Vitamin K2 is fat-soluble and plays an important role in the human body, especially for blood clotting and bone formation. The vitamin is not a single substance, but a group of K vitamins comprising several representatives, which differ in the length of their side chains. While vitamin K2 has only become known as a dietary supplement in Europe in recent years, the vitamin is already approved in Japan for the prevention and treatment of osteoporosis.
Among other things, the K vitamins play an important role in blood clotting and the regulation of bone tissue, as well as in cell growth and the maintenance of vascular integrity. This is because they contribute to the normal function of certain enzymes, which in turn influence important bodily reactions. While the influence of vitamin K2 on blood clotting has been known and proven for some time, the effect of the K2 representatives on the activation of specific bone proteins is still treated quite stepmotherly, especially in Germany.
Essential function in calcium distribution
Studies show that vitamin K – and vitamin K2 in particular – has a positive influence on bones and bone remodeling, and for this reason, suitable for the prevention and treatment of osteoporosis patients. The vitamin also plays a decisive role in the health of the cardiovascular system and in the prevention of arteriosclerosis. This is because vitamin K helps regulate and distribute calcium throughout the body, which is so important for bone health.
While too much calcium deposits on the vascular walls of the arteries and promotes arteriosclerosis, a calcium deficiency leads to decalcification of bones and teeth in the long term. Osteoporosis can also be a consequence of the deficiency of the mineral. Vitamin K2 is able to regulate calcium metabolism and transport the mineral, which is so important for bones, into the bones – instead of into the blood vessels. In the regulation and distribution of calcium, the vitamin therefore plays a key role and thus shows an extremely positive effect on the cardiovascular system.
Common deficiency of vitamin K2
Independent laboratory studies show that deficiency of vitamin K2 is widespread in Western populations. The most important reason for this undersupply is that the vitamin is found only in small amounts even in supposedly healthy diets. This is partly due to the fact that industrialized animal agriculture hardly feeds any green grass (chlorophyll), which could serve as a K2 supply for the animals. Meat obtained through factory farming can therefore hardly serve as a source of vitamin K2 for humans.
Unlike vitamin K1 – which renews itself through an ingenious „recycling mechanism“ – vitamin K2 must be ingested daily with food. A vitamin deficit can occur after just seven days. The problem is that the vitamin K2 deficiency often remains undetected for a long time. Since the possible secondary diseases such as osteoporosis and arteriosclerosis only become noticeable after several years, the deficiency often remains undetected for a long time. Especially people with the disease, but also everyone else, should therefore take vitamin K2 as a dietary supplement.
Different types of K vitamins
In 1929, the Danish biochemist Henrik Dam discovered the fat-soluble vitamin K compounds. In 1943, he and his colleague Edward A. Doisy were awarded the Nobel Prize for Medicine for their research. Even today, the research situation surrounding the vitamin is comparatively confusing. Many studies demonstrating the mechanisms of action of the K siblings have only been published in recent years. For this reason, many valuable findings have not yet been included in the EU nutrition and health-related food directives.
Vitamin K2 is the name given to a whole group of substances, namely the so-called 2-methyl-1,4-naphthoquinone derivatives. These are chemically related to each other and differ in terms of the length of their side chains, i.e. the number of their isoprene units. Thus, vitamin K1 and K2 have side chains of different lengths. However, only vitamins K1 and K2 play a practical role in human metabolism. The vitamins, also known as menaquinones, originate from different sources: While vitamin K1 is produced by photosynthesis and occurs in green plants, vitamin K2 is produced by intestinal bacteria. Both are fat-soluble and heat-resistant, but show particular sensitivity when exposed to light. The two vitamin K derivatives differ fundamentally in their mode of action and have the following properties:
Vitamin K1 (phylloquinone)
Vitamin K1 is absorbed through the diet and is mainly found in green plants, i.e. numerous types of vegetables (for example broccoli and spinach) and some types of fruit (avocado). It plays a particularly important role in blood clotting. The vitamin owes its name to this function: „K“ is derived from „coagulation,“ which means clotting. For the circulatory system, vitamin K1 plays an essential role: it helps the liver synthesize the molecules that ensure blood clotting.
