Vitamin K is a fat-soluble vitamin which, depending upon the form K1 or K2, can have significant bone, immune, cardiovascular health and anti-cancer benefits, especially when coupled with vitamin D. Vitamin K levels have declined in the population, especially amongst younger people, because of poor diet. Levels are also depleted by antibiotics, PPIs and statins.
Vitamin K refers to a family of compounds each with 2-methyl-1,4-napthoquinone in common.
* Vitamin K1 is phylloquinone; it is derived from plant sources
* Vitamin K2 can be divided into several sub-compounds (menaquinones). the two key ones are:
* MK-4 - short chain derived from animal sources - meat and dairy
* MK-7 - derived from fermented foods.
MK-7 has been shown to remain in the body longer than MK-4
Vitamin K sources
Top sources for vitamin K1 are kale, mustard greens, broccoli, chard, spinach, Brussels sprouts, prunes, kiwi, green beans, avocado, soya bean oil.
Top sources for vitamin K2 are Natto, beef liver, pork chops, chicken, pate, hard and soft cheese. Your gut bacteria also synethise good volumes of K2.
Vitamin K overall Benefits
The vitamin was originally given the name ’K’ as it was originally identified by German scientists as a vitamin responsible for ’koagulation’. Many early studies did not even understand that there were more than one or two forms each with separate properties and this caused a lot of confusion.
In fact it is only Vitamin K1 that is now known to promote blood clotting. It is used, for example, with newborn babies.
Vitamin K2 appears to have significant benefits with bone health, cardiovascular health and cancer prevention. For example, 2010 research (1) in the American Journal of Clinical Nutrition showed that people with the highest intake of vitamin K have the lowest risk of cancer and a 30 per cent reduction in mortality if they do have cancer.
Many web sites report that the vitamin is in abundant supply, and this may be why it gets so little press. Well, it’s time to think again. Unfortunately, the vitamin is not stored and so you need to replenish levels on a daily basis.
There is also significant microbiome involvement. Menaquinones are known to be produced by gut bacteria (2).
As usual, modern diets put our young at higher risk of illness 
The RDA is only 65 micrograms for women and 80 for men but this will have to be adjusted as it looks like vitamin K is nowhere near as abundant as was first thought, and as more discoveries about its benefits come to light.
Sarah Beth of Tufts University at Boston has looked into the vitamin in some detail. Analysing 2000 households, she discovered that whilst the over 60’s are OK, the 18-44 age group just don’t get enough, and not even the current lowly RDA.
Vitamin K2 and Bone health?
Basically, vitamin K balances calcium in the body.
As long ago as 2007 Bolton-Smith (University of Dundee) suggested vitamin K2 enhanced the effects of vitamin D and that’s how it contributes to bone health. Two epidemiology studies - one the Boston Nurses Study involving 72,000 women over 10 years, the other the Framingham study with 800 elderly men - showed that adults with the lowest intakes of vitamin K had 30 per cent more hip fractures than those who consumed the most.
Vitamin K can play an important role in osteoporosis. In older women, research shows that vitamin K2 can reduce high levels of T-cells and control inflammation (13). Vitamin K2 MK-7 activates two osteocalcin proteins which incorporate calcium into bones.
Vitamin K2 and Cognitive Health?
Older adults with the highest plasma levels of vitamin K2, have the highest episodic memory scores (11).
Vitamin K2 and Cardiovascular benefits?
In one early study of post-menopausal women, a low dietary intake of vitamin K was associated with increased risk of aortic calcification. Vitamin K2 restricts calcification (calcium deposits in arteries) and thus a hardening of the arteries. A growing body of evidence has shown the importance of Vitamin K2 in Cardiovascular health (5). It also activates several proteins important to the vascular system; for example, matrix-GLA- protein (MGP).
Vitamin K and glucose metabolism
A 2018 study showed that older people with type-2 diabetes had vitamin K levels 63.4% lower than healthy people of the same age. In this case it was vitamin K1. It positively regulates the SIRT1/AMPK glucose metabolism pathway in the liver (12).
Vitamin K and Vitamin D
Many people have heard about vitamin K2 in the context of vitamin D3 and certainly there seems a strong synergy between them, especially for cardiovascular and bone health (4). A review by Dutch researchers in 2017 showed that vitamin D promotes the production of proteins that need vitamin K for activation. The supplementation of the two vitamins in combination has much greater benefits for health than either on its own.
Sufficient blood concentrations of Vitamin D and vitamin K2 induce bone formation in vitro with stimulation of osteoblast-specific gene expression. In Japanese research, the inclusion of extra virgin olive oil and vitamin B6 gave even stronger benefits for bone health in post-menopausal women. Similar results were found in post-menopausal women with osteoporosis.
Studies on cardiovascular health by the same Dutch team have shown that low plasma vitamin D in combination with low plasma vitamin K were associated in a 6-year follow up with higher blood pressure (systolic and diastolic) and higher hypertension (2).
Vitamin K2 and cancer
As long ago as 1993 researchers found that a vitamin K dependent protein, found throughout the nervous system, heart, lungs, stomach, kidney and cartilage systems, is both a cell growth regulating factor and has cell signalling activities.
