Water-soluble vitamins

Question 1

Ascorbic acid conversion to diketogulonic acid is ________.

Answer 1

irreversible.

Question 2

Can humans make vitamin C?

Answer 2

No way man

Question 3

Name five things vitamin C is a cofactor for.

Answer 3

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

Question 4

Scurvy is primarily caused by a ____ ____ deficiency.

Answer 4

Vitamin C

Question 5

Can vitamin C be toxic?

Answer 5

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

Question 6

Decubitus ulcers can be treated with ______.

Answer 6

Vitamin C

Question 7

Which vitamin can enhance non-heme iron absorption?

Answer 7

Vitamin C

Question 8

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

Answer 8

Diphosphate.

Question 9

Name some sources of thiamine.

Answer 9

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

Question 10

Thiamine is also known as vitamin ___.

Answer 10

B1

Question 11

What do thiaminases and antithiamines do?

Answer 11

Degrade or inactivate thiamine!

Question 12

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

Answer 12

Jejunum and ileum. SLC19 transporters can be defective.

Question 13

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

Answer 13

30 days

Question 14

Where is thiamine stored?

Answer 14

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

Question 15

Can thiamine be toxic?

Answer 15

Nope.

Question 16

Name four bioreactions in which thiamine is a cofactor.

Answer 16

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

Question 17

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

Answer 17

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

Question 18

What causes Beri Beri?

Answer 18

Thiamine deficiency

Question 19

Compare/contrast Dry and Wet Beri Beri.

Answer 19

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

Main difference is that Wet includes heart failure.

Question 20

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

Answer 20

Thiamine

Question 21

Deficiency of which vitamin causes Wernicke-Korsakoff syndrome?

Answer 21

Thiamine.

Question 22

Name the symptoms of early Wernicke encephalopathy.

Answer 22

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

Question 23

Name the symptoms of late Korsakoff’s psychosis.

Answer 23

Amnesia, confabulation, loss of spontaneity and initiative.

Question 24

Niacin is also known as vitamin ___.

Answer 24

B3

Question 25

Is niacin toxic?

Answer 25

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

Question 26

Name six biological roles of niacin.

Answer 26

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

Question 27

Niacin can be made from which AA?

Answer 27

Tryptophan

Question 28

Can Hartnup's diasease cause niacin deficiency?

Answer 28

Yeah

Question 29

What causes pellagra?

Answer 29

Niacin deficiency

Question 30

What are the symptoms of pellagra?

Answer 30

Dermatitis, dementia, diarrhea, death

Question 31

Is folate widely distributed in foods?

Answer 31

Yeah

Question 32

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

Answer 32

1. Methionine synthase reaction (B12 - methyl) | 2. Methyl Malonyl CoA Mutase reaction (B12 - adenosyl)

Question 33

What was the primary reason for mandatory folic acid fortification?

Answer 33

To decrease incidence of neural tube defects.

Question 34

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

Answer 34

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

Question 35

Where in the GI tract does folate absorption occur?

Answer 35

Small intestine

Question 36

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

Answer 36

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

Question 37

Folate is also known as vitamin ___.

Answer 37

B9

Question 38

How does B12 deficiency result in a folate deficiency?

Answer 38

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

Question 39

Aside from methylation reactions, what is folate used for?

Answer 39

N10-methyl THF is used in purine synthesis

Question 40

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

Answer 40

Too little = higher risk, too much = higher risk

Question 41

Name four risk factors for folate deficiency.

Answer 41

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

Question 42

Defieincy of which vitamins can cause megaloblastic anemia?

Answer 42

Folate (B9) or B12 deficiency.

Question 43

Chronically high homocysteine levels are associated with ______.

Answer 43

cardiac disease

Question 44

What are the dietary sources of vitamin B12?

Answer 44

1. Animal products 2. Fortified food 3. Yeast, fermented food

Question 45

Describe the steps in B12 absorption.

Answer 45

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.

Question 46

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

Answer 46

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

Question 47

What populations are at risk for B12 deficiency?

Answer 47

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

Question 48

Name four tests to assess for B12 deficiency.

Answer 48

1. CBC 2. Serum B12 3. Methylmalonic acid 4. Homocysteine

Question 49

What three diseases may result from B12 deficiency?

Answer 49

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

Question 50

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

Answer 50

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

Question 51

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

Answer 51

10

Question 52

What does "the three M's" apply to?

Answer 52

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

Question 53

In what ways does alcohol mess with thiamin?

Answer 53

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

Question 54

Does alcohol affect folate metabolism?

Answer 54

Yeah.

Question 55

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

Answer 55

Folic acid/folate or B12 deficiency.