Vitamin K under trial
7/11/2006- published in the journal Nutrition (Vol. 22, pp. 845-852), Masao Kaneki from Harvard Medical School.
A growing body of science is linking vitamin K to bone health benefits, as well as potential roles in blood clotting and liver cancer. Many questions remain unanswered however and clinical trials are on-going to cast light on these dark areas of vitamin K understanding. The vitamin is less well known than vitamins A to E, but this increasing body of research, as well as increased marketing and advertising from supplement makers, is raising public awareness of vitamin K.
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 per cent of the vitamin K in a typical Western diet; and menaquinones (vitamins K2), which make up about 10 per cent of Western vitamin K consumption and can be synthesised in the gut by microflora. A synthetic form of vitamin K, known as K3, does exist but is not recommended for human consumption.
For the most part, research has focussed on the role of vitamin K in boosting bone health. Indeed, a meta-analysis of human clinical trials using MK-4 supplements for bone health (Archives of Internal Medicine, Vol. 166, pp. 1256-1261) reported that supplements (45-milligram daily doses) resulted in reductions in hip fractures of 77 per cent, vertebral fracture of 60 per cent, and all non-vertebral fractures of 81 per cent in elderly people.
Reports of the bone benefits for the other forms of vitamin K, most notably MK-7 from natto, can also be easily found in the literature.
A recent representative cohort study (Journal of Nutrition, Vol. 136, pp. 1323-1328) reported that postmenopausal women with a dietary intake of more than four packets of natto per week (equivalent to about 1400 micrograms of MK-7) reduced bone mass loss at the top of the thighbone (femoral neck) and in the lower arm (radius) by over 80 per cent and 60 per cent, respectively.
The mechanism behind the benefits is proposed to be due to vitamin K’s influence on the secondary modification of osteocalcin, a protein needed to bind calcium to the bone matrix.
Other studies have reported differing results however, like the study from Denmark (Osteoporosis International, Vol. 17, pp. 1122-1132) that reports that vitamin K1 intake had no impact on the bone mineral density and fracture risk of peri-menopausal women.
Evidence is also increasing linking the vitamin to lower risks of atherosclerosis and cancer of the liver. The former is reported to be due to the presence of a vitamin K-dependent protein, MGP, in atherosclerotic plaque. Gene disruption of MGP is said to result in extensive calcification of the aorta.
Comment: Vitamin K1 works just fine, but must be taken in higher amounts than K2. Even newer research is being published lately, that 10 mgs a day of K1 or 1 mg of k2, has the potential to reverse calcium deposits that may exist in the soft tissues of the body like the arteries, or anywhere else it does not belong, and help put it back into the bones, where it does belong.
This may be the most exciting reason to consider taking more of this nutrient or eating large amounts of very green leafy vegetables everyday. I personally take 10 mgs a day, on top of my other supplements for this very purpose.
Christopher Wiechert, C.N.C.
Christopher Wiechert's Healthblogger is for educational or informational purposes only, and is not intended to diagnose or provide treatment for any condition. If you have any concerns about your own health, you should always consult with a healthcare professional. If you decide to use this information on your own, it's your constitutional right, but I assume no responsibility.
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