Vitamin K is often called "the forgotten vitamin" as most will know the function from other vitamins and don't know too much on what role vitamin K plays for our health and as consequence forget to supplement with it.
Vitamin K is a fat-soluble vitamin that is most well known for the important role it plays in blood clotting. After an injury, the walls of blood vessels contract to limit blood flow upon which blood platelets spread along the surface of the injured blood vessel. They form a clot just like a mesh to stop the bleeding. As a co-factor vitamin K plays a crucial role in regulating the blood clotting process.
Most of us get enough K from the diet to maintain adequate blood clotting, but NOT enough to protect you from a variety of other health problems. Vitamin K is also absolutely essential to building strong bones, preventing heart disease, and crucial part of other bodily processes. Adequate vitamin K levels will also help to prevent diabetes, slow down the occurrence of multiple types of cancer, and may even prevent Alzheimer’s disease.
In order to understand why we get enough vitamin K to prevent blood clotting but not enough to prevent or fight other diseases, you must know there are essentially two different types of vitamin K: vitamin K1 and K2.
Vitamin K1 or phylloquinone is the more prevalent form in our diet and is found in leafy green vegetables (lettuce, broccoli, cabbage, spinach etc) and vegetable oils.
In plants, phylloquinone play an important role in the photosynthesis process.
In the human body, vitamin K1 goes directly to your liver and helps you maintain healthy blood clotting.
A lack of vitamin K1 will result in a too low blood clot formation, which shows in easy bruising, bloody nose, excessive bleeding, and heavy periods. Since vitamin K1 is so abundant in leafy green vegetables, most people don’t need to worry about becoming deficient or taking a supplement. Just eat your veggies!
The other type is vitamin K2 with at least 4 different subtypes , MK-4, MK-7 , MK-8 and MK-9.
In the body, vitamin K2 goes straight to your blood vessel walls, bones, and tissues other than your liver.
The most common subtype of K2 is menatetrenone or MK-4, which is abundant in grass-fed animal fat, specifically the herbivore animals: chicken, cows, and game. Rich sources of MK-4 are grass-fed beef, grass-fed dairy, pastured eggs or wild game. Only grass fed animals will develop naturally high K2 levels because of high phylloquinone (K1) levels in green plants as opposed to grain which is devoid of phylloquinone.
Levels of K2 in meat, dairy of eggs from grain-fed animals is very low and as a result, our intake of K2 has greatly diminished and vitamin K deficiency is much more common than before.
MK-4 is also the form that the human body converts out of vitamin K1 from plants, just like herbivorous animals do, but unfortunately doesn't do so in adquate amounts as obviously, we don't eat nearly as much plants as herbivorous animals do, often not even reaching half of the recommended daily intake of 250g of vegetables a day, while twice as much as the recommended intake from green vegetables alone would be needed to be able to convert K1 into adequate amounts of K2. Not something that even the biggest vegetable-fan is going to consume on a daily basis.
The subtypes MK-8 and MK-9 are rarer and found predominantly in soft and hard cheese.
The best known subtype of vitamin K2 is MK-7 which is produced by bacterial fermentation. It's found in natto, a traditional Japanese food made of fermented soybeans. Natto is especially high in K2. Only 15 gram is needed to provide the recommended daily intake of vitamin K2. Unfortunately, eating natto is an acquired taste due to the slimy texture and strong smell and as a result it is not widely sold either. Fortunately there are other fermented foods that contain MK-7, which are Sauerkraut (fermented cabbage), and kefir.
Food frequency questionnaire-derived estimates of relative intakes in the Netherlands suggest that about 90% of total vitamin K intakes are provided by K1, about 2.5% by MK-4 and the remaining 7.5% by MK-5 through MK-9.
The importance of distinguishing between the two types of vitamin K became visible when studying osteoporosis in relation to calcium intake.
Most people still think calcium and vitamin D is all they need in order to prevent osteoporosis. "Take your calcium" used to be the mantra'. Then this mantra was replaced by "take your calcium AND vitamin D!".
