MCP Lecture 5

Question 1

What type of nutrient are vitamins and minerals referred to as? What does a deficiency in a vitamin cause?

Answer 1

• micronutrients

- loss of enzyme activity (bc they act as coenzymes)

Question 2

What is DRI? RDA?

Answer 2

DRI: dietary reference intakes
RDA: recommended daily allowance (which varies for different populations)

Question 3

How do vitamin deficiencies arise?

Answer 3

1. poor nutrition
2. increased demand
3. problem with absorption
4. interactions with medications

Question 4

What are the classifications of vitamins, and which vitamins fall in the classifications?

Answer 4

lipid soluble: A, D, K, E

water soluble: B, C

Question 5

Which vitamins are less likely to be toxic and why?

Answer 5

B and C because they are water soluble are excreted efficiently (lipid soluble can be stored efficiently so deficiencies don’t arise as easily)

Question 6

Vitamin A: function, deficiency, susceptible groups

Answer 6

Function: visual cycle (rhodopsin and cone cofactor), synthesis of certain glycoprotein and mucopolysaccharides, retinoic acid (hormone), antioxidant

Deficiency: night blindness, xerophthaliam, follicular hyperkeratosis, anemia, poor growth (children)

Susceptible groups: poor, malnourished, premies

Question 7

Sources of Vitamin A

Answer 7

retinol (vit A): egg yolks, liver, butter, whole milk (animal sources)
carotenoids (precursor vit A): plant sources (pro vitamins)

Question 8

When is Vitamin A toxic? What are the symptoms?

Answer 8

When it accumulates in the liver - nausea, diarrhea, bone pain, scaly skin, orange cast to skin

Question 9

What is follicular hyperkeratosis?

Answer 9

vitamin A deficiency - skin in permanent goosebumps

Question 10

What is xerophthalmia?

Answer 10

vitamin A deficiency - overgrowth of cornea (extreme dryness and thickening of the conjunctiva)

Question 11

Vitamin D: function, deficiency, susceptible groups

Answer 11

function: maintaining bone, calcium homeostasis, acts as hormone
deficiency: rickets, osteomalacia, increased susceptibility to breast and other cancers
susceptible: poor, elderly, alcoholics

Question 12

How is active Vitamin D synthesized?

Answer 12

skin (sunlight) - dietary sources = saltwater fish
liver (hydroxylation)
kidney (hydroxylation)

converted to D3 = calcitriol

Question 13

Vitamin K: function, deficiency, susceptible groups

Answer 13

function: localization of enzymes required for blood Klotting (helps catalyze addition of gama-carboxyglutamate to clotting enzymes)
deficiency: easy bruising, bleeding, hemorrhage
susceptible: newborn infants and long term antibiotics

Question 14

What causes deficiency in Vitamin K?

Answer 14

lack of intestinal bacteria that makes it (why its newborns and long term antibiotics) - shot now given at birth

Question 15

Vitamin E: function, deficiency, susceptible groups

Answer 15

function: ANTIOXIDANT (protect membranes, prevent oxidation of LDL)
deficiency: cardiovascular disease and neurological symptoms
susceptible: prolonged defects in absorption, genetic defects

Question 16

What are dietary sources of vitamin E?

Answer 16

OILS

Question 17

Vitamin C: function, deficiency, susceptible groups

Answer 17

function: cofactor for oxidases involved in COLLAGEN formation, synthesis of steroids, absorption of iron, antioxidant
deficiency: mild bruising and immunocompromise
severe: SCURVY (decreased wound healing, osteoporosis, hemorrhage and anemia, fatigue)
susceptible groups: pirates, people with poor diet, smokers

Question 18

What is the major function of vitamin C?

Answer 18

hydroxylation of proline and lysine - important in collagen synthesis

Question 19

What are the early and later signs of scurvy?

Answer 19

early: corkscrew hairs and pinpoint hemorrhages
later: severe periodontal disease

Question 20

What are the two subcategories of B Complex vitamins? What are the vitamins in the groups?

Answer 20

Energy releasing: B1 (thiamine), B2 (riboflavin), B3 (niacin), B5 (pantothenic acid), B6 (pyridoxine), B7 (biotin)
Hematopoietic: B9 (folate), B12 (cobalamin)

Question 21

What are common effects of deficiencies in energy-releasing B vitamins?

Answer 21

first show up in rapidly growing tissues: dermatitis, swollen red tongue (glossitis), GI (diarrhea)
also seen in nervous system bc energy demand: peripheral neuropathy (tingling of extremities), depression, confusion, lack of coordination, malaise)

Question 22

Thiamine: number, function, deficiency, susceptible groups

Answer 22

number: B1
function: cofactor for several enzymes in cellular energy metabolism, critical in nervous system
deficiency: mild - GI symptoms, depression, fatigue
moderate - wernicke korsakoff syndrome
severe - beriberi

Question 23

What is thiamine a precursor of?

Answer 23

TPP - coenzyme for critical metabolic enzymes

thiamine not stored in body - deficiency can be quick

Question 24

What is Wernicke- Korsakoff syndrome?

Answer 24

moderate/severe thiamine deficiency - seen in chronic alcoholics
-mental disturbance (like they’re drunk) - unsteady gait, uncoordinated eye movements

Question 25

What is Beriberi?

Answer 25

very severe thiamine deficiency
common in polished rice
-extreme muscle weakness, poly-neuropathy, heart failure

Question 26

Riboflavin: number, function, deficiency, susceptible groups

Answer 26

B2

function: precursor of FAD and FMN - coenzymes for redox reactions in energy metabolism
deficiency: ariboflavinosis - rash around nose, inflammation of mouth and tongue, buring and itchy eyes, light sensitivit
susceptible: alcoholics

Question 27

Niacin: number, function, deficiency, susceptible groups

Answer 27

B3
function: precursor NAD and NADP - redox reactions of energy metabolism
deficiency: pellagra
susceptible groups: people with corn or millet based diets

Question 28

What are good sources of niacin?

Answer 28

meat and other high protein foods (contain TRYPTOPHAN)

Question 29

What are niacin and riboflavin particularly important?

Answer 29

essential coenzymes for catabolism of other nutrients
niacin - NAD
riboflavin - FAD

Question 30

Biotin: number, function, deficiency, susceptible groups

Answer 30

B7

function: coenzyme for several carboxylases
deficiency: rare becasue it can be found in many foods and be synthesized by intestinal bacteria - can get by eating raw eggs

Question 31

Pantothenic acid: number, function, deficiency, susceptible groups

Answer 31

B5

function: synthesis of CoA (required for TCA cycle and metabolism of all fats and proteins)
deficiency: very rare

Question 32

Pyridoxine: number, function, deficiency, susceptible groups

Answer 32

B6

function: precursor of pyridoxyl phosphate (PLP) - required for glycogen breakdown, synthesis of GABA and heme
deficiency: irritability, nervousness, depression (GABA)
- severe: peripheral neuropathy, convulsions, decreased glucose intolerance, hyper-homocysteinemia, anemia
susceptible: patients treated with certain drugs