Vitamin K

Vitamin K is one of the lesser-known vitamins. It’s even less likely to be a major player in the multivitamins you take! Surprisingly, though, this bears no relation to its importance in the body.

Even though it may not be a miracle worker with widespread benefits, its job is very important. Read on to learn more about what Vitamin K is, what it does, and where to find it.

What Is It?

Vitamin K is a fat-soluble vitamin. Fat-soluble vitamins are those that are best absorbed by the body with the aid of fat. As such, they are best consumed with a meal containing at least a small amount of fat.

In addition to the forms of Vitamin K that the body absorbs with the help of fat from your everyday diet, the large intestine utilizes specialized bacteria to produce another type of Vitamin K. It is believed that both the ingested and intestinally synthesized forms of Vitamin K are important and contribute to your body’ overall Vitamin K levels.

What Is Its Biological Role?

The primary biological role of Vitamin K is to function as a coenzyme.[1] Coenzymes are compounds in the body other than proteins that are required for a given enzyme to function properly.

Vitamin K functions as a coenzyme for multiple enzymes, primarily those that deal with blood clotting and proper mineralization of bones. There are also some Vitamin-K dependant proteins that exist in smooth muscles, cartilage and bone.

Protein that is Vitamin K dependant will not form without proper levels of Vitamin K in the body to draw from; these proteins are currently being studied as possible ways to help address illness resulting in abnormal bone calcification.

How Does It Help Bodybuilders and People Who Work Out?

Vitamin K is crucial for all group of people to maintain optimal health. However, due to its effect on bone health, bodybuilders in particular may want to pay as much attention to their Vitamin K intake as they do their calcium intake.

Both calcium and Vitamin K are responsible to an extent for moderate proper bone density and mineralization; without these processes, the additional stress on the bones that results from weightlifting could result in injuries due to stress fractures.

What Foods Contain It?

The most abundant source of Vitamin K found in nature is green leafy vegetables,[2] such as kale, collard greens, or spinach. It can also be found in vegetable or soybean oils, and very small amounts are present in eggs and some dairy products such as certain cheeses.

How Much Of It Do You Need?

Recommended daily intake levels for individuals under 19 varies greatly depending on age and sex. After 19, men are recommended 120mcg per day while women are recommended 90mcg per day.

The recommended intake levels for women do not increase for women who are pregnant or breastfeeding. This is actually because it is quite common for infants born in a hospital setting to be treated with Vitamin K at birth.

Are There Risks Associated With Consuming Too Much Of It?

Whether or not you need to worry about consuming too much Vitamin K depends in part on what other health concerns you have. With Vitamin K mainly affecting your blood’s ability to clot, taking routine blood thinners may mean to need to moderate your Vitamin K consumption because it may reduce the effectiveness of these medications.

There is no officially established upper limit of Vitamin K for the general population however, and as such no known adverse side effects that can be characterized as Vitamin K toxicity.

Are There Risks Associated With Consuming Too Little Of It?

Most standard diets are more than sufficient in Vitamin K. Sub-par levels of Vitamin K in the body can be moderated if they are sporadic; because Vitamin K is fat-soluble, it is also stored by the body until needed and this feature can help offset occasional dips in Vitamin K levels.

Your intestines also use bacteria to make Vitamin K. Between all these factors, Vitamin K deficiency [3] does not start to produce symptoms until extremely severe. Symptoms are all various representations of your body losing its ability to clot properly and include bleeding of the gums, bruising too easily, and difficulty stopping bleeding when the skin has been cut or punctured.

Final Take

Just as with most other vitamins, researchers remain unsure whether consuming Vitamin K from supplements is as effective as consuming foods that are naturally rich in the vitamin.

Whatever you choose, Vitamin K is an oft-overlooked powerhouse that ensures your body’s timely response to injury and helps to maintain strong and healthy bones. If you’re interested in going the whole-foods route, try adding side dishes like collard greens into your rotation, or using spinach in salads over romaine.

Even adding a bit of kale into a smoothie can boost your natural Vitamin K intake. Small changes like this can make a surprisingly big impact over time.


[1] WebMD. Vitamin K: Uses, Deficiency, Dosage, Food Sources, and More., 2016.

[2] Dr. Axe, Josh. Top 10 Vitamin K Rich Foods., 2016.

[3] Dr. Johnson, Larry. Vitamin K-Nutritional Disorders., 2016.