Vitamin K cannot
be made by our bodies, but not all vitamin K needs to be obtained from
food, because bacteria in our gut can make it (as also is the case with
biotin). Probably, about half our vitamin K needs can be made by gut
Vitamin K is involved
in the formation of special liver proteins, known as coagulation factors,
which, when circulating in our blood,
reduce the risk of haemorrhage or bleeding. Conversely, if you are susceptible
to blood clotting, medication (usually warfarin) that interferes with
the formation of these vitamin-K-dependent factors may be prescribed
for you. If you are taking warfarin, you need to be particularly careful
not to alter your intake of vitamin-K containing foods without close
can sometimes suffer vitamin K deficiency, as can people who do not
absorb fat, since vitamin K is fat soluble. Those with liver disease
may require more vitamin K.
Some proteins in
bone and kidney are vitamin K dependent, so that vitamin K may have
functions in these tissues as well.
and adequate daily intake of vitamin K (U.S.A.):
Another way of expressing vitamin K requirement is to say that about
2 micrograms per kilogram of body weight per day are needed, but
half of this could come from gut bacteria.
level of intake:
milligrams of natural vitamin K can be ingested by healthy adults
without adverse effects. Synthetic forms of vitamin K can be more
of a problem in high dosages.
51: THE VITAMIN K CONTENT OF SOME FOODS
(micrograms per 100 grams of food)
Milk, cow's, skim
less than 5