Vitamin K2 plays a vital role in ensuring that calcium stays in the bones and out of the arteries. It may also protect the heart and inhibit cancer. Vitamin K1 is most effective at supporting healthy insulin levels.
Vitamin K was first recognized in 1929 for its vital role in the blood-clotting process. Research now shows that the different forms of vitamin K have distinct benefits and are found in very different foods. Studies have shown that vitamin K2 is particularly effective for the treatment of osteoporosis, heart disease and various forms of cancer.
AN INTRODUCTION TO VITAMIN K
There are two main forms of vitamin K. Vitamin K1 (phylloquinone) is found in green leafy vegetables and makes up about 90 per cent of the vitamin K in a typical western diet. Vitamin K2 (menaquinones) makes up about 10 per cent of western vitamin K consumption and can be synthesized in the gut by microflora.
Vitamin K2 is actually a group of compounds known as menaquinones or MK-n. MK-7, MK-8, and MK-9 are found in fermented food products like cheese and natto-a popular fermented soy product found in Japan. Natto is a particularly rich source of MK-7.
MK-4 is distinct from other MKs because it is not produced in significant amounts by bacteria but appears to be synthesized by animals and humans from the phylloquinone in plants and also from menadione- a synthetic form of vitamin K present in animal feed. MK-4 may be found in animal meat. It has also been an approved medication for osteoporosis since 1995 in Japan.
VITAMIN K2 SUPPLEMENTS
Vitamin supplements of both MK-4 and MK-7 are readily available throughout North America. An MK-4 supplement (45 mcg) can cost as little as 4 cents a tablet, while an MK-7 tablet of 50 mcg will cost about 25 cents for a softgel.
Is MK-7 worth the extra money? Here is what the research says.
VITAMIN K2 (Menatetrenone or MK-4)
In Japan, studies with osteoporotic women using 45 mg/day of MK-4 have reported significant reductions in the rate of bone loss. (J Orthop Sci. 2001;6(6):487-492. and Annu Rev Nutr. 1995;15:1-22) A meta-analysis of seven Japanese randomized controlled trials indicated that MK-4 supplements increased bone mineral density and reduced fracture incidence. The studies indicated lowered risk for vertebral fractures by 60%, hip fractures by 77%, and nonvertebral fractures by 81%. (Arch Intern Med. 2006;166(12):1256-1261) A 45 mg/day dose of MK-4 supplements used in a 3-year placebo-controlled study of 325 postmenopausal women also found improved measures of bone strength compared to a placebo.(Osteoporos Int. 2007;18(7):963-972) In Japan, MK4 has been an approved medication for osteoporosis since 1995. (Note that if a supplement says it contains Menaquinone, it is probably MK-4. Supplements that are MK-7 (menaquinone-7) are usually explicit about mentioning it.)
VITAMIN K2 (Menaquinone-7 or MK-7)
Vitamin K supplements in the form of MK-7 are derived from fermented soy (natto) and are generally more expensive than MK-4 supplements.
Research conducted in Japan has been very encouraging regarding the contribution of MK-7 to improved bone health. A study of 944 women (20-79 years old) over three years found that dietary natto intake helped to increase bone mineral density (BMD) in the hips of the postmenopausal women and slowed the loss of BMD in the femoral neck and the forearm. (2006 American Society for Nutrition J. Nutr. 136:1323-1328, May 2006)
Supplement manufactures argue that MK-7 remains in the blood longer than MK-4 but there are no published studies demonstrating that this claim has been clinically proven or that a longer plasma half-life is beneficial to bone health.
It is clear from the above studies that both MK-4 and MK-7 are excellent for bone health. However, the research does not clearly demonstrate that MK-7 produces superior results and therefore warrants the additional cost of the supplements. This lack of clinical proof has not prevented many people who are taking an MK-7 supplement from reporting outstanding health benefits.
A year’s supply of 90 mcg Vitamin K2 (MK-7) will cost approximately $90.
*** Note that anyone who has a heart condition or is taking anti-coagulants (blood thinners) such as Warfarin or Coumadin should only take vitamin K supplements on the advice of a doctor.