Have the teen remove his or her shoes and stand with heels touching the wall. Height-for-age charts are also available at http://www.cdc.gov/growthcharts/(Figs. 1.22 and 1.24).
  3. Body mass index: The body mass index (BMI) is equal to the weight in kilograms divided by the square of

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the height in meters or BMI = kg/m2. The BMI is easily determined, is highly reliable, and has a correlation of 0.7 to 0.8 with body fat content in adults. The correlation coefficient of BMI with body fat content in children and adolescents is 0.39 to 0.90. Adolescents who are overweight or deemed at risk for overweight have a BMI between the 85th and 95th percentiles for age and gender, and those who are obese have a BMI exceeding the 95th percentile for age and gender. BMI values in adolescents are listed in Chapter 1 (Figs. 1.25and 1.26). BMI-for-age charts are available at www.cdc.gov/growthcharts/.

TABLE 6.1
Fat and Sodium Contents of Popular Fast Foods

Food

Serving Size (g)

Calories

Cholesterol (mg)

Sodium (mg)

Calories from Fat (%)

Hamburgers:

         

 Jumbo Jack (Jack in the Box)

 271

550

 75

 880

 49

 Big Mac (McDonald's)

 219

560

 80

1,010

 50

 Original Whopper (Burger King)

 291

710

 85

 980

 54

 Famous Star (Carl's Jr.)

 254

590

 70

 910

 49

Sandwiches:

         

 Arby's Roast Beef

 154

320

 45

 950

 34

 Filet-O-Fish (McDonald's)

 156

470

 50

 730

 51

 Chicken Sandwich (Jack in the Box)

 164

400

 40

 770

 45

Other:

         

 Large fries (McDonald's)

 170

520

 0

 290

 44

 Kentucky Fried Chicken Original Recipe breast

 161

370

145

1145

 49

 Taco (Taco Bell)

 99

220

 25

 560

 41

 Domino's Classic cheese pizza (two slices of 12-in. pizza)

 159

375

 23

 784

 27

 Small chocolate shake (McDonald's)

333 mL

440

 40

 250

 22

Ice cream:

         

 Häagen-Dazs ice cream bar (vanilla/milk chocolate)

       

 64

 Vanilla ice cream

       

 50

 Frozen yogurt

       

 20

 Sherbet

       

 29

 Gelato

       

 29

A Comparison of Two Fast-Food Meal Choices

Meal Option

Calories

Total Fat (g)

Calories from Fat (%)

Saturated Fat (%)

Cholesterol (mg)

Typical meal:

         

 McDonald's Quarter Pounder with cheese

 510

 26

 40

 46

 90

 Chocolate shake, small

 440

 10

 20

 60

 40

 Large fries

 570

 30

 47

 20

 0

 Total

1520

 66

 39

 36

130

Lower-fat, lower-calorie alternative:

         

 McDonald's Grilled Chicken Deluxe without mayonnaise

 300

 5

 15

 20

 50

 Small fries

 250

 11

 40

 23

 0

 Medium Coca-Cola

 210

 0

 0

  0

 0

 Total

 760

 16

 19

 22

 50

  1. Skin fold measurements: Triceps skin fold measurement is helpful in evaluating the adipose tissue component and degree of obesity. Barlow and Dietz (1998) published a chart of triceps skinfold thickness for age and sex (Table 32.1). This measurement does not take into account the regional distribution of body fat, which in adults has been correlated with future obesity-related health risk. However, skin fold thickness is a more direct measure of adiposity than BMI and correlates well with body fat content in both children and adults. This technique requires training and has lower intraobserver and interobserver reliability than height and weight measurements used in the calculation of the BMI.
  2. Waist-hip ratio: The waist-hip ratio (WHR) is useful in young adults. The WHR is equal to the circumference of the waist divided by the circumference of the hips. Its reliability is similar to that of the BMI and it

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may be a better predictor of the sequelae associated with adult obesity. A WHR >1.0 in adult men or >0.8 in adult women has been shown to predict complications from obesity, independent of BMI. It should be noted that the WHR has not been evaluated in all ethnic groups.

