Vitamin K

(phylloquinone, menaquinone)

Chief functions

·  Used by the liver in production of prothrombin (clotting factor)

·  Involved in bone metabolism

·  Necessary for synthesis of a protein that helps vitamin D regulate blood calcium levels

Deficiency symptoms

·  Prolonged clotting time

·  Hemorrhaging and possibly bleeding to death in surgery

Toxicity symptoms

·  Breakage of red blood cells

·  Jaundice

·  Brain damage

·  Interference with anticlotting medications

Stability

·  Resistant to heat

·  Resistant to oxygen

·  Resistant to moisture

·  Destroyed by strong acids

·  Destroyed by alkali and ultraviolet light

Nutrient-nutrient reactions and absorption

·  Too much vitamin E interferes with blood-clotting function of vitamin K

·  Absorbed moderately well from jejunum and ileum (40% to 70%)

·  Some absorption in the colon by passive diffusion

·  Absorption mostly depends upon normal flow of bile and pancreatic juice

·  Absorption is enhanced by dietary fat

·  Severe liver disease hinders utilization of vitamin K in the formation of prothrombin

·  Effectiveness enhanced when used with warfarin, heparin, and salicylates

DRI / mcg
0-0.5 year / 2
0.5-1 year / 2.5
1-3 years / 30
4-8 years / 55
9-13 years / 60
14-18 years / 75
Male 19-70 years / 120
Female 19-70 years / 90
Pregnant / 90
Lactating / 90

DRI=Dietary Reference Intakes, mcg=microgram

Tolerable upper limits are not determined for vitamin K. This is because of lack of data of adverse effects and concern with regard to the lack of ability to handle excess amounts.

Dietary sources

·  Beef liver

·  Broccoli

·  Brussels sprouts

·  Cabbage

·  Cauliflower

·  Dark-green leafy vegetables, such as:

–  Kale

–  Spinach

–  Turnip greens

–  Collards

–  Swiss chard

–  Mustard greens

–  Parsley

–  Romaine

–  Green leaf lettuce

·  Eggs

·  Green tea

·  Olive, soy, and canola oils

·  Soybeans

Groups at highest risk for deficiency

·  Persons taking antibiotics that kill intestinal bacteria

·  Individuals who combine an anticoagulant with a high intake of vitamin K

·  Patients with chronic biliary obstruction

·  People with fat malabsorption disease

·  Newborns whose gastrointestinal tract is not yet inhabited by bacteria

Other facts

·  Vitamin K is manufactured by bacteria in the intestines

·  Toxicity is rare

·  Toxic levels are not a result of excessive dietary intake, only from supplemental vitamin K

·  DRI is based on the assumption that one-half of daily intake comes from bacteria synthesis

·  A normal mixed diet usually contains 300 mcg to 500 mcg of vitamin K

·  The vitamin K content of commonly consumed foods is not known with precision, which is why it is not given in food composition tables

·  Breast milk has very low vitamin K content

·  Deficiency of vitamin K is rare

·  Low intake is associated with hip fractures in older adults

References and recommended readings

Agriculture Research Service, National Agricultural Library, Nutrient Data Lab. USDA National Nutrient Database for Standard Reference. US Dept of Agriculture Web site. http://ndb.nal.usda.gov/. Accessed August 16, 2013.

Food and your bones. National Osteoporosis Foundation Web site. http://www.nof.org/foods. Accessed August 16, 2013.

Linus Pauling Institute, Micronutrient Information Center. Vitamin K. Oregon State University Web site. http://lpi.oregonstate.edu/infocenter/vitamins/vitaminK/. Accessed August 6, 2013.

Mahan LK, Escott-Stump S, Raymond JL. Krause’s Food and the Nutrition Care Process. 13th ed. St Louis, MO: Elsevier Saunders; 2013.

National Agricultural Library, Food and Nutrition Information Center. Dietary Reference Intakes: UL for vitamins and elements. US Dept of Agriculture Web site. http://fnic.nal.usda.gov/nal_display/index.php?info_center=4&tax_level=3&tax_subject=256&topic_id=1342&level3_id=5140. Accessed August 16, 2013.

The Nutrition Source. Vitamin K. Harvard School of Public Health Web site. http://www.hsph.harvard.edu/nutritionsource/vitamin-k/. Accessed August 16, 2013.

Vitamin K. University of Maryland Medical Center Web site. http://umm.edu/health/medical/altmed/supplement/vitamin-k. Accessed August 16, 2013.

Vitamin K: what does it do? EatingWell® Web site. http://www.eatingwell.com/nutrition_health/nutrient_library/vitamin_k. Accessed August 16, 2013.

US National Library of Medicine, National Institutes of Health. Vitamin K. MedlinePlus Web site. http://www.nlm.nih.gov/medlineplus/vitamink.html. Accessed August 16, 2013.

Review Date 8/13

G-0748