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Amazing Vitamin K
By Jack Challem, The Nutrition Reporter™
For many years, vitamin K was pretty much the Rodney Dangerfield of vitamins. It just
didn’t get any respect. Most doctors and dietitians figured the body didn’t need much
vitamin K. After all, the official government recommendation is for a scant 90 mcg daily.
And its only biological role seemed to be in promoting blood clotting.
But recent research has shown broad and
impressive health benefits from vitamin K
The ABCs of Vitamin K1, K2, and K3
Researchers have identified three main forms of vitamin K: Vitamin K1, vitamin K2, and vitamin K3. Furthermore, there
are two principal forms of vitamin K2. Each has slight
reducing the risk of diabetes, lowering the
differences in chemical structure, but all seem to be used by
risk of some types of heart disease, and
the body. Vitamin K3 is not used in supplements for people, so the important forms are vitamins K1 and K2.
possibly preventing cancer. Vitamin K is
. Known also as phylloquinone, Vitamin K1 is
naturally found in leafy green vegetables, such as dark lettuce varieties, spinach, kale, and broccoli. It promotes normal
History and Basic Functions of Vitamin K
blood coagulation and bone strength.1 It’s available as a
Vitamin K was discovered in the early 1930s
supplement, but does not appear to be as potent as vitamin
by Henrik Dams, Ph.D., a Danish researcher
occurs in several forms, but two appear to have
the most biological activity: MK-4 (menatetrenone-4)
,” and the “K”
. Both forms seem to have advantages, but in different ways.
designation stuck. A few years later, Edward
The MK-4 form of vitamin K is naturally found in egg yolk,
delineated the chemical structure of vitamin
egg mayonnaise, chicken thighs, and dairy products. Substantial research shows that very high supplemental doses
(45 mg daily) of the MK-4 form of vitamin K2 can prevent
The MK-7 form of vitamin K is naturally found in natto, a
Most of vitamin K’s benefits derive from its
type of fermented soybean food. One ounce of natto provides
about 250 mcg of MK-7.1 The MK-7 form of vitamin K2 is
including osteocalcin, which is needed for
absorbed much better than vitamin K1. It’s unclear at this point whether MK-7 is absorbed better than MK-4, but the
strong bones. More technically, vitamin K
MK-4 form does seem to stay in the blood longer.
promotes the carboxylation
of glutamic acid.
Unfortunately, human studies have not yet directly compared the health benefits or therapeutic effects of MK-4 and MK-7,
chemists call a carboxyl group
so no one knows how large amounts of MK-4 might compare
containing one carbon, one hydrogen, and
with small amounts of MK-7. As a result, there are still many
unknowns when it comes to choosing between them. Several studies examining the benefits of MK-7 in people are
necessary step in the creation of several
currently underway in Europe, and the results should be
released over the next one to three years. In the mean time,
use your best judgment as a consumer to purchase the type of vitamin K that’s best for you.
Health Benefits of Vitamin K
Rather than being pure calcium, bone actually consists of a matrix of
calcium, phosphorus, magnesium, and protein. Production of one of the key proteins of
the matrix, osteocalcin, depends on vitamin K. Indeed, numerous studies have shown that low intake of vitamin K interferes with normal bone development and increases the risk of broken bones and osteoporosis. In recent years, both Dutch and Japanese researchers have used large amounts of vitamin K2 daily to treat and reverse osteoporosis in women.1 2 Nearly all of these studies used 45 mg (not mcg) daily of the MK-4 form of vitamin K. (See sidebar explaining MK-4 and other forms of vitamin K.) In one of the studies, Dutch researchers asked 325 postmenopausal women to take either 45 mg of vitamin K2 or placebos daily for three years. Bone density improved among women taking vitamin K2 but decreased among those taking placebos. An analysis of seven studies, published in the Archives of Internal Medicine
, found that high-dose vitamin K2 supplements consistently reduced bone fractures in women by more than 60 percent.3 Vitamin K also reduces bone loss caused by cortisone, blood-thinning drugs, menopause, diabetes, and other health issues. In a number of studies, the bone-building benefits of vitamin K were enhanced with the addition of vitamin D supplements.4 5
Increasing research suggests that vitamin K is an important nutrient for
cardiovascular health—apart from its role in blood clotting. Calcium deposits in the walls
of blood vessels can lead to “arterial calcification,” which contributes to hardening of the
arteries. The body needs vitamin K to make “matrix Gla protein,” or MGP, and animal
studies suggest that MGP helps direct calcium to bone instead of to arteries.
