Fat, CHO, Fibre, Water and Micronutrient Requirements during Adulthood Flashcards
1
Q
Linoleic acid and a-linolenic acid compete for the same __________.
A
Desaturase enzymes
2
Q
When is the ratio of linoleic:a-linolenic important?
A
When diet is very low in AA (arachidonic acid), EPA, DHA
3
Q
How does the AI for N-6 FAs (linoleic) change at 50 years old for males and females?
A
Males: drops from 17 g/day to 14 g/day
Females: drops from 12 g/day to 11 g/day
4
Q
How is the AI determined for linoleic and a-linolenic acid?
A
based on highest median intakes in US populations where no evidence of deficiency
5
Q
What is linoleic acid metabolized in our body?
A
readily used for energy
6
Q
What is the AI for N-3 (a-linolenic) FAs during adulthood for males vs females?
A
Males: 1.6 g/day
Females: 1.1 g/day
7
Q
An overnight fasted male produces ~ how much glucose /day? What sources does he get the glucose from?
A
210-270 g/day
50% from glycogenolysis & 50% from gluconeogenesis
8
Q
In subjects fully adapted to starvation, ketoacids make up what % of the brain’s energy requirements? Therefore how much glucose is required?
A
80%
22-28 g/day
9
Q
What is the EAR for COH based on? What two things does this assume?
A
amount that would provide brain with adequate supply of glucose without additional glucose production from protein or TG and without increase ketones greater than the amount observed after overnight fast
- energy sufficient in diet with AMDR of CHO 45-65%
- glucose is not limiting to the brain
10
Q
Which one of our organs is ONLY dependent on CHO?
A
Brain
11
Q
What is the recommended amount of dietary CHO to decrease the risk of chronic disease?
A
Unknown
12
Q
In urbanized societies, what are 4 long term consequences that may be associated with a low CHO diet (which includes increased ketoacids)?
A
- Bone mineral loss
- High blood [cholesterol]
- Increased risk of kidney stones
- Urinary tract deposits
13
Q
What is dietary fiber?
A
Non-digestible CHO and lignin intrinsic /intact in plants
14
Q
What is functional fiber?
A
Isolated, non-digestible CHO shown to have beneficial physiological effects in humans
15
Q
Total fiber =
A
dietary fiber + functional fiber
16
Q
There is a strong indirect correlation between _________ and risk of CHD. There is a weak/nonexistent correlation between __________ and risk of CHD.
A
cereal fiber,
fruits and vegetable fiber
17
Q
How much fiber is recommended for heart health?
A
14 g dietary fiber/1000 kcal - particularly from cereals
18
Q
What are 4 benefits of eating fiber?
A
- Ameliorate constipation and diverticular disease
- Fuel for colonic cells
- Decrease blood [glucose] and [lipids]
- Source of nutrient rich low-energy foods satiety & decreases risk of obesity
19
Q
- What is the Dietary Fiber AI for men and women? When does it switch?
A
- Men: 38 g/d until 50 years old, then 30 g/day
2. Women: 25 g/day until 50 years old, then 21 g/day
20
Q
How is the AI determined for dietary fiber?
A
Based on strong data on relationship between dietary fiber intake and CHD risk
21
Q
Why can the EAR for total fiber not be determined?
A
Because the benefits of increased fiber intake are continuous across range of intakes
22
Q
Which type of fibers cause the greatest reduction in CHD?
A
Cereal fiber and some functional fibers (psyllium & pectin)
23
Q
- Certain kinds of fiber bind _______ and ________ absorption which decreases risk of CHD.
A
- Cholesterol
2. prevent
24
Q
- Beverages and food make up what % of water consumed by humans each day?
A
Beverages (80%) food (20%)
25
_______, not ______, dictates daily fluid intake
Behavior / thirst
26
What 2 things trigger thirst?
1. Decreased body water (sensed by low blood volume)
| 2. Increased [Na] (primarily sensed by cells of the brain)
27
How is thirst not well correlated with fluid needs?
You only get feeling of thirst ONCE you had significant fluid losses or a change in Na status
28
What is the primary indicator of water status? How is it assessed?
Hydration status which is assessed by plasma or serum osmolarity
29
What 3 things have a substantial influences on water needs?
1. PA
2. Environment
3. Diet
30
How do dietary factors influence water requirements?
metabolizing dietary proteins and organic compounds + varying intakes of electrolytes create an osmotic load which must be accommodated by adequate total water consumption
31
Is there a general daily total water requirement?
no
32
What is a side effect of dehydration?
unable to dissipate heat
33
When you are dehydrated and unable to release heat as sweat, in what two ways does this affect your body?
1. increases body core temperature
| 2. increase strain on cardiovascular system
34
What is the AI for water for males and females: sedentary vs. active?
Sedentary:
Males: 3.7 L/d ~ 16 cups
Females: 2.7 L/d ~ 12 cups
Active:
Males: > 3.7 L/d
Females: > 2.7 L/d
35
What condition can someone obtain if they drink waaaay too much water?
hypoatremia (rare) condition that occurs when the level of sodium in your blood is abnormally low
36
What is acute water toxicity?
