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nutrition thru life > Fat/Carb/Micronutrient/Fibre requirements (adults) > Flashcards

Fat/Carb/Micronutrient/Fibre requirements (adults) Flashcards

1
Q

Why is the AI for linoleic and linolenic acid higher for males?

A

Readily oxidized for energy; males have higher metabolic rates and require more energy

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2
Q

True/False: linoleic acid is elongated to produce DHA

A

False. linolenic can be converted to DHA

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3
Q

How can the body adapt during carbohydrate depletion to support the brain?

A

ketoacid oxidation - alternate fuel for brain, glucose needs are reduced significantly
Glycogenlysis and gluconeogenesis also contribute to glucose supply

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4
Q

Why is the ratio of linolenic and linoleic acid so important?

A

They compete for the same desaturase enzyme required for elongation. If there is too much linoleic acid, then the products of linolenic acid will not be made.

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5
Q

How can supplementation with DHA or EPA help with a deficiency in linolenic acid?

A

linolenic acid is converted by the body to produce DHA and EPA; if those fatty acids are already in good supply, then the omega 3s will be spared

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6
Q

True/False: DHA and EPA are essential in the diet.

A

False. The essential fatty acids are linoleic and linolenic.

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7
Q

What essential fatty acid can be converted to arachidonic acid?

A

Linoleic acid

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8
Q

True/False: there are RDAs established for the essential fatty acids

A

False; only AI (median in populations without deficiency)

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9
Q

A diet high in omega 6 and low in omega 3 would lead to high levels of ____ acid, and low levels of ___ and ____ .

A

arachidonic; EPA; DHA

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10
Q

Differentiate dietary and functional fibre

A

Dietary: fibre found naturally in food (nondigestible carbohydrates - cellulose, lignins, etc)
Functional: isolated fibre (psyllium), can be used as supplement or fortification, but may lack the other health benefits of dietary fibre

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11
Q

What organ in the body is DEPENDENT on glucose?

A

brain

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12
Q

How is the recommended fibre intake calculated?

A

14g per 1000kcal intake

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13
Q

What is total fibre?

A

Sum of dietary and functional

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14
Q

What are the risks of long term low carb diets?

A

Can lead to kidney stones, urinary tract deposits, high blood cholesterol, loss of bone mineralization

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15
Q

How might fibre lower CHD risk?

A

certain types bind to bile acids, removing them and lowering cholesterol levels.

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16
Q

Fibres from what source in particular have been associated with lowered risk of coronary heart disease?

A

Cereals

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17
Q

What are the benefits associated with fibre consumption?

A
  1. prevent constipation/diverticulosis
  2. fuel for colon cells
  3. lower blood glucose and lipids
  4. usually in nutrient rich low energy foods, contribute to satiety
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18
Q

True/False: the body will send thirst signals to indicate fluid needs, which is a good indicator for intake.

A

False. Thirst signifies that water levels have already dropped significantly (or Na levels have increased significantly) - body is already under stress!

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19
Q

What does water intake mostly depend on?

A

Behaviour (not thirst)

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20
Q

How is hydration status assessed?

A

plasma/serum osmolality

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21
Q

True/False: water intake refers to the amounts of water and beverages consumed.

A

False. It also includes the water present in food items. (20%)

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22
Q

Why is water impacted by dietary factors?

A

Water is needed for digestion/metabolism

Metabolism and dietary electrolytes create OSMOTIC LOAD

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23
Q

Define osmolality and osmolarity, and explain which is preferred for measuring hydration status.

A

Osmolality: mols solute/kg SOLVENT
osmolarity: mols solute /L SOLUTION
osmolality is preferred since the intake of fluid would increase the weight of the solution, making it difficult to determine osmolarity.

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24
Q

Why can we not set an EAR or RDA for water?

A

Needs are too variable for the population, and even for a person from day to day, depending on physical activity, environment, diet, etc.

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25
Q

Why do males have a higher water AI?

A

More water needed for metabolism

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26
Q

Dehydration can impair ____ ____, which can cause strain on the cardiovascular system.

A

heat dissipation (results in higher core temp)

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27
Q

How could water toxicity occur?

