Vitamin K Deficiency and Excess

Vitamin K is anti-hemorrhagic and is essential in blood clotting processes. Some studies support that it may play an important role in keeping bones strong in old age.

Vitamin K is one of the four fat-soluble vitamins, necessary for good health , since it participates, among other functions, in blood coagulation and bone metabolism .

Where is vitamin k found?

This vitamin is present in many foods, so if you follow a varied and balanced diet it is easy to meet your needs. It can be found in:

  • Green leafy vegetables such as spinach, kale, collard greens, broccoli, lettuce …
  • Vegetable oils.
  • Some fruits like figs or blueberries.
  • Meat, cheese, eggs.
  • In soybeans

How much vitamin do you need daily?

The amount of vitamin that is needed daily depends on age and sex . In children, there is no difference between sexes, so babies up to six months need 2.0 micrograms (mcg) a day; babies 7 to 12 months 2.5 mcg; from 1 to 3 years they need 30 mcg; ages 4-8, 55 mcg; ages 9-13, 60 mcg; ages 14 to 18, 75 mcg. The men over 19 need 120 mcg a day, and women over 19, 90 mcg , including breast feeding or pregnancy.

Vitamin K deficiency

Vitamin K deficiency is rare , since it is present in many foods, so that, in developed countries, following an adequate diet achieves the recommended daily needs . In addition, the bacteria in the colon produce a certain amount of this vitamin that the body is able to absorb. There are some population groups with a higher risk of suffering from a deficiency of this vitamin, and if this occurs and the deficiency is significant, it can have some consequences such as:

  • Appearance of bruises and bleeding problems because blood clotting worsens, which is much slower. The most common are nasal bleeding, mucosal bleeding, gastrointestinal bleeding, stool bleeding, much heavier and longer menstrual periods.
  • The strength of the bones can be reduced and the risk of osteoporosis increased due to its participation in bone metabolism.

Population groups at higher risk of suffering from vitamin K deficiency

  • Newborn : vitamin K does not cross the mother’s placenta easily, newborns do not have intestinal bacteria yet, so they will not be able to produce vitamin K, and in breast milk (or artificial milk) there are sufficient levels. Therefore, intramuscular vitamin K is administered, if not, the risk of bleeding is high.
  • People with certain disorders (such as cystic fibrosis, celiac disease, ulcerative colitis, short bowel syndrome) that decrease the amount of vitamin K that the body absorbs.
  • People who have had bariatric surgery .
  • People who take blood clotting inhibitor (anticoagulant) drugs or antibiotics for long periods of time, severe liver problems, and people with fat absorption problems.

How is this deficit diagnosed?

The diagnosis is made through a blood test. The suspicion of vitamin deficiency occurs when there are abnormal and habitual bleeding in a person in the risk population group. The blood test measures the speed of clotting and helps confirm the diagnosis.


If deficiency is diagnosed, vitamin K is usually given orally or by injection under the skin . If the cause is a drug, the dose should be adjusted or more supplements given. For newborns, an injection of the vitamin is given.

Excess of vitamin k

There are not many studies evaluating the toxicity of vitamin K, and hypervitaminosis values cannot be reached through diet alone.
The consequences could appear after the administration of supplements (menadione) , when it is in very high doses, producing hypervitaminosis . The effects can be:

  • Interference with some antioxidants.
  • Irregular blood clotting
  • Jaundice (yellowish color) in the skin and eyes due to excess bilirubin.
  • Liver problems
  • Hemolytic anemia.
  • Neurological conditions in infants.

Therefore, taking vitamin K supplements without consulting the doctor is not recommended in any case, but there must always be a diagnosis that confirms that there is a problem with said micronutrient.
What you should know…

    • Newborns are at risk of vitamin K deficiency because they do not get enough of it before birth and because they cannot yet synthesize this vitamin on their own, or it is given to them by injection.
    • It is present in many foods, so if you follow a varied and balanced diet it is difficult not to meet your needs.
    • Suspicion of vitamin K deficiency occurs when there are abnormal and habitual bleeding in a person in the risk population group.

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