About 80 percent of the amount of vitamin K that we humans ingest is accounted for by vitamin K2. Once absorbed into the human metabolism, vitamin K1 remains there for only about 1.5 hours.
Vitamin K2 (menaquinone)
Natural sources of vitamin K2 are primarily animal products such as meat, eggs and dairy products. Other K2 suppliers are fermented foods, for example sauerkraut, yogurt or fermented soybeans. However, the foods in question contain the vitamin only in small amounts. Fermented dairy products, for example, contain an average of about 15 micrograms of K2 per 100 grams. In view of the fact that the daily K2 requirement is 100 to 200 micrograms, the supply via conventional foods is therefore not as easy to achieve as with vitamin K1. An adequate supply of vitamin K2 therefore requires the intake of dietary supplements.
However, the variety of K vitamins does not end with the distinction between vitamin K1 and vitamin K2. For example, vitamin K2 also has different forms, which are distinguished according to the number of their chemical side chains as menaquinone 4 to 13. The length of the side chains also determines how well the active substance can be absorbed by the organism and how long it remains available in the body. Menaquinone-4 (MK-4) and menaquinone-7 (MK-7) have been well researched. Although the variants of vitamin K2 serve the same purpose, they differ in their effectiveness. Mk-7 emerges as the clear winner in this respect: although both vitamins have very good bioavailability and are almost completely absorbed from the respective substances supplied. The decisive difference, however, can be seen in the half-life: While the body excretes MK-4 after just a few hours, MK-7 remains active in the blood for 72 hours.
Types of vitamin K2 production and possible quality differences
Differences between vitamin K2 cis- and all-trans
Vitamin K2 thus occurs in the variants MK-4 to MK-13. K2 MK-7, in turn, is subdivided into two further molecular forms: cis- and all-trans. The cis- and trans-isomers differ only in their geometric structure – which, however, has decisive consequences for their bioavailability. Thus, the human body can only bind the trans form of MK-7. Due to their geometric prerequisites, the trans isomers dock easily to the corresponding enzymes, while the cis molecules hardly bind at all and therefore remain largely ineffective.
This difference between cis and all-trans plays an essential role in the selection of vitamin K2 preparations. Thus, time and again, products are sold that consist largely of the ineffective cis isomers. There are clear differences in quality here. On the one hand, when buying a vitamin K2 preparation, you should make sure that it contains the active ingredient vitamin K2 MK-7. On the other hand, it should be the trans form of MK-7.
MK-7 – natural natto or fermented oils?
To make sure that you are buying the best and most effective form of vitamin K2 at the moment, you should therefore look out for the article designation „Vitamin K2 MK-7 all-trans“. Only products that have a trans content of more than 98 percent receive this designation. A whole range of dietary supplements of this type of MK-7 are available on the market. However, buyers as well as end customers should take a close look. The reason: MK-7 all-trans is offered in two different forms:
– MK-7 menaquinone, which is derived from natural natto cultures through fermentation.
– MK-7 menaquinone, which is produced by organic synthesis from vegetable oils.
Thus, the difference between the two variants lies in their method of production. In both cases, a natural source material is used. For example, vitamin K2 MK-7 is obtained from natto, a traditional Japanese food made from soybeans. Fermentation takes place, which means that the starting material is converted into acid, gases or alcohol by adding microorganisms to it. Well-known fermented products are dairy products such as cheese or buttermilk, sourdough or alcoholic beverages such as beer. The nutrient medium for MK-7 is usually the soybean. Since this contains several allergens, chickpeas are also used.
The disadvantage of obtaining MK-7 from natto is that the quality of the end product is subject to great fluctuations. The forms of vitamin K2 produced by fermentation only include MK-4, MK-6 and MK-9. To obtain MK-7, these K2 variants must be separated from each other in a complex process. The purity and quality of the result vary greatly depending on the manufacturer.
In contrast, to produce MK-7 by organic synthesis, one synthesizes the plant oils geraniol and citronella. The two oils, which are very similar in structure, enter into a compound and thereby change their original properties – resulting in 100 percent pure vitamin K2 MK-7. While currently only about 30 percent of available MK-7 is obtained from synthetic production, this number is continuously increasing. NutraK2 products contain vitamin K2 from organic synthesis and thus 100 percent pure, highly efficient vitamin K2 MK-7 all-trans.
