If you’re wondering what this all means for your supplement routine, right now, well, the answer is not much.
“Some companies offer vitamin D3 and vitamin K2 combination supplements, and that’s fine,” says mbg director of scientific affairs Ashley Jordan Ferira, Ph.D., RDN. “They are simply two of the four fat-soluble vitamins our body needs, though, and the direct combination of them in supplements has nothing to do with their absorption; that’s a misconception.” (Vitamin D is required for calcium absorption, hence why you’ll almost always find some necessary vitamin D in calcium supplements.)*
In many cases, fat-soluble vitamins are combined together in supplements for convenience, according to Ferira, who says that supplement complexes containing all four fat-soluble vitamins are also found in the market, including in a high-quality, comprehensive multivitamin.
Ultimately, though, pairing vitamin D and vitamin K2 together in a supplement doesn’t affect the absorption or bioavailability of either, Ferira says, urging that “there is no science to back such a proposition.”
When it does really make sense to see vitamin D (specifically vitamin D3, which is the body’s preferred form) and vitamin K2 together in one supplement? If it’s specifically formulated to support bone or heart health, says Ferira, “like a bone- or heart-health targeted complex.” After all, both nutrients contribute to these areas of your health in significant ways.*