Vitamin C, Niacin, Thiamine Flashcards

1
Q

where is vitamin c found

A

-present in many rapidly growing foods

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2
Q

how can vitamin c get degraded?

A

-storage and food preparation

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3
Q

characteristics of vitamin c in small intestine

A

-dose dependent and residual large doses can cause bloating and diarrhea

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4
Q

metabolite of vitamin c

A

-oxalic acid

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5
Q

4 broad roles of vitamin c

A
  • antioxidant
  • contributes to protein and neurotransmitter metabolism
  • can facilitate absorption of non-heme iron
  • has a role in two stages of collagen synthesis
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6
Q

risk of vitamin c def

A
  • poor diet
  • intestinal disease or malabsorption
  • alcoholics
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7
Q

when is the vitamin c RDA increased

A
  • in smokers

- however, this by itself will not lead to a flat out def

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8
Q

Vitamin C leads to Scurvy which has the following symptoms

A
  • bleeding (petechiae and ecchymoses)
  • impaired soft tissue integrity such as poor wound healing or bleeding gums
  • impaired growth and bone growth
  • CNS alterations in mood and mental status
  • infection
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9
Q

vitamin c toxicity

-symptoms

A
  • usually occurs due to supplement use
  • bloating
  • diarrhea
  • may increase the risk of oxalate kidney stones in susceptible users
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10
Q

thiamine is found in

A

-a variety of foods including grains and animal foods

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11
Q

thiamine degradation and enrichment

A
  • may be degraded during processing so the grain is enriched
  • may also be due to thiaminases or antithiaminases but this is rare
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12
Q

alcohol and thiamine

A
  • impairs the transport of thiamine after it has been absorbed in the small intestine as well as impairs its phosphorylation into its active form
  • this contributes to thiamine def in alcoholics
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13
Q

body pool and intake requirements

A
  • body pool is 30mg which is roughly equal to 30 days of intake
  • this means we need a fairly regular intake
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14
Q

transketolase and thiamine

A
  • involved in the pentose phosphate pathway

- this forms the basis of a diagnostic test for deficiency

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15
Q

dehydrogenases and thiamine

A
  • pyruvate dehydrogenase

- without this enzyme you will get an accumulation of lactate

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16
Q

thiamine in nerves

A

-participates in synthesis of acetylcholine and GABA

17
Q

risk factors for thiamine def

A
  • poor dietary intake
  • alcoholism
  • persistent voimting
  • GI disease or malabsorption
  • HIV/AIDS
  • refeeding syndrome
18
Q

syndromes associated with thiamine def

A
  • beriberi (dry and wet)

- wernicke korsakoff

19
Q

dry beriberi

A
  • peripheral neuropathy

- calf pain

20
Q

wet beriberi

A

-tachycardia
-edema
-low peripheral resistance and heart failure
-

21
Q

infantile beriberi

A

-born to mothers with a thiamine def but are asymptomatic

22
Q

wernicke encephalopathy

A
  • opthalmoplegia with lateral gaze palzy and/or nystagmus
  • ataxia
  • confusion
23
Q

korsakoff psychosis

A
  • amnesia
  • confabulation
  • loss of spontaneity and initiative
24
Q

thiamine toxicity

A

-no known tox

25
Q

why do we need niacin

A

-to make NAD and NADP

26
Q

how is niacin synthesized

A

-from tryptophan

27
Q

what is niacin bound to in some foods, what is the complication

A
  • in some foods, such as corn, niacin is bound to carbohydrates
  • unless treated with alkali, it will remain bound and not bioavailable
28
Q

what can a high niacin intake be used to treat

A

-dyslipidemia

29
Q

NAD and NADP

A

-coenzymes involved in a wide variety of energy utilization, synthetic reactions, DNA repair, and cell replication and differentiation

30
Q

populations at risk for niacin def

A
  • poor diets
  • malabsorption and other GI disorders
  • disorders of tryptophan such as Hartnups (impaired absorption)
  • carcinoid tumor (increased tryptophan utilization)
31
Q

niacin deficiency results in

A

pellagra

32
Q

what is pellagra characterized by?

A

The four D’s:

  • dermatitis in sun exposed areas
  • diarrhea
  • dementia
  • death
33
Q

UL of niacin

  • based on what
  • how is this caused
  • other signs of tox
A
  • 35mg/day
  • this is based on flushing
  • almost always due to supplements or prescription meds
  • other signs of tox include heartburn, nausea, vomiting, liver toxicity, elevated uric acid, and impaired insulin sensitivity