Adolescent NutritionKathryn Camp, MS, RD, CSP

Topics for Discussion

Adolescent growth and developmentPsychosocial developmentNutritional issues for adolescentsAcute and chronic disease riskInfluences on adolescent eating behaviorsEffective nutrition interventions

Adolescence:The Vulnerable Life Stage

Big changes: BiologicalBoysget tall, lean, and dense (bones, that is)Attain 15% of final adult ht during puberty Lean body mass doublesLarge calorie needsincrease from 2,000 at 10 yr to 3,000 at 15 yr

Adolescence:The Vulnerable Life Stage

Girlsget taller and fatter% body fat increases from the teens into the mid-20sGain almost 50% of their adult ideal weight 6-9 mo before ht rate increases during pubertyDieting can have a negative impact on linear growth during this timeCalorie needs increase by only 200 from 10 yr to 15 yr

CognitiveThinking style changes from concrete to hypothetical and abstracttakes the adolescent beyond the here and now into the realm of possibilities (David Elkind, 1984)

Identity developmentAttempt to figure out who they areSuccess is dependent on positive interaction with the environmenthome, school, and the communityThey will try on different lifestyles looking for the right fitRisk taking behaviorsalcohol, drugs, tobacco, sexual behaviors, self-injury and suicideImmediate and severe consequences

Behaviors with Less Pronounced ConsequencesEating choices Physical activity and exerciseAffect adolescents sense of well-being, energy and health in the short termAffect adult-onset chronic disease risk in the long term

Another form of Risk-Taking Behavior

Nutrition Issues in Adolescent HealthCardiovascular and cancer disease riskOsteoporosis and bone mineralizationOverweight and obesityType 2 diabetesEating disorders

Cardiovascular Disease and Cancer RiskOne-third of CVD and cancer-related morbidity attributed to dietary patternsDiets high in sat fat, total fat, and sodium and low in fiberDiets low in fruits and vegetablesDietary fatRecommended:

FiberRecommended: Age + 5Consume: this amountFruits and vegetables-high in fiber and low in fat and sodiumthe least consumed food groups for teens1/4 eat 2 or more servings of fruit/d

Eating Away from HomeTeens directly spend more than$5.4 billion in fast food restaurants$9.6 billion in food and snack stores$736 million in vending machines78% in schoolFast foods tend to be low in Fe, Ca, riboflavin, vitamin C, and folic acid More meals missed at home thus the choice of foods away is more important than the time or place

Frequency of Fast Food Restaurant Use Among Adolescents (French 01)Positively associated with Total kcal, % kcal from fat, daily servings of soda, cheeseburgers, french fries and pizzaStudent employment, TV watching, home availability of unhealthy foods Negatively associated withDaily servings of fruit, vegs, milkPerceived maternal and peer concerns about healthy eatingNot associated with overweight status

Overweight, Obesity, and Type 2 Diabetes

Etiology of ObesityHeritabilityHomeostasisSpecific syndromes

HeritabilitySurvival advantage to conserve energy as fat through human evolutionHumans enriched for genes that promote energy intake and storage and minimize expenditure.Enhance female fertility and ability to breastfeed offspring

In modern industrial environment easy access to calorically dense foodsencourages sedentary lifestyleMetabolic consequences of these genes are maladaptive

34 single gene mutations in 83 individuals reported by 2001> 250 susceptibility genes linked with human obesity phenotypesGenetic Factors account for 20-40% of heritability of BMI Buchard 97 Rankinen 02Familial Risk:2-3 fold for moderate obesity5-8 fold for severe obesityBouchard 01

Obesity Associated Syndromes and Conditions

Overweight Prevalence Increasing

Overweight tracks into AdulthoodOverweight teenagers are 4-5 times as likely to be obese adults (Guo and Chumlea 99)

BMIs of the University of Miami Blocking Machine

Causes of Marked Increase in OverweightReflects a shift towards positive energy balanceenergy intake = energy expenditure

McDowell 94; Kann 99; Troiano 00, NHANES II to III

Other Contributors to Sedentary LifestylesVideo and computer gamesParental work schedulesUnsafe neighborhoodsdiscourage parents from allowing children to play outdoorsforce parents to drive children to schoolLack of recreational facilities in low-income neighborhoods

Prevalence of Overeating Among 4,746 Adolescents (Ackard 03)17.3% of girls and 7.8% of boys reported overeating and were more likely to:be overweight or obesehave dieted in the past yearbe currently trying to lose wtThose who met the criteria for binge eating syndrome (3% of girls and 1% of boys) had higher suicide risk (28% for girls and boys)

Psychological and Economic Consequences of Adolescent ObesityDiscrimination, rejection and low self-esteem (Gortmaker 93), particularly for femalesLess participation in PE and sports activitiesLower college acceptance rates (Canning 1966)

Health Issues in Overweigt AdolescentsGrowthTaller, advanced bone age, mature earlierEarly maturation is associated withincreased fatness and truncal fat distribution in adulthood

Hepatic SteatosisOrthopedic ProblemsSleep Apnea Occurs in 17% of obese children and teens (Marcus 1996)Deficits in learning, memory, and vocabulary (Rhodes 1995)Obesity hypoventilation syndrome (rare, potentially fatal disorder)

