Vitamin K Products – What Makes Sense?

Vitamin K is of paramount importance for blood clotting. It is mostly found in plant foods like kale and spinach.

The essentials in brief:

• Vitamin K is of great importance for blood clotting and also plays a role in relation to bone health.
• A diet-related vitamin K deficiency is rare – even if suppliers like to talk about a hidden vitamin K2 deficiency. Statements about how vitamin K helps with osteoporosis or vascular diseases have not been scientifically proven and are not permitted for dietary supplements.
• Attention: There can be interactions with medication, especially anticoagulants.

What is behind the advertising for vitamin K?

Vitamin K is often found in dietary supplements and is advertised, among other things, as contributing to blood clotting and healthy bones. It is true that vitamin K is important for the body, but it is naturally contained in many plant (vitamin K ₁ ) and animal (K ₂ ) foods. However, there is also synthetically or bacterially obtained vitamin K2, which is approved as a novel food ingredient . Nutrition experts assume that the population has an adequate supply of vitamin K and that additional pills are not necessary.

Only two health claims are allowed for vitamin K:

• Vitamin K contributes to normal blood clotting
• Vitamin K contributes to the maintenance of normal bones

On the other hand, the disease-related statements according to which vitamin K (not even K 2 !) protects against osteoporosis or vascular diseases are not scientifically proven and also not permissible.

What should I look out for when using vitamin K products?

The vitamin K compounds formed by microorganisms and plants are not dangerous for healthy people, even in high doses. Except for rare, isolated allergic hypersensitivity reactions, no signs of overdose are known. For this reason, the European Food Safety Authority (EFSA) has not set an upper limit.

These vitamin compounds are approved for vitamin K in food supplements in Germany and other EU countries in accordance with EU Directive 2002/46/EC, Annex II (version of March 20, 2021) or the Union List for Novel Foods:

• Phyllochinon (Phytomenadion, K₁)
• Menachinon (K₂)
• Synthetic vitamin K2 (menaquinone-7) ( novel )

Despite their different physiological significance and bioactivity, no distinction has been made between vitamin K 1 and vitamin K 2 in the intake recommendations (except for food supplements).

For the prophylaxis of thrombosis diseases, vitamin K antagonists (e.g. Marcumar), i.e. “opponents” of vitamin K, so to speak, are often administered. This inhibits vitamin K absorption and delays blood clotting. If you have been prescribed such anticoagulant drugs, you do not need to change your diet to a diet low in vitamin K. In any case, you should avoid taking additional vitamin K from dietary supplements or medication  without first consulting your doctor, as this can endanger the success of the therapy in the long term. As little as 10 µg of vitamin K ₂ can have a negative effect on anticoagulant therapy.

For this reason, the Federal Institute for Risk Assessment (BfR) suggests not fortifying foods with vitamin K, since many older people take vitamin K antagonists to prevent thrombosis.

The BfR recommends 80 µg K ₁ or 25 µg K ₂   per daily dose as the maximum amount in food supplements . Furthermore, the BfR recommends a warning on the packaging for food supplements with vitamin K, according to which people taking anticoagulant drugs (of the coumarin type) should seek medical advice before consuming food supplements containing vitamin K.

What does the body need vitamin K for?

“Vitamin K” does not mean a single vitamin, but a group of compounds with a similar basic structure.

The K vitamins are involved in the formation of a wide variety of protein building blocks. For example, they are involved in the production of proteins for blood clotting and are important for proteins in blood plasma, kidneys and bones. This also explains the influence of vitamin K on the bone disease “osteoporosis”. Studies have also shown that women with low vitamin K intake are at higher risk of fractures. However, it remains unclear what role the vitamin compounds actually play in the development of the disease and whether an additional intake of vitamin K is beneficial. The influence of vitamin K on the protection of cardiovascular diseases is also discussed.

The amounts of vitamin K that humans need can only be estimated, since there are no meaningful experimental studies. For this reason, the German Society for Nutrition only gives estimates for an appropriate intake of vitamin K.

• For men between the ages of 15 and 50, this value is 70 µg, for men aged 51 and over it is slightly higher at 80 µg.
• For women, the appropriate intake is estimated to be somewhat lower: girls and women between the ages of 15 and 50 should take in around 60 µg, women over 51 years of age 65 µg.
• For older people, the value is about 10 percent higher to take into account a possibly higher need due to digestive disorders (see below) or medication intake.

A vitamin K deficiency leads to blood clotting disorders. This visible and invisible bleeding can in turn cause dangerous damage in a wide variety of organs and organ systems – from the gastrointestinal tract to the skin and mucous membranes to the adrenal glands, liver and brain. With the help of a single dose of vitamin K into the veins, it is possible to determine whether coagulation disorders are due to a vitamin K deficiency.

However, a diet -related vitamin K deficiency does not occur in healthy people in Germany. If there is a vitamin K deficiency, this is often due to chronic gastrointestinal diseases such as celiac disease, fat indigestion, Crohn’s disease or the so-called “short bowel syndrome”. As a result, not enough vitamin K is absorbed. Chronic liver damage, on the other hand, can lead to insufficient utilization of vitamin K. Deficiency symptoms are also associated with long-term use of certain medications such as antibiotics, medication for epilepsy or tuberculosis, medication to inhibit blood clotting and long-term use of salicylates, e.g. by aspirin, possible.

Can I cover my daily requirement through food?

The fat-soluble vitamin K compounds (K ₁ and K ₂ ) are absorbed into the small intestine cells with the help of special transport mechanisms. The uptake rate can vary between 20% and 70%, as various factors increase or inhibit uptake.

Vitamin K in its natural form is made by plants and microorganisms. Plant-produced phylloquinone, also called vitamin K1, is abundant in the chloroplasts of green plants. Even small amounts (30-100 g) of green vegetables, such as kale, spinach and broccoli, are enough to meet the estimate for adequate intake.

Vitamin K can also be found in oils, legumes, fruits, grains and black tea. Vitamin K ₂ (menaquinone) is absorbed through egg yolk, dairy products and meat. Because the farm animals absorb vitamin K2 with their food. In the case of bacterially fermented foods such as cheese and yoghurt, the vitamin K ₂ content fluctuates depending on the bacterial strain used. Vitamin K is rarely lost through food preparation because the vitamin compounds in food are relatively stable to the effects of heat and oxygen. However, losses are possible during longer storage of food due to the sensitivity of the vitamin K compounds to light.

Certain bacteria in the human intestine are also able to form vitamin K 2 . However, the importance in terms of meeting requirements is probably low, since the vitamin is formed in a section of the intestine where fat-soluble vitamins are rarely absorbed.

Since newborns do not yet have sufficient vitamin K stores, they are dependent on a rapid supply of vitamin K after birth. The nutrition commission of the German Society for Child and Adolescent Medicine (DGKJ) therefore recommends giving vitamin K to prevent bleeding in infants. However, these are medicines and not food supplements. The oral administration of three times 2 mg of vitamin K as drops is recommended. The first dose is given immediately after birth as part of the preventive medical check-up U1.

With a varied diet that includes plenty of green plants, you get a lot of vitamin K and don’t have to worry about deficiency symptoms!