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Head-to-head evidence comparison — which supplement is right for you?
Omega-3 wins 2 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Probably helps
15 of 23 studies with measurable effects showed benefit.
Top outcomes
Verdict
Likely helps
18 of 23 studies with measurable effects showed benefit.
Top outcomes
Shared outcomes (1)
Outcomes where both Omega-3 and Selenium have evidence — compare verdict strength side-by-side.
2-3g combined EPA+DHA daily
With meals containing fat
Triglyceride form fish oil
100-200mcg
With food
Selenomethionine (best absorbed)
4-8 weeks
2-4 weeks
Immediate
4-12 weeks
4-8 weeks
4-8 weeks
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.
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.
Selenium, antioxidants, cardiovascular disease, and all-cause mortality: a systematic review and meta-analysis of randomized controlled trials
The American journal of clinical nutrition (2020) · Meta analysis · n=9423
However, a decreased risk with antioxidant mixtures was seen for CVD mortality when selenium was part of the mix (RR: 0.77; 95% CI: 0.62, 0.97; P = 0.02), with no association when selenium was absent.
Selenium for preventing cancer
The Cochrane database of systematic reviews (2018) · Meta analysis · n=27232
For analyses of RCTs with low risk of bias, the summary risk ratio (RR) for any cancer incidence was 1.01 (95% confidence interval (CI) 0.93 to 1.10; 3 studies, 19,475 participants; high-certainty evidence).
Selenium and prostate cancer: systematic review and meta-analysis
The American journal of clinical nutrition (2012) · Meta analysis · n=13254
Three high-quality studies included in the meta-analysis of toenail selenium and cancer risk indicated a reduction in prostate cancer risk (estimated RR: 0.29; 95% CI: 0.14, 0.61) with a toenail selenium concentration between 0.85 and 0.94 μg/g.
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.
Based on Cochrane systematic review showing moderate-certainty evidence for TPO antibody reduction. Effects on thyroid hormone levels (TSH, T4, T3) were inconsistent across studies.
AI-estimated from published studies. Interpret as directional guidance.
Omega-3 has a higher evidence score (9/10 vs 9/10) and wins in 2 of 3 categories.
For reduce inflammation, Omega-3 has a higher relevance score (90 vs 52).
No known interactions between Omega-3 and Selenium have been documented in our database. However, always consult a healthcare provider before combining supplements.