What Is Vitamin K? - Benefits, Foods & Symptoms of Deficiency

Instructor: Jayne Yenko

Jayne has taught health/nutrition and education at the college level and has a master's degree in education.

We all need vitamins to maintain our health. Explore witamin K - what does it do in the human body, where does it come from, and what happens if we don't get enough.


Vitamin K is an organic, non-caloric substance found in living things that is essential for the human body to function properly. Organic in this instance means that the substance contains carbon, a vital component in all living things. Vitamin K is fat-soluble, meaning fat is required for the body to absorb it.

Vitamin K was discovered by a Danish scientist, Henrik Dam, in 1935. Dr. Dam was awarded the Nobel Prize for Physiology or Medicine in 1943 for his research into vitamin K.

Portrait of Henrik Dam
Henirk Dam, Discoverer of Vitamin K


The major role of vitamin K is to help make four of the thirteen proteins necessary for blood clotting. Without adequate amounts of vitamin K, excessive bleeding will result. Studies are being done to explore the role of vitamin K in bone health and also in cancer prevention. So far, those studies have been inconclusive.


Spinach, a good source of vitamin K
Spinach, a good source of Vitamin K

Good food sources of vitamin K are dark green leafy vegetables like broccoli, turnip greens, kale, spinach, and asparagus. Chlorophyll, the substance that gives plants their dark green color, contains vitamin K.

The bacteria in our digestive system also provide vitamin K, which is unique for vitamins.


Deficiencies of vitamin K are very rare, particularly for adults, but can arise from health conditions that cause absorption issues, such as Crohn's disease, gallbladder disease, or cystic fibrosis. Liver disease can cause vitamin K deficiency, as can long-term dialysis or chronic malnutrition.

Newborn infants lack the intestinal bacteria necessary for vitamin K production. To prevent the risk of bleeding, most newborns throughout the industrialized world are given an injection of vitamin K at birth. Pregnant women who take anti-seizure medications may be provided with a vitamin K supplement for the two to four weeks prior to giving birth to help reduce the chance of bleeding.

Symptoms of vitamin K deficiency include excessive bleeding, such as nose bleeds, bleeding gums, blood in the feces and/or urine, or extremely heavy menstrual periods. These symptoms can also indicate other health issues, so consultation with a physician is necessary.

The recommended amounts of vitamin K are 90 mcg for women and 120 mcg for men. There are no recommended maximum levels for vitamin K, although excessive amounts of vitamin K, usually from extreme supplementation, can result in severe allergic reactions.

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