Creatine vs Vitamin D
Both are commonly discussed for focus & cognition and energy. Creatine has the stronger research base (strong evidence), while Vitamin D is rated moderate.
Evidence last reviewed May 2026
Evidence
🟢Strong Evidence
🟡Moderate Evidence
Research says
Research agrees
Partially supported
Expert mentions
161
3 recommend
245
3 recommend
Studies
20
referenced
20
referenced
Study dose
3000–5000mg
The majority of reviewed trials and meta-analyses used maintenance doses in the 3–5 g per day range of creatine monohydrate, with loading protocols (typically 20 g/day for 5–7 days) used in some studies but considered unnecessary for long-term saturation by expert consensus. Higher doses have been studied in specific clinical contexts but are not typical for general health or performance goals.
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Best timing
MorningEveningPre-workoutPost-workoutWith foodEmpty stomach
MorningWith food
Who recommends
Caution
Generally safe
Generally safe
Creatine
Key findings
- ·Multiple meta-analyses consistently show creatine supplementation combined with resistance training increases muscle hypertrophy and strength gains in adults under 50.
- ·A meta-analysis of RCTs found creatine supplementation improved memory performance in healthy individuals, supporting a role in cognitive function beyond athletic performance.
- ·A dedicated meta-analysis on renal outcomes found no evidence of kidney damage from creatine supplementation in healthy populations at standard doses.
Evidence gaps
- ·Evidence in specific populations — including women across the lifespan, children and adolescents, and older adults — is based largely on moderate-quality narrative reviews rather than large, well-controlled trials.
- ·The magnitude and durability of cognitive benefits remain uncertain; most cognitive research is shorter-term and the clinical significance of memory improvements in non-deficient, healthy adults is unclear.
Vitamin D
Key findings
- ·A strong-quality meta-analysis supports combined calcium and vitamin D supplementation for reducing osteoporosis risk in postmenopausal women.
- ·A single moderate-quality RCT (D-Health trial) found limited evidence that vitamin D supplementation significantly reduces major cardiovascular events.
- ·One moderate-quality RCT found vitamin D supplementation was associated with higher testosterone levels in men, but this has not been sufficiently replicated.
Evidence gaps
- ·No studies in this review directly tested health outcomes at the specific serum vitamin D range of 60–80 ng/mL, leaving expert claims about optimal target levels unsupported by the current evidence base.
- ·The testosterone finding comes from a single moderate-quality RCT; additional well-powered replication trials are needed before this can be considered an established benefit.