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Head-to-head evidence comparison — which supplement is right for you?
Iodine vs Melatonin: Melatonin has the stronger overall evidence (8.5 vs 8.5/10); 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.
Melatonin wins 2 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Mixed evidence
4 of 11 studies with measurable effects showed benefit.
Top outcomes
Verdict
Likely helps
14 of 19 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)
0.5-1mg
30-60 minutes before bed
Immediate-release tablet or sublingual
and 2 more not shown
and 6 more not shown
4-12 weeks
4-8 weeks
Same night
1-3 days
Next morning
First week
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.
Melatonin in cancer treatment
The Cochrane database of systematic reviews (2025) · Meta analysis · n=126
We downgraded the certainty of the evidence because of high risk of bias, small sample size, the width of the 95% confidence interval, and indirectness due to inadequate reporting of cancer type.
Comparative Efficacy, Tolerability, and Acceptability of Donanemab, Lecanemab, Aducanumab, Melatonin, and Aerobic Exercise for a Short Time on Cognitive Function in Mild Cognitive Impairment and Mild Alzheimer's Disease: A Systematic Review and Network Meta-Analysis
Journal of Alzheimer's disease : JAD (2024) · Meta analysis · n=4599
Melatonin may be a better potential disease-modifying treatment for cognitive decline in mild AD and MCI.
Melatonin for sleep disorders in people with autism: Systematic review and meta-analysis
Progress in neuro-psychopharmacology & biological psychiatry (2023) · Meta analysis · n=595
According to the global analysis, the wake after sleep onset and night awakening parameters were not statistically significant.
Based on meta-analyses showing urinary iodine concentration increases with supplementation. Effects only meaningful in iodine-deficient populations. Excessive intake (>300mcg) may increase thyroid cancer risk. Most studies used potassium iodide; kelp-derived forms have variable bioavailability.
Based on meta-analyses showing 7-12 minute reduction in sleep onset. Higher doses showed diminishing returns and increased morning grogginess. Sublingual forms may be more effective at lower doses.
AI-estimated from published studies. Interpret as directional guidance.
Melatonin has a higher evidence score (8.5/10 vs 8.5/10) and wins in 2 of 3 categories.
For fertility support, Melatonin has a higher relevance score (85 vs 70).
No known interactions between Iodine and Melatonin 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".
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.
The honest tier list — proven staples vs situational vs mostly marketing. The hub the other guides feed into.
The right pick depends on your goals. Answer a few quick questions for a personalised recommendation — or dig into the full evidence on each.