Is Vitamin K2 as Important as Calcium for Your Bones?

This trifecta will help support strong bones. 

Strong bones are an important foundation for health at every age. They allow you to lift heavier and run farther, and may help protect your organs. As you age, strong bones can help prevent fractures. The first nutrient that often comes to mind for supporting strong bones is calcium. (Got milk?) But did you know vitamin K2 is also linked to bone health? Vitamin K comes in a few forms that play a role in heart health, blood clotting, and bone health. Here’s what you need to know about its health benefits. 

What You Should Know About Vitamin K2 and Bone Health

Bone strength is usually pinned on calcium and vitamin D, but vitamin K2 plays a special role in the way we absorb these bone-supporting nutrients. Your body can’t make calcium on its own, so it relies on dietary sources. Calcium is the major mineral in your bones (where it is primarily stored) while vitamin D helps your gut absorb more calcium. Vitamin K2, on the other hand, is absorbed slowly by your body and works in conjunction with calcium and vitamin D to build strong bones. Vitamin K2 helps activate osteocalcin, a protein that helps calcium bind to bones to build and maintain them. As a bonus, it’s thought to direct calcium away from being deposited into your arteries, potentially protecting your cardiovascular health. 

Vitamin K is a fat-soluble vitamin that is found in two primary subtypes. Vitamin K2 (also called menaquinone) is found in animal products, fermented foods, and some cheeses. Unlike K1, much of it is produced by the bacteria in our gut during digestion.

Where K2 specifically shines is how it directs calcium, steering it into bone tissue to be stored and away from the bloodstream and arteries. “Vitamin K2 functions very differently in the body than vitamin K which is a blood clotting vitamin,” says Caroline Thomason Bunn, RD, CDCES. That’s what separates it from vitamin K1 (phylloquinone), the form found primarily in leafy greens. K2 is primarily found in animal products and fermented foods.

Going Deeper on Vitamin K2 and Your Bones

Bone density measures how much calcium and other minerals are present in your bone tissues, according to MedlinePlus. Bone density peaks between the ages of 25 and 35, and declines as you age. Nutrients in a well-rounded diet work together to support bone health. And research suggests that vitamin K2 is another piece in the puzzle helping to build strong bones. 

K2 activates proteins that determine where calcium moves in the body, shuttling it into the bones and away from soft tissue. Research published in the International Journal of Endocrinology found that vitamin D and vitamin K — both fat-soluble vitamins — rely on each other to build bone strength (and support heart health). Vitamin K helps direct calcium away from arteries, and low vitamin K status has been linked to more vascular calcification — part of why vitamin D and K are thought to work best together. You might consider adding foods rich in Vitamin K2 or talking to your doctor about a bone health supplement that includes vitamin K2 if you need one, Bunn says. 

New research also suggests diets rich in K2 may even help reduce fracture risk, though more understanding is needed in this area. A 2020 review found that supplementing with calcium, vitamin D, and K2 may improve bone quality and reduce fracture risk in patients who have low bone density. The research in this area is new, so for now, calcium and vitamin D are still the established nutrients of concern for of bone health, and K2 may play a supporting role.

The Takeaway

Vitamin K2 is an important nutrient to focus on (alongside calcium and vitamin D) if you’re worried about bone health. It comes from dietary sources, primarily animal products and fermented foods — things like natto (fermented soy), chicken breast, some cheeses, and egg yolks.

Currently, there’s no recommendation specific to K2. Instead, the adequate intake for vitamin K is 120 micrograms a day for men and 90 micrograms for women. But remember vitamin K and K2 are very different nutrients. It’s important to talk to your doctor before starting a new  supplement, especially if you’re taking blood thinners. 

Bottom Line

Right now, research is still evolving on the benefits of K2’s role in both bone health and fracture risk reduction. More research is needed, but dietary intake of vitamin K2 can help support your overall health. Well-researched calcium and vitamin D are still the way to build strong bones, but K2 should be a complement to the conversation.