fnh 371- adolescence

what are the goals of nutrition in adolescence?

• nutrient and energy to support rapid growth and maintenance of nearly adult sized bodies 

• independence in food choices and food skills

what is an accurate definition of adolescence?

onset puberty until physical, psychosocial and cognitive maturity are reached

what is adolescence?

• period of transition between childhood and adulthood 

• begins with the onset of physiologically normal puberty and ends with adult identity and behaviour are accepted 

when is adolescence?

typically 10-19 yrs but better to use biological and psychosocial indicators rather than ages 

what changes happen in adolescence?

• major physical and psychosocial changes 

what biological changes occur in adolescence?

• gain heigh, weight

• build bone mass 

• changes in body composition 

• sexual maturation 

• variable timeline 

what psychosocial changes occur in adolescence?

• what struggle for independence 

• social roles 

• relationships with peers 

• adolescent turmoil is normal (ex. stress, emotions and choices)

what hormones are most active before puberty?

hypothalamus→ CRH → anterior pituitary → ACTH → adrenal cortex → ¹sex hormones (DHEA- secreted before puberty, around 6)

→²cortisol (stress response) (the more stress in adolescence= poor stress response when older)

what hormonal changes occur during pubery?

hypothalamus → GnRH → anterior pituitary → FSH, LH → testies/ ovaries → testosterone/ estrogen+progesterone

what happens during puberty?

• changes that transform child’s body into adult body

• a lot of variation in age of onset and rate of progression 

what is sexual maturation?

• development of pubic hair 

• breast and genitalia development 

• menarche (menstruation)

how many stages of are in the Tanner Scale (sexual maturity rating)?

5 stages 

when is the max age of females height spurt?

12.5 years

what is the max age of males height spurt?

14 years

how does the growth pattern of females and males differ?

males start and end their height spurt later while females have their height spurt earlier

when is the average start of menstruation for females?

12.5 years 

what are the 4 stages of a growth spurt cycle?

1. increased hunger and food intake 

2. body fat gain 

3. height gain and body fat loss 

4. decreased hunger and food intake 

what is the body composition of females?

body fat increases to 23%

what is the body composition of males?

body fat decreases to 12%

what hormone affects female body composition?

estrogen affects cartilage in the hip joint

what hormone affects male body composition?

testosterone affects cartilage in the shoulder joint

when is peak bone mass reached?

during adolescence- half of total bone mass is acquired during adolescence 

what nutrients are needed to rapid increase in bone mass?

calcium, phosphorus and magnesium

how are DRIs used for adolescents?

• 2 age groups: 9-13 and 14-18

  • separate recommendations for males and females (based on biological sex not gender)

• DRI generally based on chronological age not growth/sexual maturity

• many mirconutrient needs reach adult levels by age 14 (some are higher than adult needs)

why do males have higher energy requirements?

males have more lean mass

why are energy requirements have a large variability?

• peak requirements for growth and maintenance of almost fully- grown body

• large variability in growth conforms energy intakes with growth

how does protein and fat AMDR differ between adolescence and adulthood?

adolescence requires a bit less protein and a bit more fat for energy dense source of calories 

how does protein intake differ from adolescence to adulthood?

decreased from 0.85 to 0.8

how does vitamin A, folate, and vitamin D differ from adolescence to adulthood?

the same nutrient needs 

how does calcium, phosphorus, and magnesium differ from adolescence to adulthood?

increase nutrient needs in adolescence

how does iron differ from adolescence to adulthood?

adolescent males needs less than females due to menstruation, adult males need less iron and adolescent males and intake for females increase into adulthood

what are iron level patterns in adolescence?

iron deficiency anemia is not common but many may have reduced iron stores 

what is the RDA of iron for adolescence?

males: 11mg/d

females: 15 mg/d

1.8x these values for people with plant based diets

what are the risks factors for iron deficiency?

heavy menstruation, vegetarian diet, endurance athletes, disordered eating, low socioeconomic status, lack of balanced diet, inadequate nutritional intake

what is synaptic pruning?

• “use it or lose it”

• refining connections

what is myelination?

• faster/stronger neural connections

• occurs from the back to front of brain

• the pre-frontal cortex is the last to fully mature

why is the pre-frontal cortex important":

higher thinking, decision making, emotions, personality, planning

what is neuroplasticity?

• ability to make new connections/synapses

where do sex hormones interact with neurons

ventral striatum= high reward sensitivity

amygdala= increased exploration and risk-taking 

pre-frontal cortex= emotional development and social plasticity (heightened awareness of social cues and social experiences shape brain networks) 

hippocampus= learning

how does brain development affect food behaviours?

• increased risk taking → trying drugs/alcohol 

• increased reward seeking → sugar, ultra processed foods 

• less planning → not waiting for meals (more snacking) and eating for the “now”

• exploration → want to make their own choices 

• more impressionable → following fads/trends and following peers

what are developmental tasks during adolescence?

1. independence → choosing what to eat 

2. body image → eating disorders

3. peer relations → where, when, what to eat, how they feel about themselves

4. identity → sense of self, values, social responsibility

how does diet affect depression levels in adolescence?

• ultra-processed foods, SSB, and screen time= increase depression

• mediterranean diet and physical activity= decrease depression

what are common eating behaviours in adolescence?

• eating away from the home 

• snacking (25% of calories comes from snacks) 

• meal skipping (especially breakfast)

how should nutritional education be directed to teens?

• focus on what is relevant to now

• depression/ mental health

• eat to do better at sport/school

how is healthy eating habits shown to adolescenece?

modelling good nutrition and creating interventions that align with adolescents’s values and social environment