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Head-to-head evidence comparison — which supplement is right for you?
Iodine vs Multivitamin: Multivitamin has the stronger overall evidence (6 vs 8.5/10); 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.
Multivitamin 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
Too few graded studies
Top outcomes
Shared outcomes (2)
Outcomes where both Iodine and Multivitamin have evidence — compare verdict strength side-by-side.
150-300mcg for maintenance; higher only if deficient under supervision
Any time with food
Potassium iodide (most common and studied)
1 serving daily (as directed on label, typically 1-2 tablets/capsules)
With breakfast, With lunch (if GI sensitive)
Capsule or softgel
and 2 more not shown
and 7 more not shown
Where both products contain iodine, the combined amount can pass the upper limit. Iodine excess can cause underactive or overactive thyroid, and people with autoimmune thyroid disease or thyroid nodules are more sensitive to it.
Check the iodine content of both labels, and count iodised salt and seaweed, then add them. Keep the total within 600 mcg a day, the EU upper limit. People with autoimmune thyroid disease should not add a standalone iodine supplement to a multivitamin that contains iodine without their clinician.
4-12 weeks
4-8 weeks
3-6 months
4-8 weeks
2-6 weeks
6-12 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.
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.
Multivitamin has a higher evidence score (6/10 vs 8.5/10) and wins in 2 of 3 categories.
For boost daily energy, Iodine has a higher relevance score (95 vs 75).
Where both products contain iodine, the combined amount can pass the upper limit. Iodine excess can cause underactive or overactive thyroid, and people with autoimmune thyroid disease or thyroid nodules are more sensitive to it. Check the iodine content of both labels, and count iodised salt and seaweed, then add them. Keep the total within 600 mcg a day, the EU upper limit. People with autoimmune thyroid disease should not add a standalone iodine supplement to a multivitamin that contains iodine without their clinician. Consult a healthcare provider for personalized advice.
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.
On Ozempic/Wegovy/Mounjaro? What actually helps — muscle preservation, GI relief, nutrient gaps (no upsell).
The right pick depends on your goals. Answer a few quick questions for a personalised recommendation — or dig into the full evidence on each.