There are two natural kinds of vitamin K: vitamin K1 (phylloquinone or phytonadione) and vitamin K2 (menaquinone). In different ways, both are extremely important for health.
Vitamin K1 is found in plants and algae, which use it to help transform sunlight into food. It enters animals who eat the plants, and then the vitamin finds a new function – it helps wounds heal through blood coagulation. That’s why it’s called K – from Koagulations-Vitamin, which is what it was called by the German scientists who discovered it. The amount of vitamin K1 in the typical human diet is 10 times that of vitamin K2.
Vitamin K1 molecular structure
Vitamin K2 is made by bacteria in the human gut. It performs a range of functions that we are just beginning to understand. For instance, much of it is concentrated in the mammary glands – because babies need it to grow. Like K1, it is used by the liver to make coagulation proteins, but we now know that it also works in our bloodstreams to help place calcium where it belongs, in the bones rather than the arteries.
Menaquinone includes a range of related forms, which differ mainly in the number of isoprenyl groups in the side chains of the molecule. If there are 4 such groups, it is called K2-4 (or MK-4, for menaquinone K-4). If there are 7, is called K2-7 (or MK-7).
Vitamin K2-4 is a short-chain menaquinone that is found in meat and chicken, egg yolks, some cheeses and butter made from the milk of grass-fed cattle. You can also buy K2-4 in a synthetic form. Unfortunately, this has a short half-life and remains at therapeutic levels in the blood for only a few hours. To maintain useful levels of synthetic MK-4 in the blood, you need to dose yourself every few hours.
Vitamin K2-4 molecular structure
Vitamin K2-7 is a long-chain menaquinone. The best dietary source is natto, a traditional Japanese dish. It can also be found in certain types of cheese and butter.
Studies have shown that K2-7 has better bioavailability than other forms – that is, it is absorbed more easily by the body. It also has a longer half-life, which results in more stable serum concentrations. With prolonged intake, MK-7 accumulates to higher levels (7- to 8-fold) than other forms of vitamin K. It thus induces more complete carboxylation of osteocalcin – one of the essential processes for healthier bones and arteries. MenaquinGold® is vitamin K2-7.
Vitamin K2-7 molecular structure
Vitamin K3 (menadione) is actually a synthetic analogue of the vitamin which can be toxic in large doses. It is not recommended for human use due to its toxicity. It is mainly used for animal feed.
All things considered, then, for healthy bones and arteries, the supplement you take should contain vitamin K2-7 : MenaquinGold®