 

FIGURE 6.3 Diet questionnaire for adolescents. (Adapted from Fomon S. Nutritional disorders of children: prevention, screening, and follow-up [DHEW Publication (HSE) 78–5104]. Rockville, MD: U.S. Department of Health, Education, and Welfare, Health Services Administration, 1976.)

Clinical Evaluation

The clinical evaluation includes examination of skin, eyes, lips, tongue, gums, teeth, hair, and nails. The following is an illustrative list of clinical findings and possible nutritional causes.

  1. Skin
  2. Pallor: Iron deficiency
  3. Follicular hyperkeratosis: Vitamin A deficiency or excess
  4. Xanthoma: Hyperlipidemia
  5. Petechiae: Vitamin C deficiency
  6. Eyes
  7. Night blindness: Vitamin A deficiency
  8. Angular palpebritis: Riboflavin, niacin deficiencies
  9. Lips
  10. Angular stomatitis, cheilosis: Riboflavin, niacin deficiencies
  11. Tongue
  12. Glossitis: Niacin, folic acid, vitamin B12, or vitamin B6deficiencies
  13. Papillary atrophy: Riboflavin, niacin, folic acid, vitamin B12, or iron deficiencies
  14. Loss of taste: Zinc deficiency
  15. Gums
  16. Soft, spongy, or bleeding: Vitamin C deficiency
  17. Teeth
  18. Excessive dental cavities: Diet high in refined sugar
  19. Hair
  20. Dry, dull, and brittle: Protein–calorie malnutrition
  21. Nails
  22. Brittle with frayed borders: Malnutrition, iron or calcium deficiency
  23. Concave or eggshell (free edge curved sharply outward): Vitamin A deficiency
  24. Other nutritional signs of general malnutrition
  25. Muscle wasting
  26. Delayed sexual maturation and growth

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  1. Amenorrhea
  2. Hepatomegaly

TABLE 6.2
Recommended Dietary Allowances for Adolescents

 

Male (yr)

Female (yr)

     

Category

11–14

15–18

19–24

11–14

15–18

19–24

Pregnancy

Lactating (first 6 mo)

Lactating (second 6 mo)

Adapted from Food and Nutrition Board, National Research Council. Recommended dietary allowances, 10th ed. Washington, DC: National Academy Press, 1989.

Weight (kg)

45

66

72

46

55

58

     

Height (cm)

157

176

177

157

163

164

     

Energy (cal)

2,500

3,000

2,900

2,200

2,200

2,200

+300

+500

+500

Protein (g)

45

59

58

46

44

46

 60

 65

 62

Minerals

                 

 Iron (mg/d)

12

12

10

15

15

15

 30

 15

 15

 Zinc (mg/d)

15

15

15

12

12

12

 15

 19

 16

 Iodine (µg/d)

150

150

150

150

150

150

 175

 200

 200

Vitamins

                 

Vitamin A (IU)

10

10

10

10

10

10

 10

 10

 10

Laboratory Tests

Laboratory tests helpful in assessing nutritional status include hemoglobin, hematocrit, ferritin, serum protein, and albumin.

Nutritional Requirements

Dietary reference intakes (DRIs) represent the new approach to providing quantitative estimates of nutrients used to plan and evaluate diets for healthy people. The DRIs are a set of four nutrient reference values that have replaced the 1989 recommended dietary allowances (RDAs).

  1. Recommended dietary allowance (RDA): This is the dietary intake level that is sufficient to meet the nutrient requirements of almost all healthy individuals (97%–98%) in the United States.
  2. Adequate intake (AI): This is the value based on observed or experimentally determined approximations of nutrient intake by a group—used when RDA cannot be determined.
  3. Estimated average requirement (EAR): This is the intake value that is estimated to meet the requirement defined by a specified indicator of adequacy in 50% of an age- and gender-specific group. At this level of intake, the remaining 50% of the specified group would not have its needs met.
  4. Tolerable upper intake level (UL): This is the maximum level of daily nutrient intake that is unlikely to pose risks of adverse health effects to almost all of the individuals in the group for whom it is designed.

