Chapter 14 Adolescent Nutrition Through the Life Cycle

Chapter 14 Adolescent Nutrition Through the Life Cycle Judith E. Brown

Vegetarian Diets during Adolescence • About 4% of adolescents report following a vegetarian diet • Reasons adolescents adopt a vegetarian diets include: – – – Cultural or religious beliefs Moral or ethical concerns Health beliefs To restrict fat and/or calories A means of independence from family

Types of Vegetarian Diets and Food Excluded

Nutrient Intake of Vegan Adolescents • Well-planned vegetarian diets can offer many healthy advantages – Best when small amounts of animal-derived foods • Vegans may have inadequate intakes – Protein – Calcium, Zinc, and Iron – Vitamins D, B 6, and B 12

Total Fat and Essential Fatty Acid Intake of Vegan Adolescents • Vegans may have inadequate intakes – Total fat – Essential fatty acids especially alpha-linolenic acid • Encourage intakes of – Soy products: Soybean oil & Soybeans – Flaxseed, Walnuts, Tofu – Walnut oil, Canola oil – Eggs

Nutritional Needs in a Time of Change • Health-compromising eating behaviors – Excessive dieting – Meal skipping – Use of unconventional nutritional and nonnutritional supplements – Fad diets

Nutritional Needs in a Time of Change • Health-enhancing eating behaviors – Healthful eating practices – Physical activity – Interest in a healthy lifestyle

Normal Physical Growth and Development • Puberty occurs during early adolescence • Biological changes of puberty include: – Sexual maturation – Increases in ht & wt – Accumulation of skeletal mass – Changes in body composition • The sequence of maturation events is consistent but great individual variation in age of maturation

Normal Physical Growth and Development • Variations in reaching sexual maturity affect nutrition requirements of adolescents • Sexual maturation (or biological age)—not chronological age—should be used to assess growth and development and nutritional needs

Sexual Maturation Rating or “Tanner Stages” • Sexual Maturation Rating (SMR) (a. k. a. “Tanner Stages”)—scale of secondary sexual characteristics used to assess degree of pubertal maturation – SMR 1=prepuburtal growth & development – SMR 2 -4=occurrences of puberty – SMR 5= sexual maturation has concluded

Maturation and Growth of Females • Menarche (onset of first menstrual period) occurs 2 -4 years after initial development of breast buds • Age of menarche ranges from 9 to 17 years • Peak linear growth occurs ~6 to 12 months prior to menarche • Severely restrictive diets may delay or slow growth

Maturation and Growth of Males • Males show great deal of variation in chronological age at which sexual maturation takes place • Peak velocity of linear growth occurs during SMR 4 & ends with appearance of facial hair at ~age 14. 4 • Linear growth continues throughout adolescence ceasing at ~age 21

Changes in Weight, Body Composition, and Skeletal Muscles in Females • Peak weight gain follows linear growth spurt by 3 to 6 months – Gain of ~18. 3 pounds per year • Average lean body mass decreases – 44% increase in lean body mass (LBM) – 120% increase in body fat • 17% body fat is required for menarche to occur • 25% body fat needed to maintain normal menstrual cycles

Changes in Weight, Body Composition, and Skeletal Muscles in Males • Peak wt gain at the same time – Peak linear growth & – Peak muscle mass accumulation • Peak wt gain, ~20 lb per year • Body fat decreases to ~12% • ~Half of bone mass is accrued in adolescence

Normal Psychosocial Development • Adolescents develop: – A sense of personal identity – A moral & ethical value system – Feelings of self-esteem or self-worth – A vision of occupational aspirations

Normal Psychosocial Development • Three periods of psychosocial development: – Early adolescence (11 to 14) – Middle adolescence (15 to 17) – Late adolescence (18 to 21)

Normal Psychosocial Development • The need to fit in can affect nutritional intake – Who they eat with – Where they eat • Peer influences may be greater than family – May improve dietary intake – May lead to poor dietary intake

Health and Eating-related Behaviors during Adolescence • Factors affecting eating behaviors – Peer influence – Parental modeling – Food availability, preferences, & cost – Personal & cultural beliefs – Mass media – Body image

Conceptual Model for Factors Influencing Eating Behavior of Adolescents

Health and Eating-related Behaviors during Adolescence • The model depicts 3 interacting levels of influence on adolescent eating behaviors – Personal or individual – Environmental – Macrosystem

Health and Eating-related Behaviors during Adolescence • Busy lives lead to different eating styles – Little time to sit down for a meal – Snacking and meal skipping common – Eating away from home and at fast-food restaurants – Consuming more soft drinks, less nutrient dense drinks – Eating meals in front of the television