When fluid consumption is > kidney's max excretion rate (0.7-1.0 L/h)
37
What is the RDA for calcium for men and women?
1000 mg (25 mmil)/day
38
What 3 things are correlated with inadequate Ca intake?
1. increase risk of osteoporosis
2. hypertension
3. colon cancer
39
Phosphorus is found in what form in the body?
PO4
40
___% of adult body P is in ____.
85%, bone
41
What 3 molecules can phosphorus be found in in the human body?
1. phospholipids
2. nucleotides
3. nucleic acids
42
How does P work with pH?
it buffers excess acids/bases to maintain normal pH
43
P is required for _______, the activation of many catalytic proteins.
phosphorylation
44
What is the absorption efficiency of P?
60-65%
45
What % of body magnesium is found in bone?
50-60%
46
___ (fraction) of skeletal Mg is exchangeable as reservoir for maintaining normal extracellular [Mg].
1/3
47
Mg is popular in the body as a...
coenzyme
48
What increases the EAR of magnesium as people age?
renal function declines, elderly eat more fibre
49
What fraction of our body iron is found in hemoglobin? What % is found in myoglobin?
2/3
15%
50
What 4 factors are used in determining iron requirements?
1. basal iron losses (feces, urine, sweat, skin cells)
2. menstrual losses
3. fetal requirements in pregnancy
4. Growth: expansion of blood volume, and/or increase tissue and storage iron
51
What is the EAR for Iron based on?
need to maintain minimal functioning Fe store
52
How is Fe absorption regulated in our body?
The more serum ferritin we have, the less Fe will be absorbed -- there is max 15 ug/L of ferritin in serum - we don't need more and this means stores are full
53
What is the bioavailability of iron in children > 1 years old, adolescents, & non-pregnant adults on a mixed diet?
18%
54
What is the upper limit of iron?
18% absorption
55
What is the EAR based on in men and women?
Men: basal Fe losses
Women: basal iron losses and menstrual losses
56
What are the electrolytes?
P, K, Na,
57
What 4 things is adequate K intake important for?
1. lowering blood pressure
2. blunting the adverse blood-pressure effects of salt intake
3. Reduces the risk of kidney stones
4. Potentially reducing bone loss
58
What is the primary route of loss of sodium in sedentary adults via physically active adults?
```
Sedentary = urine via kidney regulation
Active = sweat
```
59
Which amino acids is sulphur present in?
1. methionine
2. cystine
3. cysteine
60
Sulfur is an essential component of what essential compound?
glutathione
61
What are sources of sulfur in our diet?
S containing a.a.s from protein digestion
62
What is the recommended intake of sulfur?
None because intake typically exceeds needs & recommendation for sulfur aa intake covers the need for inorganic sulfate
63
Why is there no need to set sulphate RDA in a North American diet?
adequate to excess protein
64
What does Thiamin function as in our body?
coenzyme on metabolism of CHO and branched chain AAs
65
What is the thiamin requirement based on?
Thiamin needed to achieve and maintain RBC transketolase activity without excessive thiamin excretion
66
In what 3 ways can thiamin status be assessed?
1. erythrocyte transkelotase activity
2. [Thiamin] & its phosphorylated esters in blood
3. Urinary thiamin excretion under basal conditions or after thiamin loading
67
Do biochemical changes of thiamin deficiency occur in our body before of after the appearance of physical signs?
before
68
What is the down biochemical function of thiamin?
Thiamin pyrophosphate (TPP) in CHO metabolism
69
By what % do the thiamin requirement for women and men differ?
10%
70
What is the function of riboflavin?
coenzyme in numerous oxidation-reduction reactions
71
What are the requirements of riboflavin based on?
1. erythrocyte glutathione reductase activity coefficient
2. RBC [riboflavin]
3. Urinary riboflavin excretion
72
What 3 things is the EAR for riboflavin based on?
1. studies of occurrence of signs of clinical deficiency
2. biochemical values
3. urinary excretion in relation to dietary intake
73
What is the function of niacin?
cosubstrate or coenzyme for H ion transfer (dehydrogenases)
74
What is the primary criteria for RDA of niacin ?
urinary excretion of niacin metabolites
75
What is niacin requirements expressed as?
niacin equivalents
76
Which amino acid can be converted to niacin?
tryptophan - wide variation in efficiency of conversion of tryptophan to niacin
77
Vitamin B6 is a coenzyme in the metabolism of what 3 things?
a.a.'s
glycogen
sphingoid bases
78
What is the primary criterion used to estimate RDA of vitamin B6?
maintenance of adequate blood 5'-pyridoxal phosphate levels
79
What is the RDA of vitamin B6 for men and women?
1.3 mg/day for both
80
What is the function of folate?
coenzyme in single-carbon transfers in the metabolism of nucleic and amino acid
81
What are the 2 primary indicators for RDA estimates of folate?
