vitamin D

Question 1

Vitamin D differs from other nutrients in the body because?

a. It can be stored in the liver for 3 – 5 years
b. It can be produced in the body on exposure to sunlight can be produced in the skin
c. It can be produced in adequate amounts by colonic bacteria
d. It can be produced in the liver from essential amino acids

Answer 1

Vitamin D can be produced in the body on exposure to sunlight

Question 2

Which of these deficiency diseases is not associated with vitamin D?

     a. Osteoporosis  	
 b. Osteopaenia  	
 c. Osteosarcoma
 d. Osteomalacia

Answer 2

Osteosarcoma is a form of bone cancer and not associated with vitamin D. Osteoporosis, Osteopaenia & Osteomalacia are deficiency diseases associated with Vitamin D.

Question 3

Which of these major minerals is vitamin D most closely associated with?

     a. Iron  	
 b. Potassium  	
 c. Calcium  	
 d. Magnesium

Answer 3

The actions of vitamin D are closely linked with blood levels of calcium

Question 4

Vitamin D is called

Answer 4

Calcitriol

Question 5

Why is vitamin D a hormone

Answer 5

Vitamin D is produced in the body from cholesterol, it is transported via the bloodstream and has the ability to directly interact with receptors

Question 6

Vitamin D increases blood calcium concentration by:

Answer 6

• Increasing intestinal absorption of dietary calcium
• Increasing reabsorption of calcium in the kidneys
• Mobilization of stem cells in bone marrow to become osteoclasts

Question 7

How does the release of parathyroid hormone (PTH) stimulates the kidneys to activate more vitamin D ?

Answer 7

Two step process through the liver and the kidneys, resulting in the active form of vitamin D, calcitriol

Question 8

Where can vitamin D be found in our diets?

Answer 8

Low vitamin D is foods. In Australia best dietary sources of vitamin D are those fortified margarine, milk, butter. Also veal, beef, egg yolks, liver, fatty fish (salmon, sardines, herring).

Question 9

What could a deficiency in vitamin D lead to?

Answer 9

Rickets (bones unable to calcify properly so growth retardation - bowed legs).
Osteomalacia - soft, flexible, brittle, deformed bones.
Osteoporosis - loss of calcium in bones

Question 10

Vitamin D toxicity

Answer 10

Most likely of vitamins to cause problems when taken in excess as it raise blood calcium levels, which can soften bones, and cause calcification of soft tissues (kidneys, vessels, heart, lungs, around joints)