Vitamin K is actually a group of chemicals required by the human body. Deficiencies of vitamin K can occasionally cause bleeding disorders.
What Does It Do?
It is most important for producing blood clotting factors, especially prothrombin. Also, evidence is increasing that it is helpful for bone strength.
How Do We Get It?
Most of our vitamin K comes from food. Spinach, kale, parsley, broccoli, cabbage, turnips, liver, cereals and green tea are all good sources. It is found in lots of other foods in lesser amounts.
While we get most of our vitamin K from food, the bacteria in our gut also produces some. While we absorb that produced by bacteria in the small bowel, we don't absorb that produced in the large bowel.
Newly born babies need a higher dietary intake of vitamin K. This is probably partly because they don't have any bacteria in their gut, so need to get their intake from elsewhere. Also, vitamin K is fat-soluble and the placenta doesn't easily transmit substances that are fat-soluble. Consequently, new borns have low vitamin K levels.
What are the Symptoms and Signs of a Deficiency?
Although a deficiency can cause a bleeding disorder, this doesn't often happen, unless a person has a pre-existing illness.
We tend to become deficient in vitamin K for these reasons:
New born babies are often given supplementation with vitamin K. This is sometimes administered orally and sometimes by intramuscular injection. Insufficiency in premature babies is a particular problem, and babies whose mother's take anti-epilepsy medicines are also particularly at risk. Severe deficiencies in babies can cause a hemorrhagic disease.
People with insufficient levels of vitamin K have an increased likelihood of bruising and bleeding.
Should We Supplement?
If you eat a varied diet there should be no real need to take extra supplementation. As we store vitamin K in the liver and fat cells, deficiency is generally less of a problem than with some other vitamins and we don't need a daily intake. However, some people take vitamin K2 supplements when they are taking calcium for their bone strength. It is thought to aid more efficient calcium absorption. If you do decide to supplement, the United Kingdom's National Health Service (NHS) recommendation is that you take 1mg or less daily. People taking anti-coagulating drugs should be careful about their intake. It can affect how these medications work. Simply eating a balanced, healthy diet is the best way to maintain adequate levels.