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Nutr 221 > Vitamin B > Flashcards

Vitamin B Flashcards

1
Q

what are the 3 major functions of thiamin?

A

energy transformation (remove CO2), synth of pentoses and NADPH (PPP), membrane and nerve conduction

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2
Q

what is the noncoenzyme form of thiamine associated possibly with beriberi?

A

TTP

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3
Q

what is the coenzyme form of thiamine?

A

TPP

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4
Q

what are food sources of thiamine?

A

whole grains, seeds and legumes, pork, enriched white flour and minute rice, veg and fruit

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5
Q

2 situations where beriberi occurs?

A

1) lack of thiamin in diet

2) alcoholism (secondary)–>Wernicke encephalopathy

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6
Q

examples of foods with thaminase?

A

raw fish, raw ferns/Nardoo

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7
Q

examples of foods with anti-thiamin factors?

A

fermented tea and betel nut (polyhydroxyphenols)

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8
Q

what are symptoms of Wernicke enephalopathy?

A

ocular motor signs, ataxia, derangement of mental functions

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9
Q

what is the static test of thiamin? What is the functional test?

A

urinary excretion (recent intake); RBC transketolase activity (measures usage thru stimulation test)

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10
Q

what is the enzyme stimulation test?

A

erythrocyte transketolase activity test: in vitro stimulation–>if stimulated activity >20%=marginal deficiency, if >25% = deficient

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11
Q

what is the EAR and what is based on?

A

1.0 mg for men, 0.9 for women; depletion/repletion ETKA

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12
Q

what is the RDA?

A

1.2 in men and 1.1 in women

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13
Q

What is the name of vitamin B2?

A

riboflavin

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14
Q

what coenzymes are riboflavin involved in?

A

FMN, FAD

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15
Q

what are the three components of a nucleotide?

A

base, sugar, phosphate

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16
Q

FMN+AMP=?

A

FAD

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17
Q

what are the two functions of riboflavin?

A

1) add or remove hydrogens

2) metabolism of other vitamins

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18
Q

glutathione reductase is found in____

A

red blood cells

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19
Q

if low in riboflavin, will have 2ndary deficiency in:

A

B6, folate, vit A, niacin, choline

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20
Q

what reactions need FAD?

A

succinate–>fumarate; pyruvate–>Acetyl CoA

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21
Q

what reactions need FADH2?

A

GSSG–>2GSH; breakdown fatty acids

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22
Q

what are food sources of riboflavin?

A

milk, whole grains, enriched grains, meat

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23
Q

What is deficiency in riboflavin called?

A

ariboflavinosis

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24
Q

what is the key symptom of ariboflavinosis?

A

cheilosis

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25
Q

what is the static test? what is the functional test? (For riboflavin)

A

urinary riboflavin; EGR stimulation test

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26
Q

what is EGRAC?

A

Erythrocyte glutathione reductase activity coefficient–>determined thru stim test: % above unstimulated enzyme activity

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27
Q

what is the EAR for riboflavin? what is the RDA?

A

1.1mg M/0.9mg F; 1.3mg M/1.1mg F (2 SDs away from EAR)

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28
Q

what is vitamin B3?

A

niacin

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29
Q

an AC for riboflavin > ___ shows deficiency

A

1.4

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30
Q

what are the two chem forms of niacin?

A

nicotinic acid and nicotinamide

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31
Q

what are some noncoenzyme roles for niacin?

A

donates ADP ribose to chromosomal proteins, histones (gene silencing)

32
Q

what are 5 coenzyme roles of niacin?

A

1) pyruvate dehydrogenase
2) synth of f.a.(donate H)
3) krebs cycle (3 rxns)
4) regenerate antioxidants
5) activate other vitamins

33
Q

what are the 3 rxns in Krebs that use niacin as coenzyme?

A

malate–>oxaloacetate; isocitrate–>alphaketoglutarate; alphaketoglutarate–>succinyl coA

34
Q

Niacin is an inhibitor of ____ , preventing gene silencing

A

sirtuin (Sir-2)

35
Q

what are the 2 ways to obtain niacin?

A

exogenous (food), endogenous (made from tryptophan)

36
Q

what is the bound form of niacin?

