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Head-to-head evidence comparison — which supplement is right for you?
Multivitamin vs Selenium: Selenium has the stronger overall evidence (6.5 vs 6/10); take care combining them — there's a flagged interaction. Take the 60-second quiz for a pick tailored to your goals.
Selenium wins 2 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Too few graded studies
Top outcomes
Verdict
Probably helps
9 of 13 studies with measurable effects showed benefit.
Top outcomes
Shared outcomes (1)
Outcomes where both Multivitamin and Selenium have evidence — compare verdict strength side-by-side.
1 serving daily (as directed on label, typically 1-2 tablets/capsules)
With breakfast, With lunch (if GI sensitive)
Capsule or softgel
100-200mcg
With food
Selenomethionine (best absorbed)
and 7 more not shown
Where both products contain selenium, the combined amount can approach or pass the upper limit. Long-term excess causes selenosis: hair and nail loss, garlic breath, skin and nerve symptoms.
Check the selenium content of both labels and add them. Keep the total from supplements and diet at or below 255 mcg a day, the EU upper limit. Most people with an adequate diet do not need a standalone selenium supplement on top of a multivitamin that already contains selenium.
3-6 months
4-8 weeks
2-6 weeks
6-12 weeks
4-8 weeks
4-8 weeks
Effect of multivitamin-mineral supplementation versus placebo on cognitive function: results from the clinic subcohort of the COcoa Supplement and Multivitamin Outcomes Study (COSMOS) randomized clinical trial and meta-analysis of 3 cognitive studies within COSMOS
The American Journal of Clinical Nutrition (2024) · Meta analysis · n=5203
Pooled 5,203 non-overlapping participants from three cognitive substudies of the COSMOS trial of US adults aged 60 or older: COSMOS-Clinic (573), COSMOS-Mind (2,158) and COSMOS-Web (2,472).
Effects of cocoa extract and a multivitamin on cognitive function: A randomized clinical trial
Alzheimer's & Dementia (2023) · Rct · n=2262
COSMOS-Mind: 2,262 older adults (mean age 73, 60% women) randomised in a 2x2 factorial design to cocoa extract and to a commercial multivitamin-mineral, each versus placebo, for 3 years, with cognition tested by telephone.
Long-term multivitamin supplementation and cognitive function in men: a randomized trial
Annals of Internal Medicine (2013) · Rct · n=5947
5,947 male physicians aged 65 or older in the Physicians' Health Study II, randomised to a daily multivitamin or placebo, with up to 4 telephone cognitive assessments over 12 years.
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
Systematic review and dose-response meta-analysis of 12 trials, case-control and cohort studies with 13,254 participants and 5,007 prostate cancer cases, on selenium intake or status.
Selenium has a higher evidence score (6.5/10 vs 6/10) and wins in 2 of 3 categories.
For support immune system, Multivitamin has a higher relevance score (82 vs 20).
Caution: Where both products contain selenium, the combined amount can approach or pass the upper limit. Long-term excess causes selenosis: hair and nail loss, garlic breath, skin and nerve symptoms. Check the selenium content of both labels and add them. Keep the total from supplements and diet at or below 255 mcg a day, the EU upper limit. Most people with an adequate diet do not need a standalone selenium supplement on top of a multivitamin that already contains selenium. Always consult a healthcare provider before combining these 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.