Lecture 10 - The NRV's

Question 1

what is the estimated average energy requirement (EAR)

Answer 1

a daily nutrient level estimated to meet the requirements of half the healthy individuals of a particular life stage and gender group

Question 2

what is the recommended dietary intake (RDI) (also the same as the RDA)

Answer 2

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

Question 3

what is the adequate intake (AI)

Answer 3

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

Question 4

what is the upper level of intake (UL)

Answer 4

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

Question 5

what are other NRV terms we need to know

Answer 5

• acceptable macronutrient distribution range (AMDR)
• suggested dietary target (SDT)
• estimated energy requirement (EER) - this is an average

Question 6

what are the recommendations in New Zealand and Australia

Answer 6

Nutrient Reference Values (NRV’s)

Question 7

what are the recommendations in the United States and Canada

Answer 7

Dietary Reference Intakes (DRI’s)

Question 8

what are the recommendations in Europe

Answer 8

Dietary Reference Values (DRV’s)

Question 9

what is the name for the average requirement in USA/ Canada, Aus/NZ and Eurpoe

Answer 9

USA/ Canada + NZ/AUS = EAR

Europe = AR

Question 10

what is the recommended intake level in USA/ Canada, Aus/NZ and Eurpoe

Answer 10

USA/ Canada = RDA (recommended dietary allowance )

NZ/AUS = RDI

Europe = PRI (population reference intake)

Question 11

what is the safe intake in USA/ Canada, Aus/NZ and Eurpoe

Answer 11

USA/ Canada = AI

NZ/AUS = AI

Europe = AI

Question 12

what are the applications of DRI, NRV and DRVs

Answer 12

• assessment and surveillance
• planning diets
• inform policy
• education
• food labelling and marketing
• emergency food aid

Question 13

what is the physiological requirement

Answer 13

the quantity of a nutrient needed by the body to maintain a particular level of function

Question 14

what are the dietary requirements of iron

Answer 14

~8mg, 18mg

Question 15

ways of determining physiological requirement

Answer 15

• factorial estimation
• depletion / repletion study
• animal studies

Question 16

physiological requirements are influenced by

Answer 16

• 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

Question 17

steps to establishing the EAR

Answer 17

1. determine the distribution of physiological requirements for nutrient
2. determine average physiological requirement
3. determine variation in physiological reqs
4. adjust for inefficient use of consumed nutrient (bioavailability in habitual diet, bioconversion of nutrient)

Question 18

setting an RDI when the SD of the EAR is known

Answer 18

RDI = EAR + 2SDREQ

in most cases we don’t have enough data to have known standard deviation

Question 19

setting an RDI is the SD of the EAR is not known

Answer 19

use CV for EAR

CV for most is assumed = 10%

RDI = EAR x (1+ 0.1 + 0.1)

Question 20

what is a UL

Answer 20

highest level of intake of a nutrient that poses no risk of adverse effects

Question 21

when determining a UL it is intake from

Answer 21

all sources : food, water, nutritional supplements

Question 22

when determining a UL it is ideally based on

Answer 22

NOAEL = “no observed adverse effect level”

• highest continuing intake of a nutrient at which no adverse effects have been observed

Question 23

if there is no NOAEL when determining a UL, then it is based on

Answer 23

LOAEL = “lowest observed adverse effect level”

and

Uncertainty factor (UF)

Question 24

if there is no NOAEL when determining a UL, in what cases will there be a larger UF

Answer 24

there will be a larger uncertainty factor if applied to animal data or when over consumption has serious health effects

Question 25

what are the uncertainties of NRV’s

Answer 25

• 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

Question 26

what are the underlying assumptions of NRV’s

Answer 26

• population is healthy
• nutrient intake is usual intake
• requirements for energy and other nutrients are being met
• nutrient requirements and intake are not correlated

Question 27

what is meant by nutrient requirements and intake are not correlated

Answer 27

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