Micronutrients

Question 1

What three metal ions are essential micronutrients?

Answer 1

Copper, zinc, iron

Question 2

What are micro and macronutrients?

Answer 2

Macronutrients: energy yielding e.g. fat, carb

Micronutrients: include vitamins and minerals

Question 3

What are vitamins?

Answer 3

Small organic molecules that can’t be made by body, so obtained from diet

Question 4

How can interactions between trace metal affect homeostasis?

Answer 4

Can affect each others oxidation state, leading to increased uptake or release.

For example iron is uptaken better in ferrous Fe3+ state. Cu changes Fe to 3+ state

Question 5

What is the recommended dietary intake of Zinc?

Answer 5

Dietary intake: 8mg for women, 11mg for men

Question 6

How is zinc distributed in the body?

Answer 6

Distribution: 1-2g in body, any in plasma mainly bound to albumin.

Question 7

What is the role of zinc?

Answer 7

Role: DNA/RNA polymerases, alkaline phosphate, carboxypeptidase, transcription factors

Question 8

What is the recommended dietary intake of copper?

Answer 8

Intake: 900 microgram per day

Question 9

How is copper distributed in the body?

Answer 9

100mg in body, mainly in skin, muscle , bone marrow.

Question 10

What is the role of copper?

Answer 10

Caeruloplasmin involve in Fe homeostasis

Connective tissue synthesis

Cytochrome oxidase

Superoxide dismutase

Question 11

What is the recommended dietary intake of iron?

Answer 11

Males: 8mg
Females: 18mg
Pregnant females: 27mg

Question 12

How is iron distributed in the body?

Answer 12

Hemoglobin: heme proteins and accounts for greater than 65% of body iron.

Non-haem iron enters circulation across small intestine

25% stored as ferritin

Question 13

What chelates to iron inside the cell?

Answer 13

Ferritin

Question 14

How much stored iron to males and females have?

Answer 14

Males 1000mg

Females 300mg

Question 15

What is the role of iron?

Answer 15

Haemoglobin and myoglobin function. Essential for transferring oxygen from the lungs to the tissues. Myoglobin, in muscle cells, stores, and releases oxygen.

Component of certain proteins, essential for respiration and energy metabolism, and as a component of enzymes involved in the synthesis of collagen and some neurotransmitters.

Iron is needed for proper immune function.

Question 16

How much ingested iron is absrorbed?

Answer 16

5% to 35% depending on circumstances and type of iron.

Question 17

What carries iron in Fe3+ state between absorption storage and utilisation sites?

Answer 17

Transferrin

Question 18

What is the role of hepcidin?

Answer 18

Regulates iron balance, binds to the transferrin receptor (FNP1)

Question 19

What happens when levels of hepcidin increase?

Answer 19

Negatively regulates iron balance, reduces iron absorption

Iron in macrophages is increased and GI iron is decreased.

Question 20

What happens when iron levels are low (regulatory)?

Answer 20

Hepcidin levels are low, iron released from stores and more absorbed

Question 21

Compare water soluble and fat soluble vitamins?

Answer 21

Water soluble: usually coenzyme precursors

Fat soluble: only absorbed in presence of dietary fat

Question 22

What is role of niacin (vitB3)?

Answer 22

Precursor of NAD+ and NADP (cofactor for dehydrogenase reactions i.e in glycolysis and TCA cycle)

Question 23

What is role of riboflavin

(vitB2)?

Answer 23

Precursor of FAD/FMN cofactor for dehydrogenase reactions e.g. FAD part of succinate dehydrogenase, FMN part of complex I

Question 24

What is role of pyridoxine

(vitB6)?

Answer 24

Precursor of pyridoxal phosphate - cofactor for transamination and decarboxylation

Question 25

What is thiamine | (vitB1)?

Answer 25

Precursor of thiamine pyrophosphate, cofactor for PDH (catalyses pyruvate to acetyl CoA) and alpha ketoglutarate dehydrogenase

Question 26

What are roles of folic acid (vitB9)?

Answer 26

Involved in purine and pyrimidine biosynthesis

Question 27

What is symptom of folic acid deficiency?

Answer 27

Neural tube defect, megaloblastic anaemia

Question 28

What is role of vitB12?

Answer 28

Cofactor in DNA synthesis, FA and AA metabolism important for nervous system functioning

Question 29

How is vitamin B12 absorbed?

Answer 29

Absorbed using intrinsic factor from parietal cells

Question 30

What is the deficiency of niacin?

Answer 30

Pellagra Characterized by diarrhea, sun-sensitive dermatitis, dementia, hyperpigmentation, amnesia, delirium, and eventually death, if left untreated.

Question 31

What is the deficiency of riboflavin?

Answer 31

Riboflavin deficiency (similar to pellagra) Painful red tongue with sore throat, chapped and fissured lips. Oily scaly skin rashes. The eyes can become itchy, watery, bloodshot and sensitive to light. Anemia with normal cell size and normal hemoglobin content (i.e. normochromic normocytic anemia). Congenital heart defects and limb deformities.

Question 32

What is the deficiency of pyroxidine?

Answer 32

B6 deficiency Characterized by weakness, irritability and nervousness, insomnia, and difficulty in walking. Cheilosis (cracks at the corners of the mouth) that is not responsive to biotin or riboflavin Infants consuming B6 -deficient milk formula have convulsive seizures

Question 33

What is the deficiency of thiamine

Answer 33

Beri Beri It is characterized by ophthalmoplegia, sixth nerve palsy, nystagmus, ptosis, ataxia, confusion, and coma, which may terminate in death. Oftentimes, the confusional state persists after treatment of the acute thiamin deficiency. This is known as Korsakoff’s psychosis.

Question 34

Where is beri-beri most seen?

Answer 34

In alcoholics who consume alcohol in preference to food and thus have a minimal intake of thiamin.

Question 35

A cofactor for enzyme-catalysed carboxylation reactions

Answer 35

Biotin (B7)

Question 36

The consequences of severe iron deficiency

Answer 36

Hypochromic, microcytic anaemia

Question 37

What is a sensitive indicator of depletion of body iron stores?

Answer 37

Serum ferritin

Question 38

In people consuming a corn-based diet that is marginally adequate, what problem would they develop?

Answer 38

Pellagra

Question 39

What amino acid has a positive effect on niacin deficiency?

Answer 39

Tryptophan

Question 40

The absorption of Vitamin B12 from the gastrointestinal tract is dependent on?

Answer 40

Transcobalamin Intrinsic factor