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Nutrition Through Life > How each DRI was determined > Flashcards

How each DRI was determined Flashcards

1
Q

DRI for omega-3 & 6 was established based on what?

A

(AI) highest median intakes in US pop. where no evidence of deficiency

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2
Q

DRI for CHO based on what?

This assumes what 2 things?

A

(EAR) amount that would provide brain with adequate supply without additional glucose production from protein/TG & without increased ketones greater than observed after an over night fast.

This assumes:

  1. energy sufficient diet (45-65% CHO)
  2. glucose not limiting to the brain
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3
Q

What is used to set the DRI for fibre?

A

(AI) relationship between dietary fibre intake and CHD risk

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4
Q

Why can EAR not be made for fibre?

A

benefit of increasing total fibre intake is continuous across range of intakes

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5
Q

How is hydration status assessed?

A

plasma / serum osmolarity

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6
Q

What is the purpose of the DRI set for water?

A

(AI) - to prevent effects acute of dehydration - metabolic and functional abnormalities

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7
Q

Why is there no UL set for water?

A

excess fluid consumption can lead to hyponatremia (low Na level in blood) which is super rare

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8
Q

What is the DRI for Calcium based on?

A

(RDA) Intakes to achieve small gains in bone mineral Ca. Based on clinical trial data showing an increase in bone mineral density in women given certain Ca intake

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9
Q

What is the DRI for phosphorus based on?

A

(EAR/RDA) the lower end of the normal adult [P] range

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10
Q

What is the DRI for Mg based on?

A

(EAR) - maintenance of total body Mg

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11
Q

Why does the EAR of Mg need to increase with age?

A

Because renal function declines with age – more instances of negative balance in elderly

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12
Q

What are the 4 components of Fe requirements that are used as factors in determining DRIs?

A
  1. basal iron losses (faces, urine, sweat, skin cells)
  2. menstrual losses
  3. fetal req. in pregnancy
  4. Growth - expansion of blood volume &/or increase tissue/storage iron
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13
Q

What 2 things is the EAR of iron based off of?

A

Need to maintain a normal, functional [Fe] but only a minimal store

  • Upper limit of 18% absorption
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14
Q

How is the EAR for iron in men looked at differently than women?

A

Men: accounts for basal Fe losses

Women: accounts for basal Fe losses + menstrual losses

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15
Q

What is the difference in DRI for potassium for sedentary adults and physically active adults?

A

no difference

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16
Q

A person who sweats a lot can lose up to how much Na per day compared to the DRI?

A

~ 5 times (can exceed 10 g/day loss compared to 1.5g/day AI

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17
Q

How does the DRI for sodium change from a sedentary person to a physically active person?

A

a physically active person just needs > the AI

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18
Q

Why is no DRI established for sulfur?

A

Intake exceeds needs. In North America, but diet provides adequate/excess protein so no need to set RDA

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19
Q

What is the DRI for thiamin based on?

A

(EAR) the amount needed to achieve and maintain RBC transketoltase (pentose phosphate pathway of RBCs) activity w/o excess thiamin excretion

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20
Q

What is the difference in the EAR and RDA of thiamin?

A

small, 10% change - literally a 0.1 change

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21
Q

What is the median intake of thiamin in US relative to the DRI?

A

double! 2x!

22
Q

What 3 things is the riboflavin requirement based on?

A
  1. erythrocyte glutathione reductase activity coefficient
  2. RBC [riboflavin]
  3. Urinary riboflavin excretion
23
Q

What 3 things is the DRI for riboflavin derived from?

A

(EAR)

  1. studies of occurrence of signs of clinical deficiency
  2. biochemical values (because biochemical changes occur before appearance of physical signs of deficiency)
  3. Urinary excretion due to diet
24
Q

What is the median intake of Riboflavin in N. Am. relative to DRI?

A

>

25
Q

What is the main way that the DRI for niacin is determined?

A

(RDA) urinary excretion of niacin metabolites !

26
Q

What is the niacin median intake in Canadian populations relative to RDA?

A

Waaaaaay higher like 4x men & 2x women

27
Q

What is the DRI for vitamin B6 determined from?

