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Vitamin K Benefits, Uses, and Side Effects

By Sasha de Beausset Aparicio, MSc

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Vitamin K

Vitamin K is a fat-soluble vitamin, particularly important for blood clotting function. The “K” in its denomination stands for “Koagulationsvitamin,” which in German means “the coagulation vitamin.” Its name hence clearly establishes its most quintessential function. However, the nutrient has been attributed numerous other health-enhancing properties which we will further develop in the sections below.

There are three types of vitamin K known today, each with important benefits for certain body functions and processes. Vitamin K1, known as phylloquinone, directly influences the blood clotting function, as it is usually transported directly into the liver. This type is obtained from various dietary sources and is particularly abundant in green leafy vegetables. Vitamin K 2 or menaquinone is synthesized by the human body, in the GI tract from where it goes to support bone, blood vessel, and other tissue function other than that of the liver. Vitamin K3 known as Menadione is the synthetic form of vitamin K and may present a series of toxic side effects which should be discussed with a healthcare professional.

Because the nutrient is fat soluble, the body can make deposits of it and use as needed; this is why a deficiency is rare. Still, there are certain aspects of health that require additional vitamin K intakes, which we will further discuss.

Vitamin K Functions & Benefits

Vitamin K is sometimes referred to as “the forgotten vitamin” due to important benefits that are usually overlooked by scientists and nutritionists. Most commonly, when talking about this nutrient, the context is that of blood coagulation. The process of blood coagulation scientifically referred to as “coagulation cascade” is a series of interdependent events that finally result in clot formation. In this process, there are seven vitamin K-dependent factors, without which coagulation is not possible. These factors are synthesized at the liver level, hence liver conditions usually lead to uncontrolled bleeding and a higher risk of death in case illness is linked to bleeding. Anticoagulant medication works directly to stop Vitamin K function and hence prevent blood clots formation, which in some cases may prevent blood from circulating and lead to serious, potentially lethal, conditions. Vitamin K1 is the type that is involved in this process.

Bone formation is one of the processes dependent on Vitamin K, particularly the K2 type. Several proteins present in the bone mass are formed in the presence of vitamin K. These proteins are involved in the processes of preventing cartilage calcification and loss of bone mass and supporting bone mineralization. Increasing evidence points out the importance of optimum levels of this nutrient in the prevention of osteoporosis, freckle bones, and bone fractures associated with low bone density.

Another important benefit of the nutrient is encouraging cell growth and cell proliferation. Particularly, the vitamin is needed for the production of the Gas6 protein, which enjoys cell signaling properties as well as cell growth regulating properties. The protein is present in several cell tissues, such as the nerve cell, the lung, heart, and kidney and cartilage cells. The exact mechanism of action of the protein needs however further studying.

The relation between vitamin K and cardiovascular disease has also attracted increased attention from the scientific world. Because the vitamin plays a major role in calcium binding to the bone matrix, a deficiency of it means that excess calcium is free to travel in the blood, where it may be deposited on arteries’ walls, hence leading to a hardening of the arteries. In time this turns into a serious health condition called atherosclerosis which, in severe cases, may become fatal.

Cancer prevention is one other significant presumed benefit of this nutrient. Several studies involving the K1 and K2 types determined that the nutrient can slow down the growth of cancerous cells in the lungs, while several other studies showed that leukemia might find stabilization in the use of vitamin K. Although further research is needed to fully validate the extent of the action that the nutrient exercises on various types of cancer, results are promising.

Other numerous benefits of the nutritious substance played the central role in various clinical trials and scientific studies. While in-depth research may be needed to support these allegations, there are positive conclusions which indicate that vitamin k may benefit patients with Alzheimer’s disease (in the sense of preventing it), and people prone to developing type 2 diabetes (as the nutrient seems to improve insulin sensitivity). Also, the vitamin may possess antioxidant benefits which lead the way to a whole new set of potential benefits.


At the recommended dose, the nutrient is known to have a limited number of side effects, including a set of allergic reactions. Supplementation with this nutrient should be carefully considered by pregnant and breastfeeding women (because the vitamin can cross over the placenta and into breast milk as well), people who take Warfarin (an anticoagulant) or other blood thinning medications, people taking medications that lower cholesterol, or those who use weight loss medications which lower fat absorption capacity and hence the ability to assimilate vitamin K.

There are also several categories of people who cannot absorb proper amounts from this nutrient, including those who suffer from gallbladder disease, Chron’s disease, cystic fibrosis, or celiac disease. Infants up to one year of age should consume 2-2.5 mcg of vitamin k, while the dose increases to 75 mcg for adolescents aged 14 to 18. The adult dose varies according to age and gender: male adults should consume 120 mcg of vitamin K, whereas women are advised a 90 mcg daily intake. Pregnant and breastfeeding women should consider talking to their healthcare professional before setting their dose, which should vary between 75 and 90 mcg of vitamin K.


The nutrient can be obtained from a variety of food sources, while the body also synthesizes important amounts. One tablespoon of olive oil contains 8.1 mcg of vitamin k, while 1 cup of broccoli may provide the body as much as 220 mcg of vitamin K. Parsley, spinach, green lettuce, and kale also provides rich amounts from this vitamin. It is important to remember however that this is a fat-soluble vitamin and hence eating fat when taking a vitamin K supplementation is essential to nutrient absorption.