Men's Health Women's Health Senior's Health Antioxidants Sports Nutrition Diet & Weight Loss Vitamins & Minerals Herbs Specialty Supplements Targeted Supplements Spa Products Anti-Aging Basics Body Systems Body Structure Book Store Pet Health My Recommendation My Favorite Articles Our Most Popular Specials Bargain Basement Brands

MSM

Health News Archive 665 - Vitamin K Levels
<<back to structure/function index

Vitamin K Deficiency More Common Than Thought

Many apparently healthy people may be vitamin K deficient, says a new review, potentially increasing the risk of bone loss and also for arterial calcification.

Writing in the journal Thrombosis and Haemostasis, scientists from University of Maastricht's VitaK & Cardiovascular Research Institute CARIM state that it is questionable if present recommendations are sufficient to cover the requirements of [non-liver] tissues.

Indeed, tests looking at levels of under-carboxylated species of osteocalcin and matrix Gla protein (MGP) - generated in vitamin K deficiency - were substantial in "apparently healthy subjects", said the reviewers. "This raises the intriguing question of whether all apparently healthy adults are subclinically vitamin K deficient," wrote lead author Ellen Cranenburg.

"As compared with other vitamins, the dietary intake of vitamin K is very low. The recommended dietary allowance (RDA) is 1 micrograms per kilogram of body weight per day," added Cranenburg. "Also, its biological half-life time is relatively short: upon deprivation experimental animals develop symptoms of vitamin K-deficiency within a few days."

There are two main forms of vitamin K: phylloquinone, also known as phytonadione, (vitamin K1) which is found in green leafy vegetables such as lettuce, broccoli and spinach, and makes up about 90 percent of the vitamin K in a typical Western diet; and menaquinones (vitamins K2), which make up about 10 percent of Western vitamin K consumption and can be synthesized in the gut by microflora.

Menaquinones (MK-n: with the n determined by the number of prenyl side chains) can also be found in the diet; MK-4 can be found in animal meat, MK-7, MK-8, and MK-9 are found in fermented food products like cheese, and natto is a rich source of MK-7.

MK-4 is distinct from other MKs because it is not a major constituent of the spectrum of MKs produced by gut microflora, but can be derived from K1 in vivo.  A synthetic form of vitamin K, known as K3, does exist but is not recommended for human consumption.

"Poor vitamin K status must be regarded as a serious risk factor for increased postmenopausal bone loss and for artery calcification, notably in diabetes, endstage renal disease and aging," wrote the authors.

Cranenburg and co-workers added that several clinical trials have reported the benefits of supplementary vitamin K for decreasing bone loss, as well as in maintenance of bone strength and carotid artery elasticity.

"For K-1 and MK-4 these effects have been reported at pharmacological doses ranging between 1 and 45 milligrams per day," they said.

"On the basis of its longer half-life time and extra-hepatic tissue distribution it is to be expected that similar effects will be obtained with MK-7 at nutritional doses (i.e. below the RDA for vitamin K). Therefore, MK-7 is the obvious choice for enrichment of dietary supplements and functional foods to be used for disease prevention in healthy subjects."

Source: E.C.M. Cranenburg, L.J. Schurgers, C. Vermeer; Vitamin K: The coagulation vitamin that became omnipotent; Thrombosis and Haemostasis; July 2007, Volume 98, Issue 1, Pages 120-125

back to top