In one animal study, researchers found that both vitamin K1 and K2 reduced arterial
calcification by about 50 percent.6 Some physicians, such as cardiologist Stephen Sinatra,
M.D., recommend 150 mcg of the MK-7 form of vitamin K to prevent or reverse arterial
calcification. Vitamin K might also protect against varicose veins, based on a study that
found low MGP (and thus low vitamin K) activity was related to the formation of
The newest frontier for vitamin K may be in preventing or reversing type 2
diabetes. In August 2007, researchers from Columbia University in New York City
reported their discovery that the bone protein osteocalcin also functions as a hormone.
Osteocalcin regulates the number of insulin-producing cells in the pancreas, the secretion
of insulin, sensitivity to insulin, and the size of fat cells. 8 Of course, vitamin K is needed
to make osteocalcin.
Other research also supports the role of vitamin K, through osteocalcin, in maintaining
normal blood sugar levels. Studies of young men in Japan found that low vitamin K
levels were associated with poor insulin function, one of the signs of prediabetes.
Vitamin K2 supplements improved insulin function in response to a glucose-tolerance
A further link between glucose tolerance and vitamin K was identified earlier this year by
researchers at Tufts University in Boston. The researchers investigated the relationship
between vitamin K1 intake and glucose tolerance in 2,719 men and women. Higher
intake of vitamin K1 was associated with better glucose tolerance and insulin sensitivity
after glucose-tolerance tests.10
Some research suggests that vitamin K may help reduce the risk of cancer. An
eight-year study of eating habits found that men who consumed the most vitamin K2
from food had a 63 percent lower risk of developing prostate cancer. Vitamin K1 did not
provide similar protection.
The most dramatic study found that vitamin K2 significantly reduced the risk of
developing liver cancer. Japanese researchers treated 21 women with viral liver cirrhosis,
giving them 45 mg of vitamin K2 daily for eight years. Vitamin K had two significant
benefits. First, it reduced bone loss in the women, compared with a group of 19 women
who did not take vitamin K supplements. Second, only two of the 21 women receiving
vitamin K developed liver cancer. In contrast, almost half of the women not taking
vitamin K supplements developed liver cancer.11 Interactions Between Coumadin and Vitamin K
Doctors frequently prescribe Coumadin and other blood-thinning drugs to people who
have had a heart attack or stroke or have had an artificial heart valve inserted. More than
2 million people in the United States currently take Coumadin, and more than 300,000
new prescriptions are written for the drug each year, according to a pharmaceutical
industry report. Coumadin and related anti-coagulant drugs interfere with vitamin K to
reduce the risk of blood clots. By doing so, however, Coumadin reduces carboxylation of
osteocalcin and MGP.
Because of how Coumadin affects vitamin K and osteocalcin, the drug increases the risk
of bone fractures.12 13 It also increases calcification of the arteries and could potentially
increase the risk of diabetes. Moreover, physicians typically ask patients taking
Coumadin to minimize their intake of vitamin K-containing foods and to avoid vitamin K
Is there a compromise? In a recent study, published in the Journal of Thrombosis and
, researchers gave vitamin K1 supplements (100 mcg daily) to patients and
also increased their Coumadin dosage. They found that vitamin K levels were actually
more stable and predictable with the supplements, so the drug dose could also remain
This is very important:
If you take Coumadin, ask your physician if he can prescribe an anti-coagulant
that does not interfere with vitamin K activity. If he cannot switch you to another anti-coagulant drug
(that does not target vitamin K), ask him if you can safely take a low-dose (100 mcg) vitamin K
supplement. If you are taking anti-coagulants, do not
take vitamin K without your doctor’s approval.
So, How Much Vitamin K Should You Take?
You can maintain optimal intake of vitamin K through diet or supplements—or both.
Many different types of vegetables are rich sources of vitamin K1, including kale,
collards, spinach, Brussels sprouts, broccoli, scallions, asparagus, dark green lettuce,
endive, and sauerkraut.15 Cheese is a good source of the MK-4 form of vitamin K.
Fermented soybeans, particularly natto, are rich in the MK-7 form of vitamin K. (See side
bar explaining the different forms of vitamin K.)
If you opt for supplements, decide on whether your objective is general health
maintenance or part of a more aggressive prevention or self-care regimen. Large amounts
of vitamin K1—about 1,000 mcg (1 milligram) daily—do seem to reduce the risk of
osteoporosis. But Vitamin K2, at daily doses of 5 mg (5,000 mcg), may do a better job at
preventing osteoporosis and fracture.
