Vitamin K is an essential vitamin. It is one of the four fat-soluble vitamins, along with vitamin A, vitamin D, and vitamin E. It was named vitamin K after the German word koagulation, because vitamin K’s role in blood coagulation was first discovered in Germany. Vitamin K can be found in dark green vegetables, matcha tea and natto (fermented soybeans). Vitamin K2 can also be found in animal products, since it is a result of bacterial fermentation.
The Recommended Daily Intake (RDI) of vitamin K is sufficient to support healthy blood coagulation. Higher levels of vitamin K, however, provide benefits for cardiovascular and bone health. Unfortunately, it is difficult to obtain high levels of vitamin K from food alone. Most people don’t like natto enough to eat 50g a day, so supplementation of vitamin K is a popular option.
Optimal levels of vitamin K are associated with improved bone circumference and diameter. Vitamin K can also protect cardiovascular health. It reduces the calcification and stiffening of arteries, which reduces the risk of cardiovascular-related mortality. Vitamin K may have a role to play in cancer therapy and anti-aging treatments. It may also help with regulating insulin sensitivity and reducing skin reddening, but more research is needed to determine if vitamin K has an active role to play in these areas.
Vitamin K’s main mechanism is through the vitamin K cycle, which is a cyclical metabolic pathway that uses vitamin K to target specific proteins. When a protein expresses glutamate, it is targetted by vitamin K, which causes it to collect more calcium ions. Calcium ions are removed from the blood stream, which prevents buildup in the arteries.
Vitamin K is often supplemented alongside vitamin D, since vitamin D also supports bone health. In fact, taking both together will improve the effects of each, since they are known to work synergistically. Excessive vitamin D can lead to arterial calcification, but vitamin K reduces this buildup.