Summary
Vitamin K (“Koagulationsvitamin”) is a fat-soluble vitamin stored in fat tissue and the liver. It is best known for its role in helping blood clot properly. Vitamin K also plays an important role in bone health. People who have higher levels of vitamin K have greater bone density, while low levels of vitamin K have been found in those with osteoporosis.
It is rare to have a vitamin K deficiency. That’s because in addition to being found in leafy green foods, the bacteria in your intestines can make vitamin K. Sometimes taking antibiotics can kill the bacteria and lead to a mild deficiency, mostly in people with low levels to begin with. Vitamin K deficiency can lead to excessive bleeding, which may begin as oozing from the gums or nose. Other things that may lead to vitamin K deficiency include:
- Health problems that can prevent your body from absorbing vitamin K, such as gallbladder or biliary disease, cystic fibrosis, celiac disease, and Crohn’s disease
- Liver disease
- Taking blood-thinners, such as warfarin (Coumadin)
- Long-term hemodialysis
- Serious burns
Sources
Foods that contain a significant amount of vitamin K include beef liver, green tea, turnip greens, broccoli, kale, spinach, cabbage, asparagus, and dark green lettuce. Chlorophyll is the green substance in leaves providing vitamin K.
Freezing foods may destroy vitamin K, but heating does not affect it.
Safety and limits
Assuming no interfering medication, Vitamin K in its natural forms has an extremely low potential for toxicity. The Council for Responsible Nutrition recommends a safe upper limit of 10 mg / day.