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 calcium together?
You don’t need to take them together.
As of August 2026, vitamin D and calcium have been tested together in 1 trial, in healthy postmenopausal women, and no clear added effect was found. Scored under the same rules as everything here.
7 studies · 1 tested the actual pair · 1 caution
What you’re seeing
- Vitamin D renders hollow: for bone, it is well studied and it does not work.
- Calcium renders hollow: for bone, it is well studied and it does not work.
- The woven cord is the rare part: one trial gave both together, and no clear added effect was found.
- The red spark: In the largest trial of this pair, calcium plus vitamin D increased the risk of kidney stones. Stay near label doses and talk to your doctor if you have had stones.
You can tell before you read a word.
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 pair trial
- 2006Randomized trial · 36,282 people · healthy postmenopausal women · no clear effectsource
The other 6 studies on file tested each one alone. See all 7 studies
Fair questions
Is it safe to take vitamin D and calcium 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?+
1 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
Calcium
- Bonehollow
- Pregnancyhalf-there
Pairs that have been tested+
- Vitamin D has been tested with magnesium, selenium, folate, chromium, probiotics, omega-3.
- Calcium has been tested with magnesium, probiotics, kava, vitamin K2.
These are the combinations someone has actually run a study on. Every other pairing here is air.
Worth knowing+
- In the largest trial of this pair, calcium plus vitamin D increased the risk of kidney stones. Stay near label doses and talk to your doctor if you have had stones.