Vitamin K: The complete guide!

Vitamin K is an essential nutrient that plays a particularly important role in blood clotting in the body. It also has several other functions.

In this article you will read about the functions of vitamin K, sources of vitamin K, the consequences of an excess or deficiency and more.

Vitamin K is a fat-soluble essential nutrient. Fat-soluble means it dissolves in fat, not in water. Therefore, it is better absorbed when combined with fat.

In addition, your body stores the substance, rather than urinating it out when you have an excess. While there are no downsides to taking too much vitamin K, it's best not to overdo it with supplements, as with any fat-soluble vitamin. The harmful effects of such supplements are unclear.

There are two different types of vitamin K:

• Vitamin K1 (phytomenadione)
• Vitamin K2 (menaquinone)

Vitamin K2 is a bit more complex, as there are several different forms of vitamin K2. The most common of these are:

• Vitamin K2 MK-4
• Vitamin K2 MK-7

In addition, there are some forms of vitamin K2 (called menaquinones) such as MK-5, MK-6 and MK-8. However, these are much less common. [4]

To give you an idea of ​​the different types of vitamin K , we have worked this out in an image.

Both vitamin K1 and vitamin K2 have similar effects in the body. However, one form (vitamin K1) is broken down more quickly than the other (vitamin K2).

For optimal body function, you want to get enough of both types. Here are some differences between the various forms of vitamin K.

Vitamin K1:

• Also called phytomenadione
• Found mainly in plant foods (green leafy vegetables, broccoli)
• Is broken down faster by the body

Vitamin K2

• Also called menaquinone
• Comes in several forms: MK-7 is the most effective
• Mainly found in animal foods (meat, dairy, eggs)
• Also found in fermented products
• Can be produced by intestinal bacteria
• Is broken down more slowly by the body

While many vitamins have a wide range of functions, vitamin K is more concise. The vitamin primarily influences two specific bodily processes: blood clotting and bone health.

The best-known function of vitamin K is its contribution to normal blood clotting. It supports proteins that, in turn, ensure proper blood clotting. This discovery was made by chance in the late 1920s when animals with a deficiency bleed more. The same was found to be true for humans.

In addition, vitamin K supports bone health. It plays a role in both bone formation and bone maintenance. Vitamin K also plays a role in the absorption of calcium from the blood.

Vitamin K2 supports calcium metabolism. A vitamin K2 deficiency from food can contribute to higher calcium levels in the blood vessels. This is not beneficial for blood vessel function[1].

If you eat a healthy and varied diet, a vitamin K deficiency is rare. However, it can happen, for example, with long-term use of antibiotics or an inadequate diet. The Reference Intake (RI) for adults is 75 micrograms per day.[3]

The optimal dosage of vitamin K can vary based on age and individual needs. General recommendations are provided below.

Newborn babies naturally have a vitamin K deficiency. Babies are therefore given vitamin K drops immediately after birth. This supports healthy blood clotting in the baby[2][3].

Breastfed babies should also receive 150 micrograms of vitamin K drops as a supplement from their doctor for the first 12 weeks. Formula already contains vitamin K, so supplementation isn't necessary, provided the baby drinks enough.

Of course, discuss this first with a medical specialist.

It's very important for a pregnant woman to get enough vitamin K during pregnancy. However, this isn't necessary for the baby, as vitamin K cannot be passed to the baby through the placenta.

Getting enough vitamin K is important during pregnancy because a vitamin K deficiency from food can lead to bleeding, which you absolutely want to avoid.

Below is a table of some good food sources of vitamin K, with the amount of vitamin K per 100 grams.

As you can see, the largest amounts are found in green leafy vegetables, herbs, and fermented products like Natto.

Plant foods are rich in vitamin K1 , while animal foods and some fermented foods such as natto are rich in vitamin K2.

If you eat a healthy and varied diet (including animal products), vitamin K deficiency is generally unlikely. This is different for babies. They do develop vitamin K deficiencies, which is why they receive a supplement at birth and afterward.

There is a possibility that a newborn baby has a vitamin K deficiency. This can be due to a number of causes:

1. The placenta - Vitamin K cannot reach the baby through the placenta.
2. Intestinal bacteria - Babies do not yet have enough intestinal bacteria, which means they cannot produce vitamin K themselves.

A more common cause of vitamin K deficiency in adults is the use of antibiotics. Antibiotics kill all bacteria, but unfortunately, they also kill the good bacteria that produce vitamin K2 in your intestines.

A vitamin K deficiency can therefore occur when killing these bacteria. This risk is greater with prolonged or regular use of antibiotics.

Because vitamin K contributes to normal blood clotting and bone health, a deficiency in dietary vitamin K may have the following consequences[2]:

1. Spontaneous or severe bleeding (in infants)
2. Delayed blood clotting
3. Bruising more easily
4. Wounds heal less quickly
5. Long-term bone problems

There are no known cases of vitamin K overdose. Therefore, no maximum dosage has been established for vitamin K.

People who use blood thinners should be careful when using vitamin K as a supplement.[3]

Taking extra vitamin K can hinder the effectiveness of blood thinners. Therefore, do not take high doses of vitamin K if you are taking these types of medications and always consult a medical specialist.[4]

Vitamin K is a vitamin with important functions, such as promoting healthy blood clotting and maintaining strong bones.

It is important that you get enough vitamin K through a healthy and varied diet rich in green leafy vegetables, other vegetables and sources such as eggs, meat and liver.

An inadequate diet or medications can cause a deficiency and it is important to avoid this for healthy bones and good blood clotting.

There are many vitamin K supplements on the market, but not all are equally absorbable. When taking a supplement, choose one that's easily absorbed and of good quality.

Sources

1. www.ncbi.nlm.nih.gov/pmc/articles/PMC8596038/
2. www.ivg-info.nl/voedingssupplementen/vitamines/vitamine-k/vitamine-k-tekort /
3. www.voedingscentrum.nl/encyclopedie/vitamine-k
4. www.ncbi.nlm.nih.gov/books/NBK551578/