For Bones and Heart – Effect of Vitamin K2
The Rotterdam Study, which has been ongoing since 1990, shows that an above-average intake of vitamin K2 MK-7 is associated with a reduced risk of atherosclerosis as well as a reduced risk of cardiovascular disease. Lower all-cause mortality was also observed in the individuals studied. This positive effect is exclusively associated with the increased intake of vitamin K2. It can therefore be concluded that only vitamin K2 is capable of activating the corresponding proteins.
Bone and dental health
Vitamin K2 is responsible for controlling and regulating calcium metabolism – and thus for a variety of important functions and processes in the body. For example, the messenger substance calcium serves, among other things, to form and maintain bones and teeth.
The occasional designation of vitamin K as the „bone vitamin“ therefore speaks for itself. Menaquinone is an important key to building and maintaining healthy bones. The reason for this is that the vitamin contributes to the activation of crucial protein compounds such as osteocalcin as well as the matrix GLA protein (MGP, gamma-carboxylglutamic acid). Vitamin K2 causes the so-called carboxylation, the connection of calcium present in the body with proteins. As a result, osteocalcin and MGP are activated and can perform their task – binding free calcium in the blood and storing it in bones and teeth. Vitamin K2 thus helps calcium to reach the bones and not to be deposited in the arteries. This prevents calcification of the arteries and therefore has a positive effect on the cardiovascular system.
In particular, the activation of the peptide hormone osteocalcin plays a role in bone health. One percent of the bone matrix consists of osteocalpin, and it also regulates the structure and mineralization of the skeleton. If, on the other hand, the calcium-binding proteins are inactive, calcium can accumulate in the vessels. The long-term consequences are porous bones and teeth, the risk of fracture increases and the teeth become more susceptible.
So in addition to its effect on bone health, vitamin K2 also plays an essential role in protecting the arteries from calcification and plaque buildup. Both counteract the development of arteriosclerosis. These findings are supported, for example, by the Rotterdam Study from 2004, which worked with several comparison groups. In addition, the study results suggest the positive influence of a high vitamin K2 level on vascular elasticity.
Since the matrix GLA protein is activated by the supply of vitamin K2 and free calcium ions are thus bound, they cannot be deposited on the vessel walls. Thus, K2 proves to be an efficient agent in the fight against vascular calcification and osteoporosis. Compared to K1, vitamin K2 therefore scores not only with a longer retention time in the metabolism, but also with a different, higher efficacy and a higher activity potential.
The plaque-reducing properties of vitamin K2 have also been scientifically proven. For example, a study published in the Dutch journal Atherosclerosis shows that a diet rich in vitamin K2 significantly reduces the formation of plaque deposits in blood vessels. The Rotterdam study also demonstrated over a ten-year observation period that individuals whose diets were higher than average in vitamin K2 had fewer calcium deposits in the arteries than others. In addition, the study found that a sufficiently high intake of vitamin K2 can reduce the risk of atherosclerosis by 50 percent. The likelihood of dying from cardiovascular disease also drops by 50 percent.
According to a study in which rats were given the vitamin K antagonist warfarin, vitamin K2 is even capable of reversing existing calcifications. The rats were given the warfarin, which has an opposite effect to vitamin K2, to achieve calcification of the arteries. The drug inhibits blood clotting and is a common ingredient in blood-thinning medications, especially in the United States. It prevents vitamin K2 from regulating calcium levels. For this reason, known side effects of warfarin are arteriosclerosis and osteoporosis.
Some of the rats suffering from arteriosclerosis were fed with diet containing vitamin K2, the rest were fed normal diet. The administration of vitamin K2 resulted in a 50 percent reduction in arteriosclerosis compared to the control group.
Studies show that an above-average K2 intake during pregnancy can be beneficial to both mother and child. Since the unborn, growing child has a high demand for calcium, many pregnant women suffer from calcium deficiency. In addition, infants often suffer from a vitamin K2 deficiency due to the low proportion of the vitamin in breast milk.
