Deck 16: Vitamins

Question 1

Compound 'Z' is considered a vitamin if:

A) It is vital for physiological processes in humans and is not synthesised in adequate amounts in the body.
B) Its basic chemical structure must be that of an amine.
C) It is an organic compound and its deficiency is associated with a disease or disorder.
D) The body needs it in amounts measured in less than a gram every day.
E) Undesirable toxic effects are unlikely when ingested in excessive amounts.

Answer 1

C

Question 2

Which of the following statements about vitamins is FALSE?

A) Apart from being categorised as fat-soluble or water-soluble, vitamins can be classified as essential and non-essential vitamins.
B) Some of the water-soluble vitamins such as thiamin, niacin and biotin act as co-enzymes in metabolic reactions to generate energy for cellular activity.
C) Provitamins such as carotenoids need to be converted into an active form before they can achieve most of their functions.
D) Factors affecting the absorption and utilisation of a vitamin can have an impact on the biological activity of that vitamin.
E) Fat-soluble vitamins are not needed on a daily basis because they can be accumulated and stored within the body.

Answer 2

A

Question 3

Which of the following statements is FALSE?

A) Vitamin A (or its related compounds) is needed in a number of physiological processes such as growth, immunity and reproduction in addition to its role in visual function.
B) Calcitriol (1,25-OH vitamin D) works with calcitonin and parathyroid hormone in the control of calcium homeostasis.
C) The major role of vitamin E is to protect lipids and prevents polyunsaturated fatty acids from oxidation. Therefore, its requirement depends in some measure on the source, amount and type of dietary fat.
D) Vitamin K is needed in the synthesis of blood-clotting factors and in the maintenance of healthy bones.
E) Toxicity from fat-soluble vitamins can occur in those with malabsorption syndromes such as in cystic fibrosis.

Answer 3

E

Question 4

Three major organs are involved in the production of the active form of vitamin D. List the organs (in order) where the following steps occur. 7-dehydrocholesterol (provitamin D3) ----------> cholecalciferol (vitamin D3)
Cholecalciferol ----------> calcidiol (25-hydroxy cholecalciferol, 25-OH vitamin D)
Calcidiol ----------> calcitriol (1,25-dihydroxy cholecalciferol, 1,25-OH vitamin D)

A) liver, kidney, skin
B) skin, kidney, liver
C) liver, skin, kidney
D) skin, liver, kidney
E) kidney, liver, skin

Question 5

Which of the following statements is FALSE?

A) Without thiamin or compounds derived from it, the body cannot generate energy from carbohydrates.
B) The riboflavin derivatives, flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN), are required in the conversion processes required for other nutrients.
C) Vitamin B-6 is a water-soluble vitamin that is stored in muscle and liver as a cofactor of glycogen phosphorylase. Mega-doses can still be consumed however, as excesses are excreted in the urine.
D) Humans can store enough vitamin B-12 in liver for about 5 years and efficiently recycle it in the enterohepatic circulation with bile so depletion can be delayed for a long time.
E) Most o folates in animal foods are readily absorbed unaltered, and hence are more bioavailable than those in plant foods.

Question 6

Which statement is TRUE with respect to vitamin C (ascorbic acid)?

A) Good sources are meats, dairy products, fruits and vegetables.
B) It's quite stable when exposed to heat, air and drying, so it can be retained during the preparation and cooking of foods.
C) It acts as an effective water -soluble antioxidant and an enzyme cofactor for biosynthesis of many chemicals.
D) It has to be supplemented in an average healthy adult because a healthy diet cannot provide sufficient amount to prevent scurvy.
E) Megadoses are always safe because, unlike other antioxidants, it never becomes pro-oxidant or causes damages to DNA.

Question 7

Which fat-soluble vitamin is associated with the following statements?

- $\bullet$ Its deficiency is one of the world's major nutritional problems; it can lead to blindness and increase the risk of infection

A) vitamin A
B) vitamin E
C) vitamin D
D) vitamin K

Question 8

Which fat-soluble vitamin is associated with the following statements?

- $\bullet$ In addition to its important role in calcium homeostasis, emerging evidence indicates that it is involved in other physiological systems including muscles and immune systems, and in cell turnover

A) vitamin A
B) vitamin E
C) vitamin D
D) vitamin K

Question 9

Which fat-soluble vitamin is associated with the following statements?

