Thursday, May 3, 2007

Vitamin K It's role in bone health

Vitamin K facilitates the action of calcium in building bone and clotting blood. Many people in America may be taking drugs that effect the absorption of Vitamin K.

forms: Phylloquinone or phytonadione (K1), menaquinone (K2), menadione (K3)

Worldwide, only a handful of researchers study vitamin K—long known for its critical role in blood clotting. But with the aging of the U.S. population, this vitamin may command a bigger following as its importance to the integrity of bones becomes increasingly clear. It activates at least three proteins involved in bone health, says Sarah Booth. She is in the Vitamin K Laboratory at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University in Boston.

"Not too long ago," Booth says, "it looked like Americans consumed several times the recommended dietary allowance for vitamin K. But improved analytical methods show that the vitamin isn't as abundant in the diet as once thought."

Read the whole article here

• mechanism: Steroidal anti-inflammatory drugs (including prednisone) cause increased loss of vitamin K through the urine. Though widely observed, the clinical implications of this pattern remain unclear.
(Buist RA. Intl Clin Nutr Rev 1984;4(3):114; Pronsky Z. 1991, 60.)

• nutritional support: Individuals using corticosteroids (including prednisone) for periods longer than two weeks should consult with their prescribing physician and/or a nutritionally trained healthcare professional about the potential need to supplement with vitamin K to counter the depleting effects of the drug(s). A typical dose in such situations would be in the range of 65-80 mg of vitamin K per day, a level easily obtained by eating leafy green vegetables

I have a client who has an undiagnosed inflammatory condition, she was given prednisone to treat it. 2 years later (using prednisone the whole length of time) she has received 2 hip replacements, and her lumbar area is decreasing in bone mass. Not once has the Doctor suggested anything about vitamin K, it's role in bone health or diet modification. It is also important to note, she had irritable bowel symptoms and vitamin K2 is made by intestinal bacteria. Antibiotics also have an effect on vitamin K absorption in the gut. So it seems when it comes to bone health we should be thinking about vitamin K along with Calcium.

Booth says (from that as much as 30 percent of total vitamin K intake may come in the form of dihydrophylloquinone (found in hydrogenated oils), but it is less biologically active than phylloquinone ( found in organic soy bean oil, dark green vegetables). In fact, it was half as active with a clot-forming protein and was completely inactive with a bone-forming protein. "So hydrogenated oils shouldn't be considered an important source of vitamin K," she emphasizes.

• The naturally occurring forms of vitamin K are all fat soluble. They are stored in the liver, though not to any great extent. Stable to heat and reducing agents, they are destroyed by light, acid, alkali, oxidizing agents, and alcohol.
• Most supplemental forms of chlorophyll, as a vitamin K source, are water soluble.
• K1: phytonadione or phylloquinone (Aquamephyton): is a natural derivative from fish or plants.
• K2: menaquinone: fat-soluble form made by intestinal bacteria.
• K3: menadione: the synthetic water-soluble form tends to have a greater degree of toxicity.

• Vitamin K1 is absorbed in the upper GI tract and requires bile salts for absorption.

• Vitamin K acts as a cofactor in the final synthesis of proteins with a modified amino acid residue.
This modified glutamic acid residue is found in bone proteins and can bind onto calcium ions to cause calcification.It is also found in the blood and along vessel walls, and along with platelet-derived phospholipid, binds calcium, and is an integral part of the clotting process.
• Vitamin K facilitates the action of calcium in building bone and clotting blood.
• Vitamin K is involved in the synthesis of a protein, osteocalcin, which is found in high amounts in bone. It allows calcium ions to bind, thus resulting in the calcification of bone.
• Vitamin K is involved in the synthesis of a kidney protein that functions in the inhibition of calcium oxalate stone formation via its ability to bind onto calcium in the kidneys.
• Vitamin K is involved in the synthesis of proteins C and S. These two proteins, formed in the liver, promote fibrinolysis and anti-coagulation. Thus, they are involved with reducing inflammation.

dietary sources:
• Lettuce, spinach, kale, cauliflower, cabbage, egg yolk, soybean oil, liver, kelp, alfalfa and other green plants, cow's milk, liver. Leafy green vegetables are the single best dietary source of vitamin K because of their high chlorophyll content.
• Probiotic flora in intestines with a healthy ecology normally manufacture vitamin K.

• A clinically significant vitamin K deficiency, as manifest by uncontrolled bleeding, is rare. Those cases which do develop are usually associated with malabsorption diseases.
• Infancy: Hemorrhagic disease of the newborn has been related to Vitamin K deficiency. This is due to poor transport across the placenta: especially with premature infants. Also, because of the relatively sterile infant gut, the ability to make vitamin K is impaired. The practice of supplementing pregnant women with vitamin K and providing vitamin K to newborn infants has significantly reduced the risk of deficiencies among infants, especially those who are breast-fed.
• Easy bleeding in children: especially spontaneous nose bleeds.
• Osteoporosis: A deficiency of vitamin K leads to impaired bone mineralization due to inadequate osteocalcin levels.
(Hart JP, et al. J Clin Endocrinol Metab. 1985 Jun;60(6):1268-1269; Hodges SJ, et al. Clin Sci (Colch). 1990 Jan;78(1):63-66; Hodges SJ, et al. Bone. 1991;12(6):387-389.)
• Vitamin E may interfere with the absorption and utilization of vitamin K.
• Many drugs, particularly antibiotics, cephalosporins and anticonvulsants such as phenytoin


Click the above link for more info on drug interactions and vitamin K

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