A

Consuming vast amounts of water that exceeds the kidney filtration rate.

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28
Q

How might low potassium be associated with bone demineralization?

A

Lack of available mineral buffers to neutralize acid in body -> body will draw minerals from bone

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29
Q

What is the difference between the potassium found in salt substitutes and the natural potassium in food? Why would natural potassium be more beneficial?

A

Salt substitute: KCl
Natural: K citrate
K citrate can be converted to bicarbonate and act as a buffer in the body, while KCl does not have buffering capacity.

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30
Q

What are the main minerals in bone?

A

Ca, P, some Mg

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31
Q

What macromineral is needed in the highest quantity?

A

Ca

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32
Q

How is the EAR of P determined?

A

Looking at response of serum P with greater intake (the lower range in the population); rate of increase declines sharply once adequacy is reached

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33
Q

Most of the body’s iron is contained in ____.

A

RBCs

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34
Q

85% of the body’s phosphorus stores are in ____. Where is the remainder found?

A

bone;
phospholipids, nucleotides, nucleic acids
act as buffer

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35
Q

How is the Ca RDA determined?

A

Through calcium balance studies

based on amount needed for small increases in bone mineral content

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36
Q

What serves as a reservoir for minerals?

A

bone

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37
Q

In addition to being a constituent in body molecules/structures, what other roles does phosphorus serve?

A

Temporary energy storage/transfer (ATP, Creatine-P)
Buffer
Activate/deactivate proteins through phosphorylation

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38
Q

Magnesium is an important _____ for many ____ systems.

A

cofactor; enzyme

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39
Q

Why would elderly people suffer more Mg losses?

A

recommended high fibre diets (fibre binds to Mg)

decreased renal function

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40
Q

True/False: iron is an important part of many enzymes for oxidative metabolism (and other critical functions)

A

True.

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41
Q

Most of iron is contained in the proteins ____ and ____.

A

Hemoglobin; myoglobin

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42
Q

How is the RDA for magnesium determined?

A

Balance studies (maintenance of body Mg)

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43
Q

True/False: Iron RDA is determined through balance studies.

A

False. Determined through factorial analysis.

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44
Q

What is the Iron EAR based on?

A

Enough iron for functional concentration, but with minimal stores (as ferritin)

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45
Q

What does the body do if serum ferritin reaches 15ug/L?

A

Absorption will decrease

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46
Q

What are the factors considered for the Fe RDA? (4)

A
  • Basal losses (sweat/skin/urine/feces)
  • menstruation
  • Fetal requirements
  • Growth
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47
Q

True/False: elderly women need less iron.

A

True; no more menstrual losses.

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48
Q

True/False: All sources of iron are equal.

A

False. Heme has much higher bioavailability; nonheme iron may be bound to or interact with other components (such as Ca) and is limited by solubility

49
Q

True/False: Heme iron is found in meat, while nonheme is found in plants.

A

False: Heme is found only in meat, but nonheme is present in all foods.

50
Q

True/False: the RDA and EAR amounts are equal to the amount of iron needed in our body

A

False; assume only 18% bioavailability of consumed iron (need to adjust numbers for more consumption)

51
Q

What is the primary loss of sodium? What controls this?

A

Urine; controlled by adjusting the reabsorption rate by kidneys

52
Q

How is potassium beneficial for blood pressure?

A
  • Lowers blood pressure

- Blunts the adverse effects of Na on blood pressure

53
Q

True/False: athletes require more salt intake.

A

True. Sweat will lead to sodium loss.

54
Q

What are the sources of sulfur?

A

Amino acids

55
Q

What is the intake requirement for sulfur?

A

None established.

56
Q

True/False: Sulfur intake is a concern for North Americans.

A

False. North Americans get sufficient protein in the diet and so sulfur is usually not a concern (usually excess)

57
Q

Thiamine is an important ____ in metabolism of ____ and ____.

A

coenzyme (Thiamine Pyrophosphate); branched AA; carbs

58
Q

Sulfur is an important component of what essential antioxidant?

A

Glutathione

59
Q

Which B vitamin is important coenzyme for redox reactions?

