Vitamin K
Vitamin K is not a single chemical substance but rather a family of chemically related substances that go by the general name of "vitamin K." Over the past 20 years, no vitamin family has undergone a greater change in terms of our scientific understanding of its chemistry and function. In the past, members of the vitamin K family have traditionally been referred to as vitamin K1, vitamin K2, and vitamin K3. This terminology is largely being replaced by a different set of terms to describe what has now been determined to be a more complicated set of vitamin K compounds.
All types of vitamin K fall into a large chemical category of substances called naphthoquinones. Within this naphthoquinone category, there are two basic types of vitamin K. The first type, called phylloquinones, is made by plants. The second basic type, called menaquinones, is made by bacteria.
Contrary to some previous scientific assumptions, we get most of our dietary vitamin K in the form of phylloquinones from plant foods. In fact, up to 90% of our dietary vitamin K comes in this form, and within that 90%, over half comes from vegetables— especially green leafy vegetables. Many different types of bacteria in our intestines can make vitamin K in the form of menaquinones.
Several forms of vitamin K are used around the world as medicine. Vitamin K1 is generally the preferred form of vitamin K because it is less toxic, works faster, is stronger, and works better for certain conditions.
In the body, vitamin K plays a major role in blood clotting. So it is used to reverse the effects of “blood thinning” medications when too much is given; to prevent clotting problems in newborns who don’t have enough vitamin K; and to treat bleeding caused by medications including salicylates, sulfonamides, quinine, quinidine, or antibiotics. Vitamin K is also given to treat and prevent vitamin K deficiency, a condition in which the body doesn’t have enough vitamin K.
Persons deficient in vitamin K are first and foremost likely to have symptoms related to problematic blood clotting or bleeding. These symptoms can include heavy menstrual bleeding, gum bleeding, bleeding within the digestive tract, nose bleeding, easy bruising, blood in the urine, prolonged clotting times, hemorrhaging, and anemia.
A second set of vitamin K deficiency-related symptoms involves bone problems. These symptoms can include loss of bone (osteopenia), decrease in bone mineral density (osteoporosis), and fractures—including common age-related fractures like that of the hips.
Yet another set of vitamin K deficiency-related symptoms involves excess deposition of calcium in soft tissues. These calcification-based problems include hardening of the arteries or calcium-related problems with heart valve function.
Any health problems that compromise digestion and/or absorption of nutrients can contribute to deficiency of vitamin K. Problems with pancreatic function, liver function, or gallbladder function can also increase our risk of vitamin K deficiency.
Because our intestinal bacteria help supply us with vitamin K, any drugs that alter our normal intestinal bacteria can compromise our vitamin K status. At the top of this drug list would be antibiotics but also included would be some anti-seizure medications, sulfa-drugs, and salicylate-containing drugs.
There is some evidence that the process of aging itself may contribute to deficiency of vitamin K. The reasons for this potential connection between aging and vitamin K are not clear.
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