As a matter of fact, the importance of vitamin D3 for health has become so well known over the past few years it was voted to be the 'supplement of the year 2016' in the Netherlands.
However, in countries like Japan or China, where far less calcium is consumed, osteoporosis is much rarer than in Western countries. Once this was discovered, milk was wrongly being blamed for delivering the 'wrong' type of calcium and other sources as the 'right' type of calcium, to the extent people were advised NOT to consume dairy. However, that was the wrong way to look at it.
Instead, a very strong relation was found with consumption of vitamin K, and more specifically vitamin K2.
Japanese women that consumed more natto, nature's richest source of vitamin K2 , had a much lower incidence of hip fracture.
Vitamin K2 from natto is far better absorbed than vitamin K from vegetables. Circulating vitamin K2 concentrations after the consumption of natto have been shown to be about 10 times higher than those of vitamin K1 after eating spinach.
Although fermented food products provide the highest source of vitamin K2, even relatively low vitamin-K1-containing vegetables like lettuce, consumed one or more times per day, have produced a 45 percent lower risk of hip fracture as compared to women who consumed lettuce once or fewer times per week. Despite the lower conversion of K1 into MK-4 it is still worthwhile to keep eating vegetables.
How come vitamin K2 is successful in preventing osteoporosis? Once calcium has been absorbed, K2 helps to deposit calcium in the bones where it is needed and prevents deposit of calcium in arteries where it is undesirable.
Vitamin K2 helps to prevent hardening of the arteries, which is a common factor in coronary artery disease and heart failure. Vitamin K2 helps to keep calcium out of your artery linings and other body tissues, where it can cause damage.
Taking vitamin K2 doesn't just prevent the hardening of arteries, but it can even help reverse atherosclerosis and completely reverse bone loss. In combination with strength training, vitamin K2 supplementation even increases bone mass in people with osteoporosis.
So, the new mantra should be : "take your calcium AND vitamin D AND vitamin K too!".
homever takes vitamin D3, should also take vitamin K since both vitamins work closely together and almost everyone is deficient in both anyway. If you are deficient in one, neither works optimally in your body.
The beneficial function of K1 for clotting and K2 to prevent osteoporosis as well as atherosclerosis doesn't stop here.
There are many other important functions of vitamin K2 in the body. Adequate levels of vitamin K2 increase insulin sensitivity and may prevent and even treat adult onset diabetes. People who get the most vitamin K2 from their foods are about 20 percent less likely to develop type 2 diabetes.
Due to its role in building up bones, vitamin K is also important for dental health.
Vitamin K2 also plays a role in increasing testosterone levels, both in women but particularly in men.
Another major role is to regulate cell growth, which includes undesirable cell growth from tumours. As such there is a positive correlation between high vitamin K levels and low incidence of various cancers, especially hormone dependent cancers like prostate and breast cancer. Men taking the highest amounts of K2 had about 50 percent less prostate cancer.
It is also thought vitamin K2 deficiency may be a contributing factor to Alzheimer's disease.
And last but not least, vitamin K2 is necessary for children's growth, to the extent that most newborns now receive vitamin K2 injections after birth to prevent growth problems.
The following conditions may put you at an increased risk of vitamin K deficiency: a poor or calorie-restricted diet, an intestinal disease that interferes with nutrient absorption, a liver disease that interferes with vitamin K storage as well as taking drugs such as broad-spectrum antibiotics, cholesterol drugs and aspirin.
You can obtain all of the vitamin K2 you need (about 200 micrograms) by eating 15 grams of natto daily. It's a small amount and not very expensive IF you can find it, but most from non-Japanese origin find it too unpalatable to even consider eating it regularly.
The next best thing is a high-quality K2 supplement. Remember to always take your vitamin K supplement with fat since it is fat-soluble and won't be absorbed without it.
If you have experienced stroke, cardiac arrest, or are prone to blood clotting, you should not take vitamin K2 without consulting your physician.