The DRIs cover the following groups of nutrients:

  1. Calcium, vitamin D, phosphorus, magnesium, and fluoride
  2. Folate and other B vitamins
  3. Antioxidants (e.g., vitamin C, vitamin E, selenium)
  4. Macronutrients (e.g., proteins, fats, carbohydrates)
  5. Trace elements (e.g., iron, zinc)
  6. Electrolytes and water
  7. Other food components (e.g., fiber, phytoestrogens)

Energy Requirements

Energy requirements are determined by basal metabolic rate, growth status, physical activity, and body composition. Energy requirements of adolescents vary depending on the timing of growth and pubertal development. As such, energy needs are based on height because it provides a better estimate of total daily caloric recommendations. Suggested caloric intakes are listed in Table 6.2, but these will vary widely according to body size and activity level.

Protein

Protein provides 4 kcal of energy in each gram. Protein requirements are based on the amount of protein needed to maintain existing lean body mass and the increase in additional lean body mass with growth and development. Protein requirements are highest during the peak height velocity. Most teenagers' diets exceed the RDA for protein.

Carbohydrates

Carbohydrates provide 4 kcal of energy in each gram. Carbohydrates are the primary source of dietary energy. Carbohydrates should make up approximately 50% of the daily caloric intake. However, no more than 10% to 25% of calories should come from sweeteners (sucrose and high fructose corn syrup). Beverages with caloric sweeteners, sugars and sweets, and other sweetened foods that provide little or no nutrients are negatively associated with diet quality and can contribute to excessive energy intakes. In fact, 12% of all carbohydrates consumed by adolescents come from the added sweeteners in soft drinks.

Carbohydrate-containing foods include grain products, fruits, and vegetables. Approximately 25 to 35 g of fiber should be consumed daily. Fiber is found in whole grain foods, fruits, vegetables, legumes, nuts, and seeds.

Glycemic index (GI) classifies carbohydrate foods on the basis of the response they bring about in the body, specifically the effect on blood glucose. The GI of foods is

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ranked according to this “glycemic response”. The index ranges from 0 to 100; with glucose or other reference standard being 100. Hence, the lower the GI, the lower the expected rise in blood sugar for a given food. In general, foods are classified into low GI (<40), moderate GI (40–70), and high GI (>70).

TABLE 6.3
Recommended Dietary Allowances (Light Face Type) and Adequate Intake (Bold Face Type) Values, by Age

 

Male (yr)

Female (yr)

Pregnant (yr)

Lactating (yr)

Daily Amount

9–13

14–18

19–30

9–13

14–18

19–30

<19

19–30

<19

19–30

Adapted from Food and Nutrition Board, National Academy of Sciences. U.S. Department of Agriculture. www.nalusda.gov/fnic/etext/000105.html. 1998.

Calcium (mg)

1,300

1,300

1,000

1,300

1,300

1,000

1,300

1,000

1,300

1,000

Phosphorus (mg)

1,250

1,250

700

1,250

1,250

700

1,250

700

1,250

700

Magnesium (mg)

240

410

400

1,250

1,250

700

1,250

700

1,250

700

Fluoride (mg)

2

3

4

2

3

3

3

3

3

3

Selenium (pg)

40

55

55

40

55

55

60

60

70

70

Vitamin C (mg)

45

75

90

45

65

75

80

85

115

120

Vitamin D (µg)

5

5

5

5

5

5

5

5

5

5

Vitamin E (mg)

11

15

15

11

15

15

15

15

19

19

Thiamine (mg)

1.2

1.2

1.2

0.9

1.0

1.1

1.4

1.4

1.5

1.5

Riboflavin (mg)

0.9

1.3

1.3

0.9

1.0

1.1

1.4

1.4

1.6

1.6

Niacin (mg)

