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Head-to-head evidence comparison — which supplement is right for you?
Ashwagandha and Vitamin D3 are closely matched across evidence, studies, and safety.
Verdict
Likely helps
14 of 14 studies with measurable effects showed benefit.
Top outcomes
Verdict
Probably helps
18 of 30 studies with measurable effects showed benefit.
Top outcomes
300-600mg daily (standardized extract)
Morning for daytime stress, Evening for sleep support
KSM-66 or Sensoril standardized extract
2000-4000 IU daily
Morning with breakfast
D3 (cholecalciferol) softgel or liquid
2-4 weeks
2-4 weeks
2-4 weeks
First week
4-8 weeks
4-8 weeks
2-4 weeks
4-8 weeks
Effects of Ashwagandha (Withania Somnifera) on stress and anxiety: A systematic review and meta-analysis
Explore (NY) (2024) · Meta analysis · n=873
Significant effect on the Perceived Stress Scale (PSS) (MD = -4.72, 95 % CI = [-8.45 to -0.99]).
Effects of Withania somnifera Extract in Chronically Stressed Adults: A Randomized Controlled Trial
Nutrients (2024) · Rct · n=131
Our findings demonstrate the stress-reduction capabilities of this well-characterized aqueous extract of WS (root and leaf) at the low dose of 125 mg/day, in a dose-dependent manner, via the modulation of the HPA axis.
Plant-derived nootropics and human cognition: A systematic review
Critical reviews in food science and nutrition (2023) · Systematic review
Bacopa monnieri improves language, learning and memory.
Vitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial
Nature communications (2025) · Meta analysis · n=5205
Mean body mass index (BMI) was 27.5 kg/m2 (SD = 5.3), with 51% female and 17% Black race/ethnicity.
Vitamin D Supplementation for Patients with Dysmenorrhoea: A Meta-Analysis with Trial Sequential Analysis of Randomised Controlled Trials
Nutrients (2024) · Meta analysis · n=687
TSA revealed that the current RCTs provide sufficient information.
Vitamin D and respiratory tract infections
BMJ (2017) · Meta analysis · n=11321
12% reduction in respiratory infections overall
Based on meta-analysis showing significant HAM-A score reduction (p=0.0007) and RCT evidence at 125mg dose. High heterogeneity (I2=98%) in pooled analysis suggests variable response. Extract standardization affects bioavailability.
Meta-analysis showed 12% overall reduction in respiratory infections, with greater benefits in severely deficient individuals. Daily dosing more effective than bolus. Conservative estimate assumes most users not severely deficient.
AI-estimated from published studies. Interpret as directional guidance.
Both Ashwagandha and Vitamin D3 are closely matched — the best choice depends on your specific health goals.
For menopause support, Vitamin D3 has a higher relevance score (90 vs 72).
No known interactions between Ashwagandha and Vitamin D3 have been documented in our database. However, always consult a healthcare provider before combining supplements.