Vitamin K refers to a group of fat-soluble vitamins that play a role in blood clotting, bone metabolism, and regulating blood calcium levels.
The body needs vitamin K to produce prothrombin, a protein and clotting factor that is important in blood clotting and bone metabolism. People who use blood-thinning medications, such as warfarin, or Coumadin, should not start consuming additional vitamin K without first asking a doctor.
Deficiency is rare, but, in severe cases, it can increase clotting time, leading to hemorrhage and excessive bleeding.
Vitamin K1, or phylloquinone, comes from plants. It is the main type of dietary vitamin K. A lesser source is vitamin K2, or menaquinone, which occurs in some animal-based and fermented foods.
Kale and other cruciferous vegetables are good sources of vitamin K.
Phylloquinone, also known as vitamin K1, is found in plants. When people eat it, bacteria in the large intestine convert it to its storage form, vitamin K2. It is absorbed in the small intestine and stored in fatty tissue and the liver.
Without vitamin K, the body cannot produce prothrombin, a clotting factor that is necessary for blood clotting and bone metabolism.
Most Americans are not at risk of a vitamin-K deficiency. It is most likely to affect newborns and those with a malapsorption problem, due, for example, to short-bowel syndrome, cystic fibrosis, celiac disease, or ulcerative colitis.
Newborns normally receive a vitamin K injection to protect them from bleeding in the skull, which could be fatal.
The recommended adequate intake for vitamin K depends on age and gender. Women aged 19 years and over should consume 90 micrograms (mcg) a day, and men should have 120 mcg.
Vitamin K benefits the body in various ways.
There appears to be a correlation between low intake of vitamin K and osteoporosis.
Several studies have suggested that vitamin K supports the maintenance of strong bones, improves bone density and decreases the risk of fractures. However, research has not confirmed this.
Increased blood levels of vitamin K have been linked with improved episodic memory in older adults.
In one study, healthy individuals over the age of 70 years with the highest blood levels of vitamin K1 had the highest verbal episodic memory performance.
Vitamin K may help keep blood pressure lower by preventing mineralization, where minerals build up in the arteries. This enables the heart to pump blood freely through the body.