Vitamin K

Question 1

What are the two forms of Vitamin K?

Answer 1

Phylloquinones (K1)
– Plants: green leafy vegetables,
broccoli, peas and green beans
– Most biologically active form

Menaquinones (K2)
– From bacterial synthesis
– Gut bacteria produces 10% of
daily requirement, but absorption is
not optimal in colon, suggesting
that contribution is mininal
– Present in fermented foods
(bacterial fermentation)
– Synthetic compound menadione
can be converted to menaquinone
in tissues

Question 2

How is Vitamin K absorbed?

Answer 2

• Best absorbed in the presence of fat
• 80% absorbed in small intestine via micelles
• menaquinones produced by gut bacteria are passively diffused into the colon

Question 3

How is Vitamin K transported?

Answer 3

• Via chylomicrons in the lymphatic system to the liver

- From the liver its transported via lipoproteins to tissue

Question 4

What is the function of Vitamin K?

Answer 4

Main function is as a cofactor of the carboxylase enzyme
- carboxylase is used in the synthesis of clotting factors (converts pre-prothrombin to prothrombin in the liver)

Also needed for healthy bone function

Question 5

What are the causes of Vitamin K deficiency?

Answer 5

• newborns are given Vit K injection
• long term antibiotic use
• high dose vit. A interferes
• high dose vit. E

Question 6

What are good sources of Vitamin K?

Answer 6

• Kale
• Spinach
• Brussel Sprouts
• Broccoli