How it works
Bacteria make vitamin K in the colon, from where it is absorbed back across the colon wall into the bloodstream to become one of several of blood clotting factors. It is also needed for the production of proteins that help to keep teeth and bones healthy and strong.
Absorption helpers Probiotic foods, such as yoghurts containing "live" bacteria, can help promote the growth of good bacteria in the colon and enhance vitamin K production in the body.
Absorption inhibitors Cholestyramine, a drug taken for the treatment of raised cholesterol levels, and aspirin, taken for pain relief, can both reduce the absorption of Vitamin K in the body. Antibiotics, taken to kill disease-causing bacteria, actually kill all bacteria, whether good or bad. They also kill vitamin K bacteria by synthesizing them.
Taking vitamin K supplements
No adult RDA has been set because humans make adequate vitamin K in the colon. However, vitamin K is present in the diet, supplying 60-80mcg per day. This is equivalent to a serving of Brussels sprouts.
Precautions Mega-doses of vitamin K should be avoided as they can build up, causing the breakdown of red blood cells. While blood-thinning drugs such as Dicumarol can inhibit the absorption of natural vitamin K, synthetic K in supplement form can counteract its effectiveness and is therefore best avoided. Large doses of vitamin K may lead to liver damage and problems such as jaundice in infants and children.
Why take this supplement?
The drug warfarin, prescribed to regulate blood clotting, stops bacterial production of vitamin K in the colon and could increase dietary requirements if taken in the long term. All newborn babies are given vitamin K either as supplements or in form of an injection in order to improve their blood clotting abilities. People who suffer from malabsorption problems, such as the newly diagnosed Coeliac disease, colitis, and Crohn's disease, may also benefit from vitamin K supplements as could women who experience excessive menstrual bleeding, and people who have undergone surgery. Signs that you may need a vitamin K supplement include:
RDA for adults
No RDA has been established
Top sources of vitamin K (no figures available)
© 2002-12 Pakvisit Solutions. All rights reserved