Vitamin K’s primary function is to help make a protein known as prothrombin, which is necessary for helping blood to clot. It also aids the body in making some other proteins for the blood, bones, and kidneys. And it may have another function: helping to prevent Alzheimer’s. A 2016 study done at the University of North Carolina suggests that vitamin K affects calcium in the brain, which in turn lessens the risk of Alzheimer’s.
Vitamin K is unique in that as well as being obtained from the diet, it is also made in the body from bacteria in the intestines. The prolonged use of antibiotics may affect your level of K because they destroy some bacteria in your intestines. If you’re on antibiotics, it may make sense to supplement your vitamin K levels. There have been no reported problems in ingesting excess amounts of vitamin K, though moderation is always the best policy. Vitamin K has no established UL (upper limit).
Foods rich in vitamin K include wheat bran, wheat germ, beef liver, egg yolk, broccoli, cabbage, and green leafy vegetables, like turnip greens, spinach, and kale.