A

niacytin

37
Q

1 NE= __ mg niacin = ___ mg tryptophan

A

1; 60

38
Q

if you are deficient in ____ can’t convert TRP into niacin

A

Vit B6 (PLP)

39
Q

assume good quality protein have ___% TRP

A

1

40
Q

how to calculate NE from protein intake?

A

g protein/100 = g TRP x 1000 = mg TRP / 60 = NE

41
Q

What are the 3Ms?

A

maize, molasses (CHO), meat (pork fat)

42
Q

what are the 3Ds?

A

diarrhea, dementia, dermatitis

43
Q

what is niacin deficiency called?

A

pellagra

44
Q

why is corn low in quality protein?

A

only 0.6% TRP, most niacin in bound niacytin form

45
Q

how can niacin be unbound in corn?

A

by using lime water (Ca(OH)2)

46
Q

RDA for niacin for M is __, F is ___

A

16; 14

47
Q

what is the most sensitive measure of niacin status?

A

urinary excretion of niacin metabolites (if low, means deficient)

48
Q

to set RDA from EAR, niacin uses __% SD

A

15

49
Q

what is niacin’s UL?

A

35 mg from synthetic or fortified sources only (not food or TRP)

50
Q

what are symptoms of toxicity?

A

flushing (release of histamine), severe itching, headaches, liver damage

51
Q

why is synthetic niacin taken?

A

to lower LDL and increase HDL (affordable–>self-medicate)

52
Q

what is dermatitis?

A

“flaky paint” sun exposed skin that rarely happens on face

53
Q

LOAEL of niacin is set at ___ mg based on ___ reactions. It is lowered to UL based on UF of ___

A

50; flushing; 1.5

54
Q

Coenzyme A and acyl carrier protein in fatty acid synthesis has ____

A

pantothenic acid

55
Q

when biotin is bound to ___ it is called ___; this is the form found in enzymes

A

lysine; biocytin

56
Q

You need ____ to digest (absorb) biotin and also for recycling (removing biotin from lysine in body)

A

biotinidase

57
Q

what is a non-Coenzyme role of biotin?

A

gene expression

58
Q

3C fatty acid

A

propionyl

59
Q

how does propionyl enter TCA cycle?

A

Propionoyl-CoA+CO2–>D-methylmalonyl-CoA

60
Q

propionyl CoA carboxylase requires ___ as a coenzyme

A

biotin

61
Q

what are the 3 vitamins needed in odd chan entry to TCA?

A

panthothenic, biotin, B12

62
Q

biotin is needed for the temporary addition of CO2 for the synthesis of ____

A

fatty acids

63
Q

biotin is involved with this amino acid enzyme

A

leucine

64
Q

what are food sources of biotin?

A

whole grain, meat+alt, dairy, egg yolk (esp. high cholesterol)

65
Q

why are we unable to set an EAR for biotin?

A

because we rely on intestinal synth for about half our needs

66
Q

what is the AI of biotin?

A

30 mcg

67
Q

how was the AI for biotin set?

A

set by extrapolating up from infant AI based on human milk content of biotin

68
Q

Deficiency of biotin is caused by:

A

eating raw egg whites–>have protein called avidin that tightly binds biotin and prevents absorption (destroyed by cooking)
-also in-born errors for defective biotinidase

69
Q

symptoms of biotin deficiency?

A

affects brain (hallucinate, lethargic), lethal to infants, alopecia and anorexia

70
Q

Food sources of pantothenic acid?

A

it is found in all food groups

71
Q

what are some functions of acetyl CoA?

A

In PDH complex, acetylation of cules (acetylcholine), drug metabolism, acetylation/deacetylation of histones, ACP in adding 2-C units to make f.a., wound healing

72
Q

what is the AI of pantothenic acid?

A

5 mg

73
Q

what is the AI of pantothenic acid set on?

A

based on average intake of US population

74
Q

what are symptoms of deficiency?

A

burning feet syndrome

75
Q

deficiency could occur in chronic diseases like:

A

type 2 diabetes, alcoholics, inflammatory bowel disease

76
Q

____ is sometimes fortified with pantothenic acid in Canada

A

breakfast cereals

77
Q

what are the hematopoietic B-oomplex vitamins?

A

folate, B12 and 6, pantothenic acid

Nutr 221 (17 decks)

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