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Vitamin K - Vitamins and minerals

Vitamin K is a group of vitamins that the body needs for blood clotting, helping wounds to heal.

There's also some evidence that vitamin K may help keep bones healthy.

You should be able to get all the vitamin K you need by eating a varied and balanced diet.

If you take vitamin K supplements, do not take too much as this might be harmful. Taking 1mg or less of vitamin K supplements a day is unlikely to cause any harm.

Good sources of vitamin K

Vitamin K is found in:

  • green leafy vegetables – such as broccoli and spinach
  • vegetable oils
  • cereal grains

Small amounts can also be found in meat and dairy foods.

How much vitamin K you need

Adults need approximately 1 microgram a day of vitamin K for each kilogram of their body weight.

For example, someone who weighs 65kg would need 65 micrograms a day of vitamin K. Someone who weighs 75kg would need 75 micrograms a day.

A microgram is 1,000 times smaller than a milligram (mg). The word microgram is sometimes written with the Greek symbol μ followed by the letter g (μg).

Your body stores any vitamin K you do not need immediately in the liver for future use. So you do not need it in your diet every day.


Content supplied by the NHS and adapted for Ireland by the HSE

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This project has received funding from the Government of Ireland’s Sláintecare Integration Fund 2019 under Grant Agreement Number 123.

Page last reviewed: 27 April 2023
Next review due: 27 April 2026