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Head-to-head evidence comparison — which supplement is right for you?
Selenium vs Tretinoin (Retin-A): they're closely matched on evidence (6.5 vs 8/10); the best pick depends on your goals. Take the 60-second quiz for a pick tailored to your goals.
Selenium and Tretinoin (Retin-A) are closely matched across evidence, studies, and safety.
Verdict
Likely helps
20 of 27 studies with measurable effects showed benefit.
Top outcomes
Verdict
Mostly mechanism / observational
Top outcomes
100-200mcg
With food
Selenomethionine (best absorbed)
Prescription topical: a pea-sized amount of 0.025%-0.1% cream or gel applied to clean, dry skin once nightly. Start low-strength and every-other-night to build tolerance. A prescription drug used under clinician direction — not a supplement regimen.
before-bed
Topical cream or gel, 0.025%-0.1% (prescription)
4-8 weeks
4-8 weeks
12-24 weeks
12-24 weeks
Months
8-12 weeks
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.
Topical tretinoin improves photoaged skin. A double-blind vehicle-controlled study.
JAMA (1988) · Rct
Randomized, double-blind, vehicle-controlled trial of topical tretinoin for photoaged forearm and facial skin
Tretinoin emollient cream: a new therapy for photodamaged skin.
J Am Acad Dermatol (1992) · Rct
Multicenter double-blind vehicle-controlled trial of tretinoin emollient cream for photodamaged skin
Long-term treatment of photoaged human skin with topical retinoic acid improves epidermal cell atypia and thickens the collagen band in papillary dermis.
J Am Acad Dermatol (2005) · Open label
Long-term topical retinoic acid on photoaged human skin assessed histologically
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 Selenium and Tretinoin (Retin-A) are closely matched — the best choice depends on your specific health goals.
No known interactions between Selenium and Tretinoin (Retin-A) have been documented in our database. However, always consult a healthcare provider before combining supplements.
Selenium helps; iodine can WORSEN Hashimoto’s. The honest take on "thyroid support".
CoQ10, zinc, selenium, carnitine modestly help sperm parameters — but live-birth evidence is weak.
AM/PM order, what to combine vs separate, and why sunscreen always comes first.
The proven core (sunscreen, retinoids, vitamin C) vs the viral hype tier — honestly tiered.
The right pick depends on your goals. Answer a few quick questions for a personalised recommendation — or dig into the full evidence on each.