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Head-to-head evidence comparison — which supplement is right for you?
Vitamin D3 wins 1 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Mostly mechanism / observational
2 of 2 studies with measurable effects showed benefit.
Top outcomes
Verdict
Probably helps
15 of 26 studies with measurable effects showed benefit.
Top outcomes
1-3 tablespoons (15-45ml) daily
Morning for sustained energy, Before workouts for performance, With coffee (bulletproof style)
C8 (Caprylic Acid) MCT Oil
2000-4000 IU daily
Morning with breakfast
D3 (cholecalciferol) softgel or liquid
30-60 minutes
30-60 minutes
Acute
Acute with excess
4-8 weeks
4-8 weeks
2-4 weeks
4-8 weeks
Clinical Benefits of Exogenous Ketosis in Adults with Disease: A Systematic Review
Nutrients (2025) · Systematic review
Exogenous ketosis shows potential in neurological, metabolic, and cardiovascular disorders, while evidence in psychiatric and inflammatory conditions remains scarce and preliminary.
AMPA Receptor Modulation Through Medium-Chain Triglycerides and Decanoic Acid Supports Nutritional Intervention in Pediatric Epilepsy
Nutrients (2025) · Systematic review
Methods: A systematic review was conducted, including articles from January 2000 to January 2025, to explore the potential role of medium-chain triglyceride (MCT) add-on to classic KD and as MCT supplementation in free diets in the management of pediatric drug-resistant epilepsy (DRE).
Influence of Carbohydrate Intake on Caprylic Acid (C8:0)-Induced Ketogenesis-A Systematic Review and Meta-Analysis
Nutrients (2024) · Meta analysis
Forest plot analysis showed heterogeneous data.
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 of 291 participants showing MCT decreases energy intake. Effect magnitude limited by small study sizes and heterogeneous methodology. GI tolerance varies significantly between individuals.
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.
Vitamin D3 has a higher evidence score (9/10 vs 9/10) and wins in 1 of 3 categories.
For metabolic health, MCT Oil has a higher relevance score (65 vs 55).
No known interactions between MCT Oil and Vitamin D3 have been documented in our database. However, always consult a healthcare provider before combining supplements.