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Head-to-head evidence comparison — which supplement is right for you?
Iodine vs Methylfolate: Iodine has the stronger overall evidence (8.5 vs 6/10); they're alternatives for fertility support — the best pick depends on your goals. Take the 60-second quiz for a pick tailored to your goals.
Iodine wins 2 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Limited support
1 of 4 studies with measurable effects showed benefit.
Top outcomes
Verdict
Likely helps
6 of 6 studies with measurable effects showed benefit.
Top outcomes
150-300mcg for maintenance; higher only if deficient under supervision
Any time with food
Potassium iodide (most common and studied)
400-800mcg daily
Morning with or without food, Consistent daily timing
L-Methylfolate (5-MTHF)
and 2 more not shown
4-12 weeks
4-8 weeks
2-4 weeks
1-3 weeks
4-8 weeks
Days to weeks
Maternal Iodine Status and Birth Outcomes: A Systematic Literature Review and Meta-Analysis
Nutrients (2023) · Meta analysis · n=42269
Birth weight was similar between UIC ≥ 150 μg/L and <150 μg/L (difference = 30 g, 95% CI −22 to 83, p = 0.3, n = 13, I2 = 89%) with no evidence of linear trend (4 g per 50 μg/L, −3 to 10, p = 0.2, n = 12, I2 = 80%).
Iodine fortification of foods and condiments, other than salt, for preventing iodine deficiency disorders
The Cochrane database of systematic reviews (2019) · Meta analysis · n=4317
This is equivalent to an increase of 38.32 µg/L (95% CI 24.03 to 52.61 µg/L).
Systematic review and meta-analysis of iodine nutrition in modern vegan and vegetarian diets
The British journal of nutrition (2023) · Meta analysis · n=4421
Vegan diets had the poorest iodine intake (17·3 µg/d) and were strongly associated with lower iodine intake (P = < 0·001) compared with omnivorous diets.
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.
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.
Iodine has a higher evidence score (8.5/10 vs 6/10) and wins in 2 of 3 categories.
For fertility support, Methylfolate has a higher relevance score (95 vs 30).
No documented interaction was found in the data searched. This does not establish that this exact combination is safe.
Selenium helps; iodine can WORSEN Hashimoto’s. The honest take on "thyroid support".
What’s safe while nursing, the truth about milk-supply herbs, and what to avoid (it passes into milk).
Commonly recommended vs ask-your-clinician vs avoid — a general, safety-first overview.
CoQ10, zinc, selenium, carnitine modestly help sperm parameters — but live-birth evidence is weak.
The right pick depends on your goals. Answer a few quick questions for a personalised recommendation — or dig into the full evidence on each.