More research suggested vitamin K had an anti-cancer effect and is useful in the treatment of many different types of cancer including liver, colon, stomach, leukaemia, lung and breast. There is a June 2018 Review in Oncology Letters (10) presenting research that K2 can act in many ways from encouraging differentiation to causing apoptosis to binding on mitochondrial membranes in leukaemia.
Vitamin K2 can be taken with chemotherapy to improve its effectiveness. Yoshida et al, Tokyo Medical University nt. of Oncology Sept. 2003 have shown (3) has an in-vitro effect on lung cancer cells, squamous cells and adenocarcinomas. This follows work showing apoptosis with leukaemia cells. These researchers actually recommended K2 as "safe medicine without prominent adverse effects including bone marrow suppression". Levels up to 75 micrograms were used.
Lamson DW and Plaza SM of Bastyr University, Washington have showed that both K2 "may act at the level of tyrosine kinases and phosphatases. They are affected by vitamin K, which can lead to cell cycle arrest and cell death" (August 2003 Alt Med. Rev)
Vitamin K2 and Liver cancer - The same researchers went on to show that six out of 30 patients with liver cancer had their disease stabilised after taking vitamin K. Another study, by Dr Koike at Tokyo University, indicated that vitamin K slows the spread of liver cancer. 59 per cent of patients treated with vitamin K were alive two years after the test started, whereas only 29 per cent of the control group were. Indeed there have been a good number of studies with liver cancer, one showing that postoperative use of K2 stabilised liver cancer (6-9).
Vitamin K2 exerts multiple effects on liver cancer - it affects growth receptors and signalling molecules preventing liver cancer growth; it stops replication, freezing the cell cycle and causing cell death.
There was also research showing vitamin K plays a role in the carboxylation of glutamic acid. Scientists had previously focussed on this process with bones and how the glutamate salts combine with vitamin D and calcium. But, glutamic acid and calcium ions play a role in cell membranes and even the oxygenation process in the Krebs cycle - the very energy production cycle that can go wrong when a healthy cell becomes a rapidly-dividing cancer cell. Vitamin K induces autophagy in leukaemia and bile duct cancers.
Vitamin K - are you getting enough?
To achieve the levels used in research would be almost impossible just by eating green leafy vegetables or some dairy and fermented foods and supplementation is essential. (Take with a meal as vitamin K is fat-soluble). 10-45 mcg has been the dose used in clinical trials with osteoporosis.
Vitamin K2 is not even toxic at 500 times the RDA so there are few problems with dosage. It would seem people looking to prevent should start with daily doses of 180 mcg, preferably of K2 MK-7.
If you are already buying or thinking of buying Vitamin K, you might like to look at the Natural Selection Product of Choice. You can do this by clicking here 
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References
1. Cancer and vitamin K2 2010 American Journal of Clinical Nutrition
2. The production of Menaquinones (vitamin K2) by gut bacteria.
3. Adriana J. van Ballegooljen et al; Int J Endocrinol. 2017; 2017: 7454376.
Published online 2017 Sep 12. doi: 10.1155/2017/7454376
4. Adriana J. van Ballegooljen et al; Hypertension 2017 Jun;69(6):1165-1172.doi: 10.1161/HYPERTENSIONAHA.116.08869.Epub 2017 Apr 10.
5. The role of vitamin K2 status and cardiovascular health (2017);
6. Mizuta T, Ozaki I, Eguchi Y, Yasutake T, Kawazoe S, Fujimoto K, Yamamoto K. The effect of menatetrenone, a vitamin K2 analog, on disease recurrence and survival in patients with hepatocellular carcinoma after curative treatment: A pilot study. Cancer. 2006;106:867–872. doi: 10.1002/cncr.21667.
7. Kakizaki S, Sohara N, Sato K, Suzuki H, Yanagisawa M, Nakajima H, Takagi H, Naganuma A, Otsuka T, Takahashi H, et al. Preventive effects of vitamin K on recurrent disease in patients with hepatocellular carcinoma arising from hepatitis C viral infection. J Gastroenterol Hepatol. 2007;22:518–522. doi: 10.1111/j.1440-1746.2007.04844.
8. Ishizuka M, Kubota K, Shimoda M, Kita J, Kato M, Park KH, Shiraki T. Effect of menatetrenone, a vitamin k2 analog, on recurrence of hepatocellular carcinoma after surgical resection: A prospective randomized controlled trial. Anticancer Res. 2012;32:5415–5420.
9. Zhong JH, Mo XS, Xiang BD, Yuan WP, Jiang JF, Xie GS, Li LQ. Postoperative use of the chemopreventive vitamin K2 analog in patients with hepatocellular carcinoma. PLoS One. 2013;8:58082. doi: 10.1371/journal.pone.0058082
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Please be clear: At CANCERactive we do not consider the above compound to be a cure for cancer, despite what the research says or experts doing the research may claim. The above, is an article on the compound from published research and expert opinion in the public domain. At CANCERactive we do not believe that any single compound (drug, vitamin, whatever) is a cure for cancer. We believe that people can significantly increase their personal odds of survival by building an Integrated Programme of treatments. Equally, cancer prevention is best practiced through a width of measures.