Vitamins

Question 1

What are vitamins?

Answer 1

Vitamins are a group of organic nutrients required in small quantities for a variety of biochemical functions that, generally can not be synthesised by the body so must be supplied in diet or supplement.

Question 2

How many vitamins do humans require in diet for proper functioning of body tissues and organs?

Answer 2

At least 12 vitamins

Question 3

General function of fat soluble and water soluble vitamins?

Answer 3

Water soluble vitamins function as coenzymes while fat vitamins participate in diverse biochemical reactions such as blood clotting, visions, etc.

Question 4

Tocopherol?

Answer 4

Vit E

Question 5

Cholecalciferol

Answer 5

Vit D

Question 6

Fat soluble vitamins?

Answer 6

A
D
É
K

Question 7

How are excess water soluble vitamins removed from the body?

Answer 7

Excreted through urine

Question 8

How are fat soluble vitamins transported in the body?

Answer 8

They are absorbed and transported by the chylomicron complex

Question 9

Absorption by chylomicron complex of fat soluble vitamins is dependent on?

Answer 9

• Adequate bile salts
• Healthy mucosa cells
• Pancreatic secretions

Question 10

Factors that may lead to vit deficiency

Answer 10

• Deficiency of vitamins in food (dietary deprivation): This may occur in people who live on non nutritious food or in anorexia
• Inability of the body to absorb vitamins from food (mal-absorbtive state): This can be found in disease of alimentary canal, biliary disease, pancreatic disease, alcohol liver disease.
• Increased vitamin needs: such as women during pregnancy or lactation, infants, children or when there’s tumor in the body.

Question 11

Adequacy of vitamin supply depends on?

Answer 11

The amount of vit absorbed

• The needs of the body.

Question 12

Retinoid comprises?

Answer 12

Retinoid acid, retinol, retinal.

Question 13

Compounds that have Vit A activity

Answer 13

• Retinoid (only in foods of animal origin)
• Carotenoids (only in plants).

Question 14

How is retinol gotten from carotenoids?

Answer 14

Carotenoids are cleaved in the intestinal mucosa by carotene dioxygenase to yield retinal which is reduced to retinol.

Question 15

Why should palm oil not be left under the sun?

Answer 15

Palm oil is a source of vit A and since vit A is stable to heat but sensitive to UV light, this palm oil should not be left in contact with the sun

Question 16

Which of the photoreceptor cells doesn’t receive colour?

Answer 16

Rods

Question 17

What are the major functions of vit A?

Answer 17

• Vision
• Regulation of gene expression & tissue differentiation

Question 18

Who discovered the role of vitamin A in vision? When?

Answer 18

George Wald. 1943

Question 19

Vision is based on _____?

Answer 19

Absorption of light by photoreceptor cells

Question 20

_____ function in dim light

Answer 20

Rods

Question 21

What photoreceptor cell is responsible for colour vision?

Answer 21

Cones

Question 22

What is the photoreceptor molecule in rods called?

Answer 22

Rhodopsin

Question 23

Rhodopsin?

Answer 23

Is the photoreceptor molecule found in rods. It’s made up of light-sensitive opsin proteins covalently linked to 11-cis-retinal (retinaldehyde) that serves as a prosthetic group in the retina.

Question 24

What photoreceptor molecule is present in cones?

Answer 24

Iodopsin

Question 25

What type of retinoic acid regulates growth, development & tissue differentiation?

Answer 25

All trans-retinoic acid and 9-cis-retinoic acid

Question 26

How does retinol regulate the transcription of specific genes?

Answer 26

By binding to nuclear receptors (present on the nuclear membrane) like other hormones thus bringing about the transcription of specific genes.

Question 27

Function of 9-cis-retinoic acid

Answer 27

Regulate growth, development and tissue differentiation.

Question 28

The prostatic group of the opsin protein present in the retina is?

Answer 28

11-cis-retinal

Question 29

Richest source of vit A?

Answer 29

Fish oil (cod liver oil)

Question 30

The richest source of carotenoids?

Answer 30

Palm oil

Question 31

Sources of vit A

Answer 31

Fish oil, palm oil, vegetables, sweet potatoes, liver of animals (especially polar bears), diary products, carrots, etc.

Question 32

How is vit A carried in the blood?

Answer 32

Vit A is carried in the blood as vit A- retinol binding protein (RBP) complex.

Question 33

Causes of Vit A deficiency

Answer 33

• In protein malnutrition, the carrier protein (RBP retinol binding protein complex) that carries Vit A in the blood will be unavailable.
• Zinc deficiency can lead to Vit A deficiency because it’s needed in the synthesis of RBP
• In pregnancy there’s a measurable drop in the plasma level of Vit A by the 6th week after conception and there’s a further decrease to half the preconception level after 12 weeks.
• Liver disease can lead to vit A deficiency since the liver stores and transports Vit A.

Question 34

What’s the major effect of vit A deficiency?

Answer 34

Preventable blindness

Question 35

Earliest sign of deficiency of vit A?

Answer 35

Loss of sensitivity to green light followed by impairment to adapt to dim light and night blindness

Question 36

Effects of vit A deficiency

Answer 36

• Preventable blindness: loss of sensitivity to green light, impairment to adjust to dim light, night blindness
• Growth retardation, anorexia, dermatitis, hypogeusia (loss of taste sensitivity)
• Mild deficiency leads to susceptibility to infectious diseases