Vitamin K is a nutrient originally identified as an essential factor for blood clotting. Recently, vitamin K has emerged as a potential protector against osteoporosis and hepatocarcinoma (liver cancer). Natural vitamin K from plants is called Vitamin K1, phylloquinone, or phytonadione. Vitamin K2, or menaquinone, is derived from bacteria in the gut. The results of recent studies have suggested that simultaneous use of menaquinone and vitamin D may substantially reduce bone loss. Vitamin K3, or menadione, is a synthetic derivative. The three vitamin Ks function similarly in helping with blood clotting, but for other important functions vitamin K1 appears to be substantially superior. Vitamin K1 plays an important role in bone health as it is responsible for converting the bone protein ostecalcin from its inactive to its active form. Osteocalcin is the major protein incorporated in bone matrix during bone formation. Vitamin K is necessary for allowing the osteocalcin molecule to join with calcium and hold its place within the bone.
Poor intake of vitamin K is common. Insufficient vitamin K can result in abnormal cartilage and bone mineralization. A deficiency of vitamin K have been found in patients with fractures due to osteoporosis. The lower the level of vitamin K, the greater the severity of the fracture. Vitamin K is found in green leafy vegetables and may be one of the protective factors of a vegetarian diet against osteoporosis.
Rich Sources of Vitamin K
Rich sources of vitamin K include dark green leafy vegetables, green tea, spinach, broccoli, lettuce, and cabbage. Good sources are asparagus, oats, whole wheat, and fresh green peas. The Recommended Daily Intake (RDI) for vitamin K is 1 microgram per 2.2 pounds of body weight. The daily dietary vitamin K intake is usually estimated to be in the range 124-375 microg/day, but recent data suggest that the requirement in relation to bone health might be higher.
It is known that vitamin K is not only distributed in the liver and bones but also abundantly distributed in the brain and kidney. Recent studies show that vitamin K deficiency reduces testosterone production in the testis. Supplemental vitamin K is required for normal hemostasis (stoppage of bleeding) in infancy. Infants born outside the hospital may not receive prophylactic vitamin K. They may suffer from bleeding into various tissues and are likely to present to the emergency department.
Arterial Calcification and Osteoporosis
The "calcification paradox" occurs frequently in postmenopausal women. Since the amount of vitamin K needed for converting the bone protein ostecalcin into its active form is significantly higher than what is provided through diet alone, women should take vitamin K and D supplements. Several studies have found that a supplement containing vitamins K1 and D has a beneficial effect on the elastic properties of the arterial vessel wall in postmenopausal women.
Regression of hepatocellular carcinoma (HCC, liver cancer) during vitamin K administration has been reported in an 85-year-old man with HCV infection and diabetes mellitus who was diagnosed as having hepatocellular carcinoma about 5 inches in diameter). Three months after starting vitamin K, the liver tumor was markedly regressed. In another study, patients with recurrent hepatocellular carcinoma were treated with menatetrenone, a vitamin K2 analog. The survival rates for the patients who received menatetrenone were 100% at 12 months. The study findings suggested that menatetrenone may have a suppressive effect on recurrence of HCC and a beneficial effect on survival.1
Top 10 Foods Rich in Vitamin K
Basil, dried; Sage, ground; Thyme, dried; Parsley, raw; Coriander leaf, dried; Kale, frozen, cooked; Swiss Chard; Marjoram, dried; Celery flakes, dried; Spinach, cooked, boiled.
Effects of Excess Intake of Vitamin K
If vitamin K consumption from foods or supplements is increased dramatically, it can weaken the effect of warfarin, the anticoagulant drug that blocks the
enzyme that activates vitamin K. Deactivation of these enzymes thereby prevents
the synthesis of blood-clotting factors. People using warfarin should avoid
excessive intake of green leafy vegetables which are rich in vitamin K and
consume similar amounts of vitamin K daily to keep warfarin activity