Dietary Intake and Adequacy among Adolescents • Many adolescents have diets that do not match the Dietary Guidelines for Americans or the My. Pyramid Recommendations • Most have inadequate consumption of: – Dairy – Grains – Fruits – Vegetables

Dietary Intake and Adequacy among Adolescents • Data from NHANES-adolescents’ diets consist of – Less than 1 serving of vegetables per day • White potatoes make up half of the vegetables – Less than 1 serving fruits per day – Adequate intake of grains but whole grains less than adequate – 32% of calories from fat & 21% from added sugars

Percentage of Adolescents Meeting the Recommended Number of My. Pyramid Servings

Energy and Nutrient Requirements of Adolescents • Increases in lean body mass, skeletal mass and body fat • Energy & nutrient needs during adolescence exceed those of any other point in life • Needs correspond to physical maturation stage

Energy and Nutrient Requirements of Adolescents • Dietary references intakes for selected vitamins & minerals are on Table 14. 7 • Professional judgment needs to be used • Nutrient recommendations based on chronological rather than biological development

Nutrient Intakes of Adolescents • U. S. adolescents have inadequate intake of vitamins & minerals including: – Folate – Vitamins A, B 6, C, & E – Iron & zinc – Magnesium – Phosphorus & calcium

Nutrient Intakes of Adolescent

Energy Requirements of Adolescents • Energy needs are influenced by: – Activity level – Basal metabolic rate (BMR) – Pubertal growth & development • Because males have greater increases in ht, wt, & lean body mass (LBM) & higher BMR, they have a higher caloric need than females • Level of physical activity declines during adolescence resulting in reduced energy requirements

Protein Requirements of Adolescents • Protein requirements influenced by protein needed: – To maintain existing LBM – For growth of new LBM • DRI is 0. 85 g/kg body wt • Low protein intakes linked to: – Reductions in linear growth – Delays in sexual maturation – Reduced LBM

Requirements for Selected Nutrients of Adolescents • Carbohydrates: – 130 g/day or 45 -65% of calories • Dietary Fiber: – AAP recommends • 26 g/day for adolescent females • 31 g/day for males <14 years of age • 38 g/day for older adolescent males

Requirements for Selected Nutrients of Adolescents • Fat: – Required as dietary fat and essential fatty acids for growth and development – 25 -35% of calories from total fat – <10% calories from saturated fat

Calcium Requirements for Adolescents • Adequate intake of calcium is critical to ensure peak bone mass • Calcium absorption rate in females is highest around menarche • Calcium absorption rate in males highest during early adolescence

Calcium Requirements for Adolescents • ~4 times more calcium absorbed during early adolescence compared to early adulthood • Adolescences who do not include dairy should consume calcium-fortified foods • Soft drink consumption displaces nutrientdense beverages such as milk & fortified juices

Calcium Requirements for Adolescents • DRI for ages 9 -18 years is 1300 mg/d • Average intake is: – 865 mg for females – 1130 mg for males • Weight-bearing activities may lead in increased bone mineral density

Iron Requirements for Adolescents • Increased iron needs related to: – Rapid rate of linear growth – Increase in blood volume – Menarche in females • In females, iron needs greatest after menarche • In males, iron needs greatest during the growth spurt

Iron Deficiency in Adolescents • Iron deficiency vs. iron-deficiency anemia – Iron deficiency • Determined by low serum iron, plasma ferritin & transferrin saturation • Iron deficiency more frequent • Often undiagnosed because of expense

Iron Deficiency in Adolescents • Iron deficiency vs. iron-deficiency anemia – Iron-deficiency anemia • Determined by simple and inexpensive hemoglobin or hematocrit levels • Indicates more advanced stage of iron deficiency • Less frequent but almost exclusively females

Iron Deficiency in Adolescents • Estimates of iron deficiency: – 9% of 12 -15 y/o females – 5% of 12 -16 y/o males – 11% of 15 -19 y/o females – 2% of 15 -19 y/o males

Vitamin D Requirements for Adolescents • Vitamin D-fat soluble: – Essential role in facilitating intestinal absorption of calcium and phosphorus – Essential for bone formation – Synthesized by the body via skin exposure of ultraviolet B rays of sunlight – Food sources: fatty fish, fish oils, egg yolks of hens fed Vitamin D fortified feed – Majority of Vitamin D from Vitamin D fortified foods (milk, breakfast cereals, margarines, and some juices)

Folate Requirements for Adolescents • Folate required for DNA, RNA & protein synthesis • DRI: 400 mcg • Severe folate deficiency leads to megaloblastic anemia • Severe deficiency rare but inadequate folate status appears to be more common

