Date: 20 Aug 1994 07:43:34 -0700
From: taltar@vertigo.helix.net (Ted Altar)
Subject: Vit K & Vegetarians
Newsgroups: rec.food.veg
Organization: Helix Internet
Lines: 38

VITAMIN K AND VEGETARIANS
                    Ted Altar

Let us do forget it since the intestinal synthesized
vitamin K is normally not at all that important or essential

Vitamin K is provided primarily by plant foods (especially
high are cruciferous and leafy vegetables).  Therefore, most
of the vitamin K ingested is the naturally occurring form,
phylloquinone, which is absorbed from the small intestine.

The menaquinones (the form of K we find in meat) are
synthesized by either external or internal bacteria and
absorbed by the distal ileum and colon.  While it is
believed some menaquinones synthesized by bacteria in the
lower digestive tract can be absorbed to SOME extent by
humans, this ability is also thought to be quite variable
between people.  (see J. W. Suttie, "Vitamin K" in Diplock
et al. FAT SOLUBLE VITAMINS, 1985, P. 225-331.),

Also, it was assumed that intestinal synthesis could vary
from 0% to as much as 50% of one's daily requirement.  But
recent studies (see Suttie, 1985) in which subjects were
made K deficient (via elimination of foods high in K) have
shown that bacterial synthesis is simply inadequate to meet
requirements even when exogenous intake was still 50 ug/day
(a 79 kg adult male needs about ug/day and a 63 kg adult
female needs 65 ug/day).

In any case, a standard diet contains at least some 300 to
500 ug vitamin K per day, several fold the amount we
actually need.  [see R. Olsen, "Vitamin K" in M. Shils et
al., MODERN NUTRITION IN HEALTH AND DISEASE, 1988, P. 328-
39.  In certain situations, however, the intestinal
production of menaquinones would probably be important, as
for example in infants dependent on only milk (which has a
low content of K) or in people with an intestinal bypass.