Vitamin K2 And D3: Should You Take Them Together?

Vitamin K2 And D3: Should You Take Them Together?

Scientifically reviewed by: Michael A. Smith, MD

What are the benefits of taking vitamin D3 and vitamin K2 together?

These two vitamins have a better harmony with each other than any other two vitamins. Together, they help optimize the proper delivery of one of the bodies most important minerals:  calcium! Accomplishing this will not only support bone health, but cardiovascular health as well.

Here, we’ll explain the benefits and answer common questions about vitamin D3 and vitamin K2.  

What is vitamin D3 good for?

Man wearing t-shirt while cycling for better vitamin d3 absorption

Vitamin D3 has been shown to provide a variety of benefits such as promoting bone health, supporting a healthy inflammatory response, supporting the immune system, and maintaining already-normal blood pressure levels.  That’s why some consider the “sunshine vitamin” to be the most important vitamin in the body.

Did you know that this nutrient is also considered a hormone? This is because vitamin D3 can be synthesized naturally in our bodies in response to sunlight, can act as a signaling molecule, and nearly every cell in our body has receptors for it.

Most notably, it enhances calcium delivery by increasing the absorption of calcium through the intestinal walls. In fact, in the absence of vitamin D3, we only absorb 10-15% of calcium from the food we eat, but when vitamin D3 is present, the calcium absorption is increased to 30-40%.

What are good sources of vitamin D3?

Sunlight is good for us, but we must be careful not to get too much. That’s why the best way to maintain optimal vitamin D3 is through daily supplementation.

You can also find vitamin D3 in the highest quantities from animal sources; good choices are seafood such as salmon, swordfish, white fish, and tuna.  Other healthy options for vitamin D3 include hard boiled eggs and white meats.

For vegans, the foods with the highest vitamin D content are mushrooms, particularly portobello mushrooms.

What is the difference between vitamin D and vitamin D3?

Woman holding two vitamin d supplement capsules

There’s actually not a meaningful difference between vitamin D and vitamin D3! Vitamin D3 is the most popular form of vitamin D on the market, and it’s commonly referred to just as “vitamin D.”

There are other types of vitamin D, such as vitamin D2, but research suggests this form does not raise levels of the active form of vitamin D as efficiently as vitamin D3. The primary reason why some people might choose to supplement with vitamin D2 over vitamin D3 is because they are looking for a vegan form of this nutrient, and vitamin D2 is usually plant-based. It’s also pretty inexpensive.

Vitamin D3 supplements are available that are vegan friendly; however, they are sometimes more expensive than animal-sourced products.  

What is vitamin K2?

Spinach being washed for a source of vitamin k1

Vitamin K is another fat-soluble vitamin that exists in two forms: vitamin K1 (phylloquinone, mainly found in green leafy vegetables) and vitamin K2 (menaquinone, mainly found in fermented dairy and produced by specific bacteria in the intestine). Vitamin K2 is the more bioavailable form, and it remains in the body longer. It further breaks down into different subtypes called its menaquinone forms.

Here are the important menaquinones forms:

  • MK-4 – This is a rapidly absorbed form that helps calcium get into the bone matrix.
  • Trans-MK-7 – This form remains bioavailable to the human body over a sustained period and helps keep your arteries healthy and flexible.
  • MK-6 and MK-9 – These forms are associated with better overall cardiovascular health, arterial flexibility, and longevity.

What are the benefits of taking vitamin D3 and K2 together?

Woman in baton race similar to how vitamin D and K work together

So how do vitamin D3 and vitamin K2 work together in harmony? Vitamin D3 directs the absorption of calcium from your intestines into the blood. Vitamin K2 takes it from there, directing that calcium into your bones.

Think of it this way: calcium is like a baton, and vitamins D3 and K2 are like runners in a game of relay baton. Taken alone, both vitamins have multiple benefits, but to fully utilize and benefit from calcium, you should supplement with both vitamin D3 and K2.  Fortunately, you can find a high-quality supplement that combines both of these vitamins and also adds iodine, which is great for supporting thyroid health.

How much vitamin D3 and K2 should I take daily?

Optimal dosing for these two is easy to figure out! You’ll need to know your starting point first, however—we recommend a simple blood test that measures a major circulating form of vitamin D in the body called 25-hydroxyvitamin D.  Life Extension advocates an optimal level of 25-hydroxyvitamin D should be between 50-80 ng/mL. This means that usually most people will need to take between 2,000-10,000 IU (50 mcg-250 mcg) daily.

For vitamin K, at least 2.5 mg of a total vitamin K (including K1 and K2) should be taken daily. Some people will need more depending on the status of their bone and arterial health; if you’re not sure where you stand, consider taking tests that evaluate bone and arterial health.

Can you take vitamin D3 without K2?

It won’t hurt to take these two supplements separately, but it will save you time to take them together. The only real consideration to keep in mind is taking vitamin D3 without taking any vitamin K, because if you have a high level of vitamin D3 without enough vitamin K, the calcium might not transfer to the bones properly and instead end up in the vascular tissue. This is because vitamin K is required to activate proteins that concentrates calcium to bones, such as matrix GLA and osteocalcin.

Vitamin D3 and K2: Are there any side effects?

Both vitamins have a strong safety profile even at high dosages. If you’re taking any medications, check with your doctor about your vitamin K intake, however.

References