Vitamin K is the blood clotting vitamin par excellence.
In addition to its anti-haemorrhagic role, it also helps to maintain healthy bone tissue.
There are several forms of vitamin K, one synthesised by plants and another by bacteria in the intestinal flora of humans and animals.
Although very rare in adults, vitamin K deficiency is common in newborn babies.
Vitamin K characteristics
- There are three forms of vitamin K: K1, K2 and K3.
- Vitamin K1 is of plant origin, K2 is of animal origin and K3 is synthetic.
- Enables blood clotting and maintains bone tissue.
- Supplementation is strongly recommended in newborn babies to prevent haemorrhagic disorders.
- Food intake can be controlled with anti-vitamin K treatment.
The benefits of vitamin K
Blood clotting
Vitamin K enables the synthesis of prothrombin and other proteins responsible for activating several clotting factors.
It is the coagulation vitamin par excellence.
It limits the risk of bleeding.
Bone health
Vitamin K helps maintain healthy and strong bone mineral mass.
It supports the action of osteocalcin, a protein that is important for the calcification of bone tissue.
At all stages of life, a good intake of vitamin K is essential to promote the growth and subsequent renewal of bone tissue.
It also helps to prevent diseases associated with bone demineralisation, such as osteoporosis.
Foods rich in vitamin K
There are two dietary forms of vitamin K: vitamin K1 and vitamin K2.
Vitamin K1 is found mainly in plant foods and K2 in animal foods.
Foods - Portions - Amounts of vitamin K in µg/mcg
- Cooked cabbage - 1/2 cup = 442-561 mcg
- Cooked spinach - 1/2 cup = 469-543 mcg
- Turnip, dandelion and beet leaves, cooked - 1/2 cup = 280-368 mcg
- Beet leaves, cooked - 1/2 cup = 303mcg
- Broccolini, cooked - 1/2 cup = 169 mcg
- Mesclun lettuce - 1 cup = 154 mcg
- Raw spinach - 1 cup = 153mcg
- Raw escarole - 1 cup = 122mcg
- Cooked Brussels sprouts - 4 cabbages (80g) = 118mcg
- Lettuce leaves - 1 cup = 103mcg
- Red lettuce - 1 cup = 82mcg
- Asparagus, raw or cooked - 1/2 cup = 48-76mcg
- Parsley - 15ml (1 tbsp) = 62mcg
- Romaine lettuce - 1 cup = 60-61mcg
- Cabbage, raw or cooked - 1/2 cup = 39-55mcg
- Kiwi - 1 large (90g) = 37mcg
- Okra, cooked - 1/2 cup = 34 mcg
- Chinese cabbage, raw or cooked - 1/2 cup = 30-31 mcg
- Green beans, raw - 1/2 cup = 29mcg
Vitamin K requirements
Adequate Intake (AI)
- Infants 0-6 months = 2 mcg
- Infants 7-12 months = 2.5 mcg
- Infants 1 to 3 years = 30mcg
- Children 4 to 8 years = 55mcg
- Boys 9 to 13 years = 60mcg
- Girls 9 to 13 years = 60mcg
- Boys 14 to 18 years = 75mcg
- Girls from 14 to 18 years = 75mcg
- Men from 19 to 50 years = 120mcg
- Women aged 19 to 50 = 90mcg
- Men aged 50 and over = 120mcg
- Women aged 50 and over = 90mcg
- Pregnant women = 90mcg
- Women who are breastfeeding = 90mcg
Vitamin K for babies
Vitamin K supplementation in infants is very common and even systematic.
It makes up for the lack of intake through breast milk and the lack of reserves in the newborn.
This supplementation limits the risk of haemorrhagic disease in the first few months of life.
Vitamin K supplements
Vitamin K supplements are particularly recommended for the prevention of osteoporosis and cardiovascular disease associated with vascular calcification.
The competent authorities recommend that doses not exceed 25 micrograms per day to avoid the risk of overdose, the long-term effects of which are still unknown.
Vitamin K deficiency
Vitamin K deficiency is extremely rare in adults, but newborn babies are most at risk.
Deficiency can lead to bleeding disorders in babies and abnormalities in bone growth.
In adults, the main medium-term risk is bleeding.
In the long term, bone demineralisation and disorders such as osteomalacia or osteoporosis may occur.
Is too much vitamin K bad for your health?
There are no scientific studies to prove that an excess of vitamin K is harmful.
However, as a precaution, it is recommended that you consult your doctor before considering supplementing with this vitamin.
Vitamin K and anticoagulant treatment
Vitamin K interacts with anticoagulant (anti-vitamin K) treatments.
In addition, prolonged treatment with antibiotics reduces vitamin K levels.
In fact, a small amount of vitamin K is synthesised by bacteria in the intestinal flora.
However, antibiotics weaken these bacteria and can therefore cause a significant reduction in vitamin K production.
In the case of anti-vitamin K treatment, it is advisable to limit the dietary intake of this vitamin.
On the other hand, in the case of prolonged antibiotic therapy, it may be worth considering supplementation.
Chemical properties
There is no single vitamin K, but rather a group of fat-soluble vitamins.
They are essential for blood clotting and the mineralisation of bone tissue.
There are 3 types of vitamin K, all of which belong to the quinone family.
Vitamin K1 (phylloquinone) is only synthesised by plants. It is therefore found in foods of plant origin (cabbage, green leafy vegetables, etc.).
Vitamin K2 (menaquinone) is synthesised by bacteria in the intestines of mammals and is found in foods of animal origin.
Finally, vitamin K3 (menadione) is a synthetic form.
It is no longer used in human food.
As it is three times more active than other forms of vitamin K, it can cause serious side effects (nausea, headaches, anaemia, etc.).