Final - Magnesium

Question 1

What are the sources of magnesium?

Answer 1

chocolate, nuts, legumes, whole-grains, seafood, green leafy vegetables (present in cholrophyll, Mg 2+ containing pigment)

Question 2

What is an Mg 2+ containing pigment?

Answer 2

chloryphyll

Question 3

What reduces the content of magnesium in food?

Answer 3

food processing/grain refining

Question 4

What are the supplemental forms of Mg?

Answer 4

Magnesium sulfate (epsom salt)
Magnesium oxide
Magnesium chloride
magnesium lactate

Question 5

How is the homeostasis of Mg maintained?

Answer 5

gut absorption
renal excretion (reabsorption) bone resorption

Question 6

What impairs the absorption of magnesium?

Answer 6

phytates, fiber
Ca, P (competition)
fatty acids (soaps)

Question 7

What enhances the absorption of magnesium?

Answer 7

carbohydrates (fructose and lactose), protein, vitamin D

Question 8

Resorption of magnesium

Answer 8

1/3 of the Mg in the bone is loosely bound to the surface of bone crystals

• exchangable pool with plasma
• dependent upon calcium metabolism

Question 9

What are the functions of magnesium?

Answer 9

• Magnesium is bound to phospholipids in cell membranes
• > 300 enzymes require magnesium as a cofactor
• Has regulatory roles

Question 10

Which enzymes require magnesium as a cofactor?

Answer 10

Enzymes that require ATP and ADP

• hexokinase and phsophofructokinase (glycolysis)
• Glucokinase
• Transketolase
• Creatinine kinase
• Oxidative decarboxylation (krebs cycle)
• Acyl coA synthase (b-oxidation initiation)
• Amino acid activation

Question 11

What are the regulatory roles of magnesium?

Answer 11

transcription
protein synthesis
cyclic AMP formation 
cardiac and smooth muscle contraction 
insulin action

Question 12

What are the symptoms of Magenisium deficiency?

Answer 12

Rare in healthy humans

nausea, vomiting, anorexia; tetany & convulsions, hypo Ca, hypoNa, hypoK and abnormal neuromuscular and neurological function

Question 13

What other pathological conditions is Mg deficiency associated with?

Answer 13

CVD, renal disease, and diabetes

• Vomiting & diarrhea
• Severe PEM
• Alcoholics (increased Mg excretion)

Question 14

How is Mg related to Ca?

Answer 14

Mg is required for Ca homeostasis

• Mg increases PTH secretion (high Mg inhibits release)
• PTH increases Ca (bone reabsorption; kidney reabsorption; intestine absorption & converts Vitamin D to its active form

Mg interferes with Ca metabolism

• inhibits intracellular release from SR
• inhibits blood clotting
• competes for binding sites on troponin C/inhibits contraction
• Inhibits phosphorus absorption , increased phosphorus reduces Ca absorption