Folate Requirements for Adolescents • Folate added to fortified foods is better absorbed than folate from natural foods • Adequate folate intake for female adolescents reduces incidence of birth defects like spina bifida

Folate Requirements for Adolescents • It is imperative that women of reproductive age (15 to 44 years) consume adequate folic acid • Increased risk of folate deficiency – Skipping breakfast – Not consuming orange juice or fortified cereals

Vitamin C Requirements for Adolescents • Vitamin C—marginally adequate among adolescents • Involved in the synthesis of collagen and other connective tissues • Acts as an antioxidant • Smoking need for Vitamin C

Nutrition Screening, Assessment, and Intervention • The AMA recommends all adolescents receive annual health screening & guidance • Screening should include: – – – – Wt, ht, & BMI Disordered eating tendencies Blood lipid levels Blood pressure Iron status (hemoglobin/hematocrit) Food security/insecurity Dietary intake/adequacy

Nutrition Screening, Assessment, and Intervention • Nutrition screening should include a brief dietary assessment – Food frequency questionnaires – 24 -hour recalls – Food diaries or Food Records • Table 14. 12 lists the advantages and disadvantages of each dietary assessment method • Table 14. 13 lists the nutrition risk indicators that may warrant further assessment and counseling

Nutrition Education and Counseling • Considerations when educating & counseling adolescents: 1) Initial component of session should involve: – Getting to know adolescent, including personal health or nutrition-related concerns – Providing overview of events & content of counseling session

Nutrition Education and Counseling • Considerations when educating & counseling adolescents (cont. ): 2) Involve adolescent in decision-making process 3) Encourage adolescent to suggest ways to change 4) Work toward only 1 or 2 goals per counseling session

Nutrition Education and Counseling • Use of technology to facilitate education and counseling – Text messaging – Podcasts – You. Tube – Facebook – Twitter • Technology can serve as a means to convey nutrition info in an engaging way

Physical Activity and Sports • Physical activity—any bodily movement produced by skeletal muscles that results in energy expenditure • Exercise—a subset of physical activity that is planned, structured, & repetitive & done to maintain physical fitness • Physical fitness—set of attributes that are either health or skill related

Benefit of Physical Activity • Regular physical activity leads to: – Improved aerobic endurance & muscle strength – Reduced risk of obesity – Greater bone density – Positive self-esteem & self-concept – Lower levels of anxiety & stress

Recommendations on Physical Activity • The Physical Activities Guidelines for Americans recommend adolescents: – Be physically active every day – Engage in 60 minutes or more physical activity – Include muscle- and bone-strengthening activities at least 3 days a week

Physical Activity Practices of U. S. Adolescents • • Only 35% met activity guidelines 25% reported no moderate to vigorous activity Activity declines throughout adolescence More males than females meet daily activity guidelines • More white teens than African or Mexican American teens meet activity guidelines

Factors Affecting Physical Activity • Adolescents more likely to be physically activity if they have: – – Confidence in ability to exercise Positive perceptions of activity or sports Positive attitudes toward activity Peer & family support

Nutritional Considerations for Physically Active Adolescents • High levels of activity combined with growth & development increase needs for energy, protein & certain vitamins & minerals • Nutrient needs higher during intense training & competition seasons • Monitor changes in body weight to assess for adequate energy and protein intake

Nutritional Considerations for Physically Active Adolescents • Competitive athletes may need 500 -1500 additional calories per day • Protein should supply no more than 30% of calories in the diet • Special concern for vegetarian athletes or restricted caloric intake to maintain a particular weight

Promoting Healthy Eating and Physical Activity Behaviors • Effective nutrition messages for youth – Teens are “present oriented” – Concerned about appearance – Achieving maintaining a healthy wt – Having lots of energy – Optimizing sports performance – Environmental or moral aspects of food

Promoting Healthy Eating and Physical Activity Behaviors • Parent involvement • Target parents • They are gatekeepers of foods • Serve as role models • Teenagers eat based on availability and convenience • Parents can capitalize on this • Stock a variety of nutritious ready-to-eat foods

Nutrition Education in Schools • Nutrition instruction required by 67% of middle schools & 72% of high schools • Most nutrition is offered in health education courses • Nutrition education to health ed teachers has from 43% to 65% from 2000 to 2006

School Wellness Policies • All school districts with a federally-funded school meals program must have a wellness policy that addresses nutrition & physical activity

Model Nutrition Program • Numerous innovative nutrition programs exist that promote nutrition to youth • One example is CANfit (California Adolescent Nutrition & Fitness) • Visit the CANfit website at: http: //www. canfit. org/