Caffeine vs Vitamin D for strength: which has better evidence?
Caffeine has the stronger evidence for strength (Caffeine Grade B vs Vitamin D Grade C). For strength, Caffeine has the stronger evidence grade.
Platform evidence comparison
These existing platform assessments are separate from the source-reported findings below. They do not represent a direct trial comparing these treatments.
| Caffeine | Vitamin D | |
|---|---|---|
| Grade | grade B | grade C |
| Certainty | high | low |
| Effect | reliable ergogenic effect on power and endurance performance | Systematic review and meta-analysis in community-dwelling older adults: vitamin D monotherapy showed limited and inconsistent effects on sarcopenia-related measures such as muscle strength; benefit, where present, was concentrated in those who were deficient. |
| Studied dose | 3–6 mg/kg pre-exercise | varies by trial |
| Population | exercising adults | community-dwelling older adults |
| Safety | 1 modeled interaction(s) | 1 modeled interaction(s) |
Grade B / high: helps most people at studied doses; the size of the effect is well-characterized even if the ceiling isn't.
Direct comparison evidence
There are no direct RCTs in our corpus comparing Caffeine and Vitamin D head-to-head for strength. What we present above is an indirect comparison: each side's own trials, contrasted. This is standard practice for supplement comparisons — dose, population, and outcome-instrument differences between the two evidence bases add uncertainty on top of each side's own grade.
Can you take both?
No modeled interaction between Caffeine and Vitamin D in our corpus. Absence of a recorded interaction is not proof of additive benefit — combined-effect trials are usually absent for supplement pairs, so treat "stack" claims skeptically.
Decision guidance
- If certainty matters most — choose whichever side carries the higher certainty rating at a similar grade.
- If you're on medications — check each side's interaction pages before deciding; safety differences dominate small evidence-grade gaps.
- If your population is under-studied — the smaller-effect side with better population evidence often wins over the higher-grade side studied in a different demographic.
- If cost matters — form and dose page differences (Caffeine vs Vitamin D) can invert the practical winner.
Grade history
No grade changes yet. Initial grade assigned; re-reviewed on every 12 months (Grade A/B) — next review by . Methodology v1.
Re-review cadence: every 12 months (Grade A/B) · next scheduled by · methodology v1.
Frequently asked
Which has stronger evidence: Caffeine or Vitamin D for strength?
Caffeine carries Grade B at high certainty; Vitamin D carries Grade C at low. The stronger evidence points to Caffeine, subject to the caveat that direct head-to-head trials are usually absent for supplement pairings.
Can I take Caffeine and Vitamin D together?
No modeled interaction between Caffeine and Vitamin D; combining is not documented to be problematic, but combined-effect trials are also absent, so treat additive benefit claims skeptically.
Have Caffeine and Vitamin D been compared head-to-head?
Direct RCTs comparing the two for strength are uncommon. This page contrasts each side's own trial evidence — that is an indirect comparison, which introduces confounds from population and dose differences. See the direct-comparison block above.
What decides between Caffeine and Vitamin D for me?
Read the decision guidance below — the split usually comes down to population fit, interaction risk with your other medications, and how much certainty you want behind the recommendation.
Related
Cite this page
Citation is encouraged. The proposed reuse license is CC-BY-4.0; status: pending-governance-ratification.
Plain-text citation
Substrate. Caffeine vs Vitamin D for strength. https://evidencebased.info/compare/caffeine-vs-vitamin-d-for-strength. Updated 2026-07-14.
BibTeX
@misc{substrate_svitamindforstrength,
author = {Substrate editorial},
title = {Caffeine vs Vitamin D for strength},
year = {2026},
url = {https://evidencebased.info/compare/caffeine-vs-vitamin-d-for-strength},
note = {evidencebased.info}
}