Vitamins and minerals

Question 1

What are Vitamins?

Answer 1

• Micronutrient needed for normal metabolism.
• Can’t be synthesised in the body
• 2 groups: fat soluble (A,D, E & K) & water soluble (B &C)

Question 2

Outline water soluble vitamins.

Answer 2

1. Non-B-Complex:
   - Ascorbic acid (Vitamins. C)
2. B complex:
   - Energy releasing: Thiamine (B1), riboflavin (B2), Niacin (B3), Pantothenic acid (B5), Biotin (B7).
   - Haematopoietic: Folic acid (B9), Cobalamin (B12)
   - Other: Pyroxidine (B6)

Question 3

Outline fat soluble vitamins.

Answer 3

Vitamin A (Retinoids)
Vitamin D (Calcitriol)
Vitamin E (Tocopherol)
Vitamin K (Phylloquinones, menaquinones)

Question 4

What the dietary sources of fat soluble vitamins?

Answer 4

• Vitamin A: animal- retinal esters (REs) in red meat, plant- beta carotene (pro vitamin A) in carrots, green veg
• Vitamin D: Sunshine, fortified milk
• Vitamin K: K1- Green veg, K2- gut micro-flora in the large intestine.
• Vitamin E: seeds, oils, nuts, oily fish

Question 5

Describe the absorption of fat soluble vitamins.

Answer 5

• Pancreatic and biliary function needed for absorption.
• Fat soluble vitamins are cleaved from carrier proteins by pancreatic enzymes, bile salts solubilise them for absorption into micelles and chylomicrons.
• Transported to the liver for storage via the lymph system.

Question 6

What the dietary sources of water soluble vitamins?

Answer 6

Vitamin B: green veg, beans, liver, milk, fish, eggs
Vitamin C: citrus fruits, papayas, strawberries, kiwi

Question 7

Describe the absorption of water soluble vitamins.

Answer 7

• Via intestinal absorption by active transport across enterocyte membranes, followed by transport to the liver and peripheral tissues in portal & systemic circulations

Question 8

B1 function, deficiency & symptoms.

Answer 8

• Function: involved in conversion of pyruvate to acetyl CoA, branched-chain amino acid oxidation
• Deficiency: Beriberi; Wernicke- Korsakoff syndrome (common in alcoholics)
• Symptoms: tachycardia, vomiting, convulsion, apathy, loss of eye movements, loss of memory

Question 9

B2 function, deficiency & symptoms.

Answer 9

• Function: Electron transfer
• Deficiency: Ariboflavinosis
• Symptoms: inflamed lips, angular stomatitis, dermatitis, vascularisation of the cornea

Question 10

B3 function, deficiency & symptoms.

Answer 10

• Function: Electron transfer
• Deficiency: Pellagra, known as the 3D
  disease
• Symptoms: Diarrhoea, Dermatitis, dementia and death
  **High doses of niacin used to treat hyperlipidaemia

Question 11

B5 function, deficiency & symptoms.

Answer 11

• Function: Required for the synthesis of CoA, also as an acyl carrier
• Deficiency: Rare but can occur
• Symptoms: Numbness, tingling of hands and feet, vomiting and fatigue

Question 12

B6 function, deficiency & symptoms.

Answer 12

• Function: Co-enzyme for enzymes, particularly in amino acid metabolism
• Deficiency: Rare but can happen
• Symptoms: Glossitis, neuropathy, microcytic hypo-chromic anaemia
• Toxicity: yes
  **Sensory neuropathy occurs at high doses

Question 13

B7 function, deficiency & symptoms.

Answer 13

• Function: attached at the active site of carboxylase
• Deficiency: Rare but can happen
• Symptoms: scaly red rash around the eyes, nose, mouth (‘biotin deficient face’) & genital area, depression, neuropathy
  **^ Consumption of egg white can induce deficiency.

Question 14

B9 function, deficiency & symptoms.

Answer 14

• Function: Coenzymes in single carbon transfer reactions, biological methylation reactions, synthesis of methionine from homocysteine, purines and thymidine monophosphate
• Deficiency leads to: megaloblastic anaemia, neural tube defects
• Symptoms: Anaemia, higher than normal levels of plasma homocysteine, low birth weight
  ** ^ levels of folic acid deficiency can mask vitamin B12 deficiency

Question 15

B12 function, deficiency & symptoms.

