Supplement IQ

Pairs › Vitamin D + vitamin K2 Dataset v1

Tested together · 3 trials
Vitamin DVitamin K2
What do the states mean?+
  • Solid: well studied, and it works.
  • Half-there: the science is still forming.
  • A ghost: almost no real studies.
  • Hollow: well studied, and it does not work.
  • A cord: the pair itself has been tested together.
  • Air: nobody has ever tested this pair.

The full scoring method: How we score

Can you take vitamin D and vitamin K2 together?

Tested together, early signs.

As of August 2026, vitamin D and vitamin K2 have been tested together in 3 trials, in older men with calcium build-up on a heart valve, children on dialysis and adults with long COVID, and the early results lean positive, though the largest trial found no clear effect. Scored under the same rules as everything here.

35 studies · 3 tested the actual pair

See all 35 studies

What you’re seeing

  • Vitamin D renders hollow: for bone, it is well studied and it does not work.
  • Vitamin K2 renders half-there: for bone, the science is still forming.
  • The woven cord is the rare part: three trials gave both together, and the early results lean positive, though the largest trial found no clear effect.

You can tell before you read a word.

Creatine monohydrate · solid2 scored studies on its main claim.
Vitamin B12 · half-there1 scored study on its main claim.
Deer antler velvet · a ghost1 scored study on its main claim.
NEVER TESTED TOGETHERSCREENED AUG 2026MagnesiumL-theanine

Magnesium + L-theanine are sold together in the same aisle. No trial has ever tested the pair. When that is true, we draw nothing between them. The nothing is the review.

The three pair trials

  • 2022Randomized trial · 365 people · older men with calcium build-up on a heart valve · no clear effectsource
  • 2022Randomized trial · 60 people · children on dialysis · the pair helpedsource
  • 2025Randomized trial · 151 people · adults with long COVID · the pair helpedsource

The other 32 studies on file tested each one alone. See all 35 studies

Fair questions

Is it safe to take vitamin D and vitamin K2 together?+

The studies on this page gave both together and reported no harm from the combination. That is not the same as a safety trial, and it says nothing about your dose or your medication.

How many studies is this based on?+

3 that gave the pair together. The papers are listed above with links to the source.

Deeper

What each one is on its own+

Vitamin D

  • Bonehollow
  • Blood sugarsolid
  • Pregnancyhalf-there

Vitamin K2

  • Bonehalf-there
  • Blood sugarhalf-there
  • Cholesterolhollow
  • Hearthalf-there
  • Inflammationhollow
  • Moodhalf-there
  • Strength and powerhalf-there
Pairs that have been tested+

These are the combinations someone has actually run a study on. Every other pairing here is air.