Vitamin K: Where to find it and how to use it?

Vitamin K

Vitamin K is the blood clotting vitamin par excellence. In addition to its anti-hemorrhagic role, it also helps to preserve the health of bone tissue. There are several forms of vitamin K, one synthesized by plants and the other by bacteria in the intestinal flora of humans and animals. Although very rare in adults, vitamin K deficiency is common in newborn babies.

Characteristics of vitamin K:

  • There are three forms of vitamin K: K1, K2 and K3
  • Vitamin K1 is of vegetable origin, K2 of animal origin and K3 is synthetic
  • Allows blood coagulation and maintenance of bone tissue
  • Supplementation is strongly recommended in newborns to avoid hemorrhagic disease
  • In case of anti-vitamin K treatment, food intake can be controlled

Why consume foods rich in vitamin K?

Vitamin K: definition and benefits

Blood clotting

Vitamin K allows the synthesis of prothrombin and other proteins responsible for the activation of several coagulation factors. It is the coagulation vitamin par excellence. It limits the risk of hemorrhage.

Bone health

Vitamin K ensures healthy and strong bone mineral mass. It supports the action of osteocalcin, an important protein for the calcification of bone tissue. At all stages of life, a good supply of vitamin K is essential to promote the growth and then the renewal of bone tissue. It also helps prevent disorders related to bone demineralization such as osteoporosis.

Foods Rich in Vitamin K

There are two dietary forms of vitamin K: vitamin K1 and vitamin K2. Vitamin K1 is mainly found in foods of plant origin and K2 in foods of animal origin.

20 foods sources of vitamin K

Food Servings (µg)
Collard or kale, cooked                                                 1/2 cup                     442-561 mcg        
Boiled spinach 1/2 cup 469-543 mcg
Turnip, dandelion and beet greens, boiled 1/2 cup 280-368 mcg
Swiss chard cooked 1/2 cup 303mcg
cooked broccoli 1/2 cup 169 mcg
mesclun lettuce 1 cup 154 mcg
Raw spinach 1 cup 153mcg
raw escarole 1 cup 122mcg
Brussels sprouts cooked 4 cabbages (80 g) 118mcg
cooked broccoli 1/2 cup 86-116 mcg
leaf lettuce 1 cup 103mcg
red lettuce 1 cup 82mcg
Asparagus, raw or cooked 1/2 cup 48-76mcg
fresh parsley 15 ml (1 tbsp) 62mcg
Boston and romaine lettuce 1 cup 60-61mcg
Cabbage, raw or cooked 1/2 cup 39-55mcg
Kiwi 1 large (90g) 37mcg
Okras (okras), boiled 1/2 cup 34 mcg
Chinese cabbage, raw or boiled 1/2 cup 30-31 mcg
Raw green beans 1/2 cup 29mcg


How to properly use vitamin K?

Use of vitamin K

Vitamin K requirements

Adequate intake (AI)                                           
Babies 0-6 months                                                          2 mcg
Babies 7-12 months 2.5 mcg
Babies 1-3 years old 30mcg
Children 4-8 years old 55mcg
Boys 9-13 years old 60mcg
Girls 9-13 years old 60mcg
Boys 14-18 years old 75mcg
Girls 14-18 years old 75mcg
Men 19-50 years old 120mcg
Women 19-50 years old 90mcg
Men 50 and over 120mcg
Women 50 and over 90mcg
Pregnant women 90mcg
Nursing women 90mcg

Vitamin K in babies

Vitamin K supplementation in babies is very common, even systematic. It makes it possible to compensate for the lack of intake via breast milk and the non-existent reserves of the newborn. Thus, this supplementation limits the risk of hemorrhagic disease in the first months of life.

Vitamin K food supplements

Food supplements containing vitamin K are particularly recommended to prevent osteoporosis and cardiovascular diseases linked to the calcification of the vessels. The competent authorities recommend not to exceed the dosage of 25 micrograms per day to avoid the risk of overdose, the long-term consequences of which are still unknown.

Adverse effects of vitamin K

Vitamin K deficiency

Vitamin K deficiency in adults is extremely rare, newborns are most at risk. A deficiency can lead to hemorrhagic disease in the baby as well as abnormalities in bone growth. In adults, the main medium-term risk is bleeding. In the long term, it is possible to observe a demineralization of the bone and the occurrence of disorders such as osteomalacia or osteoporosis.

Is too much vitamin K dangerous for health?

There is no scientific study proving the deleterious effects of an excess of vitamin K. As a precaution, however, it is recommended to seek the advice of a doctor before considering drug supplementation with this vitamin.

Vitamin K and anticoagulant treatments

Vitamin K interacts with anticoagulant treatments (anti-vitamin K). Also, there is a decrease in vitamin K levels in case of prolonged antibiotic treatment. Indeed, a small part of vitamin K is synthesized by the bacteria present in the intestinal flora. However, antibiotics weaken these bacteria and can therefore induce a significant decrease in the production of vitamin K. In the event of anti-vitamin K treatment, it is therefore advisable to limit the dietary intake of this vitamin. On the contrary, in the event of prolonged antibiotic therapy, it may be worth considering supplementation.

Chemical properties

There is not a vitamin K but vitamins K forming a group of fat-soluble vitamins. They are essential for blood coagulation and the mineralization of bone tissue.

There are 3 vitamin K, all belonging to the quinone family. Vitamin K1 (phylloquinone) is only synthesized by plants. It is therefore found in foods of plant origin (cabbage, leafy green vegetables, etc.). Vitamin K2 (menaquinone) is synthesized by bacteria in the gut of mammals. it is found in foods of animal origin. Finally, vitamin K3 (menadione) is a synthetic form. Today, it is no longer used in human food. Indeed, being three times more active than other forms of vitamin K, it can cause significant side effects (nausea, headache, anemia, etc.).


Nutrient history

It was at the beginning of the 1920s that the Danish biochemist C. Dam made the fortuitous discovery of vitamin K. At the time and while he was carrying out studies on cholesterol, he realized that chickens deprived of lipids suffer from bleeding. This is how he discovered the presence of vitamin K (for Koagulation in German), the molecule responsible for blood clotting.

Fifteen years later, he succeeded in purifying vitamin K from alfalfa and then chemically synthesizing it with the help of E. Doisy. In 1943, a Nobel Prize in Medicine was awarded to C. Dam and E. Doisy for their discoveries about vitamin K.

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