Ingredient information: Vitamin K
What is vitamin K?
Vitamin K is a term referring to several molecules belonging to the quinone family. It is a fat-soluble vitamin.
There are 3 distinct forms:
- Vitamin K1: phylloquinone, phytomenadione
- Vitamin K2: menaquinone
- Vitamin K3: Menadione
What are the properties of Riboflavin?
Vitamin K is fat-soluble, heat-resistant, but sensitive to light.
Menadione salts are water-soluble. Menadione should no longer be used in food supplements due to its toxicity .
Vitamin K plays several roles in the body, the best known being its involvement in blood clotting. In fact, there are four coagulation factors dependent on vitamin K (prothrombin, proconvertin, antihemophilic factor, and Stuart factor).
Vitamin K also serves as a cofactor for several carboxylase enzymes (CO2 fixation).
A (rare) vitamin K deficiency leads to clotting defects and hemorrhages.
What foods are richest in vitamin K?
Vitamin K is present in most foods and can be synthesized by the gut microbiota (vitamin K2). Sauerkraut and cabbage are among the richest sources.
Below are some examples of foods and their vitamin K concentration (µg/100g):
- Sauerkraut: 200 - 3000
- Parsley: 600 - 900
- Cabbage: 200 - 600
- Salad: 80 - 200
- Meats and livers: 20 - 150
⚠️ Vitamin K is sensitive to light.
Vitamin K deficiency is very rare because it is normally well supplied by food. However, malabsorption can occur.
The sufficient intake of vitamin K is 79 µg/day in adults .
What are the health claims of vitamin K?
EFSA authorises the use of health claims for products containing vitamin K.
They must provide a minimum of 11µg of vitamin K per 100g, 100ml or per portion.
Products meeting these criteria can claim to contribute to:
- to blood clotting,
- to the normal functioning of bones
What are the contraindications, side effects and interactions of vitamin K?
There are no known major side effects from taking vitamin K (except for vitamin K3 or menadione).
The precautions to take are related to drug interactions.
Drug and food interactions:
Anti-vitamin K (AVK) treatments "inhibit" vitamin K, this is the desired effect and it is advisable not to consume too many foods rich in vitamin K during these treatments.
There is a risk of hypothrombinemia during treatment with cephalosporins (cefamandole, cefoperazone, latamoxef...).
There are interactions in case of excess of vitamins A or E: coagulation problems.