Saturday, May 23, 2009

Vitamin K

Vitamin K
Vitamin K is a fat-soluble vitamin, so it is stored in the body's fat tissue and liver. It is best known for its role in helping blood clot (coagulate) properly (the "K" comes from its German name, Koagulationsvitamin). Vitamin K also plays an important role in bone health.
It is rare to have a vitamin K deficiency, because in addition to being found in leafy green foods, the bacteria that are found in the intestines can make vitamin K. Sometimes taking antibiotics can kill the bacteria and lead to a mild deficiency. Vitamin K deficiency can lead to excessive bleeding (hemorrhage), which may begin as oozing from the gums or nose. Other circumstances that may lead to vitamin K deficiency include:
Health problems that can prevent the absorption of vitamin K (such as gallbladder or biliary disease, which may alter the absorption of fat), cystic fibrosis, celiac disease, and Crohn's disease
Liver disease
Use of blood-thinning medications (such as warfarin)
Continuing hemodialysis
Serious burns
Other conditions that benefit from vitamin K include:
Excessive Bleeding
Vitamin K is used to reduce the risk of bleeding in liver disease, malabsorption syndromes, or in association with long-term use of antibiotics.
In the U.S., Canada, Great Britain, and many other countries, all newborns receive vitamin K injections to prevent the possibility of hemorrhage (particularly in the brain) just after delivery. Babies are born without any bacteria in their intestines and do not get enough vitamin K from breast milk to tide them over until their bodies are able to make it. (However, if a mother eats lots of green vegetables on a daily basis, she can improve the amount of vitamin K in breast milk.) Even though vitamin K deficiency in newborns is very rare, it is dangerous enough to warrant these measures. Newborns at greatest risk for vitamin K deficiency are those who are born prematurely or whose mother had to take seizure medications during the pregnancy. Mothers on seizure medications are often given oral vitamin K for 2 weeks prior to delivery.
Vitamin K is needed for proper use of calcium in bones. Higher vitamin K levels correspond to greater bone density, while low levels of vitamin K have been found in those with osteoporosis. There is increasing evidence that vitamin K improves bone health and reduces risk of bone fractures, particularly in postmenopausal women who are at risk for osteoporosis. In addition, studies of other groups (such as male and female athletes) have also shown bone enhancing benefits from vitamin K supplements.
Dietary Sources:
Foods that contain a significant amount of vitamin K include beef liver, green tea, turnip greens, broccoli, kale, spinach, cabbage, asparagus, and dark green lettuce. Chlorophyll is the substance in plants that gives them their green color and provides vitamin K.
Freezing foods may destroy vitamin K, but heating does not affect it.
Available Forms:
There are 3 forms of vitamin K:
Vitamin K1 (phylloquinone, the natural version of K1 and phytonadione, the synthetic type of K1)
Vitamin K2 (menaquinone)
Vitamin K3 (menaphthone or menadione)
K1 and K3 are both available as part of multivitamin complexes or alone, in 5 mg tablets. These fat-soluble forms are an excellent source of vitamin K.
Water-soluble chlorophyll is the most common form of vitamin K found over the counter. It is available in tablet, capsule, and liquid forms.
How to Take It:
As with all supplements, check with a health care provider before taking vitamin K or giving it to a child.
People with vitamin K deficiencies related to malabsorption (such as gallbladder or biliary disease, cystic fibrosis, celiac disease, and Crohn's disease) will benefit most from a multivitamin containing vitamin K, rather than an individual vitamin K supplement. In certain circumstances, your doctor may administer vitamin K by injection.
Daily intake for dietary vitamin K (according to the U.S. RDA) are listed below:
Infants birth to 6 months: 2 mcg
Infants 7 - 12 months: 2.5 mcg
Children 1 - 3 years: 30 mcg
Children 4 - 8 years: 55 mcg
Children 9 - 13 years: 60 mcg
Adolescents 14 - 18 years: 75 mcg
A single injection of vitamin K is also given at birth.
Males 19 years and older: 120 mcg
Females 19 years and older: 90 mcg
Pregnant and breast-feeding females 14 - 18 years: 75 mcg
Pregnant and breast-feeding females 19 years and older: 90 mcg
Because of the potential for side effects and interactions with medications, you should take dietary supplements only under the supervision of a knowledgeable health care provider.