Answer 15

• Function: Biological methylation reactions: homocysteine to methionine; synthesis of succinyl-CoA
• Deficiency comes from pernicious anaemia: leads to dementia and spinal degeneration
• Symptoms: Higher than normal levels of homocysteine, megaloblastic anaemia
  **Needs to bind to intrinsic factor to be absorbed in the gut, malabsorption can lead to deficiency.

Question 16

Vitamin C function, deficiency & symptoms.

Answer 16

• Function: Anti-oxidant, co-enzyme for hydroxylation reactions e.g. synthesis of collagen
• Deficiency leads to: scurvy due to impaired collagen synthesis
• Symptoms: Sore spongy gums, loose teeth, poor wound healing
• Toxicity: Yes. At risk for calcium oxalate stones
  **Benefits of supplementation is not established in trials.

Question 17

Vitamin A function, deficiency & symptoms.

Answer 17

• Function: Vision, promote growth, gene expression, maintain reproduction, differentiation and maintenance of epithelial cells
• Deficiency: infertility, night blindness, retardation of growth, xerophthalmia, impairment of immune system, dermatological (skin) problems
• Symptoms: dryness of eyes, bitot’s spots
• Toxicity: Yes, excess leads to hyper-vitaminosis
  **Excess vitamin A ^ incidence of #s.

Question 18

Vitamin D function, deficiency & symptoms.

Answer 18

• Function: regulation of calcium uptake in the body
• Deficiency leads to rickets in children, osteomalcaia in adults
• Symptoms: soft, pliable bones, bow shaped legs
• Toxicity: Yes
  ** Sunscreen lotions or presence of dark skin colour decreases its synthesis

Question 19

Vitamin K function, deficiency & symptoms.

Answer 19

• Function: Major role in the coagulation cascade; acts as a cofactor
• Deficiency: occurs in the new-born (haemorrhagic disease of the new-born), rare in adults
• Symptoms: Bleeding
• Toxicity: Rare
  **Produced by intestinal bacteria

Question 20

Vitamin E function, deficiency & symptoms.

Answer 20

• Function: Anti-oxidant, protects polyunsaturated fatty acids (PUFA) from peroxidation
• Deficiency: is rare but can happen
• Symptoms: red blood cell fragility leads to
  haemolytic anaemia, skeletal pain
  **benefit of supplementation not established in trials

Question 21

Hyper-Vitaminosis of vitamins.

Answer 21

1. Vitamin A:
   - Acute: vomiting, vertigo, blurry vision
   - Chronic: hyper-lipidemia, hepatotoxicity, bone and muscle pain, visual impairment
   - Teratogenic: Spontaneous loss of fetus; Fetal malformations
2. Vitamin D:
   - Hyper-calcaemia: Ca deposits in tissues, joints, lungs, brain, kidney (renal calculi)
   -Muscle weakness
3. Vitamin E:
   - Fatigue, headache, diarrhoea, blurred vision
   - Impaired blood coagulation

Question 22

What the dietary sources of minerals?

Answer 22

Question 23

Describe the absorption of macro minerals.

Answer 23

• K: Not fully understood
• Na: Na+/glucose co-transporter in the enterocyte & Electro-neutral Na+ and Cl- co-transport mechanism
• P: sodium dependent transport system enhanced by calcitriol (vitamin D)
• Cl: follows Na+ in via a tight junction
• Mg: Low level: carrier mediated active transporter and High level: Simple diffusion

Question 24

Describe the absorption of micro minerals.

Answer 24

• Cu: carrier mediated transport
• Zn: carrier mediated transport
• Se: amino acid transport systems
• Cr: not fully understood
• I: amino acid transport systems

Question 25

What is the function of macro minerals in the body?

Answer 25

Question 26

What is the function of micro minerals in the body?

Answer 26

Question 27

What are the deficiencies of macro minerals in the body?

Answer 27

Question 28

What are the deficiencies of micro minerals in the body?

Answer 28