Hyperlipidemia-- LDL and TG, HDLHypertensionLow frequency in childrenMuscatine Study (Rames 1978)1% of 6600 children 5 to 18 had persistently elevated BP60% with BP were >120% of IBW

Cardiovascular

Type 2 Diabetes3-10 fold increase in prevalence in adolescentsMean age is 13.5 yrs95% of teens with Type 2 diabetes have a BMI >85%ileincreased insulin resistance 21% of adolescents with BMIs >95th%ile had impaired glucose tolerance (Rocchini 02)Tremendous public health implicationsLonger duration of disease, > risks of complicationsDabelea 99; Vinicor 00; Richards 85

How Do Teens Attempt to Lose Weight?1999 Youth Risk Behavior Surveillance58% exercised40% ate less food or lower fat foods13% fasted8% took diet pills5% vomited or took laxativesKann 1999

Weight-Related Eating Disorders

Anorexia nervosaSelf-starvation, weight loss, intense fear of weight gain, body image distortion

Bulimia nervosaBinge eating and purgingBinge eating disorderBinge eating without purging resulting in weight gain

Anorexic andBulemic BehaviorsExpressed in 10-20% of adolescent girlsMimic behaviors in AN and BN but are not done with the frequency or severity to classify as mental illnessHalf of teen girls and 15% of boys report dieting behaviorsRanging from eating less fat to fasting (Neumark-Sztainer 00)

Osteoporosis and Bone MineralizationOsteoporosis affects 25-30 million adults in the US, women > men15-25% with hip fractures require long-term institutional careTreatment of osteoporosis costs $14 billion/yrEtiology complexgenetic, hormonal, physical activity, dietary factors

Maximum peak bone mass (PBM) at skeletal maturity is protective PBM is achieved during the late stage of pubertal development90-95% of PBM is attained by the 2nd decade of life40% of which is during adolescence

Low bone mineral density is associated with fractures late in lifeAdequate nutrition, including energy, protein, vitamins and minerals are associated with good bone health

CalciumMilk and dairy products are primary source of calcium in the USOnly 49% of boys and 20% of girls consume the recommended number of servings from the dairy group.AI for calcium for 9-18 yr is 1300 mg/dGirls 14-18 yrs consume 55% of this goal at 713 mg 42 mg/d (Grove 98)

Calcium Content of Foods

Soda Consumption: Effects on body weight, dental health and nutritional statusNo association with dental caries (Heller 01)25% of adolescents drink >26 oz of soda/dInverse relationship between intake of nutrients found in milk and fruit juice with soda consumptionRiboflavin, vitamin A, calcium, phosphorus, and vitamin C (Harnack 99)

Mean Nutrient Intake by Level of Soft Drink Consumption in Adolescents* p

To Review Risky Adolescent Nutritional IssuesWeight gain leading to obesity and type 2 diabetesCalcium intake and soft drink consumption leading to inadequate bone mineralizationEating habits that result in disordered eating practicesLow consumption of fruit and vegetables and high consumption of fat and sodium are related to adult-onset disease risk

The relationship between the adolescent diet and chronic disease risk is predicated on the assumption that eating behaviors are learned and solidified during childhood and adolescence and are maintained into adulthood (Lytle 02)

What Influences Adolescents Food Choices?PsychosocialStrong InfluencesFood preferencesEarly childhood experiences, exposure, geneticsTaste and appearanceWeak influenceHealth and nutritionOnly 26% of college students were motivated by health when making dietary choices (Horacek 98)

The Meaning of FoodStudy of 93 Canadian adolescent girlsEating Junk food was associated with pleasure, being with friends, weight gain, independence, guilt, affordability, and convenience.Eating healthful food was associated with family, meals, and being at homeChapman 93

Influences contBiologicalI was hungry is often the first response when asked why a specific food was eatenLifestyleTime and convenienceTeens would rather sleep than eat breakfast (Neumark 99)CostIn a study of 12 high schools, consumption of fresh fruits and vegs when cost was by 50% (French 01)

More InfluencesFamilymajor influenceFood providerInfluences food attitudes, preferences and valuesDespite increased eating outside the home, teens still obtain 65% of their total energy from home.Dinner at home is the most important meal80% of parents and teens place high importance on this meal1/3 of teens eat dinner q night at home

Effective Nutrition Interventions for AdolescentsBehaviorally basedUse developmentally appropriate strategiesInclude an environmental componentSufficient amount of contactUse technological advances such as CD- ROMs

Hoelscher, JADA 2002;102:S52

Nutrition Intervention Programs for AdolescentsClueless in the Mall: An interactive web site on calcium for teensTexas Cooperative Extension Servicehttp://calcium.tamu.edu/Committed to Kids: An integrated, 4-level team approach to weight management for adolescentshttp://www.committed-to-kids.com/

Great Beginnings: Nutrition curriculum for pregnant adolescentsUniversity of New Hampshirehttp://ceinfo.unh.edu/Common/Documents/grtbegin.htmGimme 5: A school-based nutrition intervention for high school studentsBaylor College of MedicineAdolescent Nutrition JADA, March 2002

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