12

16

16

12

14

14

18

18

17

17

Vitamin B6 (mg)

1.0

1.3

1.3

1.0

1.2

1.3

1.9

1.9

2.0

2.0

Folacin (µµg)

300

400

400

300

400

400

600

600

500

500

Vitamin B12 (µg)

1.8

2.4

2.4

1.8

2.4

2.4

2.6

2.6

2.8

2.8

Pantothenic acid (B5) (mg)

4

5

5

4

5

5

6

6

7

7

Biotin (µg)

20

25

30

20

25

30

30

30

35

35

Choline (mg)

375

550

550

375

550

550

450

450

550

550

Alcohol provides 7 calories of energy in each gram and can also be a significant source of calories.

Fat

Fat provides 9 kcal of energy in each gram. Adolescents require dietary fat and essential fatty acids for many vital functions in the body. A teenager's diet should contain no more than 30% of calories from fat. Most adolescents' total and saturated fat intake is greater than that recommended.

Minerals

Iron

There is an increased need for iron in both males and females during adolescence because of the rapid growth, and increase in muscle mass and blood volume. In addition, females require increase in iron because of menstrual losses. High-iron foods include lean red meats, spinach, green vegetables, and fortified cereals. Nonheme iron, present in plant sources is less bioavailable, but its absorption can be enhanced by concurrent intake of vitamin C.

Calcium

Calcium, which is important for attaining skeletal health, is particularly important during adolescent growth and development. Requirements for dietary calcium increase substantially during periods of peak velocity of growth and accrual of bone-mineral content. Adolescents tend to eat a diet deficient in calcium. The DRI for calcium for 9- to 18-year olds is 1,300 mg/day (Table 6.3). Many Adolescents have inadequate calcium intakes, in part due to the substitution of carbonated beverages for milk. It is highly likely that current high levels of soft drink consumption are replacing the drinking of milk. Data from the U.S. Department of Agriculture Continuing Surveys of Food Intakes by Individuals indicate a drop in milk intake among adolescent girls from 72% on a given day in 1977 to 1979 to 57% in 1994.

Those adolescents not taking in adequate calcium from food sources may need to take supplemental calcium such as calcium carbonate, citrate, lactate, or phosphate (absorption varies from 25%–35%). Optimal absorption of the calcium supplements occurs when no more than 500 mg/dose is taken with food. In addition to dairy products, calcium is found in tofu, salmon and sardines, darkgreen leafy vegetables, and calcium-fortified foods (such as orange juice).

Zinc

Zinc is needed for adequate growth, sexual maturation, and wound healing. The RDA for zinc was set at 8 mg/day for adolescents 9 to 13 years old and 9 mg/day and 11 mg/day for females and males 11 to 14 years old, respectively. Good food sources of zinc include lean meats, seafood, eggs, and milk.

Vitamins

Vitamin requirements increase during adolescence, especially for vitamin B12; folate; vitamins A, C, D, and E; thiamine; niacin; and riboflavin (Table 6.3). It has been shown that supplements of antioxidant vitamins (A, C, E, and β-carotene) probably reduce the risk of cardiovascular disease and certain cancers, but there is no current recommendation to prescribe them routinely.

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Guidelines for Nutritional Therapy

General Recommendations

  1. Be aware of and sensitive to the family context, lifestyle, and cultural milieu.
  2. Motivate lifestyle change by stressing the positive effects of dietary changes, for example, feeling good about oneself, feeling energetic.
  3. Use the MyPyramid Food Guide (Fig. 6.1) to recommend the appropriate number of daily servings from each food group.
  4. Recommend that teenagers participate in a regular exercise program for at least 30 minutes, at least 4 days of the week. Balance dietary energy intake with physical activity to maintain normal growth and development.
  5. Simplify good nutrition concepts by recommending the following to adolescents and their families:
  • Maintain a healthy weight.
  • Eat a wide variety of nutritious foods. Include lean meat, fish, and poultry.
  • Limit solid fats (butter, margarine, shortening, lard) and choose foods low in saturated fat and trans fatty acids. Use more polyunsaturated fats.
  • Broil or bake instead of frying foods.
  • Use nonfat (skim) or low-fat milk and dairy products daily.
  • Eat plenty of vegetables, legumes, and fruits.
  • Eat plenty of cereals (including breads, rice, pasta, and noodles), preferably wholegrain.
  • Drink water instead of soft drinks or fruit drinks. Limit juice intake.
  • Eat meals and snacks regularly. In a recent study, eating family dinner was correlated with improved nutritional intake in early adolescence (Gillman et al., 2000).

