Vitamin K

Vitamin K is needed for blood clotting, which means it helps wounds heal properly.

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

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 do I 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, while a person 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).

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

Any vitamin K your body doesn't need immediately is stored in the liver for future use, so you don't need it in your diet every day.

What happens if I take too much vitamin K?

There's not enough evidence to know what the effects might be of taking high doses of vitamin K supplements each day.

What does the Department of Health and Social Care advise?

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, don't take too much as this might be harmful.

Taking 1mg or less of vitamin K supplements a day is unlikely to cause any harm.

Page last reviewed: Tue Mar 2020 Next review due: Wed Feb 2020