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Nutrition AKA The most boring class on earth > Water-soluble vitamins > Flashcards

Water-soluble vitamins Flashcards

1
Q

Ascorbic acid conversion to diketogulonic acid is ________.

A

irreversible.

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2
Q

Can humans make vitamin C?

A

No way man

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3
Q

Name five things vitamin C is a cofactor for.

A
  1. Collagen synthesis
  2. Carnitine synthesis
  3. Norepinephrine synthesis
  4. Peptide hormone synthesis
  5. Tyrosine metabolism
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4
Q

Scurvy is primarily caused by a ____ ____ deficiency.

A

Vitamin C

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5
Q

Can vitamin C be toxic?

A

Yeah, over 2g/day causes diarrhea, bloating, enhanced ion absorption, hyperoxaluria.

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6
Q

Decubitus ulcers can be treated with ______.

A

Vitamin C

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7
Q

Which vitamin can enhance non-heme iron absorption?

A

Vitamin C

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8
Q

Which form of thiamine is most commonly used as a cofactor for bio reactions?

A

Diphosphate.

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9
Q

Name some sources of thiamine.

A

Whole grains, enriched grains, cereals, some veggies, legumes, meat, fish, poultry, dairy.

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10
Q

Thiamine is also known as vitamin ___.

A

B1

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11
Q

What do thiaminases and antithiamines do?

A

Degrade or inactivate thiamine!

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12
Q

Where in the GI tract are the active transporters located that transport B1? Which ones can be defective (genetic underlying cause)?

A

Jejunum and ileum. SLC19 transporters can be defective.

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13
Q

How long does it take to build up a body pool of thiamine?

A

30 days

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14
Q

Where is thiamine stored?

A

50% of the pool is in muscle. Some in liver

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15
Q

Can thiamine be toxic?

A

Nope.

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16
Q

Name four bioreactions in which thiamine is a cofactor.

A
  1. PP shunt (transketolases)
  2. alpha-KG DH
  3. Pyruvate DH
  4. alpha oxidation of branched FAs
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17
Q

How does thiamine deficiency result in reduced ATP and GTP synthesis?

A

No PP shunt –> no ribose sugar synthesis –> no purine synthesis

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18
Q

What causes Beri Beri?

A

Thiamine deficiency

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19
Q

Compare/contrast Dry and Wet Beri Beri.

A

Dry - peripheral neuropathy and calf tenderness.
Wet - tachycardia, low peripheral resistance, edema, heart failure, peripheral neuropathy.

Main difference is that Wet includes heart failure.

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20
Q

Which vitamin is involved in the synthesis of glutamine, GABA, and acetylcholine?

A

Thiamine

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21
Q

Deficiency of which vitamin causes Wernicke-Korsakoff syndrome?

A

Thiamine.

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22
Q

Name the symptoms of early Wernicke encephalopathy.

A

Opthalmoplegia, ataxia, confusion, atrophy and ventricular dilation, cerebellum neuronal loss

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23
Q

Name the symptoms of late Korsakoff’s psychosis.

A

Amnesia, confabulation, loss of spontaneity and initiative.

24
Q

Niacin is also known as vitamin ___.

A

B3

25
Q

Is niacin toxic?

A

Yeah 35 mg/day is TUL. Toxicity symptoms include heartburn, nausea, hepatotoxicity, hyperuricemia, gout, decreased insulin sensitivity, decreased glucose tolerance, and vasodilatory flushing.

26
Q

Name six biological roles of niacin.

A
  1. Glycolysis
  2. Synthesis of FAs and cholesterol
  3. Synthesis of steroid hormones
  4. Synthesis of glutamate
  5. Synthesis of ribonucleotides
  6. Post-translational modification of proteins
27
Q

Niacin can be made from which AA?

A

Tryptophan

28
Q

Can Hartnup’s diasease cause niacin deficiency?

A

Yeah

29
Q

What causes pellagra?

A

Niacin deficiency

30
Q

What are the symptoms of pellagra?

A

Dermatitis, dementia, diarrhea, death

31
Q

Is folate widely distributed in foods?

A

Yeah

32
Q

Name two biological reactions in which B12 is used as a cofactor.

A
  1. Methionine synthase reaction (B12 - methyl)

2. Methyl Malonyl CoA Mutase reaction (B12 - adenosyl)

33
Q

What was the primary reason for mandatory folic acid fortification?

A

To decrease incidence of neural tube defects.

34
Q

Which has higher bioavailability: synthetic folic acid or folate naturally found in foods?

A

Synthetic folic acid (bioavailability is 85% vs 60% from food)

35
Q

Where in the GI tract does folate absorption occur?

A

Small intestine

36
Q

Where is folate stored? For how long can folate storage be adequate to sustain biochemical functions?

A

Stored in liver, can be adequate for 2-3 months.

37
Q

Folate is also known as vitamin ___.

A

B9

38
Q

How does B12 deficiency result in a folate deficiency?

A

Cannot regenerate THF from N5-methyl THF with methionine synthase reaction, so folate gets “trapped.”

39
Q

Aside from methylation reactions, what is folate used for?

A

N10-methyl THF is used in purine synthesis

40
Q

What is the relationship between folate intake and breast cancer risk?

A

Too little = higher risk, too much = higher risk

41
Q

Name four risk factors for folate deficiency.

A
  1. Poor diet
  2. Alcoholism - it interferes with folate metabolism
  3. Malabsorption
  4. Medications
42
Q

Defieincy of which vitamins can cause megaloblastic anemia?

A

Folate (B9) or B12 deficiency.

43
Q

Chronically high homocysteine levels are associated with ______.

A

cardiac disease

44
Q

What are the dietary sources of vitamin B12?

A
  1. Animal products
  2. Fortified food
  3. Yeast, fermented food
45
Q

Describe the steps in B12 absorption.

A
  1. B12 is liberated from protein in the stomach.
  2. R factor binds to B12.
  3. Chyme goes into duodeum, and intrinsic factor binds to B12, replacing R factor.
  4. IF-B12 is absorbed in the ileum.
46
Q

What is pernicious anemia and what does it put one at risk for?

A

It is loss of intrinsic factor - puts a person at risk of B12 deficiency.

47
Q

What populations are at risk for B12 deficiency?

A

Vegetarians, older adults, people with malabsorptive diseases like Celiac, people that have had GI surgery, people with pernicious anemia.

48
Q

Name four tests to assess for B12 deficiency.

A
  1. CBC
  2. Serum B12
  3. Methylmalonic acid
  4. Homocysteine
49
Q

What three diseases may result from B12 deficiency?

A
  1. Megaloblastic anemia
  2. Neurologic problems including: combined systems degeneration, peripheral neuropathy, optic neuropathy.
  3. Neuropsychiatric: personality changes, memory impairment, depression.
50
Q

How much more ascorbic acid do smokers need per day? Why?

A

Need 35mg/day more because smoking oxidizes vitamin C.

51
Q

Scurvy can be prevented by as little as ___ mg/day of vitamin C.

A

10

52
Q

What does “the three M’s” apply to?

A

Risk for niacin deficiency. Stands for maize, meat, molasses.

53
Q

In what ways does alcohol mess with thiamin?

A

Alcohol inhibits thiamin transport out of the intestinal epithelial cell into the blood and also inhibits its phosphorylation into the active diphosphate form.

54
Q

Does alcohol affect folate metabolism?

A

Yeah.

55
Q

Megaloblastic anemia is a result of either _____ or ______ deficiency.

A

Folic acid/folate or B12 deficiency.

Nutrition AKA The most boring class on earth (12 decks)

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