At recommended doses, vitamin K has few side effects.
Vitamin K crosses the placenta and is also excreted in breast milk. Therefore, pregnant women and women who are breastfeeding should talk to their doctor before taking vitamin K supplements.
People with an rare metabolic condition called Glucose-6-phosphate dehydrogenase (G6PD) deficiency should avoid vitamin K.
Possible Interactions:
If you are currently being treated with any of the following medications, you should not take vitamin K without first talking to your health care provider.
Antibiotics -- Antibiotics, particularly a class known as cephalosporins, reduce the absorption of vitamin K in the body. Long-term use (more than 10 days) of antibiotics may result in vitamin K deficiency because these drugs kill not only harmful bacteria but also beneficial, vitamin K-activating bacteria. This is mot likely to occur in people who already have low levels of vitamin K or are at risk for deficiency (such as those who are malnourished, elderly, or taking warfarin). Cephalosporins include:
Cefamandole (Mandol)
Cefoperazone (Cefobid)
Cefmetazole (Zefazone)
Cefotetan (Cefotan)
Phenytoin (Dilantin) -- Phenytoin interferes with the body's ability to use vitamin K. Taking anticonvulsants (such as phenytoin) during pregnancy or while breastfeeding may deplete vitamin K in newborns.
Warfarin (Coumadin) -- Vitamin K reduces the effects of the blood-thinning medication warfarin, rendering the medication ineffective. Vitamin K should not be taken while taking warfarin, and foods containing high amounts of vitamin K should be avoided.
Orlistat (Xenical, alli) and Olestra -- Orlistat, a medication used for weight loss, and olestra, a substance added to certain food products, prevent the absorption of fat and can reduce the body's absorption of fat-soluble vitamins. The Food and Drug Administration now requires that vitamin K and other fat-soluble vitamins (A, D, and E) be added to food products containing olestra. In addition, physicians who prescribe orlistat add a multivitamin with fat soluble vitamins to the regimen.
The fact that vitamin K is now added to olestra-containing foods is important to know if you should not be taking vitamin K (if you are on the blood thinner warfarin, for example).
Bile acid sequestrants -- These medications, used to reduce cholesterol, reduce the overall absorption of dietary fats and may also reduce absorption of fat-soluble vitamins. If you take one of these drugs, your doctor may recommend a vitamin K supplement:
Cholestyramine (Questran)
Colestipol (Colestid)
Colsevelam (Welchol)
Alternative Names:
Menadione; Menaphthone; Menaquinone; Phylloquinone
Reviewed last on: 9/7/2007
Steven D. Ehrlich, N.M.D., private practice specializing in complementary and alternative medicine, Phoenix, AZ. Review provided by VeriMed Healthcare Network.
Supporting Research
Behrman RE, Kliegman RM, Jenson HB, eds. Nelson Textbook of Pediatrics. 16th ed. Philadelphia, PA:WB Saunders Co. 2000:188, 526-527, 1164.
Bell RG, Sadowski JA, Matschiner JT. Mechanism of action of warfarin. Warfarin and metabolism of vitamin K1. Biochem. 1972;11:1959-1961.
Booth SL, Centurelli MA. Vitamin K: a practical guide to the dietary management of patients on warfarin. Nutr Rev. 1999;57(9 Pt 1):288-293.
Booth SL, Charnley JM, Sadowski JA, Saltzman E, Bovill EG, Cushman M. Dietary vitamin K1 and stability of oral anticoagulation: proposal of a diet with constant vitamin K1 content. Thromb Haemost. 1997;77(3):504-509.
Breen GA, St. Peter WL. Hypoprothrombinemia associated with cefmetazole. Ann Pharmacother. 1997;31(2):180-184.
Crowther MA, Julian J, McCarty D, et al. Treatment of warfarin-associated coagulopathy with oral vitamin K: a randomized controlled trial. Lancet. 2000;356(9241):1551-1553.
Feskanich D, Weber P, Willett WC, Rockett H, Booth SL, Colditz GA. Vitamin K intake and hip fractures in women: a prospective study. Am J Clin Nutr. 1999;69:74–79.
Harrell CC, Kline SS. Vitamin K -- supplemented snacks containing olestra: implication for patients taking warfarin [letter]. JAMA. 1999;282(12):1133-1134.
Hathcock, JN. Metabolic mechanisms of drug-nutrient interactions. Fed Proc. 1985;44(1):124-129.
Hey E. Effect of maternal anticonvulsant treatment on neonatal blood coagulation. Arch Dis Child Fetal Neonatal Ed. 1999;81(3):F208-210.
Huilgol VR, Markus SL, Vakil NB. Antibiotic-induced iatrogenic hemobilia. Am J Gastroenterol. 1997;92(4):706-707.
Iwamoto I, Kosha S, Noguchi S, Murakami M, Fujino T, Douchi T, et al. A longitudinal study of the effect of vitamin K2 on bone mineral density in postmenopausal women: a comparative study with vitamin D3 and estrogen-progestin therapy. Maturitas. 1999;31(2):161-164.
