Phylloquinone is another name for vitamin K1, a vitamin primarily used by the body for proper blood clotting. Vitamin K1 is a fat-soluble vitamin, which means that excess amounts are stored in the body’s fat tissue rather than being excreted like water-soluble vitamins. The name vitamin K comes from the German word for blood clotting, or koagulation.
Several foods are naturally high in phylloquinone, including vegetables such as spinach, Brussels sprouts, and cabbage. Phylliquinone is also present in avocados, coffee, green tea, and several types of beans. In addition to dietary sources, the bacteria species normally present in the human gut produce this vitamin. This production can be enhanced by consuming cultured milk and yogurt products.
The wide assortment of foods with high phylloquinone levels and the fact that this vitamin is produced in the human gut means that deficiencies of vitamin K are rare, especially in westernized countries. Some people may be at increased risk for this deficiency, however, including people on anticoagulants, with liver problems, or on very strict diets. Other people with abnormal bowel function, such as inflammatory bowel disease or people on high or extended regimens of antibiotics, may also be at risk for deficiency. Symptoms of deficiency are related to the blood clotting functions of this vitamin, and include frequent nosebleeds, bleeding gums, easy bruising, or heavy bleeding during menstruation.
A dangerous condition in newborns known as hemorrhagic disease was associated with lack of normal vitamin K1 levels. This is explained by the fact the newborns do not yet contain the vitamin K1-producing species of bacteria in their gut. For this reason, babies born in the US are given shots of vitamin K. A small minority has stated that these shots are associated with increased rates of childhood leukemia, but because no connection has actually ever been proven, vitamin K shots are standard practice in the US and are required by law in some states.
In addition to its role in blood clotting, phylloquinone is necessary for certain proteins important in bone formation. Because of the association of vitamin K with bone formation, several studies have examined the possible relationship between low vitamin K levels and the development of osteoporosis. Osteoporosis is a relatively common condition in petite women of European descent in which the bones become brittle and prone to fracture after menopause.
Although a few studies have suggested that there might be a link between low vitamin K levels and a higher risk of hip fracture, the results were inconclusive and an actual link between vitamin K and osteoporosis is unclear. Despite this lack of clarity, many natural osteoporosis treatments involve increased intake of vitamin K. In addition, several over-the-counter bone-building supplements contain this vitamin in addition to vitamin D and calcium.