Vitamin K: Forms, functions and much more.

Vitamin K is quite a newcomer to the scene relative to its fellow fat soluble friends A, D & E. This is highlighted in the famous Weston Price book ‘Nutrition and Physical Degeneration’. Price often referred to a nutrient he named ‘activator X’ which he believed to be the missing link in health alongside vitamin D & A which were known in the 1930s.

There is no doubt in my mind that Price was directly referring to vitamin K without knowing it. Price had his focus especially on the physical degeneration of the teeth and facial symmetry. We know now that vitamin K is a key driver in forming the bone matrix, especially during development. But before we get into that, what are the different forms of vitamin K?

Nutrition and Physical Degeneration by Weston Price | Dental decay and symmetry.

Forms

Two members of the vitamin K family are useful for general health (K1 & K2), although there are some synthetic family members to consider such as K3, K4, K5, K6 & K7. These family members have various industrial uses, for example as preservatives or antifungal agents. The latter K7 must not be mistaken for a sub member of the K2 family.

Back to our two beneficial vitamin Ks. First up, we have vitamin K1, also known as phylloquinone which is present in all photosynthetic plants. Because K1 is involved in blood clotting, it’s fairly efficiently recycled in the body because we would be in pretty bad shape without it.

Then we have our vitamin K2 (menaquinone). K2 is more involved in bone health and is made from K1 by bacteria in our colon (more on that later). To make things more confusing K2 can be divided into a further two categories, K2-MK4 (menaquinone-4) and K2-MK7 (menaquinone-7).

K2-MK4 is synthesized by mammals and is named this because its molecular structure has a hydro-carbon ‘tail’ that contains four double bonds. K2-MK7 on the other hand is synthesised via bacterial fermentation and has 7 seven double bonds. It’s worth noting that bacterial fermentation can produce a range of long chain menaquinones from MK-5 to MK-10 but K2-MK7 has particular importance.

Functions - K1

K1 (phylloquinone - ‘Phyll’ comes from the greek word for leaf) has particular importance for homeostasis in the body due to its involvement in blood clotting.

The role of K1 is to ‘activate’ certain proteins in our bodies named clotting factors. K1 is involved in several of the 12 clotting factors which allow blood clots to form. Once K1 activates these proteins, a ‘clotting cascade’ begins which prevents us from literally bleeding to death. A rather important role in our daily lives. Anyone who says that K1 is primarily involved in calcium regulation would be mistaken. Although there is some crossover in functions for the vitamin K family, you would need 10 times the amount of K1 as you would do K2 to do this job.

As mentioned earlier, K1 is found in all photosynthetic plants, anything that derives energy from the sun essentially. It is contained within the chlorophyll and helps plants to make energy by shifting electrons inside the cell membrane. Structurally speaking, it’s not dissimilar to coq10 which as we know is very helpful to our mitochondria in the production of ATP. The K1 content varies quite a bit across the plant world but for reference, kale contains around 1150mcg per cup, broccoli around 220mcg per cup and blueberries around 40mcg per cup.

You might be thinking, ‘am I getting enough K1 in my diet’? Well there’s a good chance you’re somewhere close. I say this because K1 is very efficiently recycled in the body given its crucial role in blood clotting. However, if you’re experiencing bleeding gums, prolonged bleeding, easy bruising you may well be on the lower end. I might add people can be on the low end due to intestinal malabsorption which isn’t as uncommon as you might think.

It is possible to buy K1 supplements, for example phylloquinone derived from primrose and these can be useful in those who are following specific diets or those with malabsorption problems. However, it’s worth noting that vitamin K, generally speaking, has a low toxicity. The only real concern is the interaction with blood thinners such as a warfarin as K1 will combat this.

Functions - K2

Now that we’ve discussed K1, it’s time to delve into K2, known as menaquinone. Specifically, I’ll be referring to menaquinone-4 and 7 (MK4 & 7). For argument's sake, they have very similar actions in the body. Just know that MK4 is synthesised by animals and is found in grass fed meat, eggs and butter whereas MK7 is synthesised by bacteria. For example Natto (fermented soybean) has one of the highest concentrations of MK7 and is a common supplement.

Moving onto functions. There are a lot, more than you can imagine. Vitamin K2 deficiency is extremely insidious and is widespread I believe. This is because the effects are subtle and gradually build over many years, for example, deposits of calcium in the arteries, low testosterone, weak bones and cavities. These things often slip by us in our daily lives and are unlikely to be connected to K2.

To get into the specifics, K2 activates (or carboxylates) certain proteins in our bodies that primarily relate to calcium. The two more prominent proteins here are osteocalcin (the most abundant protein in bone after collagen that forms the bone matrix) which attracts calcium into the bone and teeth and matrix gla protein (MGP) which sweeps calcium out of the soft tissues and arteries. Without K2, these proteins are useless. They will just float around waiting to be activated.

Unfortunately, making a truly biological MK4 supplement would be extremely expensive, but humans have found a work around by synthetically deriving it from the tobacco plant. However, unlike most synthetic vitamins, the MK-4 molecule is "bio-identical." This essentially means it contains no mirror isomers (which is what makes most synthetic vitamins bad choices).

Does it make a difference which one you supplement? Well, in some ways yes. MK4 has a shorter half life so you will need to supplement more often (3 times daily for example) whereas MK7 has a much longer half life (a few days) allowing a single daily dose. There’s also one more important consideration. MK-7 does not seem to cross the placenta, and therefore during pregnancy it is favourable to prioritise MK-4.

Other benefits of vitamin K2

In the brain, K2 has a powerful ability to work as an antioxidant. It doesn’t function like your everyday anti-oxidant here where it provides charitable electron donations, instead it somehow blocks free radical accumulation and brain cell death. It seems to prevent the free radicals from forming in the first place, perhaps due to its ability to maintain glutathione production. This is why vitamin K deficiency is linked to Alzheimer's disease, a disease which is characterised by inflammation and plaque formation. Infact, people with Alzheimers consume less than half the dietary vitamin K of their mentally healthy counterparts.

Secondly, osteocalcin which is produced by osteoblasts (stimulated by vitamin D & A), induces testosterone production in the testes which subsequently stimulates sperm production. Remember osteocalcin needs to be carboxylated or activated by vitamin K so having a deficiency here may mean reduced testosterone and fertility. This is an emerging area of research which will probably come to light much more in the coming years.

Thirdly, I wanted to mention insulin sensitivity. In 2007, research revealed that the K2 dependent protein osteocalcin has a significant impact on insulin sensitivity and production. This was a reminder that our skeleton is much more than just a framework. In the journal Cell, researchers describe how osteocalcin improves glucose tolerance and that the second highest concentrations of K2 is in the pancreas. To give you a flavour of the research in humans, in only one week of vitamin K2 supplementation, trial participants have reduced their two hour post meal insulin production by half, albeit being an indirect measure of insulin resistance.

A primary reason I have difficulty recommending vitamin D supplements alone is because your body will reach a point where it no longer has the sufficient vitamin K to activate the calcium proteins. Secondly we need sufficient vitamin A, which helps liberate the excess calcium from the body. When fat soluble vitamins are balanced, we don’t get toxicity.