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nutr 3330 midterm > thiamin, riboflavin, niacin > Flashcards

thiamin, riboflavin, niacin Flashcards

1
Q

what type of vitamins are thiamin, riboflavin and niacin (what letter)?

A

vitamin B (B1 B2 B3)

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2
Q

what are the general functions of B vitamins

A 
macronutrient metabolism
energy production
energy release
energy metabolism
transfer of single carbon units
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3
Q

B vitamins are part of the structure of _____ that are needed for _____, which drive many reactions and pathways

A

co-enzymes

enzymes

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4
Q

what are the 5 intermediary metabolism activities that vitamins are involved in?

A

CHO
-glycolysis and gluconeogenesis

PRO
-protein synthesis and AA oxidation

FATS
-FA synthesis and beta oxidation

ATP GENERATION
-respiratory chain and oxidative phosphorylation

NUCLEIC ACIDS/FA/STEROIDS
-pentose phosphate pathway

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5
Q

what is Vit B1

A

thiamin

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6
Q

what needs to happen to thiamine in order for it to act as a coenzyme

A

it needs to have two phosphates added to it

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7
Q

study reminder

A

know structure of thiamine

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8
Q

what is the co-enzyme form of thiamin

A

thiamin pyrophosphate (TPP)

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9
Q

what are the metabolic roles of thiamin

A
  • facilitiates energy release from foods
  • central role in CHO metabolism
  • oidative decarboxylation
    • -> pyruvate dehydrogenase
      - -> alpha-ketogluterate dehydrogenase
  • transketolase reactions
    • -> also req. Mg
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10
Q

CHO PRO and FAT all oxidize to ______, which is central in macronutrient metabolism

A

acetyl CoA

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11
Q

what deficiency is associated with BERI-BERI (“ I cant I cant”)

A

thiamin (B1) deficiency

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12
Q

what are general symptoms of thiamin deficiency

A
  • dec fluid intake
  • anorexia with weight loss
  • neurological symptoms
  • paralysis
  • cardiovascular and respiratory
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13
Q

can a thiamin deficiency be easily reversed

A

yes, with thiamin

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14
Q

what was done to flour in canada that has made thiamin deficiencies rare?

A

fortification of flour

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15
Q

what are the 3 types of BERI-BERI

A

WET (edema)
DRY (no edema)
INFANTILE

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16
Q

what are symptoms of WET BERI-BERI

A
  • cardiovascular, respiratory
  • heart swelling
  • pulmonary congestion
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17
Q

what are symptoms of DRY BERI-BERI

A
  • CNS impairment
  • alcoholics (Wernicke-Korsakoff Syndrome)
  • confusion, memory loss, confabulation (clear memory of something that never happened)
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18
Q

what are signs of INFANTILE BERI-BERI

A
  • brest fed infants of deficient mothers (or formula that doesnt have thiamin)
  • vomiting, diarrhea, convulsions
  • aphonia–crying but no sound coming out
  • sudden death
  • responds to thiamin quickly
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19
Q

what is the EFSA

A

European Food Safety Authority

panel on dietetic products, nutrition and allergies

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20
Q

which vitamin contributes to normal CHO and energy-yielding metabolism, and maintenance of normal neurological function

A

thiamin

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21
Q

what is Vit B2, and why is it called B2

A

riboflavin

it was the second one that was discovered

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22
Q

what are the coenzyme forms of riboflavin

A

FMN (flavin mononucleotide)

FAD (flavin adenine dinucleotide)

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23
Q

is riboflavin water or lipid soluble

A

water soluble

24
Q

what are two characteristics of the appearance of riboflavin

A

yellow

fluorescent

25
Q

what vitamin needs riboflavin to function?

why is it needed

A

Vit B6

riboflavin is essential for conversion of B6 to its co-enzyme form

26
Q

metabolic roles of FMN and FAD

A

-accept and donate hydrogens

  • part of flavin-dependent enzymes
    • called AA oxidases
  • respiratory chain/energy production
  • TCA cycle
27
Q

food sources for riboflavin

A

milk and milk products
-photolabile… need to keep out of light

liver, meat

milling of wheat results in significant losses

fortified flour in canada

28
Q

riboflavin deficiency

A

never fatal

lesion symptoms

  • cheilosis (lesions around mouth)
  • magenta tongue
  • angular stomatitis
  • seborrheic dermatitis

also affects vit B6

29
Q

what is the nutrient nutrient interaction between riboflavin and iron?

*good exam question

A

riboflavin deficiency can impair mobilization of iron from its storage protein (ferritin)
and
impair iron absorption

30
Q

what are the two chemical structures of niacin (B3) ?

which one is the major form in the blood?

A

nicotinic acid

nicotinamide (major form in blood)

31
Q

what are the co-enzyme forms of niacin

A

NAD (H) (nicotinamide adenine dinucleotide)

NADP (H)

32
Q

what AA can niacin be synthesized from?

A

tryptophan…an essential AA!

33
Q

what is the conversion of tryptophan to niacin?

A

60mg tryptophan = 1mg niacin

34
Q

what is the units used for niacin

A

niacin equicalents (NE)

35
Q

what do we have to take into consideration when calculating niacin intake?

A

protein intake

36
Q

what is the beginning and end result in the Kynurenin Pathway?

A

tryptophan—->niacin (co enzyme forms; NAD/NADP

37
Q

what two vitamins does the Kynurenine pathway need

A

riboflavin

Vit B6

38
Q

we can replace the need for niacin in the diet of rodents, dogs and pigs, by putting _____ in the diet

A

tryptophan

39
Q

why is it called the kynurenine pathway

A

because kynurenine is a key intermediate in the conversion of tryptophan to niacin (in its coenzyme form)

40
Q

niacin transfers _____ during metabolic reaction

what types of reactions are these

A

hydrogen

oxidation/reduction

41
Q

study reminder

A 
review how and where niacin is used in:
Glycolysis/gluconeogenesis
TCA cycle
ETC
pentose phosphate pathway
42
Q

during oxidation, Niacin acts as a hydrogen (acceptor/donor)

A

acceptor

NAD(P) –> NAD(P)H

43
Q

during reduction, niacin acts as a hydrogen (acceptor/donor).

A

donor

NAD(P)H becomes NAD(P)

44
Q

pentose phosphate pathway is an alternative route of ______metabolim

A

glucose

45
Q

what are the 2 purposes or the pentose phosphate pathway

A

generate NADPH, then used for syntehsis of FA and steroids

generate ribose for synthesis of nucleic acids

46
Q

what are the four D’s? (symptoms)

A

diarrhea
dermatitis
dementia
death

47
Q

Niacin deficiency

A
  • pellagra (rough skin)

- four D’s

48
Q

study reminder

A

go over pellagra case study

49
Q

what is hartnup’s disease

A

autosomal recessive disorder

-development of pellagra due to defect in absorption process for tryptophan

50
Q

Niacin and the plague of corn

what is corn limiting in?

A

niacin is bound and unavailbe
limiting in tryptophan

this leads to pelllagra

51
Q

what is the solution to the plague of corn

A

alkali treatment;

breaks the bond and makes niacin available

52
Q

what nutrients would impact niacin status

A

protein
riboflavin
Vit B6

53
Q

what nutrient has been used as a cholesterol lowering agent?

A

nicotinic acid

54
Q

Niacin and CVD

A

unique among lipid-lowering drugs like statins as it has been shown to not only reduce LDL-cholesterol but also increase HDL-cholesterol and decrease lipoprotein (a) levels

55
Q

what are some side effects of niacin treatment?

A

abdominal pain, rash, liver toxicity

nutr 3330 midterm (13 decks)

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