Vitamin K: The Forgotten Vitamin

by Melissa Chichester

Vitamin C. Vitamin D. Vitamin E. Most of us pride ourselves on being well-versed in the alphabet of letter vitamins, but what about what has been coined “the forgotten vitamin,” Vitamin K?

Vitamin K is a group of vitamins responsible for activating proteins in the body that are involved in normal blood clotting and bone health.* While Vitamin K deficiency is rare in adults, some populations are more at risk, including newborns and individuals taking antibiotics that interfere with absorption. The Vitamin K group is comprised of two main types: K1 and K2. While they are in the same group, these compounds are not found in the same food groups and are processed differently by the body.

The history of Vitamin K

Henrik Dam, a Danish scientist, discovered Vitamin K in 1929 while researching cholesterol in the diet. This study was conducted on chickens and the results were published in a German journal, which cited the compound “koagulationsvitamin.” Along with Dam’s discoveries, American biochemist Edward Adelbert Doisy researched the chemical structure of Vitamin K. This research led to both Doisy and Dam winning the Nobel Prize in 1943 for their discoveries.

Vitamin K1

Most food sources of Vitamin K consumed by humans is in the form of Vitamin K1, also known as “phylloquinone.” K1 is found in leafy greens like spinach, kale, and collard greens, and vegetables including broccoli, cabbage, and Brussel sprouts. Blueberries and pine nuts are also sources of Vitamin K1. Vitamin K1 is used by the body to help support normal blood clotting but is not as easily absorbed by the body as Vitamin K2.*

Vitamin K2

Most Vitamin K supplements come in the form of Vitamin K2.

Researchers believe the body may absorb K2 better than Vitamin K1, and that it might stay in the body longer.

Vitamin K2 is also found in several food sources, but the types of foods are very different. Vitamin K2 is very abundant in natto, a traditional Japanese food made with fermented soybeans. Natto has a slimy texture and strong smell that some say results in a bitter taste; many feel it is an acquired taste! Luckily, there are other sources of Vitamin K2 including egg yolks, beef liver, cheese curds, and dark meat chicken.

Fast facts on Vitamin K

Thanks to modern technology and research we are able to learn more about Vitamin K and its uses daily. Here are some other ways Vitamin K is being used and what we may learn about in the future:

  • Many newborns receive a Vitamin K injection.
  • Eating healthy fats with Vitamin K helps improve absorption by the body.
  • Vitamin K creams can be used on patients after cosmetic skin procedures to help with the appearance of bruised skin.
  • According to one study, people with higher Vitamin K intakes had improved joint health compared to people with low Vitamin K intake.*