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What is a good indicator of whether energy needs are being met?
Satisfactory growth
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When is the energy cost of growth an issue in infants?
Only during the 1st half of infancy
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How is energy content of tissue deposition computed for infants?
- Computed from rates of protein and fat deposition (longitudinal studies)
- ~175 kcal/d for 0 – 3 months -> 20 kcal/d for 13 – 35 months
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Why is there a single equation for EER for 0-2 years?
Lack of gender differences
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Why is PAL not included in EER equation for infants?
Limited range of physical activity?
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Why is growth velocity important in infants?
- Sensitive indicator of energy status
- Will detect growth faltering earlier than growth charts
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What is weight velocity in infants affected by?
Acute episodes of dietary intake
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What is length velocity in infants affected by?
Affected by chronic factors
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How does energy expenditure/kg compare from infants to adults?
Energy expenditure/kg is 2x greater in infants than adults
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What is the energy cost of growth?
- Energy content of newly synthesized tissue
- Estimated from cost of protein and fat deposition
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Where do infants basal metabolism come from?
Primarily brain, liver, heart and kidney
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Why does O2 consumption increase in infants?
- Increase during the transition to extrauterine life
- After birth, O2 consumption of these vital organis increases in proportion to increase in organ weight
- Brain contribution exceptionally high (70%) in newborn, and in 1st years of life (60-65%)
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How does energy cost of growth vary throughout infancy?
- Decreases from 35% at 1 month to 3% at 12 months
- Remains low until pubertal growth spurt where it increases to 40%
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What happens when a neonate is exposed to milk cold?
- Increase in non-shivering thermogenesis --> increase in metabolic rate
- Most important contribution by increase oxidation of A in brown adipose tissue
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How does PA vary as a child grows?
Increasingly larger component of TEE as child grows
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What is the purpose of energy requirements for adolescents?
Defined to maintain health, promote optimal growth and maturation, support a desirable level of PA
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What is growth defined as?
Increase in stature and weight, changes in body composition and organ systems
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What is adolescence defined as?
Developmental changes in reproductive organs, development of secondary gender characteristics, changes in cardiorespiratory and muscular systems (increase strength and endurance)
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What is the bulk of the active metabolic tissue?
Fat-free mass
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Why are there higher energy and nutrient requirement in boys during adolescence?
Marked gender differences in intensity and duration of growth spurt in FFM
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What is the carbohydrate intake required during the first 6 months of life?
~60g CHO=37% of total food energy (amount in milk is assumed to be optimal)
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How much milk is consumed in the first 6 months of life?
~0.78L/day
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How much CHO is needed during 7-12 months?
median CHO intake from weaning foods =50g/day
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How much milk is secreted at 7-12 months?
0.6L/day
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Why is solid food needed at 7-12 months?
- CHO from human milk=44g
- CHO from foods = 50g
- Total needed=94g
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What is the impact of added sugar on micronutrient intakes in infants?
- Nutrient dilution effect by nonmilk extrinsic sugars
- High [sugar] intake (>24% of energy)--> most micronutrient intakes between 6-20% below average
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Describe the rate of brain glucose consumption after age 1.
- Constant of increases modestly
- In the range reported for adults
- EAR and RDA for CHO based n information used for adults
- Same for both genders
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What is the AI for fiber for each age group?
14g/1000kcal x median energy intake
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Why are fiber recommendations a function of energy intake?
- Individuals consuming less than median energy intake need less fiber
- 1 year olds not meeting this energy consumption level will not require as much fiber and their intake should be scaled back accordingly
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Why do infants not need fiber?
- No functional criteria for fiber status reflecting response to dietary intake
- Human milk is the optimal source of nourishment and it contains no fiber
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Why are weight and lean body mass gains higher in formula-fed infants?
Formula is higher in protein than milk
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Even though it is higher in protein, why is formula not as good?
Despite lower protein intakes, breast-fed intants have better imune function and behavioural development
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How does protein intake change from 0-6 months to 7-12 months?