Special Conditions

Vegetarian Diets

Adolescents may be vegetarian because of ecological, economic, religious, or philosophical beliefs. Teens who are vegetarians (but not choosing to be vegan) are likely to have an adequate nutritional intake. Nutritional counseling may be of benefit to ensure adequate intake of energy, protein, and micronutrients as well as to assess the need for supplements.

Types of Vegetarians

Semivegetarians eat milk products and limited seafood and poultry but no red meat.

Lactovegetarians consume milk products but no eggs, meat, fish, or poultry.

Ovolactovegetarians consume milk products and eggs but no meat, fish, or poultry.

Vegans consume vegetable foods only and no foods of animal origin (i.e., no eggs, milk products, meat, fish, or poultry).

Fruitarians consume raw fruit and seeds only. Examples of such fruits include pineapple, mango, banana, avocado, apple, melon, orange, all kinds of berries, and the vegetable fruits such as tomato, cucumber, olives; and nuts.

Further information is available from the Vegetarian Resource Group on their Web site: http://www.vrg.org/.

Supplemental Needs of Vegetarians

Potential nutritional issues with vegetarian diets include macronutrient and micronutrient deficiencies such as those of protein, fat, vitamin B12, iron, zinc, calcium, and vitamin D.

Vitamins:

Semivegetarians, lactovegetarians, and ovolactovegetarians have no need for supplements if attention is paid to dietary composition. Vegans may need supplemental riboflavin and vitamins B12 and D.

Protein:

Adequate protein intake has been a traditional concern for vegetarians; however, vegetarians usually meet or exceed protein requirements (except for vegans). There is also mounting evidence that the practice of eating complementary proteins in the same meal is unnecessary.

Minerals:

There is no uniform need for supplements, but vegetarians are at increased risk for iron and zinc deficiencies. Vegetarians may need up to 50% more zinc in their diet since phytate (found in plants) and calcium hinder zinc absorption.

Lactose Intolerance

Teens with lactose intolerance are at risk of inadequate calcium intake. Some adolescents with lactose intolerance can tolerate small amounts of milk products including aged cheese or yogurt with active cultures. There are many nondairy foods high in calcium including green vegetables, such as broccoli and kale; fish with edible bones, such as salmon and sardines; calcium-fortified orange juice; and soymilk. Currently, there are a variety of lactose-reduced dairy products in the supermarket including milk, cottage cheese, and processed cheese slices. Teens often find lactase enzyme replacement pills or liquid helpful.

Pregnancy

There is limited information available regarding the nutrition needs in pregnant adolescents. Energy requirements are greater for pregnant adolescents than for nonpregnant adolescents. Younger adolescents may require higher energy intake than older women. Pregnant adolescents should not consume less than 2000 kcal/day and in many cases their needs may be higher. The best gauge of adequate energy intake during pregnancy is satisfactory weight gain. Goals for weight gain are based on prepregnancy weight, height, age, stage of development, and usual eating patterns. Young pregnant women who are below an optimal weight are advised to gain more weight than overweight women.

Folate is essential for nucleic acid synthesis and is required in greater amounts during pregnancy. Recent research suggests that taking folic acid before and during early pregnancy can reduce the risk of spina bifida and other neural tube defects in infants. Because these defects occur early in gestation, it is advised that women of childbearing age and those who are capable of becoming pregnant consume 400 µg/day of folic acid. The DRI for folate during pregnancy is 600 µg/day. Good sources of folate include leafy dark-green vegetables, legumes, citrus fruits and juices, peanuts, whole grains, and some fortified breakfast cereals.