Meanwhile, taking 45 mg daily of the MK-4 form of vitamin K2 is very effective in
reversing osteoporosis. Note:
Be sure to consult a physician if you are considering taking
such high amounts of MK-4. Finally, although human studies on the MK-7 form of
vitamin K2 are currently limited, modest amounts—150 mcg daily—may also help
strengthen bones and prevent arterial calcification.
1 Knapen MH, Schurgers LJ, Vermeer C. Vitamin K(2) supplementation improves hip bone geometry and bone strength indices in postmenopausal women. Osteoporosis International
, 2007; 18:963-972. 2 Yasui T, Miyatani Y, Tomita J, et al. Effect of vitamin K2 treatment on carboxylation of osteocalcin in earlypostmenopausal women. Gynecological Endocrinology
, 2006;22:455-9. 3 Cockayne S, Adamson J, Lanham-New S, et al. Vitamin K and the prevention of fractures: systematic review and meta-analysis of randomized controlled trials. Archives of Internal Medicine
, 2006;166:1256-1261. 4 Yasui T, Miyatani Y, Tomita J, et al. Effect of vitamin K2 treatment on carboxylation of osteocalcin in earlypostmenopausal women. Gynecological Endocrinology
, 2006;22:455-9. 5 Braam LA, Knapen MH, Geusens P, et al. Vitamin K1 supplementation retards bone loss in postmenopausal women between 50 and 60 years of age. Calcif Tissue Int, 2003;73:21-26. 6 Schurgers LJ, Spronk HMH, Soute BAM, et al. Regression of warfarin-induced medial elastocalcinosis by high intake of vitamin K in rats. Blood
, 2007;109:2823-2831. 7 Cario-Toumaniantz C, Boularan C, Schurgers LJ, et al. Identification of differentially expressed genes in human varicose veins: involvement of matrix gla protein in extracellular matrix remodeling. Journal of Vascular Research, 2007;44:444-459. 8 Lee NK, Sowa H, Hinoi E, et al. Endocrine regulation of energy metabolism by the skeleton. Cell
, 2007;130:456-469. 9 Kassi E, Papavassiliou AG. A possible role of osteocalcin in the regulation of insulin secretion: human in vivo evidence? Journal of Endocrinology
, July 21, 2008; epub ahead of print. 10 Yoshida M, Yoshida M, Booth SL, et al. Phylloquinone intake, insulin sensitivity, and glycemic status in men and women. American Journal of Clinical Nutrition
, 2008; 88:210-215 11 Habu D, Shiomi S, Tamori A, et al. Role of vitamin K2 in the development of hepatocellular carcinoma in women with viral cirrhosis of the liver. JAMA
, 2004;292:358-361. 12 Rejnmark R, Vestergaard P, Mosekilde L. Fracture risk in users of oral anticoagulants: a national case-control study. International Journal of Cardiology
, 2007;118:338-344. 13 Gage BF, Birman-Deych E, Radford MJ, et al. Risk of osteoporotic fracture in elderly patients taking warfarin: results from the National Registry of Atrial Fibrillation 2. Archives of Internal Medicine, 2006;166(2):241-6. 14 Rombouts, EK; Rosendaal, FR; Van der Meer, FJM. Daily vitamin K supplementation improves anticoagulant stability. Journal of Thrombosis and Haemostasis
, 2007; 5:2043-2048. 15 http://www.dietitian.com/vitamink.html
IFSCC conference Barcellona 2008 Novel retinol-like actives from parrots feathers / M. Rigano, M. Picaro, E. Pini, R. Stradi, M. Meloni, A. Bertelli, A. Benedusi, G. Giuliani. - In: IFSCC magazine. - ISSN 1520-4561. - 11:4(2008). - p. 323-330 Giuliani S.p.A. - Via Palagi, 2 - 20129 Milano Tel. +39 02.20541 - Fax +39 02.29401341 - www.giulianipharma.com 14th Meeting of the European So
Diplomate, American Board of Oral & Maxillofacial Surgery GENERAL POSTOPERATIVE INSTRUCTIONS We are committed to providing the same quality of care following procedures that began during your initial visit. To that end, please refer to some general postoperative guidelines below, and by all means, CALL at any hour of any day to report any continuing problem. 1. FLUID AND FOOD INTAKE IS