Transcript Chapter 4: Normal Adolescent Nutrition Pamela S. Hinton, PhD

Chapter 4:
Normal Adolescent Nutrition
Pamela S. Hinton, PhD
Reader Objectives
After studying this chapter and reflecting on the
contents, you should be able to:
• 1. Understand nutritional regulation of the
hormones that moderate growth and sexual
maturation.
• 2. Describe gender differences in growth and
development and in nutrient requirements.
Reader Objectives, cont.
• 3. Appreciate how psychosocial development
during adolescence affects health-related
behaviors, including dietary patterns.
• 4. Identify and describe sociodemographic
factors affecting dietary patterns.
• 5. Describe trends in chronic disease incidence
among adolescents.
Growth and Development
G&D: Physical Growth
• Peak height velocity. The adolescent growth spurt
takes 2-4 years to complete and is generally longer
in boys than in girls.
• The average height velocity is 5-6 cm/year during
adolescence; peak height velocity is 8-10 cm/year.
• Girls, on average, begin their pubertal growth spurt
at age 9 years and achieve their maximal rate of
linear growth, i.e., peak height velocity (PHV), at an
average chronological age of 11.5 years.
G&D: Body composition.
During adolescence, girls gain fat mass (FM) at an
average rate of 1.14 kg per year.
In contrast, boys do not experience a significant
increase in absolute fat mass. Boys also gain fatfree mass (FFM) at a greater rate and for a longer
period of time than girls; as a result, boys are
relatively leaner than girls post puberty.
At ages 8-10 boys, on average, have 15% body fat
and 24 kg of FFM. At the end of puberty, ages 18-20
years, males have 13% body fat and 60 kg of FFM.
In contrast, girls have 20% body fat and 24 kg FFM
at age 8-10 years.
G&D: Bone growth & mineralization
• Bone mass doubles between the onset of puberty and
young adulthood. Bone growth is greatest approximately
6 months after PHV; approximately 25% of peak adult
bone mass is acquired during the 2 years of peak
adolescent skeletal growth.
• Growth of the skeleton occurs via modeling which
changes both the size and shape of the bones. Bones
increase in length by ossification of the growth plates
and in diameter by periosteal apposition and endosteal
resorption.
• When the growth plates fuse post-puberty, bone mass
development (BMD) is 90-95% of peak BMD. Boys are,
on average, 10% taller and have 25% greater peak bone
mass than girls because of their later pubertal onset and
longer growth spurt.
Hormonal Mediators of the
Adolescent Growth Spurt
• Pattern of hormone secretion.
• Normal physical growth and development
during puberty depends on the integration
of the growth hormone/insulin-like growth
factor and gonadotropin axes.
• Nutritional and metabolic signals, in part,
control these hormonal systems by acting
on the hypothalamus and pituitary gland.
Hormonal Mediators of the
Adolescent Growth Spurt, cont.
• During childhood, the activity of the
hypothalamic-pituitary-gonadal axis is
suppressed by the central nervous system
(CNS).
• Hormones have effects on bone, adipose
tissue and sexual development.
Assessment of
Growth & Development
• Serial measurements of height and weight are
plotted on height-for-age, weight-for-age, and
weight-for-height growth charts from the National
Center for Health Statistics are used to evaluate
growth.
• Height growth potential is calculated from
parental height.
• Skeletal age is assessed using radiography of the
left hand and wrist. An open epiphysis indicates
skeletal immaturity and potential for additional
growth.
Adolescent Growth Disorders
• Pathological causes of short stature. A teenager
whose weight percentile is declining may be
suffering from chronic illness, poor dietary
intake, possibly of psychosocial etiology. Other
pathological causes include: endocrine disorders
such hypothyroidism and GH deficiency;
intrauterine growth retardation; chromosomal
defects, Turner, Down, and Prader-Willi
syndromes; and skeletal dysplasia.
Adolescent Growth Disorders
• Pathological causes of tall stature. Endocrine
causes of tall stature include hyperthyroidism,
precocious puberty, and GH-secreting tumors.
Adolescents with precocious puberty will end up
with compromised adult height because
estrogen and androgen levels peak early,
causing premature fusion of the growth plates.
Klinefelter, Marfan, Sotos, and BeckwithWidermann syndromes, are rare genetic
disorders that result in tall stature.
Cognitive and Psychosocial
Development During Adolescence
Cognitive and Affective Development
• The brain develops during puberty; in particular, areas
involved in regulation of behavior and emotion and in
perception and evaluation of risk and reward undergo
considerable change. Cognitive development during
adolescence results in increased self-awareness, selfdirection and self-regulation.
• During early adolescence, teenagers improve their
deductive reasoning, information processing, specialized
knowledge. The capacity for abstract, multidimensional,
planned and hypothetical thought increases into middle
adolescence.
Psychosocial Development
• The cognitive and affective development that
occurs during adolescence changes a
teenager’s self-concept and self-esteem.
Adolescents are concerned with the identity that
they project to others. The discrepancy between
an adolescent’s self-identity and the
expectations of others may be problematic.
• Rapid pubertal development or pubertal onset
that deviates from one’s peers also may result in
maladaptive behaviors.
Psychosocial Development, cont.
• In females, early maturation is associated with
increased affective disorders, delinquency and
drop-out rates, and pregnancy.