- Stays about the same 1.52g/kg/day
- May be a bit of an overestimate since growth slows down towards the end
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What method is used to estimate protein requirements?
- Factorial method
- Relationship between protein intake and nitrogen balance were utilized to estimate protein requirements by the factorial method
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What does the factorial method include?
- Estimates of maintenance requirement
- Measurement of rates of protein deposition
- Estimates of the efficiency of protein utilization for growth
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What is the factor used in the factorial method?
1.72 the efficiency of protein utilization for growth
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How much fat do infants need?
- 0-6 months: 31g/day
- 7-12 months: 30g/day
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Does human milk contain the correct amount of fat?
Yes
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For older infants, what is the fat AI based on?
Based on average intake of fat from human milk and complementary foods
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How much fat do older infants get form complementary foods?
~5.7g/day
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What is the n-6 PUFA requirement for 0-6 months based on?
- Amount of n-6 PUFAs in human milk
- 4.4g/day
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How much PUFAs do 7-12 month olds get from complementary foods?
1.2g/day
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What is the average energy intake from human milk and complementary foods for 7-12 month olds?
- Milk: 390kcal/day
- Foods:281kcal/ay
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What percentage of energy consumed is PUFAs in 7-12 month olds?
6%
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Why is n-3 more important than n-6 for infants?
Provide DHA which is important for the developing of the brain and retina
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What is the AI for n-3 for 0-6 month olds?
- 0.5g/day
- 1% of energy intake
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How much water is needed for 0-6 month olds and where does this number come from?
- 0.68L/day
- Because 0.78L of milk is consumed and milk s 87% water
- Round to 0.7L/day
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How much water do 7-12 month olds need?
Need 0.8L/day- comes from milk (0.52L) and complementary foods (0.32)
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What are water requirements in children based on?
- Normal hydration status can be achieved with a wide range of total water intakes
- AI for total water is based on median total water intake of children and adolescents
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What is the sodium and chloride AI in infancy based on?
- 0-6 months: based on mean intake of milk-fed infants
- 7-12 months: based on human milk and complementary foods
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Why are AI requirements of sodium and chloride for 1-18 years similar to adults?
Maturation of kidneys is similar im normal children by 12 months of age
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How is AI of sodium determined for children?
- Extrapolated down from the adult AI of 1.5g/day
- Using the average of median energy intake levels of the age groups for adults and for children
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What is the AI for potassium based on for 0-6 months?
- Based on average amount of potassium in human milk
- Mean intake: 0.39g/day (round to 0.4g/day)
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What is the AI for potassium for 7-12 months?
0.7g
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What are some conditions resulting from potassium deficiency in children and adolescents?
- Increased blood pressure, bone demineralization, kidney stones
- Result from inadequate intake over an extended period of time, including childhood
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How are potassium intakes for children calculated?
- Extrapolated from adult intakes
- Adjusted based on energy intake
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Why is potassium AI not adjusted based on weight?
- Adjusted based on energy intake
- Concern that adjustment based on weight might lead to a relatively low and potentially inadequate intake of potassium
- A greater intake of dietary K would be appropriate to mitigate adverse effects of Na
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How is the AI for Chloride set?
- Set at a level equivalent on a molar basis to that of Na
- Almost all dietary Cl comes with the Na added during processing or consumption of foods
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What is AI of vitamins and minerals for 0-6 months based on?
- Mean intake data from infants fed human milk exclusively
- Ad the [vitamin and mineral] of milk produced by well-nourished mothers
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How is the AI for vitamins and minerals for 7-12 months determined?
Extrapolated from estimates of nutrient intake from human milk PLUS nutrients provided by usual intakes of complementary weaning foods
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How are maintenance needs for vitamins and minerals extrapolated from adults to infants and children?
- Maintenance needs for vitamins and minerals expressed with respect to body weight (kgbody weight)^0.75
- Set to power of 0.75 to adjust for mertabolic differences related to body weight
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How is the variability in requirements due to growth rate accounted for?