The calcium recommendation during pregnancy is 1,300 mg/day for adolescents. Since most nonpregnant adolescent females consume significantly less than the recommended amount of calcium, pregnant teens should

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either add calcium-rich foods to their diet or take calcium supplementation.

Dietary counseling can be one of the most important interventions for a pregnant adolescent to ensure a healthy pregnancy and a healthy baby. Teens should be encouraged to obtain their nutrients from food. A low-dose vitamin–mineral supplement is recommended for pregnant adolescents who do not regularly consume a healthy diet. Teens should be counseled against dieting during pregnancy.

Athletes

Risk for Iron and Zinc Deficiency

Both male and female adolescent athletes are at risk for iron deficiency. Athletes (especially menstruating females and those involved in endurance sports such as distance running) should be screened for low hemoglobin or hematocrit levels. Serum ferritin can be helpful in determining loss of iron stores and need for supplementation. A ferritin level of <16 µg/L corresponds with depleted iron stores. For the athlete who is not anemic but has low iron stores, 50 to 100 mg of elemental iron daily (ferrous gluconate 240 or 325 mg twice daily or ferrous sulfate 325 mg daily or twice daily) should be recommended. For the anemic athlete, 100 to 200 mg of elemental iron daily (ferrous gluconate 325 mg three times daily or ferrous sulfate 325 mg twice daily), should be given. Laboratory measurements should be repeated after 2 to 3 months to document response to therapy. Athletes with iron deficiency anemia may also be zinc deficient. Education regarding good dietary sources of zinc and iron should be provided.

Sodium and Potassium

Athletes need increased intake of sodium and potassium. This requirement will generally be met as they increase their calorie intake.

Calories

The active athlete who engages in 2 hours/day of heavy exercise needs 800 to 1,700 extra calories/day beyond the recommended minimum for age, sex, height, and weight. According to the American Dietetic Association, the approximate distribution of calories should be carbohydrates, 55% to 60%; proteins, 12% to 15%; and fats, 25% to 30%.

Hydration

Attention must be given to hydration before and during activity.

  • The athlete should drink 10 to 16 oz of cold water 1 to 2 hours before exercise.
  • Repeat 20 to 30 minutes before exercise.
  • Drink 4 to 6 oz of cold water every 10 to 15 minutes during exercise.
  • Cold fluids are preferable because gastric emptying is more rapid.
  • Plain water can be used for exercise periods of <2 hours.
  • Sports drinks may be used to provide carbohydrates for longer events. Fructose-containing solutions should be avoided since they are not as well absorbed as solutions with sucrose or glucose and can cause gastrointestinal upset.

Weight Restrictions

Avoid any major weight restriction during the adolescent growth spurt. Alterations in diet to cause rapid weight gain or loss should be discouraged. Eating disorders are prevalent among athletes (especially female athletes), especially in those involved in running, swimming, diving, gymnastics, or dance (Chapter 33). Therefore, carefully question all athletes regarding body image, desired weight, and amenorrhea. The female athlete triad (amenorrhea, disordered eating, and osteoporosis) should be suspected in an athlete with secondary amenorrhea.

Carbohydrate Loading

Diets that are chronically high in carbohydrate are not recommended. For optimal performance, the athlete should train lightly or rest 24 to 36 hours before competition. On the day of competition, the athlete may consider a high-carbohydrate, low-fat meal 3 to 6 hours before an event and an optional snack 1 to 2 hours before the event. Foods high in carbohydrates (60% to 70%) have also been recommended after competition to replace glycogen stores. However, Hawley et al. (1995) pointed out that a diet of 5,000 kcal/day that is only 45% carbohydrate is sufficient to restore muscle glycogen within 24 hours. An initial “depletion phase” consisting of vigorous workouts and low-carbohydrate eating before competition is also no longer recommended.