• In boys, early physical maturation has mostly
positive consequences, namely increased social
status and high self-esteem. In contrast, males
with late pubertal onset are more likely to
engage in status-seeking anti-social behaviors.
• Thus, biological and social factors interact to
affect behaviors, including those with long-term
effects on health.
Youth Risk Behavior Surveillance
Study (YRBSS)
Study found that:
• In the nearly one-half of high school students
use alcohol,
• 30% binge drink,
• 25% report current marijuana use.
• The prevalence of cocaine, inhalant, heroin, and
metamphetamine is lower; lifetime rates of use
range from 3-15%.
• 5% reported using illegal steroids during the
lifetime
Nutrient Requirements and
Temporal Consumption Trends
• Absolute nutrient requirements are increased in
adolescence compared to childhood due to
increased growth and body size.
• Adolescent males have greater requirements for
most nutrients compared to females due to
differences in growth and development.
• The exception is iron; postmenarcheal
adolescent girls need more iron than boys due
to menstrual blood losses [32].
Macronutrients
• Average daily energy consumption assessed in
NHANES I (1971-1974) and III (1988-1994) has
remained relatively constant, except for
adolescent females whose energy intake
increased from 1,735 to 1,996 kcal/d.
• The proportion of energy derived from fat and
saturated fat decreased over time, but remains
above the recommendations in the Dietary
Guidelines at 33.5% for total fat and 12.5% for
saturated fat. In children over 6years , 10-18% of
saturated fat and 5-10% of total fat was
consumed in 2%-fat and whole milk products.
Minerals
• Calcium. Recent longitudinal data of bone mineral
deposition suggest that calcium requirements may be
higher--1500 mg for girls and 1700 mg for boys during
peak calcium accretion.
• Iron. Iron requirements increase during adolescents to
meet the demands of growth and inevitable losses. Iron
is lost from the gastrointestinal tract, skin, urine, and
menstrual blood in females.
• Sodium. Average daily sodium consumption has
increased by approximately 1000 mg for adolescent
boys and girls between NHANES I (1971-1974) and
NHANES 1999-2000.
Vitamins: Vitamin D.
• Dietary intake of vitamin D among adolescents
varies by ethnicity; Non-Hispanic Caucasians
had the highest intakes of vitamin D and African
Americans the lowest. As a group, adolescent
males are more likely to have adequate vitamin
D intakes than females and older males.
• Because the prevalence of lactose intolerance is
higher among African Americans (75%) than
Hispanics (53%) and Caucasians (6-22%)
avoidance of dairy products may explain the
reduced vitamin D intakes among African
American adolescents.
Vitamin D cont.
• In 2003, the FDA approved vitamin D
fortification of calcium-fortified juices and
juice drinks. African Americans and
Mexican Americans who avoid dairy
products may benefit from these fortified
products; for example, 8 ounces of fortified
orange juice provides up to 2.5 µg (100 IU)
vitamin D.
Dietary Patterns
• Serving Size-Average serving sizes for foods
eaten at home and away from home have
increased during the past 30 years. Foods
frequently consumed by adolescents--salty
snacks, ready to eat cereals, and soft drinks
have significantly increased.
• Food Groups-Adolescents do not consume the
recommended number of servings of fruits,
vegetables and dairy products and they
consume excessive amounts of added sugar, fat
and saturated fat.
Dietary Patterns, cont.
• Skipping Breakfast-1/5th of adolescents
report skipping breakfast.
• Fast Food Consumption-Most
adolescents frequently eat meals and
snacks away from home. In one study,
26% of all meals and snacks were
consumed away from home, accounting
for 32% of total energy
Sociodemographic Moderators
of Dietary Intake
• Gender, ethnicity, parental income and
education affect diet quality in adolescents.
• Advertising and marketing of foods and
beverages influences the food preferences,
purchase requests, purchase and consumption
of children and youth.
• The recent increase in adolescent overweight
and obesity has brought the food environment in
schools under increasing scrutiny.
Health Status of US Adolescents
• Increased overweight and obesity
• Incidence of diabetes, hypertension, and
hyperlipidemia in patients with cardiovascular
disease have been described as the “metabolic
syndrome”
• Iron deficiency in girls
• Children are starting to smoke at a younger age
• Adolescent pregnancy
• Eating disorders
Chapter 4 Special Section:
Public Health Nutrition Programs
for Children
Rachel Colchamiro, MPH, RD, LDN
Jan Kallio, MS, RD, LDN
Public Health Nutrition Programs
for Children
Critical Need for Pediatric Public Health
Nutrition Services:
• Prematurity
• Overweight
• Anemia
• Breastfeeding
• Hunger and Food Insecurity
Federal Public Health
Nutrition Programs
• Special Supplemental Nutrition Program for
Women, Infants, and Children (WIC)
• Food Stamp Program
• National School Lunch Program
• School Breakfast Program
• Summer Foodservice for Children
• Special Milk Program
• Child and Adult Care Food Program
• Commodity Supplemental Food Program
• The Emergency Food Assistance Program
Other Federal Programs That Respond to
the Nutritional Needs of
Infants, Children and Adolescents
• Head Start and Early Head Start
• Early Intervention
Nutrition Surveillance Systems in the US
• Pregnancy Nutrition Surveillance System
• Youth Risk Behavior Surveillance System
• National Health & Nutrition Examination
Survey