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Flashcards in DRIs Deck (70)
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1

DRIs are developped in join collaboration of

between Health and Welfare Canada + USDA, NIH, US Academy of Sciences (FNB of IOM)

2

Why there are different nutrition recommendations

due to different interpretations of the scientific evidence.

3

Why is not correct to say daily intakes

 Intake of vitamin A is very variable from day to day, so it is not occur on a daily basis, and you do not to take it daily, because you can use it from fat source

 

Compared to water soluble riboflavin, which you need to restore more often 

4

Limitations of old dietary guidelines

a lot of guidelines were determined on average intake, but not in physiological role EFAS- are based in average intake, just assuming adequacy, but not as valid as vitamin C for example, where ascorbic acid  is measured as an antioxidant capacity in the body

5

Desrcibe the structure of DRIs organiszation, how lower and upper intake levels are established

Standing Committee for the Scientific Evaluation of Dietary Reference Intakes: oversees the 5 year process.

Nutrient Expert Panels develop, in conjunction with two subcommittees, the series of DRI Reports, based on a review of the scientific literature. 

Total: 7 reports from 7 individual sub-committees dealing with 7 areas of nutrient requirements
 

6

What does nutrient expert panels do ( what thet analyze)- 5 things

  • Develop a series of DRI reports, in conjunction with the two subcommittees by analyzing:  
  1. The role the nutrient plays at each life stage;
  2. The role the nutrient plays in the development of chronic disease;
  3. The indicator of adequacy of the nutrient;
  4. The estimate average requirement of the nutrient for each life stage;
  5. The interpretation of the current intake data of North American population groups.
    • In total, 7 reports from 7 individual subcommittees are submitted, dealing with 7 areas of nutrient requirements.

7

In what 7 groups all nutrients are divided

8

What is DRI committee mandate

Mandate: to look at nutrient intakes for the prevention of nutrient deficiencies AND to consider levels of intake needed to prevent chronic disease.

9

What is the use for UL committee and DRIs subcommittee 

UL committee: derives the tolerable upper intake levels for all nutrients since supplementation and food fortification are now a major source of nutrition in addition to food itself

Uses of DRIs sub-committee: deals with appropriate applications for reference intakes  (assessment of intakes, planning for intakes of groups/individuals and nutrition education)

10

4 general concepts for DRIs

•EAR – Estimated Average Requirement (from which RDA is determined)

•RDA – Recommended Dietary Allowance, which replaces the former RDA and RNI

•AI – Adequate Intake (alternative reference when EAR and consequently RDA are not available)

•UL – Tolerable Upper Intake Level

11

The trend established to focus on chronic disease prevention has been taken further: ( 4 points)

(1) look at the RDA values for micronutrients (importance in chronic disease prevention)


(2) recommendations for deficiency disease prevention AND chronic disease prevention


(3) common use of food and nutritional supplements  à establish upper levels of intake


(4) also include non-essential food components such as phytochemicals for chronic disease prevention.

12

RDA follow what distribution 

Same scientific approaches for RDA used to derive RNI: individual variability in requirements must be considered

Many biological variables in a population follow a Gaussian distribution ->many nutrient requirements for a population follow this distribution

13

RDA: average daily intake level sufficient to meet the needs  ___ people, at what stage

97-98%

individuals in a particular life stage and gender group.

14

RDA are set for groups or individuals?

level of nutrient intake to meet nutrient requirements of individuals and NOT groups. (Individuals consuming nutrients to the RDA level would be unlikely to develop a deficiency).

15

draw the distribution with % where EAR and RDA will be labelled 

16

The basis of setting the RDA ( 5 points)

1- Define intake of nutrient that provides adequate intake for 50% of  HEALTHY individuals in a life stage and gender group. Index of adequacy differs for each nutrient and for life stage.

2- Safety factor for optimal tissue stores.

3- Factor that accounts for additional needs for growth such as for pregnancy and lactation.

4- Bioavailability: factor can be added to account for nutrients with less than 100% absorption.

5- To account for variability in nutrient needs 2 SD are added to get the final RDA value.

