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Head-to-head evidence comparison — which supplement is right for you?
Copper vs Iodine: Iodine has the stronger overall evidence (8.5 vs 5.5/10); they're alternatives for boost daily energy — 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
Too few graded studies
Top outcomes
Verdict
Limited support
1 of 4 studies with measurable effects showed benefit.
Top outcomes
Shared outcomes (1)
Outcomes where both Copper and Iodine have evidence — compare verdict strength side-by-side.
1-2 mg daily (typically to balance zinc). The cited trial gave 2 mg a day as copper glycinate for 8 weeks.
With food to reduce GI upset, Separate from zinc by 2+ hours if taking both
Copper Bisglycinate (gentle, well-absorbed)
150-300mcg for maintenance; higher only if deficient under supervision
Any time with food
Potassium iodide (most common and studied)
and 2 more not shown
Ongoing
4-8 weeks
With chronic excess
4-12 weeks
4-8 weeks
Micronutrient deficiencies in patients with celiac disease: A systematic review and meta-analysis
International journal of immunopathology and pharmacology (2025) · Meta analysis
Meta-analysis revealed a significant difference in hemoglobin levels between patients with CeD and controls (standardized mean difference (SMD) -0.59 (95% confidence interval (CI) -0.8459 to -0.3382); P = 0.0003).
Trace Elements and Risk of Immune-Mediated Skin Disease: A Systematic Review and Meta-analysis
Nutrition reviews (2025) · Meta analysis · n=7014
Meta-analysis of 113 observational studies in 7,014 patients with immune-mediated skin diseases, comparing blood zinc, copper, iron, selenium and calcium with healthy controls.
Healthy lifestyle choices: new insights into vitiligo management
Frontiers in immunology (2024) · Meta analysis · n=8542
Vitamin C [mean difference (MD), -0.342; 95% confidence interval (CI), -1.090-0.407; p >0.05), folic acid (MD, -1.463; 95% CI, -7.133-4.208; p >0.05), and selenium (MD, 0.350; 95% CI, -0.687-1.387; p >0.05) levels did not differ between the groups.
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.
Iodine has a higher evidence score (8.5/10 vs 5.5/10) and wins in 2 of 3 categories.
For boost daily energy, Iodine has a higher relevance score (95 vs 50).
No documented interaction was found in the data searched. This does not establish that this exact combination is safe.
AREDS2 works for diagnosed AMD; lutein/screen-strain claims are weaker. Who actually benefits.
When to take what, with or without food, and which supplements compete vs pair well.
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).
The right pick depends on your goals. Answer a few quick questions for a personalised recommendation — or dig into the full evidence on each.