A

Riboflavin

60
Q

What enzyme in RBCs is thiamine required for, and what does this enzyme do?

A

Transketolase; part of pentose phosphate pathway for anabolic reactions

61
Q

What is the definition of adequate thiamine?

A

Adequate RBC transketolase activity, without excessive urinary excretion

62
Q

Why are requirements generally higher for men than women?

A

bigger size, higher energy requirements

63
Q

What could cause a thiamine deficiency?

A

Poor diet

Heavy alcohol use

64
Q

How might riboflavin deficiency affect other nutrient statuses?

A

Compromises GI tract, affects metabolism of other nutrients such as Fe

65
Q

The requirement of ____ is based on RBC glutathione reductase activity. What else is it based on?

A

Riboflavin

Also based on concentrations in RBCs, and urinary excretion

66
Q

How is non-severe thiamin deficiency detected?

A

Thiamine loading (if body level is inadequate, no rise in excretion)

67
Q

The EAR for riboflavin is determined through what types of studies?

A

deficiency; balance

68
Q

What is the primary criteria for niacin RDA?

A

urinary excretion of niacin metabolites

69
Q

What amino acid can be converted (in small amounts) to vitamin B3?

A

Tryptophan

70
Q

What is the key role of vitamin B3?

A

Niacin is cosubstrate/coenzyme for DEHYDROGENASES (H transfer enzymes)

71
Q

True/False: Niacin requirement is adjusted for bioavailability.

A

False. Expressed as Niacin equivalents (take into account the amount synthesized by body)

72
Q

Why is the CV (variability) for requirements so much higher in Niacin?

A

Some conversion of Tryptophan will also provide niacin, but rate of conversion varies widely depending on diet, individuals, etc.

73
Q

In what types of reactions are dehydrogenases particularly important?

A

Synthesis (FA, steroids)

Redox

74
Q

What B vitamins have the same requirements for healthy men and nonpregnant women?

A

B6, B9, B12

75
Q

Pyridoxine is a coenzyme for metabolism of…?

A

AA, glycogen, sphingoid bases

76
Q

Folate is a coenzyme for catalyzing ____ transfer in metabolism of ___ and ____.

A

single carbon; AA, nucleic acids

77
Q

High ___ levels could indicate folate deficiency

A

homocysteine

78
Q

True/False: Natural folate is the best source in terms of bioavailability.

A

False. Supplements have higher bioavailability.

79
Q

What is the criteria for folate requirements?

A

RBC folate levels
Blood levels of homocysteine
Blood levels of folate

80
Q

The CV of what nutrient is particularly high, and why?

A

Niacin; due varying Tryptophan to niacin conversion rates among individuals

81
Q

Which vitamin is necessary coenzyme for methyl transfer reactions?

A

B12

82
Q

what is the folate recommendation?

A

400ug/day (men and women)

83
Q

What are DFEs? List them for the various sources.

A

Dietary Folate Equivalents:
1ug for food
0.6 for food/supplement/fortified
0.5 for supplement alone

84
Q

List 2 key conversion reactions that require vitamin B12

A

CoA -> succinyl coA

homocysteine -> methionine

85
Q

What B vitamins do not have an RDA? What do they have instead?

A

B5 (pantothenic acid)
B7 (biotin)
AI

86
Q

High alanine aminotransferase levels signal ____ damage caused by _____ deficiency.

A

liver; choline

87
Q

True/False: the body cannot synthesize choline and we must consume it.

A

False: we can synthesize some (but it is insufficient for most life stages).

88
Q

A choline deficiency can lead to NAFLD. What is this and how does this occur?

A

Non alcoholic fatty liver disease
Phospholipids (such as phosphotidylcholine) are required to assemble lipoproteins. Without sufficient choline to synthesize phospholipids, cholesterol and fat are deposited in the liver and cannot be exported.

89
Q

Choline and its derivatives can lower blood concentrations of ____ and _____.

A

cholesterol; homocysteine

90
Q

Biotin functions as a coenzyme in _____ reactions

A

Bicarbonate dependent carboxylation

91
Q

pantothenic acid is part of ____ and _____; it is important for metabolism of _____.

