Lecture 17 - Adolescent Nutrition Flashcards
what are the adolescent years
period of life between 11 and 19 years
energy and nutrient needs to support physical growth in adolescence are second only to those during
infancy
during adolescence they are more independent with
food choices
- they are not fed, they eat
- choose to go out, not sent out to play
what are the social pressures in adolescence
- body image
- alcohol
- drug use
pace of growth in adolescence …
speeds up abruptly and dramatically, significantly increase energy, protein and micronutrient needs
in adolescence, the sequence of change is ….
relatively predictable, but timing is highly variable
what is chronological age
out actual age, how old we are
what is biological age
more reflective of where we are in terms of growth and development, cells and tissues in the body
there are distinct growth patterns between
genders
growth and development during adolescence dictates
nutrition needs
sexual maturation is what driven
hormonal driven, affecting every organ in the body
what are the concerns during adolescence growth and development
under nutrition, over nutrition and micronutrient deficiencies
there are distinct differences in what in terms of body composition of males and females
differences in skeletal system, lean body mass and fat stores between genders
as much as what % of body weight is gained during adolescence
as much as 50% adult body weight is gained during adolescence
females gain a much larger % of
body fat
females need what % body fat for menarche
17%
females need what % body fat to maintain normal menstruation
25%
female body fat peaks between years
15-16
males gain more what than females
more lean body mass
males gain on average how many kg per year (during peak weight gain)
9kg per year
males have an average of what % body fat by the end of puberty
12% body fat
generally the adolescent growth spurt lasts about
2-3 years
females adolescent growth spurt begins at
9.5-14.5 years
males adolescent growth spurt begins at
11.5-16 years
females adolescent growth spurt generally ends around
16 years
males adolescent growth spurt generally ends around
17.5 years
the average gain in cm of females in adolescent growth spurt is
25cm
the average gain in cm of males in adolescent growth spurt is
28cm
low energy availability is defined as
mismatch between a persons energy intake and the energy expended in exercise, leaving inadequate energy to support the functions required by the body to maintain optimal health and performance
what is adequate energy availability
continually adapting energy intake to match training load
what is intentional low energy availability
restricting energy intake in the hope that becoming even leaner might improve performance
what is unintentional low energy availability
failing to increase energy intake to match a higher training load
both males and females can be affected by low energy availability, what can lead to this
- personality traits (perfectionism)
- social pressure
- pressure from coaches, parents
what athletes have a higher prevalence of low energy availability
recreational athletes have a higher prevalence compared to elite athletes
(top level athletes may be more aware and also more likely to have a support system around them to prevent this)
what type of sports have a higher prevalence of low energy availability
sports with emphasis on leanness and physique
e.g gymnastics and figure skating
what other type of sport is LEA common
endurance sports
e.g distance running, triathlons, cycling
to prevent LEA, ensure adequate energy intake in relation to exercise needs….. how
- regular meals, snacks and recovery options that are appropriate in energy and nutrients
- energy intake should be modified to reflect variations in training
- avoid prolonged periods without eating
- intake meets demands of the sport
puberty is a what period
transitional period
what matures during puberty
reproductive system
girls typically mature in puberty how many years before boys
2.5 years earlier
what is the approx onset of puberty in females
9 years
what is the approx onset of puberty in males
11 years
what are the Tanner Stages
sexual maturity - rating by stages
5 point scale ranging from pre-adolescent to mature adult
what is the sexual maturity of females
- pubic hair
- breast development
- menarche
what is the sexual maturity of males
- pubic hair
- genitalia development
what snacking / eating behaviours increase during adolescence
snacking, skipping meals, eating cheap foods are common
what factors are associated with high snacking in adolescence
picky eaters, screen time, very active, time poor, obesity
what factors are associated with low snacking in adolescence
dieting, longer sleeping, body dissatisfaction
snacking more commonly translates to ….