1. Erythrocyte folate
| 2. Blood [homocysteine] and [folate]
82
What is RDA for folate based off of?
dietary folate equivalents
83
Because food folate is only 50% bioavailable, how do we get all we need?
dietary folate equivalents
84
1 ug of dietary folate equivalents =
1. ___ ug of food folate
2. ___ ug folic acid (fortified food/supplement)
3. ___ ug supplement taken on empty stomach
1. 1.0
2. 0.6
3. 0.5
85
What is the folate RDA?
400 ug/d of DFEs (dietary folate equivalents)
86
What are the two main functions of vitamin B12?
coenzyme for methyl transfer rxn:
| 1. homocysteine --> methionine L-methylmalonyl-coenzyme A (CoA) --> succinyl-CoA
87
What is the RDA of Vitamin B12 based on?
1. maintenance of hematological (disease) status
| 2. normal blood vitamin B12 values
88
What is the RDA for men and women for Vit. B12?
2.4 ug/day
89
what is the function of biotin?
coenzyme in bicarbonate-dependent carboxylation rxns
90
What is used to set the AI for biotin?
estimates of intake
91
What is the AI for biotin for men and women?
30 ug/day
92
What 3 things is choline a precursor of?
1. acetylcholine
2. phospholipids
3. the methyl donor betaine
93
What is the primary criterion used to estimate the AI of choline?
prevention of liver damage as assessed by serum alanine aminotransferase levels
94
In what two ways can choline be found in the diet?
1. free choline
| 2. bound as esters (phosphocholine, glycerophosphocholine, shingomyelin, phosphatidylcholine)
95
What is another name for phosphatidylcholine?
lecithin - can lower blood cholesterol
96
Which enzyme works to remove cholesterol from tissues?
Lecithin-cholesterol acyltransferase
97
Choline is also used to lower the concentration of what in the blood?
homocysteine
98
What is choline requirement influenced by?
1. methionine & folate availability
| 2. gender, pregnancy, lactation, stage of development
99
What is the AI for choline for men and women? Elderly?
Men: 550 mg/d
Women: 425 mg/d
Elderly: no adjustment, although transport across BBB may decrease
100
within what molecules can pantothenic acid be found in the human body?
component of coenzyme A & phosphopantetheine
101
For what two reasons might someone become deficient in pantothenic acid even though it is so widely available?
1. semi-synthetic diet
| 2. antagonist to the vitamin
102
What is the primary criterion to estimate AI of pantothenic acid?
intake adequate to replace urinary excretion
103
What is the usual intake of pantothenic acid? Therefore what do you think the AI is for adults due to the fact that there is no evidence of inadequacy?
4/7 mg/day
AI = 5 mg/day
104
What is the AI for men / women?
5 mg/day
105
What is vitamin C?
a water soluble antioxidant
106
Vitamin C is a cofactor for enzymes involved in biosynthesis of what 3 molecules?
collage, carnotite, neurotransmitters
107
The RDA for vitamin C is based off of what?
1. maintain near-maximal neutrophil concentration
| 2. minimal urinary excretion of ascorbate
108
What is the vitamin C RDA for men / women? What is the median intake in men and women compared to the RDA?
Men: 90 mg/day
Actual intake: 102mg/d
Women: 75 mg/day
Actual intake: 72 mg/day
109
For what 4 reasons is the RDA for vitamin C lower for women than it is for men ?
1. smaller lean body mass
2. less total body water
3. smaller body size
4. maintain higher plasma [ascorbate] than men at a given intake
110
Is there a difference in vitamin C metabolism or absorption with age?
no
111
What would a low blood [Vit. C] be due to in elderly?
poor dietary intake / chronic disease
112
What 6 things is vitamin A important for?
1. normal vision
2. gene expression
3. reproduction
4. embryonic development
5. growth
6. immune function
113
What is the EAR of vitamin A based on? What does this assure?
Amount of dietary vitamin A required to maintain a given body-pool size in well-nourished subjects. This assures vitamin A reserves to cover increased needs during periods of stress and low vitamin A intakes
114
What is used to set vitamin A requirements?
retinol activity equivalents
115
In what two sources can vitamin A be found?
1. preformed vitamin A can be found in animal derived foods
| 2. Provitamin A carotenoids can be found in darkly coloured fruits and vegetables, oily fruits & red palm oil
116
What are the 3 different types of dietary provitamin A carotenoids?
1. beta-carotene = 12 ug
2. alpha-carotene = 24 ug
3. beta-cryptocantin = 24 ug
117
What is the EAR/RDA for men/women for vitamin A?
Men:
EAR = 625 ug RAE/d
RDA = 900 ug RAE/d
Women:
EAR = 500 ug RAE/d
RDA = 700 ug RAE/d
118
What does vitamin D increase the absorptive efficiency of in the small intestine?
Ca, P which helps maintain blood [Ca] and [P]
119
What are the two major physiologically relevant forms of Vitamin D?
D2 = ergocalciferol ; yeast and plant sterols
D3 = cholecalciferol ; from 7-dehydrocholesterol
120
Is vitamin D is found naturally is a lot of foods?
nah
