Vitamin C, Niacin, Thiamine Flashcards Preview

Nutrition > Vitamin C, Niacin, Thiamine > Flashcards

Flashcards in Vitamin C, Niacin, Thiamine Deck (33):
1

where is vitamin c found

-present in many rapidly growing foods

2

how can vitamin c get degraded?

-storage and food preparation

3

characteristics of vitamin c in small intestine

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

4

metabolite of vitamin c

-oxalic acid

5

4 broad roles of vitamin c

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

6

risk of vitamin c def

-poor diet
-intestinal disease or malabsorption
-alcoholics

7

when is the vitamin c RDA increased

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

8

Vitamin C leads to Scurvy which has the following symptoms

-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

9

vitamin c toxicity
-symptoms

-usually occurs due to supplement use
-bloating
-diarrhea
-may increase the risk of oxalate kidney stones in susceptible users

10

thiamine is found in

-a variety of foods including grains and animal foods

11

thiamine degradation and enrichment

-may be degraded during processing so the grain is enriched
-may also be due to thiaminases or antithiaminases but this is rare

12

alcohol and thiamine

-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

13

body pool and intake requirements

-body pool is 30mg which is roughly equal to 30 days of intake
-this means we need a fairly regular intake

14

transketolase and thiamine

-involved in the pentose phosphate pathway
-this forms the basis of a diagnostic test for deficiency

15

dehydrogenases and thiamine

-pyruvate dehydrogenase
-without this enzyme you will get an accumulation of lactate

16

thiamine in nerves

-participates in synthesis of acetylcholine and GABA

17

risk factors for thiamine def

-poor dietary intake
-alcoholism
-persistent voimting
-GI disease or malabsorption
-HIV/AIDS
-refeeding syndrome

18

syndromes associated with thiamine def

-beriberi (dry and wet)
-wernicke korsakoff

19

dry beriberi

-peripheral neuropathy
-calf pain

20

wet beriberi

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

21

infantile beriberi

-born to mothers with a thiamine def but are asymptomatic

22

wernicke encephalopathy

-opthalmoplegia with lateral gaze palzy and/or nystagmus
-ataxia
-confusion

23

korsakoff psychosis

-amnesia
-confabulation
-loss of spontaneity and initiative

24

thiamine toxicity

-no known tox

25

why do we need niacin

-to make NAD and NADP

26

how is niacin synthesized

-from tryptophan

27

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

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

28

what can a high niacin intake be used to treat

-dyslipidemia

29

NAD and NADP

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

30

populations at risk for niacin def

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

31

niacin deficiency results in

pellagra

32

what is pellagra characterized by?

The four D's:
-dermatitis in sun exposed areas
-diarrhea
-dementia
-death

33

UL of niacin
-based on what
-how is this caused
-other signs of tox

-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