Vitamin K2 And D3: Should You Take Them Together?

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 body's most important minerals: calcium! And better calcium delivery means support for bone health and cardiovascular health. Talk about a dynamic duo!

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

The benefits of taking vitamin K2 and vitamin D3

The reason why you want to take these two vitamins together is because they offer your body more benefits when combined. In fact, they work together within the body: 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 vitamin K and D combo supplement and also adds iodine, which is great for supporting thyroid health.

How much vitamin K2 and D3 should I take 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.

The best way to know how much vitamin D3 you need is to take 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.

What is vitamin K2?

Vitamin K is a 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 of vitamin K 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 is vitamin D3?

Vitamin D is both a vitamin—and also 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.  

While you can get vitamin D through sun exposure, 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. The best vitamin D food sources are 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 vitamin D good for?

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.

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 is the 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." When you hear people talking about a vitamin D supplement, chances are, they mean the D3 type.

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.

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

Can you take vitamin D3 without K2?

Yes. 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 K2 and D3: 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

• Dereje S et al. "Cholecalciferol (D₃) Versus Ergocalciferol (D₂) in Older Adults. The Consultant pharmacist: the journal of the American Society of Consultant Pharmacists., June 2017, https://pubmed.ncbi.nlm.nih.gov/28595683/
• Higdon, Jane Ph.D., et al. "Vitamin K." Micronutrient Information Center, Linus Pauling Institute, Oregon State University, 2000-2021, https://lpi.oregonstate.edu/mic/vitamins/vitamin-K
• van Ballegooijen AJ, et al. "The Synergistic Interplay between Vitamins D and K for Bone and Cardiovascular Health: A Narrative Review." Int J Endocrinol. 2017. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5613455/
• Wasilewski G, et al. "The Bone-Vasculature Axis: Calcium Supplementation and the Role of Vitamin K." Frontiers in Cardiovascular Medicine. 2019. https://www.researchgate.net/publication/330875570_The_Bone-Vasculature_Axis_Calcium_Supplementation_and_the_Role_of_Vitamin_K
• "Vitamin D Deficiency." MedlinePlus, September 2021, https://medlineplus.gov/vitaminddeficiency.html
• "Vitamin K, Fact Sheet for Health Professionals." NIH, September 2021, https://ods.od.nih.gov/factsheets/VitaminK-HealthProfessional