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Head-to-head evidence comparison — which supplement is right for you?
Methylfolate vs Selenium: Selenium has the stronger overall evidence (6.5 vs 6/10); they're alternatives for male fertility — the best pick depends on your goals. 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
Likely helps
6 of 6 studies with measurable effects showed benefit.
Top outcomes
Verdict
Probably helps
9 of 13 studies with measurable effects showed benefit.
Top outcomes
Shared outcomes (1)
Outcomes where both Methylfolate and Selenium have evidence — compare verdict strength side-by-side.
400-800mcg daily
Morning with or without food, Consistent daily timing
L-Methylfolate (5-MTHF)
100-200mcg
With food
Selenomethionine (best absorbed)
2-4 weeks
1-3 weeks
4-8 weeks
Days to weeks
4-8 weeks
4-8 weeks
Efficacy of B-vitamins and vitamin D therapy in improving depressive and anxiety disorders: a systematic review of randomized controlled trials
Nutritional neuroscience (2023) · Systematic review · n=2256
20 RCTs with 2,256 subjects with depression or anxiety, covering several B vitamins and vitamin D, not methylfolate alone.
Systematic Review and Meta-Analysis of L-Methylfolate Augmentation in Depressive Disorders
Pharmacopsychiatry (2022) · Meta analysis · n=6707
Nine articles (N=6,707 patients) were assessed qualitatively. The pooled analyses were smaller: three studies (N=483) and four studies (N=507).
Folic acid/methylfolate for the treatment of psychopathology in schizophrenia: a systematic review and meta-analysis
Psychopharmacology (2018) · Meta analysis · n=925
Ten RCTs with 925 patients were reviewed, of which two tested methylfolate (n = 96). Seven RCTs entered the meta-analysis.
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.
Two randomised trials in people whose depression had not responded to an SSRI (PMID 23212058). In the first (148 patients), L-methylfolate at 7.5 mg a day for 30 days, then 15 mg, did no better than placebo. In the second (75 patients), 15 mg a day throughout beat placebo on response and symptom scores, with side effects no different from placebo. A meta-analysis found benefit only for methylfolate at 15 mg once daily added to an SSRI, with all evidence rated low or very low quality (PMID 29442609). The 800 mcg point comes from an open-label, non-randomised trial of 44 patients where adding methylfolate to an antidepressant improved PHQ-9 scores more by day 28 (40% vs 26%), but remission did not differ (PMID 39844190). No trial compared doses head to head, so no minimum or optimal dose is set.
AI-estimated from published studies. Interpret as directional guidance.
Selenium has a higher evidence score (6.5/10 vs 6/10) and wins in 2 of 3 categories.
For male fertility, Methylfolate has a higher relevance score (95 vs 75).
No documented interaction was found in the data searched. This does not establish that this exact combination is safe.
CoQ10, zinc, selenium, carnitine modestly help sperm parameters — but live-birth evidence is weak.
Saffron, EPA omega-3, SAMe have real adjunct evidence — but these aren’t a substitute for care, and some interact dangerously.
Selenium helps; iodine can WORSEN Hashimoto’s. The honest take on "thyroid support".
The right pick depends on your goals. Answer a few quick questions for a personalised recommendation — or dig into the full evidence on each.