Vitamin K: food sources, functions, side effects and daily dosing

Vitamin K: food sources, functions, side effects and daily dosing
April 9, 2014 1:17 AM

Did you take your vitamins today? Why your body needs them? Vitamins maintain a level of nutrition in your body. Small amount of these organic compounds helps smooth functioning of metabolic processes in human body. An adequate intake of vitamins is important as deficiency of vitamins can cause complicated diseases in human body There are thirteen recognized vitamins. Each vitamin shows different biological activities in human body.

This article is about vitamin K. Its dietary sources, function and side effects in human body and dietary recommendations.

What is vitamin K?

It is a fat soluble vitamin that is used for human blood coagulation and in elders helps to maintain strong bones.

Two natural vitamins are a part of this group: Vitamin K1 and Vitamin K2.

Phylloquinone or vitamin K1 is derived from plant sources. K1 is found in green leafy vegetables like fresh spinach, fresh goutokala or swiss chard. K1 functions to produce proteins that help in blood clotting.

Menaquinone is also known as K2. K2 can be abbreviated as MK-n, where M stands for Menaquinones, K stands for vitamin and n stand number of isoprenoid side chain. . Vitamin K2 has Isopreneoid side chain that is enlarge by bacteria’s. Notably homologues of vitamin K2 range from MK-7 to MK-11.

Deficiency of K2 can cause disruption in calcium regulation. It also increases the risks of heart diseases and atherosclerosis. Lack of calcium regulation will lead to increased deposits of calcium in arteries leading to coronary thrombosis, renal and neurogenarative diseases.

Food Sources of vitamin K

We discussed two types of vitamin K, which are K1 and K2. Here are the food source of these vitamins.

Food sources of Vitamin K1

Below you can check the vitamin K1 contents (μg) (percentage of daily value in %) as per 100g serving.

  • Leafy greens: 882 (1103%)
  • Scallions: 207 (259%)
  • Brussels sprouts: 194 (242%)
  • Broccoli 220 (276%)
  • Asparagus 80 (100%)
  • Cabbage 68 (85%)
  • Parsley 11 (553%)
  • Swiss Chard 35 (636%)

Leafy Greens seems to be on top of the list. Fresh Greens leafs are used in our daily routine food like salad. Vitamin K1 can also be in vegetable oil like soybean oil, olive oil, cottonseed oil and canola oil.

Below is the list of amount of vitamin K found in vegetable oil items (as per 1Tbsp in μg).

  • Olive Oil: 8.1 (High)
  • Safflower 1.0 (Low)
  • Sesame 1.8 (Medium)
  • Sunflower 1.0 (Low)
  • Peanut oil 0.1 (Low)
  • Canola Oil 17.1 (High)

Sources of Vitamin K2

Here we will discuss the sources of vitamin K2.

Vitamin K2 is present in animal stuff like cheese, butter and fish eggs. Let’s see how much vitamin you can get from these sources (in mcg):

  • Beef pork 41.7
  • Chicken drums 35.7
  • Cream cheese 19.7
  • Egg yolk 15.5
  • Chicken Liver(raw) 14.1
  • Meat Frank 9.8
  • Soft cheese 10.2
  • Butter 15
  • Goose egg 31
  • Beef Pork Salami 28

Above data is collected from USA National Nutrient Database for Standard Reference.

Other then above proportion of Vitamin K2 is found in chicken leg, ground beef, hot dog and bacon. However in skimmed milk the amount of vitamin K2 is zero.

Vitamin K in fruits

Vitamin K can also be found in fruits like grapes, black barriers, strawberries, apricot, banana orange and watermelon. But one thing must be noted here that fruits don’t contain as much vitamin K as is present in other plant and animal sources.

Functions of Vitamin K

Vitamin K plays a vital role in regulating several important biological functions of the human body. Vitamin K mainly controls the clotting of blood and regulates the amount of calcium in the blood.

Deficiency of vitamin can cause Osteoporosis and Osteopenia. The functions of vitamin K are as follows. Vitamin K and Formation of Blood clot. When your skin gets cut and start bleeding it’s important to stop this bleeding. This process is called “hemostasis” (Hem=blood, stasis=to put a stop).

The main function of vitamin K is to prevent body form bleeding otherwise it can lead excessive bleeding and circulatory shock.

But how does vitamin K accomplishes this function?