- higher overall energy intake
- greater proportion of energy from sugar and saturated fat
- lower vegetable and fruit intake
foods high in fat, sugar and salt provide few
vitamins and minerals, and are non essential in the diet
foods high in fat, sugar and salt are. ……
energy dense and nutrient poor
on average high fat, sugar and salt(HFSS) food contribute to what % of total energy expenditure in 5-14 year olds
20%
HFSS recommendation
“limit high fat, sugar and salt (HFSS) food and drinks to occasional (less than once a week) consumption only”
energy needs in adolescence is ……. in the lifecycle with the exception of
greatest in the lifecycle, with the exception of pregnancy and lactation
what is important to know about optimal energy and nutrient intakes for adolescence
most are extrapolated from adult data = so it is important to take into account individual needs
nutrient needs rise through childhood, then …
peak in adolescence and then level off or even diminish with adulthood
it is difficult to determine optimal energy intake, it is influenced by
by BMR (basal metabolic rate) and PAL (physical activity level)
prediction equations can be used to
estimate energy needs
what is the recommendation for carbohydrates for adolescence
45-65% of total energy
- wholegrain breads and cereals
- vegetables, legumes, whole fruit
what is the recommendation for fat for adolescence
fat is 20-35% of total energy
<10% total energy from saturated fat and trans fat
- focus on mono and polyunsaturated fats
- vegetable oils, nuts, avocado
what is the recommendation for protein for adolescence
protein is 15-25% of total energy
- lean meat, poultry, seafood, eggs, milk products, legumes, tofu etc
iron needs are greatest during
periods of rapid growth
what are the periods where iron needs are highest
- adolescent growth spurt (rapid linear growth)
- increase in blood volume (due to increase in height)
- onset of menarche
iron deficiency risk is higher in
- young people with restricted diets
- young women with high blood losses
- pregnant teens
recommendations for iron in adolescence is based on
dietary iron needed to maintain iron storage levels + support the growth and development needs of adolescence
what is a main nutrient concern during adolescence
iron deficiency anaemia
- can delay or impair growth
- can result in fatigue
is it common for adolescences to not meet their needs for what nutrient
calcium, particularly common in those avoiding dairy - particularly milk
calcium needs and rates of absorption are ….. during adolescence, except
except in infancy, calcium needs and rates of absorption are higher during adolescence
calcium is crucial to
adolescent growth and development as well as blood clotting, cardiac and nerve function
usually around how much calcium is absorbed, what does this increase to in periods of peak growth
usually 30%, increases to 50-60% in periods of peak growth
when do females have greater ability to absorb calcium
greater ability to absorb calcium at the time of menarche, then decrease
calcium absorption peaks when in males
peaks during early adolescence in males, although this happens later than females
what is the RDI for calcium in adolescence
1,300mg/day
a study found approx how many young people had adequate calcium intake
1 in 3 young people
if choosing fortified milk alternatives aim for ones that
have 120mg calcium per 100ml
vitamin D is a ….. and enhances
vitamin D is a fat soluble vitamin, enhancing calcium absorption and important for bone health
what is the main source of vitamin D
sunlight
there are what dietary sources of vitamin D and what does this mean
there are few dietary sources of vitamin D so adequate status is unlikely to be achieved through diet alone
fortification of foods with vitamin D is what in NZ
voluntary
there are many factors contributing to bone health, such as
lifestyle factors, genetics and nutrition
about what % of peak bone mass is accrued during adolescence
50%
who accrues more bone mass during adolescence
males acrue more than females
what % peak bone mass is present by age 18
> 90%
at least what % of adult bone mineral is acquired during the 4 year period surrounding peak heigh velocity (~12y females, ~14y males)
26%
an individual will draw on their what for their entire life
peak bone mass
bone loss later in life occurs due to
menopause
what happens to immobilised or non weight bearing individuals
rapidly lose bone mass
- importance of skeletal loading for bone health
bone mineral acquisition requires
forces that vary in intensity and are dynamic
physical activity is important for bone mass but is also modified by
nutrition : adequate fuelling, calcium, vitamin D
what is the evidence of the associations between obesity and bone mass
contradictory evidence
what is the potential association between obesity in childhood and lumbar BMD in adulthood
potential positive association
drop of what hormone is common in low energy availability
drop in oestrogen
what is the name of the issue that is characterised by oestrogen deficiency
primary ovarian insufficiency
those with primary ovarian insufficiency have lower
bone mineral density compared with regular menstruating women
what is primary ovarian insufficiency
when the ovaries stop working before the age of 40
what is functional hypothalamic amenorrhea in adolescence
adolescent who doesnt get their period
what could functional hypothalamic amenorrhea be a result of
- low energy
- excessive exercise
- stress
a study found that amenorrhea for at least 6 months owing to weight loss, in the absence of eating disorder of stress, resulted in
vertebral bone mineral density of 2 standard deviations below the mean
