Water soluble vitamins

Question 1

where are water soluble vitamins absorbed?

Answer 1

portal blood

Question 2

do water soluble vitamins circulate in free or bound form?

Answer 2

free

Question 3

are water soluble vitamins stored?

Answer 3

no

Question 4

what are the fat soluble vitamins?

Answer 4

A, D, E, K

Question 5

how are fat soluble vitamins absorbed?

Answer 5

via bile salts

Question 6

do fat soluble vitamins circulate in free or bound form?

Answer 6

bound to carrier protein

Question 7

are fat soluble vitamins stored?

Answer 7

to some extent by body fat

Question 8

definition: dietary reference intake (DRI)

Answer 8

1. set of reference values used to plan and assess nutrient intakes of healthy people and varies by gender / life stage
2. includes RDA, AI, EAR, TUL

Question 9

definition: recommended dietary allowance (RDA)

Answer 9

average daily level of intake sufficient to meet the nutrition requirements of nearly all healthy people

Question 10

definition: adequate intake (AI)

Answer 10

established when evidence is insufficient to develop an RDA and is set at a level assumed to ensure nutritional adequacy

Question 11

definition: estimated average requirement (EAR)

Answer 11

expected to satisfy the needs of 50% of the people in that age group based on a review of the scientific literature

Question 12

what is the role of vitamin B1 (thiamine)?

Answer 12

oxidative decarboxylation of a-keto acids and 2-keto sugars

Question 13

what is the role of vitamin B2 (riboflavin)?

Answer 13

electron (hydrogen) transfer reactions

Question 14

what is the role of vitamin B3 (niacin)?

Answer 14

electron (hydrogen) transfer reactions

Question 15

what is the role of vitamin B6 (pyridoxine)?

Answer 15

coenzyme in many transamination and decarboxylation reactions

Question 16

what is the role of biotin?

Answer 16

CO2 transfer reactions, carboxylation reactions

Question 17

what is the role of folate?

Answer 17

one carbon methyl transfers, amino acid metabolism

Question 18

what is the role of vitamin B12 (cobalamin)?

Answer 18

1. methylation of homocysteine to methionine

2. conversion of methylmalonyl CoA to succinyl CoA

Question 19

what is the role of vitamin C?

Answer 19

1. antioxidant
2. collagen synthesis
3. immune function
4. absorption of non-heme iron

Question 20

what are the energy releasing B complex vitamins?

Answer 20

1. B1 (thiamine)
2. B2 (riboflavin)
3. B3 (niacin)
4. pantothenic acid
5. biotin
6. B6

Question 21

what are the hematopoietic B complex vitamins?

Answer 21

1. folate
2. B12
3. pantothenic acid
4. B6

Question 22

how does vitamin C affect iron metabolism?

Answer 22

increases absorption of non-heme iron in gut and helps with distribution of iron in body

Question 23

which B vitamins are involved in the metabolism of fat and carbohydrates?

Answer 23

thiamine (B1), riboflavin (B2), niacin (B3), pantothenic acid, biotin

Question 24

which B vitamin is involved in the metabolism of protein?

Answer 24

B6

Question 25

what is the role of B12 in homocysteine metabolism? what form must B12 be in?

Answer 25

1. catalyzes remethylation of homocysteine to methionine requiring 5-methyl-THF
2. methyl cobalamin

Question 26

what is the role of B6 and pantothenic acid in hemoglobin metabolism?

Answer 26

synthesis of heme

Question 27

what condition is associated with cobalamin deficiency?

Answer 27

pernicious anemia

Question 28

what conditions are associated with folate deficiency?

Answer 28

megaloblastic anemia, neural tube defects

Question 29

what enzyme acts as a methyl donor to convert homocysteine to methionine?

Answer 29

MTHF (methyltetrahydrofolate)

Question 30

what is the cause of pernicious anemia?

Answer 30

1. parietal cells fail to secrete intrinsic factor - B12 deficiency
2. diphyllobothrium latum tapeworm

Question 31

what is the methyl trap?

Answer 31

methyl trapped in the form of MTHF after being used as a methyl acceptor instead of a methyl donor for DNA synthesis

Question 32

what is the cause of megaloblastic anemia?

Answer 32

folate deficiency - disruption of hematopoietic precursor maturation

Question 33

folate deficiency during the first trimester of pregnancy can result in what condition?

Answer 33

neural tube defects - spina bifida

Question 34

what is the risk of heavy folate supplementation?

Answer 34

can mask B12 deficiencies (cognitive impairment), particularly in elderly patients

Question 35

what are the four Hs of scurvy?

Answer 35

1. hemorrhage
2. hyperkeratosis
3. hypochondriasis
4. hematologic abnormalities

Question 36

pellagra is the result of deficiency of what vitamin?

Answer 36

Niacin (B3)