What Is Vitamin K In?

Vitamin K may not be as widely known as other vitamins, but without it we could bleed to death from something as minor as a paper cut. The letter "K" comes from the German word "koagulation." The coagulation properties afforded by this vitamin enable blood to clot and wounds to heal. Vitamin K also plays a crucial role in bone mineralization. Fortunately, vitamin K is easily obtained in a well-balanced diet.

Vegetable Sources

Vitamin K is sometimes added to multivitamin supplements, but it's easy to obtain the necessary amount of vitamin K from the foods we eat. The best sources are leafy, green vegetables, such as kale and spinach. Just 1/2 cup of cooked spinach satisfies nearly 500 percent of your daily needs. Cruciferous vegetables, such as Brussels sprouts, broccoli, and cabbage, are also great sources of vitamin K.

Fermented Food Sources

Fermented foods are also very good sources of vitamin K. During the fermentation process, bacteria are able to convert the vitamin into forms that are useful in the body. Fermented soybeans, or tofu, and certain types of Swiss and Jarlsberg cheeses usually contain high levels. Interestingly, bacteria in the human colon produce vitamin K in a similar manner; however, very little of that is absorbed back into the body.

Daily Intake

The National Academy of Sciences has set an Adequate Intake (AI) of 90 and 120 μg/day for women and men, respectively. This is easily satisfied by consuming 1 cup of steamed broccoli, for example. Clinical deficiency is rare, but can result in excessive bruising or bleeding in extreme cases. Since toxicity is also rare, there has been no upper limit set on daily consumption.

Considerations

Vitamin K is fat-soluble, which means consuming a source of fat is necessary for optimal absorption. Persons taking anticoagulant medications should pay special attention to their vitamin K consumption, as the vitamin counteracts the effects of these drugs. Experts usually recommend that people continue to consume enough vitamin K to meet AI recommendations. However, it is important to consult with your doctor about any supplements you are taking and potential food-drug interactions.