As well as getting vitamin K from food, we also get it from our own bodies because it's produced by bacteria in our intestines.
How much do I need?
Vitamin K is a fat-soluble vitamin. This means you don't need to have it every day because any of the vitamin your body doesn't need immediately is stored in the liver for future use.
You should be able to get all the vitamin K you need by eating a varied and balanced diet.
Adults need approximately 0.001 mg per kg of body weight a day. So someone who weighs 65 kg would need 0.065 mg per day of vitamin K, while a person who weighs 75 kg would need 0.075 mg per day.
What does it do?
Vitamin K has a number of important functions. For example it's needed for blood clotting, which means it helps wounds heal properly.
There is increasing evidence that vitamin K is also needed to help build strong bones.
What happens if I take too much?
There isn't enough evidence to know what the effects might be of taking high doses of vitamin K supplements each day.
What is our advice?
You should be able to get all the vitamin K you need by eating a varied and balanced diet. But if you decide to take vitamin K supplements it's a good idea not to take too much because this might be harmful.
Taking 1 mg or less of vitamin K supplements a day is unlikely to cause any harm.