Like vitamin A, vitamin D and vitamin E, vitamin K belongs to the group of fat-soluble vitamins. In the body, it is especially important for blood clotting: If there is a vitamin K deficiency, more bleeding can occur. Such a deficiency is common in neonatal babies, which is why they are usually provided with vitamin K as part of their first check-ups. In healthy adults, a vitamin K deficiency can be easily prevented because the vitamin is contained in many foods.
Vitamin K: Important for blood clotting
Vitamin K plays a central role in our body primarily for the clotting of blood: it is involved in the production of proteins, which as coagulation factors ensure that bleeding is stopped. Vitamin K is responsible in the liver to activate inactive precursors of these coagulation factors. Consequently, if no vitamin K is present in the body, the coagulation factors can not be converted.
In addition, vitamin K is also important for the metabolism of connective tissue and bones. Together with vitamin D and various proteins, vitamin K ensures that the bones are strengthened: this reduces the risk of bone fracture and osteoporosis. But not only on the bones, but also on the cardiovascular system, vitamin K should have a positive effect by protecting against calcium deposits in the arteries.
Vitamin K: occurrence in food
The daily requirement for vitamin K is 65 to 80 micrograms. Especially rich in vitamin K are green vegetables. The daily dose of vitamin K is included, for example, in the following foods:
- 10 grams of parsley
- 15 grams of chives
- 20 grams of spinach
- 25 grams of Brussels sprouts
- 90 grams of calf's liver
- 220 grams of quark
- 400 grams of mushrooms
In addition, vitamin K is also included in foods such as milk, sauerkraut, lettuce, tomatoes, chicken, beans and peas. Foods with vitamin K should be stored as light-protected as possible otherwise the vitamin content of the food may be reduced. The losses during cooking, however, are low because vitamin K is extremely heat stable.
As a rule, the intake of vitamin K via the diet is sufficient. However, if you have an increased tendency to bleed or suffer from osteoporosis, taking vitamin K supplements may be useful.
Vitamin K: lack rather rare
A vitamin K deficiency occurs relatively rarely, because vitamin K is contained in many foods and can also be formed by our intestinal flora itself. If there is a vitamin K deficiency, this is usually due to the use of certain medications and not due to an incorrect diet.
Thus, people with liver diseases and diseases of the digestive system and cancer patients are particularly at risk of getting a vitamin K deficiency. If necessary, they should also take vitamin K supplements. In addition, a long-term treatment with antibiotics, a vitamin K deficiency may occur because the intestinal bacteria are destroyed by antibiotics.
In addition, most babies are affected by a vitamin K deficiency, since the breast milk contains only a little vitamin K. In addition, the intestinal flora of babies is not fully developed so that they can produce only a little vitamin K themselves. Because of this, newborns usually receive additional vitamin K drops.
Typical symptoms of vitamin K deficiency are slowed blood clotting and increased bleeding tendency. This is shown by frequent nosebleeds and a tendency to bruises.
Vitamin K for babies
Newborns are usually given vitamin K directly after birth (vitamin K prophylaxis) because they are born with low vitamin K reserves. If babies are fully breastfed, they should be given additional vitamin K until the end of breastfeeding.
Vitamin K can be given to the newborn either orally or by injection. In Germany, vitamin K is now given mainly orally in the form of drops, syringes are usually only premature babies. The vitamin K drops are given to the babies during the first three checkups. In other countries, however, an injection is preferred in order to achieve full protection with a single dose.
Vitamin K antagonists
In people who have an increased risk of thrombosis, the formation of vitamin K is inhibited by drugs. These drugs, which contain coumarins such as phenprocoumone or warfarin, are called vitamin K antagonists and belong to the group of anticoagulants (anticoagulants). These include, for example, Marcumar®, Phenpro Ratiopharm® or Falithrom®. Among other things, they are given to patients with an artificial heart valve or atrial fibrillation.
Vitamin K antagonists prevent the coagulation factors from being converted from their inactive precursor to their active form. This reduces the risk of a blood clot. Vitamin K-rich nutrition can reduce the effect of vitamin K antagonists.
However, it is not necessary to completely dispense with vitamin K-containing foods - in case of doubt, the dose of the anticoagulant should be slightly increased following consultation with the attending physician. Additional vitamin K supplements should not be given when taking a anticoagulant.
Overdose of vitamin K
An overdose of vitamin K occurs only very rarely, because the vitamin has no toxic effect. If very high doses are injected, an allergic skin reaction can occur. Likewise, in some cases, especially in infants, changes in the blood composition were observed: Particularly high doses can lead to red blood cell dissolution (hemolysis).