Comparative studies suggest a positive effect of vitamin K on bone density in the elderly. This is particularly true for postmenopausal women. For example, postmenopausal Japanese women who consume high levels of vitamin K are much less likely to suffer a hip fracture than those with lower levels of MK-7 in their blood. This is because the women studied who consume a lot of vitamin K2 in the form of natto have a higher bone mineral density compared to their gender counterparts of the same age.
The „Maastricht Osteostudy“ studied and treated 244 women between the ages of 50 and 60 for a period of three years. While some of the women received 180 micrograms of vitamin K2 MK-7 per day, the control group received only a placebo. Only the women taking MK-7 showed a significant increase in activated osteocalcin. In addition, age-related bone loss in the femur and lumbar spine decreased more slowly in the subjects of this group. The observed decrease in degradation was 35 to 40 percent. ); complete prevention of degradation was not possible by dietary supplementation alone. In addition, MK-7 intake significantly reduced vertebral bone loss in the lower thoracic region.
Interaction with other vital substances
Whether or not the skeleton remains healthy over the course of a lifetime depends to a large extent on the interaction of certain minerals. „Best friends“ in maintaining intact bones are above all vitamin K and vitamin D, but also calcium and magnesium. The latter are ideally present in a ratio of 2 to 1. Vitamin K2 is responsible for storing the minerals in the bones. At the same time, it relies on vitamin D to properly utilize calcium and also to activate the relevant proteins. Thus, if there is a deficiency of K2, calcium and magnesium are not transported to the bones and are instead deposited in the tissues of the soft tissues and cartilage. If, on the other hand, not enough vitamin D3 is available, there is too little usable calcium and there is a lack of proteins.
There is therefore a delicate balance between vitamins K and D. The two substances are dependent on each other and reinforce each other. The substances depend on each other and reinforce each other at the same time. For dietary supplementation, it is therefore particularly useful to always take vitamin D in conjunction with vitamin K2. This is because while vitamin D increases the concentration of calcium in the blood and helps to ensure that it is properly utilized, the calcium only gets to where it is needed with the help of vitamin K2.
When taking vitamin K2, interactions with certain drugs may occur. These are the so-called vitamin K antagonists, anticoagulants from the group of antithrombotics. These are used for the prevention and treatment of thromboembolic diseases. Frequently used examples are phenprocoumon (Marcoumar) and acenocoumarol (Sintrom). The drugs inhibit the formation of blood clotting factors by preventing the new formation of vitamin K. One of the most frequent possible interactions is organ bleeding, which is only life-threatening in rare cases.
Recommended use and dosage
Possible causes for a too low vitamin K2 content in the blood can be, for example, an unhealthy diet, but also a disturbed intestinal flora. But even a supposedly healthy, balanced diet cannot always compensate for a vitamin K2 deficiency. According to the German Nutrition Society, the daily requirement of vitamin K2 is 65 micrograms for women and 80 micrograms for men. However, numerous studies assume that these values are set too low and merely represent the minimum requirement for functioning blood clotting. To take advantage of the vitamin’s positive effects on bone metabolism, a higher dosage of between 100 and 200 micrograms a day is required.
Vitamin K2 is available as a dietary supplement in the form of capsules and drops. Unfortunately, the sole supply of the vitamin via food is hardly sufficient. It is true that there are foods, especially meat and dairy products, that are particularly rich in vitamin K2. But the respective content of vitamin K2 is usually not sufficient to ensure an optimal supply of the body and to enjoy the health-promoting aspects of the vitamin. Thus, the range of variation is very high and the foods in question rarely contain more than 40 to 60 micrograms per 100 grams.
If the intake from food is not sufficient, it is therefore advisable to take a dietary supplement. Especially older people with an increased risk of osteoporosis and hip fractures should increase their daily intake of vitamin K2. Vitamin K2 can be taken as a capsule or in the form of drops and is often offered in combination with vitamin D3 (D3K2) and calcium. The daily dosage ranges from 100 to several hundred micrograms, depending on the preparation. As a rule, the corresponding preparation is taken once a day. The risk of overdose is extremely low.