Vitamin K belongs – just like vitamin A, vitamin D and vitamin E – to the group of fat-soluble vitamins. In the body, it is particularly important for blood clotting: if there is a vitamin K deficiency, increased bleeding can occur. Such a deficiency is often found in newborn babies, which is why they are usually given vitamin K as part of their first preventive checkups. In healthy adults, vitamin K deficiency can be easily prevented because the vitamin is found in many foods.
Vitamin K: important for blood clotting
Vitamin K plays a central role in our body primarily for blood clotting: namely, it is involved in the production of proteins that act as clotting factors to ensure that bleeding is stopped. Vitamin K is responsible in the liver for activating inactive precursors of these clotting factors. If there is no vitamin K in the body, the clotting factors cannot be converted. 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 as well as osteoporosis. However, vitamin K is said to have a positive effect not only on the bones, but also on the cardiovascular system by protecting against calcium deposits in the arteries.
Vitamin K: occurrence in foods
The daily requirement for vitamin K is 65 to 80 micrograms. Green vegetables are particularly rich in vitamin K. The daily dose of vitamin K is found in the following foods, for example:
- 10 grams of parsley
- 15 grams chives
- 20 grams spinach
- 25 grams Brussels sprouts
- 90 grams calf’s liver
- 220 grams of cottage cheese
- 400 grams mushrooms
In addition, vitamin K is also found in foods such as milk, sauerkraut, lettuce, tomatoes, chicken meat, beans and peas. Foods containing vitamin K should be stored away from light as much as possible, otherwise the vitamin content of the food may be reduced. Losses during cooking, on the other hand, are minimal because vitamin K is extremely heat stable. As a rule, the intake of vitamin K from food is sufficient. However, in the case of an increased bleeding tendency as well as osteoporosis, the intake of dietary supplements with vitamin K may be useful.
Vitamin K: deficiency rather rare
A vitamin K deficiency occurs relatively rarely, since vitamin K is contained in many foods and can also be produced by our intestinal flora itself. If a vitamin K deficiency is present, it is usually due to the intake of certain medications and not to a poor diet. For example, people with liver disease and diseases of the digestive system, as well as cancer patients, are particularly at risk of vitamin K deficiency. If necessary, they should take additional vitamin K supplements. Furthermore, vitamin K deficiency can also occur as a result of long-term treatment with antibiotics, since antibiotics destroy the intestinal bacteria. In addition, babies are mostly affected by a vitamin K deficiency, since breast milk contains only little vitamin K. In addition, the intestinal flora of babies is not yet fully developed, so that they can produce only little vitamin K themselves. For this reason, newborns are usually given additional vitamin K drops. Typical symptoms of vitamin K deficiency are slowed blood clotting and an increased tendency to bleed. This is manifested by frequent nosebleeds as well as a tendency to bruise.
Vitamin K for babies
Newborns are usually given vitamin K immediately after birth (vitamin K prophylaxis) because they are born with low vitamin K stores. If babies are fully breastfed, they should be given supplemental vitamin K until the end of the breastfeeding period. Vitamin K can be administered to newborns either orally or as an injection. In Germany today, vitamin K is mainly given orally in the form of drops; injections are usually only given to premature babies. The vitamin K drops are administered to the babies as part of the first three preventive checkups. In other countries, however, an injection is preferred so that full protection can already be achieved with one administration.
Vitamin K antagonists
In people at increased risk of thrombosis, the formation of vitamin K is inhibited by drugs.These drugs, which contain coumarins such as phenprocoumon or warfarin, are called vitamin K antagonists and belong to the group of anticoagulants (blood clotting inhibitors). They include, for example, Marcumar, Phenpro Ratiopharm or Falithrom. They are administered to patients with an artificial heart valve or atrial fibrillation, among other things. Vitamin K antagonists prevent the clotting factors from being converted from their inactive precursor to their active form. This reduces the risk of a blood clot. However, the effect of vitamin K antagonists can be reduced by a vitamin K-rich diet. However, it is not necessary to completely avoid foods containing vitamin K – in case of doubt, the dose of the anticoagulant should be increased slightly after consultation with the attending physician. However, additional vitamin K preparations should not be added under any circumstances when taking an anticoagulant.
Vitamin K overdose
Vitamin K overdose occurs very rarely because the vitamin has no toxic effects. If very high doses are injected, an allergic skin reaction may occur. Likewise, in some cases – especially in infants – changes in blood composition have been observed: Particularly high doses may cause dissolution of red blood cells (hemolysis).
