What vitamin K does#
Vitamin K is best known for helping the blood clot normally. It is also part of the wider picture of bone metabolism, although it is not a stand-alone answer to bone problems.
Most adults get enough vitamin K from food, especially when the diet includes green vegetables. The vitamin is fat soluble, so it is absorbed best with a meal that contains some fat.
Food sources and supplement use#
K1 comes mainly from green vegetables such as spinach, kale, broccoli, and Brussels sprouts. K2 is found in smaller amounts in some animal foods and fermented foods. If your diet already includes vegetables regularly, you may not need a supplement at all.
Supplement claims should stay within the limits that apply to food supplements. Vitamin K is not a treatment for disease, and a product should not imply that it can fix a bone problem on its own.
Warfarin and consistency#
Vitamin K matters most when warfarin is part of the medicine list. In that situation, the important thing is consistency. Big swings in green vegetable intake or a new vitamin K supplement can change the balance of treatment, so the routine should be discussed with the prescriber first.
People using newer anticoagulants do not face the same vitamin K interaction, but a supplement still belongs in the overall medicine review, not in a guessing game.
When to seek care#
Seek care if you have unexplained bruising, a bleeding tendency, a known malabsorption problem, or a long course of antibiotics followed by new concerns about clotting. The same applies if you use warfarin and are unsure about a supplement or a major diet change.
If you have ongoing liver, bowel, or medication related concerns, the safest step is to review the whole picture before changing vitamin K intake.
Further reading and sources#
Further reading: