What does vitamin K do?

In a nutshell

In a nutshell

  • Vitamin K is vital to stop the bleeding in case of injury.
  • This vitamin helps make strong bones and prevent fractures
  • Vitamin K is produced in the guts by the good intestinal microflora. Antibiotics intake could harm this source of the vitamin.
Essential for:
blood clotting
Brain health
brain health
strong bones
Key sources:

intestinal microflora



swiss chard

swiss chard





brussel sprouts

brussel sprouts



Goose liver

goose liver

What does vitamin K do?

Vitamin K plays a significant role in the activation of the blood clotting process - it is vital to the stopping of bleeding in case of injury.
This vitamin helps make strong bones and prevent fractures- it is especially important for older adults who have an increased risk of falling. Vitamin K has also been shown to avoid the hardening of the arteries and parts of the heart. There is a modern theory that K extra intake may help in preventing or treating Alzheimer's disease. Also, there is new evidence of the anti-aging benefits of vitamin K.

Forms of the vitamin
Vitamin K is a fat-soluble vitamin. There are two forms of the vitamin - K1 and K2.
K1 can be found in plant-based food sources, especially in green, leafy vegetables. When found in plant sources, the scientific name is phylloquinone. The best K1 foods include kale, spinach, greens, swiss chard, parsley, brussel sprouts, romaine lettuce, and broccoli.
Sources of K2 (menaquinone) are the animal origin.

Vitamin K deficiency

A lack of this vitamin is rare. The shortage of vitamin K in the food hardly can be a reason for the deficiency. Deficiency usually develops as a consequence of malabsorption.

Vitamin K is produced in the guts by the good intestinal microfloraPeople who take antibiotics for extended periods may all be under increased deficiency risk, due to antibiotics defeats essential intestinal microflora as well as pathogen bacteria against which this antibiotic was prescribed.

Also, people who suffer from severe burns may all be under increased deficiency risk. The problem connected to intensive antibiotic treatment.

Symptoms of a deficiency in this vitamin include:
• Excessive bruising or bleeding;
• Loss of bone or decrease in bone density;
• Fractures;
• Calcium deposits, especially in soft tissue.

Vitamin K overdose

There are no toxicity or overdose concerns for the intake of the natural or supplement forms of this vitamin found in the United States. Therefore, there is no maximum limit for this vitamin set. Studies have been done on people who eat high levels of this vitamin naturally through diet and who also take supplements with no adverse effects to be found. There is one human-made version of this vitamin, known as menadione or K3, that can cause damage to cells, especially in the liver or kidneys. Menadione is prohibited from being sold as a supplement in the United States.

Daily Recommended Intake

The daily recommended intake of the vitamin for adults is 90-120 µg.

Sources of vitamin K
The following plant sources have high amounts of K1:
• parsley, fresh (100g) - 1640 μg of vitamin;
swiss chard (100g) - 830 μg of vitamin ;
• kale (100g) - 705 μg of vitamin;
 spinach (100g) -483 μg of vitamin;
brussel sprouts (boiled) (100g) - 140 μg of vitamin;
romaine lettuce (100g) -103 μg of vitamin ;
broccoli (100g) - 102 μg of vitamin.
Enough of this vitamin can be obtained from eating just one of these foods on a daily basis.

The following food have high amounts of K2:
goose liver (100g) - 369 µg of vitamin;
hard cheeses  (100g) - 76 µg of vitamin;
soft cheeses  (100g) -  57 µg of vitamin;
chicken liver (100g)  - 13 µg of vitamin;

Other important sources of the vitamin:
• butter;
• chicken breast;;
• whole milk;
• eggs.

Why "K"?

This vitamin was identified in 1935 by a Danish scientist who was studying clotting of blood. Henrik Dam named this as "Koagulations-vitamin", using the German word for blood clotting. This mouthful was later shortened and the vitamin was named "K".