by Jack Challem
Long recognized for its role in blood clotting, conventional physicians view vitamin K with caution. That's because excess vitamin K interferes with the activity of Coumadin and related anti-coagulant drugs, which are often prescribed after a heart attack, stroke or heart surgery.
But research shows that vitamin K has other roles in health, such as maintaining bone mass and reversing osteoporosis. Recent research also demonstrates that vitamin K may indirectly influence glucose tolerance, a finding that could shift dietary management of diabetes. But, there's more than one type of vitamin K—and the varieties may actually have different roles in the body.
Several types of vitamin K
Vitamin K1 refers to a single compound, phylloquinone, found in leafy green vegetables. In contrast, vitamin K2 refers to a family of related nutrients known as menaquinones, which are found in meats, dairy, eggs and other foods. One of the most researched members of the K2 family is MK-4.
Most recent research has focused on MK-4. • Bone health. The body needs Vitamin K to synthesize osteocalcin, a protein secreted by bone cells. In turn, osteocalcin helps regulates calcium activity in bone.
In separate studies, Dutch and Japanese researchers used relatively large amounts of vitamin K2—45 milligrams daily—to treat and reverse osteoporosis in women (Osteoporosis International, 2007; Gynecological Endocrinology, 2006). A meta-analysis of seven studies, published in the 2006 Archives of Internal Medicine, found that high-dose vitamin K2 supplements reduced bone fractures in women by more than 60 percent.
How to use vitamin K
Although some research shows benefits in bone health from vitamin K1 supplements, vitamin K2 seems to be far more biologically active and effective in preventing and reversing osteoporosis and other health problems. Consider 5 milligrams daily of vitamin K2 a preventive dose and 45 milligrams daily a therapeutic dose.
When advising customers, remember two more points about vitamin K2 and anti-coagulant drugs such as Coumadin:
Natural Foods Merchandiser volume XXVIII/number 9/p. 38