Before we can understand the function of vitamin K in the clot formation, we need to know a little about blood clotting cascade.

Clotting cascade is the activation of a cascade of enzymes, the end result of which is the production of fibrin clot. This fibrin clot puts a stop to the site of bleeding. Clotting is a complex process, at least 12 protein need in that process. At least four of clotting factors requires Vitamin K for completion of their activity.

Vitamin acts a co-enzyme and speeds up the activity of these enzymes, thus speeding up the formation of clot. But too much clotting can cause block of blood flow in the arteries of heart or in brain that can cause stoke or pulmonary embolism. That’s where nature comes in.

Body stores little amount of vitamin K and it never exceeds certain limits and never causes excessive clot formation. Vitamin K and Bone Health.

Vitamin K is a necessary element for working of proteins knows as Osteocalcin, matrix Gla protein and bone Gla protein. All these proteins are essential in the development and mineralization of the bones. These proteins then interact with the calcium, thus giving bones their hard texture.

Vitamin K is a vital element in the formation of bone. People with bowel disease are at a potential risk to develop weak bones because their gut is unable to absorb adequate vitamin K.

Researchers recommend 100 mcg of vitamin K for strong bone formation.

Vitamin K and vitamin D interaction

Vitamin K2 assists vitamin D3 function in strengthening the bones and uplifting the cardiovascular health. Vitamin D helps in absorption of calcium in building of strong bones.

Vitamin K has the ability to modulate calcium balance, researchers say. It means vitamin K deposits calcium only where it is needed (bones) and doesn’t deposit it in other sites.

Vitamin K and Cell Growth

Growth arrest specific 6 or Gas 6 is the protein that is vitamin K dependent. This protein helps in cell growth and signaling functions. The deficiency of this protein effects nervous system, lungs, kidney, stomach and cartilage. Gas6 also helps the cells communication with each other.

Side effects of vitamin K

Anything performs the needed functions only when it is kept within normal limits. As soon as it gets deficient or in excess things start to go out of order. Same is true for vitamin K as well. If you take this vitamin in a quantity more than which is needed, you might have to face following side effects:

  • Oral side effects of the recommended vitamin K dose are rare.
  • Do not take vitamin K in form of pills without consent of your health provider. People who are using supplements for heart problems or against clotting should use adequate amount of Vitamin K in form of food.
  • One side effect of vitamin K is just direct extension of its physiological function. If the amount of vitamin K exceeds normal values, abnormal blood clots can form.

Symptoms of lack of Vitamin K

Vitamin K helps in blood clotting, formation of strong bones and cell growth. However, lack of vitamin K can result in following symptoms:

  • Bleeding through gum and nose
  • Prostate cancer
  • Increased Clotting times
  • Increased menstrual bleeding
  • Blood collects under skin
  • Nose, mid face of new born are not developed properly
  • Weak muscles
  • If the dosage is as low as 300 IU it can cause Diplopia.
  • Stomach pain
  • Factor XII deficiency
  • Fractures

How much Vitamin K to take?

Vitamin K is a vital nutrient. It is recommended for every age group especially during pregnancy because there are greater chances of hemorrhagic diseases in the fetus. When the daily intake of vitamin K is inadequate in the mother, small amount of this vitamin crosses the placenta to reach to the fetus. When this happens, the chances of abnormal hemorrhage increase substantially. However, there is another side of the picture too.

Large amount of vitamin K in pregnant women can cause jaundice in the newborn. It is suggested that pregnant women between the ages of 19 to 50 should take 90 micrograms of this vitamin each day. Women that are breast feeding can use 75 micrograms of VK in day. Taking Vitamin K from natural sources will not result in any side effect.

Other recommendation

Other then above, recommendations for vitamin K are as follows:

For children:

  • From 1 year to 3 year - 30 micrograms per day
  • Between 4 to 8 years - 55 micrograms per day
  • From 9 to 13 years - 60 micrograms per day


  • In girls up to age 14 to 18 years - 75 micrograms per day
  • In boys up to age of 14 to 18 year - 75 micrograms per day

In older adults:

  • For women: 19 or up 90 micrograms per day
  • For men: 19 or up 120 micrograms per day
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Written by: Michal Vilímovský (EN)
Education: Medical student, 3rd Faculty of Medicine, Charles University, Prague, Czech Republic
Published: April 9, 2014 1:17 AM
Next scheduled update: April 9, 2016 1:17 AM
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