A

(RDA) maintenance of adequate blood 5’-pyridoxal phosphate levels

28
Q

What are the two main ways that the DRI for folate is determined?

A

(RDA)

  1. erythrocyte folate
  2. blood [homocysteine] & [folate]
29
Q

What is the RDA for folate based off of?

A

Dietary folate equivalents

30
Q

What 2 things is the DRI for vitamin B12 based on?

A
  1. maintenance of serum status

2. normal blood vitamin B12 values

31
Q

What is used to estimate the DRI of biotin?

A

(AI) estimates of intake

32
Q

What is the primary criterion used to estimate the DRI for choline?

A

(AI) prevention of liver damage as assessed by serum alanine aminotransferase levels

33
Q

What happens to a healthy man with normal B12 intake who is fed a choline deficient diet?

A

decrease plasma [choline] and [phosphotidylcholine] –> liver damage

34
Q

Why is there insufficient data for a choline EAR?

How many studies were done to determine AI for choline for men / women?

A

only 2 published studies with healthy males - only 1 level of intake tested

Men: 1 study for AI
Women = made it up based off of male results

35
Q

Choline requirements is influenced by what?

A
  1. methionine and folate availability

2. gender, preg, lactation, development stage

36
Q

In what two ways may choline requirement be met at different stages of development?

A
  1. endogenous synthesis

2. diet

37
Q

How is the DRI for pantothenic acid determined?

A

intake adequate to replace urinary excretion

38
Q

How is the DRI for pantothenic acid determined?

A

Take the average of median intake as it seems to pose no risks of inadequacy

39
Q

How is the DRI for vitamin C determined?

A

(RDA) based on Vitamin C intake to

  1. maintain near maximal [neutrophil]
  2. Minimal urinary excretion of ascorbate
40
Q

For what 4 reasons is the RDA for women less than that of men for Vitamin C?

A
  1. Smaller lean body mass
  2. Less total body water
  3. Smaller body size
  4. women maintain higher plasma [ascorbate] then men at a given intake
41
Q

How does Vitamin C DRI change with age?

A

no difference - low blood vitamin C would be due to poor dietary intake / chronic disease

42
Q

What is the DRI for vitamin A based off of?

A

(EAR) based on amount of dietary vitamin A required to maintain a given body-pool size that also assures a vitamin A reserve that will supply increase vitamin A during periods of stress / low vitamin A intake

43
Q

What is used to set vitamin A requirements?

A

Equivalents

44
Q

What are the 3 dietary provitamin A carotenoid retinol activity equivalents?

A
  1. Beta-carotene RAE = 12 ug
  2. alpha-carotene RAE = 24 ug
  3. Beta-cryptoxanthin RAE = 24 ug
45
Q

Vitamin C

A

refer to notes

46
Q

What 2 things is the Vitamin E DRI based on?

A

(RDA)

  1. Induced vitamin E deficiency in humans
  2. Correlation between H2O2-induced erythrocyte lysis and blood [a-tocopherol]
47
Q

The DRI definition of Vitamin E is limited to what?

A

2R-sterioisomeric forms

  1. RRR-
  2. RSR-
  3. RRS-
  4. RSS-a-tocopherol
48
Q 
What is the DRI for a-tocopherol? 
Relative:
1. RRR-a-tocopherol = 
2. 2R-sterioisomeric = 
3. all raw-a-tocopherol =
A

15 mg/d

  1. 15 mg/d
  2. 15 mg/d
  3. 30 mg/d
49
Q

What are plasma [vit. E] dependent on?

A

affinity hepatica-tocopherol transfer protein (a-TTP)

50
Q

What type of vitamin E molecules are used to estimate DRIs? Why do they make the cutoff? Which types are not?

A

2R-stereoisomeric forms because they are able to bind to a-TTP (a-tocopherol transfer protein).

2S-stereoisomeric forms, other tocopherols and tocotrienols don’t make the cut because they fail to bind to a-TTP

51
Q

What is the DRI for vitamin K based on?

A

based on representative dietary intake data from healthy individuals - based on highest median intake data

Nutrition Through Life (5 decks)

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