Dr Paul Clayton 2006
The critical involvement of vitamin K in calcium balance has been known for some time in clinical science. But it is still largely ignored by a medical profession that remains mired in pharmaceutical thinking.
A well-conducted meta-analysis has been reported in a respected journal. It has shifted the debate forward to the point where we can no longer continue to ignore the ‘forgotten vitamin’. In this new study, the authors could hardly have stated their case any more strongly. They stated that ‘Increased intake of vitamin K, both from diet and supplements, has a significant impact on bone health and (is linked to) striking reductions of nearly 80% in hip fractures’.
The fact that there are various forms of vitamin K has lead to some confusion in the past. K1 (phytonadione) is found in green leafy vegetables such as spinach, broccoli and kale. K1 from these foods is the major form of vitamin K in the British diet. It accounts for up to 90% of our K intake.
The other 10% consists of Vitamin K2 (menaquinone). It is actually a group of related compounds with different numbers of side chains. The main members of this group are called MK -4, -7, -8 and -9 respectively. MK-4 is found in meat.MK-8 and -9 are found in fermented foods such as blue cheese. The best source of MK-7 is the Japanese fermented soy bean dish known as natto*.
The meta-analysis summed the results of 7 major trials with K supplementation, and concluded that vitamin K (in this case MK-4) was significantly protective.It was associated with improved bone mineral density and reduced fracture rates at all sites measured. The findings matched the positive results of Japanese studies with MK-7.
Osteoporosis costs Britain over £5 million per day. Compared to that, K supplements cost pennies. Thus wide-spread supplementation would be a
spectacularly cost-effective way of improving the nation’s health. Food fortification would present problems, as K is contra-indicated in patients taking anti-coagulants. But for everyone else, a daily dose of K makes excellent sense.
*Not to be confused with the Himalayan mountain K2, and the recently exhumed K-9, a robotic extra in the TV series Dr Who!
Cockayne S, Adamson J, Lanham-New S, Shearer MJ,Gilbody S, Torgerson DJ. Vitamin K and the prevention of fractures: systematic review and meta-analysis of randomized controlled trials. Arch Intern Med.2006 Jun 26;166(12):1256-61.