Ergogenic Nutritional Supplements

The word “ergogenic” is derived from the Greek word ergon, which means “to increase work or potential for work.” Anecdotal reports suggest that compounds such as bee pollen, caffeine, glycine, carnitine, lecithin, brewer's yeast, and gelatin improve strength or endurance. However, scientific research has failed to substantiate these claims.

Teen athletes who are considering the use of nutritional supplements should be aware that the effects of long-term supplement use have not been studied. In addition, supplement use can be quite costly. Most athletes can maximize their performance through consistent, appropriate training and attention to adequate nutrition rather than relying on supplement use (http://www.drugfreesport.com/choices/supplements/). See Chapter 83 for further discussion on herbal therapies.

Web Sites

For Teenagers and Parents

http://www.mypyramid.gov/index.html. USDA web site that customizes food pyramids based on age, sex and exercise levels.

http://www.mayohealth.org. Nutrition section from Mayo Clinic.

http://www.fda.gov/fdac/features/795_teenfood.html. How to read a food label.

http://www.vrg.org. Vegetarian Resource Center.

http://www.eatright.org. American Dietetic Association Web site.

http://www.kidshealth.org/teen/food_fitness. Exercise and nutrition site for teens.

http://www.foodsafety.gov. U.S. Food and Drug Administration site on nutrition and food safety.

http://www.nal.usda.gov/fnic/etext/fnic.html. U.S. Department of Agriculture (USDA) food and information center.

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For Health Professionals

http://www.mypyramid.gov. MyPyramid from USDA.

http://www.vrg.org. Vegetarian Resource Center.

http://www.americanheart.org. American Heart Association diets.

http://www.nutrition.org. American Society for Nutritional Sciences.

http://www.iom.edu/topic.asp?id=3708. Food and Nutrition Board home page with sections on RDIs.

http://www.drugfreesport.com/choices/supplements. Nutritional supplements, NCAA sponsored site.

References and Additional Readings

Anstine D, Grinenko D. Rapid screening for disordered eating in college-aged females in the primary care setting. J Adolesc Health 2000;26:338.

Barlow S, Dietz W. Obesity evaluation and treatment: expert committee recommendations. Pediatrics 1998;102(3):e29.

Baynes RD. Iron deficiency. In: Brock JH, Halliday JW, Pippard MJ, et al., eds. Iron metabolism in health and disease. London: WB Saunders, 1994:189.

Borrud L, Wilkinson Enns C, Mickle S. What we eat: USDA surveys food consumption changes. Commun Nutr Inst 1997;1997:4.

Brown LJ, Wall TP, Lazar V. Trends in total caries experience: permanent and primary teeth. J Am Dent Assoc 2000;131:223.

Burke L. Searching for the competitive edge: commonly asked nutrition questions. Aust Fam Physician 1999;28:694.

Canadian Paediatric Society Nutrition Committee. Adolescent nutrition: 1. Introduction and summary [Part 1 of 6]. Can Med Assoc J 1983;129:419.

Donovan UM, Gibson RS. Iron and zinc status of young women aged 14 to 19 years consuming vegetarian and omnivorous diets. J Am Coll Nutr 1995;14(5):463.

Dunger DB, Preece MA. Growth and nutrient requirements at adolescence. In: Grand RJ, Sutphen JL, Dietz WH Jr, eds. Pediatric nutrition: theory and practice. Boston: Butterworths, 1987.

Food and Nutrition Board, Commission on Life Sciences, National Research Council. Recommended dietary allowances, 10th ed. Washington, DC: National Academy Press, 1989.

Forbes GB. Nutrition and growth. In: McAnarney ER, Kreipe RE, Orr DP, et al., eds. Textbook of adolescent medicine. Philadelphia: WB Saunders, 1992.

Garcia-Webb P. Iron in todays laboratory. Clin Biochemist Rev 1997;18:113.

Gidding SS, Dennison BA, Birch LL, et al. Dietary recommendations for children and adolescents a guide for practitioners: consensus statement from the American Heart Association. Circulation 2005;112:2061.

