Whole Food Nutrition
Vitamin K
Vitamin K-deficiency may occur by disturbed intestinal uptake
(such as would occur in a bile duct obstruction), by therapeutic
or accidental intake of vitamin K-antagonists or, very rarely,
by nutritional vitamin K-deficiency. As a result of the acquired
vitamin K-deficiency, Gla-residues are not or incompletely
formed and hence the Gla-proteins are inactive. Lack of control
of the three processes mentioned above may lead to the
following: risk of massive, uncontrolled internal bleeding,
cartilage calcification and severe malformation of developing
bone, or deposition of insoluble calcium salts in the arterial
vessel walls.
Vitamin K is a fat-soluble vitamin needed to produce
blood-clotting factors, such as prothrombin, that prevent
unchecked bleeding or hemorrhaging throughout the body. It also
helps strengthen the body’s bones and capillaries.
Vitamin K comes in three forms: phylloquinone, menaquinone, and
menadione. Phylloquinone, or K1, is found in green leafy
vegetables, and helps bones absorb and store calcium. One recent
study showed that increased amounts of vitamin K in the diet
might lower the risk of hip fracture; over time, a shortage of
vitamin K could lead to osteoporosis. Menaquinone, or K2, is
manufactured in the body by naturally occurring intestinal
bacteria. People that regularly take antibiotics or have a
medical condition that upsets the balance of bacteria in the
intestine are at risk of developing a vitamin K deficiency.
Menadione, or vitamin K3, is an artificial form of vitamin K,
which is water-soluble and more easily absorbed by people who
have problems with fat absorption.
Vitamin K is now being studied for its effectiveness as a cancer
treatment. Initial laboratory studies showed that vitamin K
might be as effective as some prescription drugs at slowing the
growth of cancerous tumors. Vitamin K is also be studied to see
if it increases the effectiveness of standard anticancer drugs.
The Recommended Dietary Allowance (RDA) for vitamin K is based
on an individual’s weight—about 1 microgram for every 2 pounds.
The RDA for the average male is about 80 micrograms, and the RDA
for the average female is about 65 micrograms. Greens, such as
kale, spinach, broccoli, lettuce, and cabbage are good choices;
cauliflower, soybeans, and strawberries are also high in vitamin
K. High-protein foods, such as meats and eggs, have some vitamin
K, but vegetables are far superior sources of this nutrient.
Vitamin K is also in green tea—this is the only type of tea that
contains vitamin K. You can also improve the your body’s
absorption of vitamin K by eating yogurt, which supports the
bacteria in your intestine.
Vitamin K deficiency is rare—most people get enough from food
and from their own intestinal bacteria. One notable sign of
vitamin K deficiency is abnormal bleeding and bruising as a
result of minor injuries. Nosebleeds, blood in your urine, and
intestinal bleeding are also signs of vitamin K deficiency. If
you suspect a vitamin K deficiency, you should see your doctor
immediately—left unchecked, vitamin K deficiency could result in
hemorrhaging.
Some people have a higher risk of developing vitamin K
deficiency. Newborns don’t have a supply of vitamin K in their
system, so they are usually given an injection of vitamin K at
birth, to avoid hemorrhage. People that don’t eat enough green
vegetables, regularly take oral antibiotics or
cholesterol-lowering drugs, or have a medical condition that
upsets the balance of bacteria in the intestine or interferes
with fat absorption, such as Crohn’s disease, colitis, or liver
disease, should ask their doctor about supplementation.
Some multivitamin supplements don’t contain vitamin K. Taking more than 100 micrograms of vitamin K each day
could a day cause liver damage and people taking blood-thinning
drugs should avoid this supplement altogether—it decreases the
drugs’ effectiveness.
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