Lecture 10 Flashcards
The NRVS- Who what how?
what is the estimated average energy requirement (EAR)
a daily nutrient level estimated to meet the requirements of half the healthy individuals of a particular life stage and gender group
what is the recommended dietary intake (RDI) (also the same as the RDA)
the average daily dietary intake level that is sufficient to meet the nutrient requirements of nearly all (97-98%) healthy individuals in a particular life stage and gender group
what is the adequate intake (AI)
the average daily nutrient intake level based on observed or experimentally determined approximations or estimates of nutrient intake by a group of apparently healthy people that are assumed to be adequate
what is the upper level of intake (UL)
the highest average daily nutrient intake level likely to pose no adverse effects to almost all individuals in the general population, as intake increases above the UL, the potential risk of adverse effects increases
what are other NRV terms we need to know
- acceptable macronutrient distribution range (AMDR)
- suggested dietary target (SDT)
- estimated energy requirement (EER) - this is an average
what are the recommendations in New Zealand and Australia
Nutrient Reference Values (NRV’s)
what are the recommendations in the United States and Canada
Dietary Reference Intakes (DRI’s)
what are the recommendations in Europe
Dietary Reference Values (DRV’s)
what is the name for the average requirement in USA/ Canada, Aus/NZ and Eurpoe
USA/ Canada + NZ/AUS = EAR
Europe = AR
what is the recommended intake level in USA/ Canada, Aus/NZ and Eurpoe
USA/ Canada = RDA (recommended dietary allowance )
NZ/AUS = RDI
Europe = PRI (population reference intake)
what is the safe intake in USA/ Canada, Aus/NZ and Eurpoe
USA/ Canada = AI
NZ/AUS = AI
Europe = AI
what are the applications of DRI, NRV and DRVs
- assessment and surveillance
- planning diets
- inform policy
- education
- food labelling and marketing
- emergency food aid
what is the physiological requirement
the quantity of a nutrient needed by the body to maintain a particular level of function
Losses vs dietary requirements
Losses ~1mg/day (men) 2mg/day (women)
Dietary requirements ~8mg/day; 18mg/day
ways of determining physiological requirement
- factorial estimation
- depletion / repletion study
- animal studies
physiological requirements are influenced by
- physiological factors : include pregnancy etc
- lifestyle factors : example smokers need more vitamin C
- biological and genetic factors
- environmental factors : like competing in high levels of heat, sodium will need to be higher
steps to establishing the EAR
- determine the distribution of physiological requirements for nutrient
- determine average physiological requirement
- determine variation in physiological reqs
- adjust for inefficient use of consumed nutrient (bioavailability in habitual diet, bioconversion of nutrient)
Bioavailability
-Measured % absorption non-haem iron from customary diet for population
-estimated proportion of iron intake that is haem iron
-measured % absorption haem iron
setting an RDI when the SD of the EAR is known
RDI = EAR + 2SDREQ
in most cases we don’t have enough data to have known standard deviation
setting an RDI is the SD of the EAR is not known
use CV for EAR
CV for most is assumed = 10%
RDI = EAR x (1+ 0.1 + 0.1)
what is a UL
highest level of intake of a nutrient that poses no risk of adverse effects
when determining a UL it is intake from
all sources : food, water, nutritional supplements
when determining a UL it is ideally based on
NOAEL = “no observed adverse effect level”
highest continuing intake of a nutrient at which no adverse effects have been observed
if there is no NOAEL when determining a UL, then it is based on
LOAEL = “lowest observed adverse effect level”
and
Uncertainty factor (UF)
if there is no NOAEL when determining a UL, in what cases will there be a larger UF
there will be a larger uncertainty factor if applied to animal data or when over consumption has serious health effects
what are the uncertainties of NRV’s
- limited data on distribution of physiological requirements
- data are mainly for young adult males
- limited absorption data for different diet types
- limited data on usual food intakes
- limited data on interactions between nutrients
- limited data on influence of host related factors
what are the underlying assumptions of NRV’s
- population is healthy
- nutrient intake is usual intake
- requirements for energy and other nutrients are being met
- nutrient requirements and intake are not correlated
what is meant by nutrient requirements and intake are not correlated
for energy is you are not getting enough you will be more hungry and so eat more, this is not the same for nutrients
if you do not have enough of that nutrient you will not know to have more of it