Keith DA, Gundberg CM, Japour A, et al. Vitamin-K dependent proteins and anticonvulsant medication. Clin Pharmacol Ther. 1983;34(4):529-532.
Kitchin B, Morgan SL. Not just calcium and vitamin D: other nutritional considerations in osteoporosis. Curr Rheumatol Rep. 2007 Apr;9(1):85-92. Review.
Knodel LC, Talbert RL. Adverse effects of hypolipidaemic drugs. Med Toxicol. 1987;2(1):10-32.
Kohlmeier M, Saupe J, Shearer MJ, Schaefer K, Asmus G. Bone health of adult hemodialysis patients is related to vitamin K status. Kidney Int. 1997;51:1218–1221.
Koonsvitsky BP, Berry DA, Jones MB, et al. Olestra affects serum concentrations of alpha-tocopherol and carotenoids but not vitamin D or vitamin K status in free-living subjects. J Nutr. 1997;127(8 Suppl):1636S-1645S.
Lubetsky A, Dekel-Stern E, Chetrit A, Lubin F, Halkin H. Vitamin K intake and sensitivity to warfarin in patients consuming regular diets. Thromb Haemost. 1999;8:396–399.
Matsui MS, Rozovski, SJ. Drug-nutrient interaction. Clin Ther. 1982;4(6):423-440.
McCormick RK. Osteoporosis: integrating biomarkers and other diagnostic correlates into the management of bone fragility. Altern Med Rev. 2007 Jun;12(2):113-45. Review.
National Academy of Science. Recommended Daily Allowances. Accessed August 1, 2007.
Nutrients and Nutritional Agents. In: Kastrup EK, Hines Burnham T, Short RM, et al, eds. Drug Facts and Comparisons. St. Louis, Mo: Facts and Comparisons; 2000.
Ong T, Whong WZ, Stewart J, and Brockman HE. Chlorophyllin: a potent antimutagen against environmental and dietary complex mixtures. Mutation Research. 1986;173:111-115.
Prince DM, Welshenbach MA. Olestra: a new food additive. J Am Diet Assoc. 1998;98(5):565-569.
Rashid M, Durie P, Andrew M, et al. Prevalence of vitamin K deficiency in cystic fibrosis. Am J Clin Nutr. 1999;70(3):378-382.
Schlagheck TG, Riccardi KA, Zorich NL, Torri SA, Dugan LD, Peters JC. Olestra dose response on fat-soluble and water-soluble nutrients in humans. J Nutr. 1997;127(8 Suppl):1646S-1665S.
Segel GB. Enzymatic defects: glucose-6-phosphate dehydrogenase (G6PD) and related deficiencies. In Behrman RE, Kliegman RM, Jenson HB, eds. Nelson Textbook of Pediatrics. 16th ed. Philadelphia, PA:WB Saunders Co; 2000:1489-1491.
Shils ME, Olson JA, Shike M, Ross CA, eds. Modern Nutrition in Health and Disease. 9th ed. New York, NY: Lippincott, Williams & Wilkins; 1999.
Shiraki M, Shiraki Y, Aoki C, Miura M. Vitamin K2 (menatetrenone) effectively prevents fractures and sustains lumbar bone mineral density in osteoporosis. J Bone Miner Res. 2000;15(3):515-523.
Suzuki K, Fukushima T, Meguro K, et al. Intracranial hemorrhage in an infant owing to vitamin K deficiency despite prophylaxis. Childs Nerv Syst. 1999;15(6-7):292-294.
Tamatani M, Morimoto S, Nakajima M, et al. Decreased circulating levels of vitamin K and 25-hydroxyvitamin D in osteopenic elderly men. Metabolism. 1998;47:195–199.
Thornquist MD, Kristal AR, Patterson RE, et al. Olestra consumption does not predict serum concentrations of carotenoids and fat-soluble vitamins in free-living humans: early results from the sentinel site of the olestra post-marketing surveillance study. J Nutr. 2000;130(7):1711-1718.
Weber P. The role of vitamins in the prevention of osteoporosis--a brief status report. Int J Vitam Nutr Res. 1999;69(3):194-197.
Weibert RT, Le DT, Kayser SR, et al. Correction of excessive anticoagulation with low-dose oral vitamin K1. Ann Intern Med. 1997;126(12):959-962.
Whitlock RP, Crowther MA, Warkentin TE, Blackall MH, Farrokhyar F, Teoh KH. Warfarin cessation before cardiopulmonary bypass: lessons learned from a randomized controlled trial of oral vitamin K. Ann Thorac Surg. 2007 Jul;84(1):103-8.
Wilson DC, Rashid M, Durie PR, et al. Treatment of vitamin K deficiency in cystic fibrosis: effectiveness of a daily fat-soluble vitamin combination. J Pediatr. 2001;138(6):851-855.
');}else {document.write('');}-->
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997-
var today = new Date();var year = today.getFullYear();document.write(year)
2009 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.

1 comment:

dr.steuart said...

If you have fallen in the grip of overweight and obesity and are eager to trigger off weight loss, you should opt for dieting and physical exercises in the first place. However, when dieting and physical exercises fail to yield results, get hold of diet pills such as Phentermine, Adipex etc but only after getting a doctor’s prescription for the same.