However this is now known to be only the first of two forms – Vitamin K1 (phylloquinone) found in leafy greens and Vitamin K2 (menaquinone -MK) found in fermented foods especially natto.
Vit K2 is now known to be involved in both bone metabolism and arterial health and recent discoveries make it perhaps the greatest secret in maintaining cardiovascular health – way beyond cholesterol (which many believe has been unfairly demonised as it is there to repair an already damaged vessel).
There are various subdivisions of menaquinone including MK-7 (natural) and MK-4 (synthetic) and it is the MK-7 which has the greatest interest for heart health.
One really important point: the liver (where coagulation factors are formed) takes what it needs to prevent the risk of uncontrolled bleeding (a likely death). The remaining K is left for other tissues so the risk of K-deficiency mainly occurs in extra-hepatic tissues like bone, cartilage and arteries. These tissues also contain VKD proteins: osteocalcin (OC) and Matrix Gla Protein (MGP) respectively. The same process of carboxylation (addition of COO- is needed for activation
Let’s look firstly at what it does in bone.
Bone and Vitamin K2
K2 helps osteoblasts bind calcium from the blood and draw it into the bone. It also prevents breakdown by osteoclasts so preserving good bone structure and preventing osteoporosis. Note also that Vitamin K2 and D3 work in conjunction so must be taken together if sunlight exposure is not sufficient (which will be the case in winter in the UK).
Vitamin K2 and vascular health
Most everything you’ve probably heard about heart health is largely outdated. It is neither an excess of cholesterol or inflammation that is the cause of CVD – although both are involved. Much nearer to the upstream cause is an excess of Ca deposition in the soft tissues particularly arteries. The only known inhibitor of arterial calcification is activated MK-7). So lack of K2 leads to the formation of plaques which cholesterol then comes to bind and keep stable (as if it were allowed t. o break off would form a clot and kill you!) So cholesterol is the bandaid not the problem!
Most people are Vitamin K2 deficient – especially in the west where we seldom eat fermented foods. The Japanese are the highest consumers – some in the East eat natto every day. The average daily consumption needs to be 45mcg to give 50% reduction of arterial calcification and cardiovascular death. And it is a dose dependent relationship i.e. the more you have the lower your risk. Don’t forget that the order of usage is blood vessels then bone so the higher your intake the more benefit for your bone density.
NB Statins (which have been highly promoted for reducing the risk of heart attack actually weaken the heart because they inhibit recycling in the arteries!! MK is normally recycled 7 times on average so in order to reduce your risk of calcification you would need to take extra K2 when on them. For post-menopausal women, for instance (who shouldn’t be put on statins anyway), a dose of 180mcg/day MK-7 increases arterial health and is both preventative and remedial.
These two functions (bone and arterial) are not unrelated they are both symptoms of Ca dysfunction! This is because if you are limited in your intake of K2 you use up all your K2 stores to convert osteocalcin to its carboxylated active form (cOC) leaving nothing for the use in reducing calcium build up in the arteries.
K2 and Insulin Sensitivity
Well so much for bones and arteries. Now we turn to something that virtually no doctor knows about. K2 improves insulin sensitivity within 4 weeks of supplementation via the effect of osteocalcin reducing inflammation. This can drastically reduce your likelihood of developing diabetes if you have been diagnosed ‘pre-diabetic’! And that seems to work for men and women of all ages. By implication therefore it also reduces your risk of CVD which is also associated with insulin resistance (where larger and larger amounts of insulin have to be pumped out to keep blood sugar stable causing the receptors to basically become resistant). It reduced diabetes risk by 20% and prostate cancer risk by 35%.
Metabolic functions of K2 in mitochondria
Finally here’s an astonishing piece of information that is only recently becoming known. A new role of K2 in mitochondria (the energy producing organelles) which are significant in nerve health, muscle contraction and cardiac function and output. Mitos are, surprisingly perhaps remnants of bacteria that once fused with an animal cell in a mutually beneficial marriage of convenience! Now we know that bacteria produce K2 (hence their presence in fermented foods). Bacillus species use them for what is called a ‘redox’ function (reduction/oxygenation – the adding and removal of oxygen orthe removal /adding of Hydrogen (H2) ions. This process takes place within the mitochondria of our cells to produce the energy we need for functioning via the ‘energy currency’ of ATP.
K2 plays a significant role in improving the health of each of these systems
Bone health – improves bone density
Arterial perfusion – removes calcium from arteries
Mitochondrial Health – improves function impacting on cardiac output, vascular health, muscle function
Reduces speed of ageing – increases mitochondrial function, so each cell can produce more energy and we can regenerate dying cells.
Prevents aging related tissue degeneration (inhibition of elastin and collagen calcification)
Nature’s Fountain of Youth! Dose required is 100-300mcg
The western population is sub-clinically deficient (in other words may not have overt deficiency symptoms but none the less are suffering).
 Diabetes Care 33:1699-1705, 2010
 Theuwissen et al. Food Funct. 2014 Feb:5(2) 229-34