A 10% CV for the requirement is assumed unless data are available to support another value
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How are AIs for vitamin K set?
Set on the basis of the highest median intake for each age group
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Why is there a significant increase in AI for vitamin K from infancy to early childhood?
Most likely due to the method used to set the AI for older infants and the increased portion of the diet containing vitamin K-rich fruits and vegetables as the diet becomes more diversified
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Why are newborn infants at risk for vitamin K deficiency?
Vitamin K is poorly transported across the placenta
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What can happen as a result of low [plasma clotting factors] at birth?
- Increased risk of bleeding during the first weeks of life
- Hemorrhagic disease of the newborn
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What is late HDNB?
- Between 3-8 weeks
- Usually associated with breast-feeding
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How can HDNB be prevented?
- Can be effectively prevented by administration of vitamin K
- Infants born in North America routinely receive 0.5-1mg of phylloquinone i.m.
- OR 2mg orally within 6 h of birth (less effective)
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How is AI for vitamin K determined?
Reflects a calculated mean vitamin K intake of infants principally fed human milk and provided vitamin K prophylaxis
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How is older infant vitamin K AI obtained?
By extrapolating up from young infants
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What is clinically significant vitamin K deficiency?
- Extremely rare in the general population
- Limited to individuals with malabsorption syndromes or those treated with drugs known to interfere with vitamin K metabolism
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What is the net Ca accretion and RDA for 1-3 years of age?
- 100mg/day
- Using an estimate of 20% net Ca retention
- RDA is set for Ca at 700mg/day
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What is the RDA for Calcium for males and females aged 4-8 years?
- Ca accretion=200mg/day
- Require a Ca intake of 800 to 900 mg
- RDA for calcium is 1000mg/day
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What are the 3 major lines of evidence for Ca needs for the 9-18 age group?
- The factorial approach
- Ca retention to meet peak bone mineral accretion
- Clinical trials: bone mineral content measured in response to variable Ca intake
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What is the RDA for Ca for boys ages 9-18?
1300mg/day: slightly above the 75th percentile of Ca intake
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What is the RDA for Ca for girls ages 9-18?
- 1300mg/day
- Slightly below the 90th percentile of Ca intake
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Why are calcium supplements needed in adolescents?
- Current levels of Ca intake among adolescents not adequate to support development of optimal bone mass
- Supplements may be necessary
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How is the AI for Fe determined for 0-6 month olds?
- Reflects mean Fe intake of infants principally fed human milk
- Assumed that the Fe provided by human milk si adequate to meet the Fe needs of infants exclusively fed human milk from 0-6 months
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What are the major components of Fe need for older infants?
- Obligatory: fecal, urinary, and dermal losses (basal losses)
- Increased hemoglobin mass (increased blood volume and increase in [hemoglobin])
- Increase in tissue (non-storage) Fe
- Increase in storage Fe
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What bioavailability is used to set Fe for 7-12 month olds and why?
Use 10% bioavailability because they mostly eat cereals and fruits and not many eat meat or meat mixutres
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What bioavailability is used to sed Fe EAR for 1-8 years?
Use 18% bioavailability
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What are the major components of Fe needs for children 9-18?
- Basal Fe losses
- Increase in hemoglobin mass
- Increase in tissue (non-storage Fe)
- Menstrual Fe losses in adolescent girls
- No provision for the development of Fe stores after early childhood
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What is the EAR for iodine for children 1-8 years?
65ug/day
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What is the AI for fluoride?
- 0.05mg/kg/day
- Recommended for all ages >6 months
- Protection against dental carries
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What is enamel fluorosis?
- Caused by Fe ingestion during the pre-eruptive development of the teeth
- After enamel has completed its pre-eruptive maturation--> no longer susceptible (by 8 years of age)
- Milder forms of fluorosis: white opaque patches, often most apparent on the edges of teeth (snow capping)
- Preeruptive maturation of the crowns of the anterior permanent teeth
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