- $\bullet$ It must be obtained from the diet, and its richest dietary sources are vegetable oils and nuts

A) vitamin A
B) vitamin E
C) vitamin D
D) vitamin K

Question 10

Which fat-soluble vitamin is associated with the following statements?

- $\bullet$ Intestinal bacteria produce this vitamin about 50 per cent of the amount needed by the body

A) vitamin A
B) vitamin E
C) vitamin D
D) vitamin K

Question 11

Which water-soluble vitamin is associated with the following statements?

- $\bullet$ The mandatory fortification of bread with this vitamin can reduce the development of Wernicke-Korsakoff syndrome

A) ascorbic acid
B) biotin
C) choline
D) folate
E) Niacin
F) vitamin B₆
G) vitamin B₁₂
H) thiamin

Question 12

Which water-soluble vitamin is associated with the following statements?

- $\bullet$ It can be synthesised from tryptophan, so the calculation of its content in a diet needs to include the amount of dietary protein in that diet

A) ascorbic acid
B) biotin
C) choline
D) folate
E) Niacin
F) vitamin B₆
G) vitamin B₁₂
H) thiamin

Question 13

Which water-soluble vitamin is associated with the following statements?

- $\bullet$ Its natural occurrence is the result of microbial synthesis, and its absorption requires a molecule called intrinsic factor secreted by the stomach

A) ascorbic acid
B) biotin
C) choline
D) folate
E) Niacin
F) vitamin B₆
G) vitamin B₁₂
H) thiamin

Question 14

Which water-soluble vitamin is associated with the following statements?

- $\bullet$ Its deficiency is very rare but can be seen in people who consume raw white egg for a long period of time

A) ascorbic acid
B) biotin
C) choline
D) folate
E) Niacin
F) vitamin B₆
G) vitamin B₁₂
H) thiamin

Question 15

Which vitamin(s) could contribute to the following symptoms or disorders or disease?

- $\bullet$ congenital neural tube defects

A) ascorbic acid
B) biotin
C) vitamin D
D) folate
E) Riboflavin
F) niacin
G) vitamin B₁₂
H) thiamin

Question 16

Which vitamin(s) could contribute to the following symptoms or disorders or disease?

- $\bullet$ angular stomatitis

A) ascorbic acid
B) biotin
C) vitamin D
D) folate
E) Riboflavin
F) niacin
G) vitamin B₁₂
H) thiamin

Question 17

Which vitamin(s) could contribute to the following symptoms or disorders or disease?

- $\bullet$ osteomalacia in adults or rickets in children

A) ascorbic acid
B) biotin
C) vitamin D
D) folate
E) Riboflavin
F) niacin
G) vitamin B₁₂
H) thiamin

Question 18

Which vitamin(s) could contribute to the following symptoms or disorders or disease?

- $\bullet$ beriberi

A) ascorbic acid
B) biotin
C) vitamin D
D) folate
E) Riboflavin
F) niacin
G) vitamin B₁₂
H) thiamin

Question 19

Which vitamin(s) could contribute to the following symptoms or disorders or disease?

- $\bullet$ pellagra

A) ascorbic acid
B) biotin
C) vitamin D
D) folate
E) Riboflavin
F) niacin
G) vitamin B₁₂
H) thiamin

Question 20

Which vitamin(s) could contribute to the following symptoms or disorders or disease?

- $\bullet$ pernicious anaemia

A) ascorbic acid
B) biotin
C) vitamin D
D) folate
E) Riboflavin
F) niacin
G) vitamin B₁₂
H) thiamin

Question 21

Which vitamin(s) could contribute to the following symptoms or disorders or disease?

- $\bullet$ Wernicke's encephalopathy

A) ascorbic acid
B) biotin
C) vitamin D
D) folate
E) Riboflavin
F) niacin
G) vitamin B₁₂
H) thiamin

Question 22

Meat is a good food source of many water-soluble vitamins EXCEPT:

A) thiamin (vitamin B-1)
B) riboflavin (vitamin B-2)
C) niacin (vitamin B-3)
D) folate (vitamin B-9)
E) cobalamin (vitamin B-12)

Question 23

Compare fat-soluble and water-soluble vitamins with respect to: absorption, body storage capacity, excretion, toxicity, daily requirements.

Question 24

What factors make it difficult to determine a recommended dietary intake for Vitamin D, Vitamin E and Vitamin K?

Question 25

Explain how folate fortification in cereal products could create a health problem in the elderly who are at risk of vitamin B-12 deficiency.

Question 26

List up to two foods that are good sources of the following vitamins: