K2 + D3: what do these vitamins do?

K2 + D3: what do these two vitamins do?

Vitamin D3 is known as the "sunshine vitamin". Vitamin D contributes to the normal absorption and utilisation of calcium and to the maintenance of normal bones. Vitamin K contributes to the maintenance of normal bones and to normal blood clotting. That is why the two are often offered together in one supplement. In this article you can read what both vitamins do, why they are often combined and how to choose a suitable form.

Arthur Andrew Medical

KD Ultra® – K2 D3 – 90 capsules

€50,95

Vitals

Bone and Dental Formula Pro – Calcium, Magnesium, D3, K2 & Silicon – 60 Tablets

€27,49 ~~€35,65~~ Bespaar 22%

Vitals

Vitamin K2 + D3 – 60 softgels

€19,33 ~~€25,45~~ Bespaar 24%

Trace Minerals

Ionic D3 + K2 – Liquid D3 & K2 – 59 ml

€36,67

Plent

D3 + K2 (MK-7) — 2000 IU + 75 µg — 90 capsules

€20,35

K2 and D3: how they relate, and what exactly K2 is

Vitamin D3 and vitamin K2 are often used together. Vitamin D contributes to the normal absorption of calcium and to normal blood calcium levels. Vitamin K contributes to normal blood clotting and, like vitamin D, to the maintenance of normal bones. Research also looks at the role of K2-dependent proteins such as osteocalcin and matrix Gla protein.

Because both vitamins play a role around calcium and bones, many people who use vitamin D3 choose a combination product that includes K2.

Source: EU Register on nutrition and health claims (Regulation (EU) 432/2012 — officially authorised health claims).

What exactly is vitamin K2 — and why not K1?

Vitamin K consists of two main forms: K1 (phylloquinone) and K2 (menaquinone). K1 is mainly found in green leafy vegetables. K2 is produced by bacteria — both in fermented products (natto, some cheeses) and to a limited extent by the bacteria in our own intestines.

K1 and K2 differ in their distribution in the body: K2 remains available in the blood longer than K1 and therefore also reaches tissues outside the liver, such as bones and blood vessels. Within the K2 family, MK-7 (menaquinone-7) is the form most often used in supplements; its half-life is approximately 72 hours.

Where is K2 found?

K2 is found in a limited number of foods. The best-known source is natto (fermented soybeans), a traditional Japanese dish that is rarely eaten here. Other sources are raw-milk cheeses (Gouda, Brie), egg yolk and organ meat. A supplement can be a practical addition to a varied diet.

Who often chooses a K2 + D3 combination?

People who already take vitamin D3 — a combination product is practical if you already take D3 every day.
People who pay attention to their bones — vitamin D and vitamin K contribute to the maintenance of normal bones.
Women during and after menopause — bones often get extra attention in this phase of life. K2 + D3 with calcium is then a commonly used combination; calcium also contributes to the maintenance of normal bones.
Vegans and vegetarians — K2 is mainly found in animal and fermented products.

If you only use a low dose of D3 and eat a varied diet, a separate K2 supplement is less obvious. In all cases, choose a product that suits your situation and follow the recommended daily dose on the label.

Frequently Asked Questions about K2 + D3

Can I take vitamin K2 if I am on blood thinners?

Vitamin K contributes to normal blood clotting and can affect the action of certain blood thinners (coumarin derivatives such as acenocoumarol or phenprocoumon). Individuals taking these medications should not supplement with K2 without first consulting their physician. For most other blood thinners (such as DOACs: rivaroxaban, apixaban), this interaction risk is significantly lower, but consultation with your physician remains advisable.

How much K2 do I need per day?

There is no separate recommended intake for K2. For vitamin K as a whole, the reference intake is 75 micrograms per day. Supplements usually use the MK-7 form. Follow the recommended daily dose on the label and consult your doctor or pharmacist if in doubt or if you take medication.

When is the best time to take K2 + D3?

Both vitamins are fat-soluble, so taking them with a fat-containing meal is advisable. The time of day matters less than the presence of fat — many people choose breakfast or lunch.

Can I combine K2 with magnesium and calcium?

Yes, they are often combined. Calcium, magnesium, vitamin D and vitamin K all contribute to the maintenance of normal bones, and vitamin D contributes to the normal absorption of calcium. Many bone formulas already combine these substances in one product.

Is K2 also suitable for pregnant women?

K2 supplementation is generally not specifically necessary for pregnant women, and the required approach varies per individual. Always discuss this with your midwife or doctor. For D3 during pregnancy, there is a specific recommendation from the Dutch Nutrition Centre.

Which K2 + D3 form is right for you?

Choosing the right combination

There are three main routes to combine K2 and D3 — as a ready-made combination product, as a separate supplement to an existing D3 intake, or as part of a broader bone formula. Which route is best depends on your current supplement use and preference.

Capsules (combination product)

A combination capsule with both K2 and D3 is the most practical route: one capsule per day, a fixed ratio between the two vitamins, taken with a fat-containing meal. Pay attention to the K2 form (preferably choose MK-7) and the dosage — and follow the recommended daily dose on the label.

Liquid (drops)

For those who do not want to swallow capsules, or for those who want to be able to vary the dosage, a liquid combination offers flexibility. Drops are also useful for the elderly or people with swallowing difficulties.

Bone formula (all-in-one)

For those who want more than just K2 + D3, there are bone formulas that contain calcium, magnesium, and silicon in addition to K2 and D3. These are often chosen by people who want several nutrients for the bones in one product.

In the Plenthera range

Arthur Andrew KD Ultra combines full-spectrum vitamin K2 (MK-4 + MK-7) with vegan vitamin D3 (100 micrograms / 4000 IU) in one capsule. This equals the safe upper limit that EFSA applies for adults, so do not combine it with other vitamin D supplements. Vegan. Plenthera is the exclusive supplier of Arthur Andrew Medical in the Netherlands and Belgium. For those who prefer a ready-made capsule with a classic ratio: Vitals Vitamin K2+D3 (60 caps, vegan). For fans of drops: Trace Liquid D3+K2 (59 ml).

Disclaimer: This article is for informational purposes only and does not replace medical advice. A dietary supplement is not a substitute for a varied and balanced diet and a healthy lifestyle. If in doubt or taking medication: consult a doctor or pharmacist. Do not exceed the recommended daily dose. Keep out of reach of young children.

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