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Head-to-head evidence comparison — which supplement is right for you?
Niacin and Selenium are closely matched across evidence, studies, and safety.
Verdict
Probably helps
8 of 15 studies with measurable effects showed benefit.
Top outcomes
Verdict
Likely helps
18 of 23 studies with measurable effects showed benefit.
Top outcomes
500-2000mg daily for lipid effects; 50-500mg for general health
With food (reduces flush), Evening for lipid effects, Split doses for high amounts
Immediate-release niacin (nicotinic acid)
100-200mcg
With food
Selenomethionine (best absorbed)
4-8 weeks
4-8 weeks
30-60 minutes after dose
4-8 weeks
4-8 weeks
Niacin for primary and secondary prevention of cardiovascular events
The Cochrane database of systematic reviews (2017) · Meta analysis · n=39195
Participants randomised to niacin were more likely to discontinue treatment due to side effects than participants randomised to control group (RR 2.17, 95% CI 1.70 to 2.77; participants = 33,539; studies = 17; I2 = 77%; moderate-quality evidence).
Effect of lipid-lowering therapies on lipoprotein(a) levels: a comprehensive meta-analysis of randomized controlled trials
Atherosclerosis (2025) · Meta analysis · n=145314
Among available LLTs, PCSK9mAbs, inclisiran, CETPi, and niacin significantly decreased Lp(a) levels.
A terminal metabolite of niacin promotes vascular inflammation and contributes to cardiovascular disease risk
Nature medicine (2024) · Meta analysis
Lastly, treatment with physiological levels of 4PY, but not its structural isomer 2PY, induced expression of VCAM-1 and leukocyte adherence to vascular endothelium in mice.
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 HDL increases. Higher doses increase discontinuation rates due to side effects (RR 2.17). Immediate-release forms have better lipid effects but more flushing.
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.
Both Niacin and Selenium are closely matched — the best choice depends on your specific health goals.
For reduce inflammation, Niacin has a higher relevance score (85 vs 52).
No known interactions between Niacin and Selenium have been documented in our database. However, always consult a healthcare provider before combining supplements.