17

When setting RDA we should have a measurable ___

Outcome

18

why there is a problem with data from healthy population?

One general limitation: young adults that are tested, so on elderly assumptions are made based on young, but not the research, the same thing for childhood

19

What studies should be also considered apart from usual intake distribution of healthy people

•Deficiency states

•Balance studies (You have a daily loss of nutrients through skin, urine, etc.-> how much you need to take to meet your losses. Given nutrient free diet and then look how much of the nutrient they are losing and then determine the level. Not many studies)

  • Animal research

Experimentally obtained data via balance studies, epidemiological studies or extrapolated from data on other age groups.

Deficiency and balance studies show a quantitative relationship between intake below a certain level and deleterious changes in biochemical & physiological responses.

20

RDA must account for 

•Individual variability in a population (i.e., coefficient of variability of population) -

Depending on the variability, SD can be narrow or wide

Infancy is the very variable, so you need to take SD that are larger

•Bioavailability (The ability to absorb the nutrient ( iron from meat or vegetables), iron requirements as well ass zinc are higher for vegetarian based diet, phytates, tannins, oxylates restruct iron absorption

•Sex and age differences (

Different body composition, different hormones-> different needs

All stages of growth adds more all nutrient requirements)

•Physiological state (pregnancy, lactation)

21

What is EAR and how it is derived

dietary intake of a nutrient meeting the needs of 50% of the population. Typically derived from balance studies and serves as the foundation for setting the RDA.

-Based on a specific criterion of adequacy

-E.g.: EAR for vitamin C is based on “an amount thought to provide antioxidant protection as derived from the correlation of such protection with neutrophil ascorbate concentrations”.

22

Using EAR what can you determine

•Suitable method to assess the prevalence of inadequate intakes for GROUPS

23

How SD of EAR should be calculated if there no SD available

•Assume CVEAR = 10%

•CVEAR = SDEAR/EAR

•SD = (EAR x CV)

•RDA = EAR + 2SDEAR

•RDA = EAR + 2(EAR x 0.1)

•RDA = EAR (1.2)

24

Major difference between RDAs and RNIs

  1. When possible, the reduction in the risk of chronic degenerative disease is included in the formulation of the RDA.
  2. Concepts of probability and risk explicitly underpin the determination of the DRIs, and applications.
  3. Upper levels of intake are established.
  4. Food components that may not meet the traditional concept of a nutrient are considered.

 

The main criticism of the former RDAs and RNIs were that the indices of nutritional adequacies that were used were based on insufficient information, as there were no metabolic studies to estimate their recommendations. The mean intakes of the healthy population, lacking signs of deficiencies, were used as the standard for nutrient adequacies and recommendations, which may not reflect the actual requirement or a person or a group of people.

25

Energy requirements are estimated based on

Energy requirements are estimated on an individual basis using sex, age, height, weight, and physical activity level to estimate total energy expenditure.

26

Why mean intake should be used as a reference number to set the requirement for energy requirement 

- It is assumed that for energy there is a high correlation between intake and expenditure (or requirement) so that energy balance is closely maintained.

--> A healthy individual will ordinarily meet energy needs by adjusting food intake.

-Risk that setting higher intakes will cause an overconsumption of energy

27

Is diet analysis is suffient to judge nutritional adequacy

•RDAs are a reference point ONLY in evaluating diets of individuals

•Allow estimate of probable risk of deficiency for an individual when diet is assessed over time

Can tell only the probability of the deficiency 

28

If the person intake is below RDA, does it mean he has deficiency

what is the cut-off

and when the person is said to be deficient (what percent of RDA)

-Intake below RDA cannot give certainty of nutritional deficiency

-Probability of risk increases the lower the intake goes below RDA. Cut-off = 2/3 of RDA

-Someone consuming a nutrient at 50% of RDA is likely to be deficient.

29

How requirements for RDA can be met

-Requirements can be reached by a well balanced diet.

30

Should you consume all the nutrients daily?

-Intakes of the required nutrient are averaged over a period of time.

-Certain nutrients show a high day to day variability of intake (vit. A) or low variability (protein, vit. B6)