Vitamin K plays a role in blood clotting. A Dutch study suggests that a vitamin K deficiency could worsen coronavirus infection. How? ‘Or’ What ? In which foods to find it? Should we supplement? What are its other benefits?
[Mis à jour le lundi 8 juin à 12h48] Is there a link between vitamin K deficiency and severe form of Covid-19 ? Yes, according to a study by scientists from the Netherlands conducted in partnership with the Maastricht Cardiovascular Research Institute and relayed by The Guardian on June 5, 2020. To reach this conclusion, the scientists compared blood tests of a group made up of 184 patients hospitalized for a severe form of coronavirus with those of another control group made up of uninfected people. They quickly found that people admitted to intensive care had vitamin K deficiencies compared to people with a mild form of Covid-19. Doctors explain that a severe form of Covid could cause blood to clot, which would cause the breakdown of elastic fibers in the lungs. Without these fibers, the lung would be more fragile and more easily infected with a virus. Vitamin K is essential for producing proteins capable of regulating blood clotting. “My advice would be to take these vitamin K supplements. While this does not help with severe Covid-19, it is good for your blood vessels, bones and probably also for your lungs“, recommends in the Guardian Dr. Rob Janssen, scientist specialist on the subject. What is the role of vitamin K? Where is it found? In what foods? How much is needed per day?
Vitamin K is a fat-soluble vitamin (soluble in fat), like vitamins A, D and E. It exists mainly in two forms: vitamin K1 (phytomenadione, phylloquinone or phytonadione) and the vitamin K2 (menaquinones). She is provided both by food, especially the green vegetables, and by the intestinal flora. Vitamin K1 is more directly involved in the coagulation process, while K2 acts more on the calcification of soft tissue. There is a third form (vitamin K3), synthetic, which is found in drugs, supplements or in multi-vitamin supplements.
Vitamin K requirements
- Man : 1 μg / kg body weight / d
- Women : 1 μg / kg body weight / d
Its name comes from German Koagulation in relation to the fact that it plays a role in blood clotting.
Vitamin K is essential to the process of blood clotting by allowing the production of certain factors of this coagulation in the liver. It also intervenes at the level of bone metabolism. “At any age, it is essential to have a good supply of vitamin K to promote growth and then renewal of bone tissue”, assures Professor Luc Christiaens, head of Cardiology at the Poitiers University Hospital. “It also plays an important role in bone mineralization: it is also proposed in the prevention of osteoporosis,”
Vitamin K is mainly known for its key role in blood clotting (and more specifically vitamin K1). She prevents bleeding by activating many coagulation factors.
Vitamin K supplementation is routinely given to the newborn in the maternity ward. It thus makes it possible to compensate for the nonexistent reserves of vitamin K in infants. This contribution limits the risk of bleeding in the first months of life.
To prevent hemorrhagic risks (which fortunately remain rare), doctors prefer to systematically supplement infants with vitamin K from birth and throughout the duration of exclusive breastfeeding.
Vitamin K1 is mainly found in dark green vegetables such as spinach, broccoli, kale and asparagus, as well as vegetable oils (olive, rapeseed, soy…). Vitamin K2, on the other hand, is found in fermented milk products (mature cheeses, yogurts, milk), organ meats and fish oils.
Examples of sources of vitamin K1 (contents taken from the ANSES Cliqual table):
- Kale (817 µg per 100g)
- Watercress (541 µg per 100g)
- Spinach (482 µg per 100g)
- Swiss chard (327 µg per 100g)
- Broccoli (141 µg per 100g)
- Rapeseed oil (71 µg per 100g)
- Olive oil (60 µg per 100g)
Examples of sources of vitamin K2 (contents from the ANSES Cliqual table):
- Goose liver (369 µg per 100g)
- Chicken leg (34.3 µg per 100g)
- Edam (34.3 µg per 100g)
The fruits richest in vitamin K (they contain between 1 and 10 µg per 100g) are: apple, date, fig, grape, peach, plum, rhubarb, blueberry, strawberry …
The foods poorest in vitamin K (less than 1 µg per 100g) are cow’s milk, yogurts, corn, white bread, potatoes, peanuts, mushrooms, turnips, cucumbers. .
The fruits poorest in vitamin K are: melon, watermelon, orange, pomelo, mango.
“Adequate daily intake is variable depending on age and sex: 30 to 75 mcg between 1 and 18 years old, 90 mg in adult women and 120 mcg in adult men. This vitamin K is stored in the liver for several months“, explains our doctor. Consequently, vitamin K deficiencies are rare in adults. However, they can appear during chronic intestinal diseases, cirrhosis of the liver or taking certain drugs. They will then lead to blood clotting failure (hypoprothrombinemia), which results in bruising, nosebleeds, heavy periods and brittle bones.
Many anticoagulant treatments (antivitamins K) work by blocking the activity of vitamin K. “In case of antivitamin K treatment, patients are advised to limit their consumption of foods rich in vitamin K and to avoid taking food supplements containing them” ensures our interlocutor. A decrease in the level of vitamin K is also to be reported in the event of prolonged antibiotic therapy. In fact, antibiotics by partially destroying the intestinal flora reduce the production of vitamin K. “In this case, it may be worth considering supplementation” concludes the professor.
Thank you to Professor Luc Christiaens, head of Cardiology at the Poitiers University Hospital.
–
