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 L-arginine and vitamin D together?
Nobody has tested this pair.
As of August 2026, no human trial has given L-arginine and vitamin D together. We searched PubMed for trials naming both on 26 August 2026 and read every candidate it returned; none tested the pair.
35 studies · none tested the actual pair · 1 caution
See what each one is on its own
What you’re seeing
- L-arginine renders half-there: for endurance, the science is still forming.
- Vitamin D renders hollow: for bone, it is well studied and it does not work.
- Nothing is drawn between them, because nothing has been run. The empty space is the review.
You can tell before you read a word.
Vitamin D + vitamin K2 is what the other answer looks like. Someone ran the study, so a cord is drawn between them. That is the whole difference.
Fair questions
Is it safe to take L-arginine and vitamin D together?+
No trial has tested the combination, so there is no evidence either way. Nobody has found a problem, and nobody has looked.
Why does this page say nobody has tested it?+
Because we ran the search and read the results. The date above is the day we ran it. We do not claim a pair is untested without a logged search behind it.
Will this page change?+
Yes, if a trial publishes. We re-run these searches and the page changes from air to a cord the day the evidence does.
Deeper
The search we ran+
On 26 August 2026 we asked PubMed for trials, reviews and meta-analyses naming both L-arginine and vitamin D. It returned 3 candidates. We read every one and none gave the two together. This page carries a date because the answer can change: if a trial publishes, the air becomes a cord.
What each one is on its own+
L-arginine
- Endurancehalf-there
- Asthma and breathinghalf-there
- Blood pressurehalf-there
- Cholesterolhalf-there
- Gut and digestionhalf-there
- Hearthollow
- Immunity and coldshalf-there
- Inflammationhalf-there
- Performance and vitalityhalf-there
- Pregnancya ghost
- Sprint and repeated-effort powerhalf-there
- Strength and powerhalf-there
- Testosterone and libidohalf-there
- Weight and body fathollow
- Wound healinghalf-there
Vitamin D
- Bonehollow
- Blood sugarsolid
- Pregnancyhalf-there
Pairs that have been tested+
- L-arginine has been tested with L-theanine, creatine monohydrate, selenium, L-lysine, L-glutamine, probiotics.
- Vitamin D has been tested with magnesium, selenium, folate, chromium, probiotics, omega-3.
These are the combinations someone has actually run a study on. Every other pairing here is air.
Worth knowing+
- L-arginine: Searching 21 health outcomes returned no trial of L-arginine on its own for any of them. This is not the same as a supplement nobody has studied. L-arginine is a nutrient your body needs, and there is research on it. What that research is about is multi-antioxidant fertility formulations and clinical nutrition, rather than arginine taken alone. None of it tells you whether taking extra helps someone who already gets enough.