A

coenzyme A, phosphopantetheine

Fatty acids

92
Q

Why do RDAs not exist for choline?

A

insufficient number of studies

93
Q

Choline is a precursor for:

A

acetylcholine, phospholipids, betaine

94
Q

True/False: B5 is widely distributed in foods and deficiencies are rare.

A

True.

95
Q

True/False: Aging will naturally decrease vitamin C absorption.

A

False. No change in absorption/metabolism with age, unless poor diet and chronic disease.

96
Q

For optimal vit C levels, the levels of ____ should be maximized, while ____ should be minimized.

A

neutrophils

urinary excretion

97
Q

What are the main functions of vitamin C in the body? (2)

A

Antioxidant

Cofactor for synthesis of collagen, carnitine, neurotransmitters

98
Q

How are the different dietary sources of vitamin/provitamin A compared?

A

Retinol Activity Equivalents

99
Q

Vitamin A adequacy is based on the amount needed to ____.

A

maintain a healthy vitamin A store in body (in case of periods of stress or low intake)

100
Q

What are the ways vitamin A can be supplied in the diet?

A

As preformed vitamin A (animal sourced)

As carotenoid provitamin A (dark fruit/veg, oil)

101
Q 
What are the RAEs for 
vitamin A (preformed)
beta carotene
alpha carotene
beta cryptoxanthin
A

1ug, 12ug, 24ug, 24 ug

102
Q

What is vitamin A important for? (6)

A 
(VIGGER)
Vision
Reproduction
Embryo development
Growth
Gene expression
Immune function
103
Q

A vitamin D deficiency could cause deficiencies in the minerals ___ and ___. Why?

A

Ca, P

Vitamin D increases intestinal absorption of Ca and P

104
Q

What forms does vitamin D occur in food?

A

Ergocalciferol (D2)

Cholecalciferol (D3)

105
Q

How does vitamin D affect cell growth?

A

decreases proliferation, increases differentiation

106
Q

True/False: vitamin D is found naturally in a variety of foods.

A

False. Found naturally in very few foods (supplemented in milk).

107
Q

How might vitamin D be regulatory and prevent cancer growth?

A

antiproliferative effects, prevent uncontrolled cell growth

108
Q

What is the vitamin E requirement based on?

A

sufficient levels to protect against PEROXIDE induced lysis of RBCs in in-vitro studies

109
Q

Vitamin E prevents lipid _____.

A

peroxidation propagation/oxidation

110
Q

How are the antioxidant functions of vitamin C and E different?

A

Vitamin C is water soluble (target water soluble free radicals) while vitamin E is fat soluble and prevents lipid oxidation

111
Q

True/False: Synthetic vitamin E is more effective than natural sources.

A

False; only certain stereoisomers of a certain configuration of vitamin E are useful
Mixtures of synthetic alpha tocopherol are only 50% effective

112
Q

Your main source of vitamin E is from supplements. You read the label and see that you are consuming the appropriate amount for the RDA. Is there any problems with this scenario?

A

The RDA is for 2R a-tocopherol only; by consuming supplements (an all-rac mix) you are also consuming 2S and so only getting 50% of what the bottle says.

113
Q

True/False: the ineffectiveness of some types of vitamin E is due to limited absorption

A

False; they are absorbed but have LOW AFFINITY for hepatic alpha-tocopherol transfer protein, and so are not effectively distributed

114
Q

What forms of vitamin E exist?

A

Tocopherols and tocotrienols (alpha, beta, gamma, and delta forms)
- each has 8 stereoisomer forms

115
Q

What is the natural form of vitamin E in food?

A

All R (RRR) alpha tocopherol

116
Q

What forms of vitamin E are effective?

A

R isomers of alpha tocopherol

117
Q

Vitamin K is a coenzyme for synthesis of ____, which are important for what purposes?

A

proteins

blood clotting, bone metabolism

118
Q

What are the dietary and endogenous forms of vitamin K?

A

in diet: phylloquinone

Endogenous: Menaquinones (from gut microbiota)

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