Gillman MW, Rifas-Shiman SL, Frazier AL, et al. Family dinner and diet quality among older children and adolescents. Arch Fam Med 2000;9:235.

Hawley JA, Dennis SC, Lindsay FH, et al. Nutritional practices of athletes: are they sub-optimal? J Sports Sci 1995;13:75S.

Hedley A, Ogden CI, Johnson CI, et al. Prevalence of overweight and obesity among U.S. children, adolescents, and adults, 1999–2002. JAMA 2004;291:2847.

Himes JH, Dietz WH. Guidelines for overweight in adolescent preventive services recommendations from an expert committee. The Expert Committee on Clinical Guidelines for Overweight in Adolescent Preventive Services. Am J Clin Nutr 1994;59:307.

Lifshitz F, Tarim O, Smith MM. Nutrition in adolescence. Endocrinol Metab Clin North Am 1993;22:673.

Loosli AR. Reversing sports-related iron and zinc deficiencies. Phys Sportsmed 1993;21:70.

Marion DD, King JC. Nutritional concerns during adolescence. Pediatr Clin North Am 1980;27:125.

National Center for Health Statistics. Caloric and selected nutrient values for persons 1–74 years of age: first health and nutrition examination survey 1971–1974 [Vital and Health Statistics Series 11, 209, DREW publication (PHS) 79–1657]. Hyattsville, MD: National Center for Health Statistics, 1979.

Nielsen P, Nachtigall D. Iron supplementation in athletes. Sports Med 1998;26:207.

Probart CK, Bird PJ, Parker KA. Diet and athletic performance. Med Clin North Am 1993;77:757.

Rees JM, Worthington-Roberts B. Position of the American Dietetic Association: nutrition care for pregnant adolescents. J Am Diet Assoc 1994;94:449.

Reynolds RD. Vitamin supplements: current controversies. J Am Coll Nutr 1994;13:118.

Squire DL. Heat illness: fluid and electrolyte issues for pediatric and adolescent athletes. Pediatr Clin North Am 1990;37:1085.

Steen SN. Nutrition for young athletes: special considerations. Sports Med 1994;17:152.

Steen SN. Timely statement of the American Dietetic Association: nutrition guidance for adolescent athletes in organized sports. J Am Diet Assoc 1996;96:611.

Story M, Stang J. Nutrition needs of adolescents. In: Stang J, Story M, eds. Guidelines for adolescent nutrition services. School of Public Health, University of Minnesota: Center for Leadership, Education, and Training in Maternal and Child Nutrition, Division of Epidemiology and Community Health, 2005:21.

U.S. Department of Agriculture, U.S. Department of Health and Human Services. Nutrition and your health: dietary guidelines for Americans. Home and garden bulletin 232. Washington, DC: U.S. Government Printing Office, 1985; revised 1990.

U.S. Department of Health, Education, and Welfare. Ten state nutrition survey, 1968–1970: highlights. Washington DC: U.S. Department of Health, Education, and Welfare, Health Services and Mental Health Administration, Centers for Disease Control, U.S. Government Printing Office, 1972.

U.S. Department of Health, Education, and Welfare. Millar HEC, ed. Adolescent health care: a guide for BCHS-supported programs and projects. DHEW publication (HSA) 79–5234. Washington, DC: U.S. Government Printing Office, 1979.

U.S. Food and Drug Administration. FDA consumer special issue on food labeling [S/N 017-017-01200360-5]. Washington, DC: U.S. Government Printing Office, 1993.

Van den Berg P, Wertheim EH, Thompson JK, Development of body image, eating disturbances, and general psychological functioning in adolescent females: a replication using covariance structure modeling in an Australian sample. Int J Eat Disord 2002;32:46.

White R, Frank E. Health effects and prevalence of vegetarianism. West J Med 1994;160:465.

Wyshak G. Teenaged girls, carbonated beverage consumption, and bone fractures. Arch Pediatr Adolesc Med 2000;154:610.