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Head-to-head evidence comparison — which supplement is right for you?
Omega-3 vs Vitamin D3: Omega-3 has the stronger overall evidence (9 vs 7.5/10); they're alternatives for reduce inflammation — the best pick depends on your goals. Take the 60-second quiz for a pick tailored to your goals.
Omega-3 wins 2 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Probably helps
18 of 27 studies with measurable effects showed benefit.
Top outcomes
Verdict
Probably helps
18 of 30 studies with measurable effects showed benefit.
Top outcomes
Shared outcomes (2)
Outcomes where both Omega-3 and Vitamin D3 have evidence — compare verdict strength side-by-side.
2-3g combined EPA+DHA daily
With meals containing fat
Triglyceride form fish oil
2000-4000 IU daily
Morning with breakfast
D3 (cholecalciferol) softgel or liquid
4-8 weeks
2-4 weeks
Immediate
4-12 weeks
4-8 weeks
4-8 weeks
2-4 weeks
4-8 weeks
Marine n-3 Fatty Acids and Prevention of Cardiovascular Disease and Cancer
The New England journal of medicine (2019) · Rct · n=25871
During a median follow-up of 5.3 years, a major cardiovascular event occurred in 386 participants in the n-3 group and in 419 in the placebo group (hazard ratio, 0.92; 95% confidence interval [CI], 0.80 to 1.06; P=0.24).
Omega-3 fatty acids for intermittent claudication
The Cochrane database of systematic reviews (2024) · Meta analysis · n=1830
Omega-3 compared with a control may have little to no effect on ankle-brachial index (MD -0.02, 95% CI -0.08 to 0.04; 3 studies, 168 participants; very low-certainty evidence).
A systematic review and meta-analysis of the omega-3 fatty acids effects on brain-derived neurotrophic factor (BDNF)
Nutritional neuroscience (2024) · Meta analysis · n=587
The present systematic review and meta-analysis indicate the efficacy of omega-3 FAs in increasing the serum concentration of BDNF.
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 multiple meta-analyses showing EPA-dominant formulas >1g/day most effective. Effects plateau around 2-2.5g. Adjunctive use with antidepressants shows better outcomes than monotherapy.
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.
Omega-3 has a higher evidence score (9/10 vs 7.5/10) and wins in 2 of 3 categories.
For reduce inflammation, Omega-3 has a higher relevance score (90 vs 58).
No known interactions between Omega-3 and Vitamin D3 have been documented in our database. However, always consult a healthcare provider before combining supplements.
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The right pick depends on your goals. Answer a few quick questions for a personalised recommendation — or dig into the full evidence on each.