Iodine
Iodine (Potassium Iodide / Kelp)
Essential trace mineral for thyroid hormone production — deficiency is common and affects metabolism, energy, and cognition.
Iodine is essential for synthesizing thyroid hormones T3 and T4, which regulate metabolism, energy, body temperature, and brain development. Deficiency remains common worldwide despite iodized salt, particularly in those avoiding salt or eating organic/unprocessed foods. Supplementation benefits those with true deficiency but excess can harm thyroid function.
Mechanisms of Action
Thyroid Hormone Synthesis
Essential building block for T3 and T4
Recommended Dose
150-300mcg for maintenance; higher only if deficient under supervision
Optimal Timing
- Any time with food
Take with food
Best Form
Potassium iodide (most common and studied)
Alternatives: Kelp (natural but variable), Nascent iodine, Lugol's solution
Kelp iodine content varies widely. Potassium iodide is more reliable for precise dosing.
Duration
Minimum: 8 ongoing if deficient
Optimal: ongoing if deficient
Cycling: Not required
Note: Can be taken any time. Consistent daily intake matters more than timing.
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Thyroid Normalization
Restored thyroid function if deficient
Energy Improvement
Better energy and metabolism
Higher needs (220-290mcg); essential for fetal brain development
Controversial — may worsen autoimmune activity; consult endocrinologist
Who Should NOT Take This
- Hyperthyroidism
- Hashimoto's (use with extreme caution)
- Dermatitis herpetiformis
Drug Interactions
May alter thyroid medication requirements
Additive hypothyroid effects
Potassium iodide adds potassium load — may affect electrolyte balance or enhance fluid loss — may affect electrolyte balance or enhance fluid loss
Possible Side Effects
Tip: Don't exceed recommended dose; monitor thyroid
Tip: Take with food
Tip: Reduce dose
Warnings
- More is NOT better — excess iodine can harm thyroid
- Test thyroid function before supplementing long-term
- Those with autoimmune thyroid conditions should be very cautious
- High doses can trigger hyperthyroidism or worsen Hashimoto's
Top studies from 40+ peer-reviewed papers
Greenwood DC et al. • Nutrients (2023)
“Whilst associations were modest-sized, we recommend maintaining iodine sufficiency in the population, especially for women of childbearing age on restricted diets low in iodide.”
Key Findings:
- 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%).
- I:Cr was similar, but with nonlinear trend suggesting I:Cr up to 200 μg/g associated with increasing birthweight (p = 0.02, n = 5).
- Birthweight was 2.0 centiles (0.3 to 3.7, p = 0.02, n = 4, I2 = 0%) higher with UIC ≥ 150 μg/g, but not for I:Cr.
- UIC ≥ 150 μg/L was associated with lower risk of SGA (RR = 0.85, 0.75 to 0.96, p = 0.01, n = 13, I2 = 0%), but not with I:Cr.
Santos JAR et al. • The Cochrane database of systematic reviews (2019)
“The evidence on the effect of iodine fortification of foods, beverages, condiments, or seasonings other than salt on reducing goitre, improving physical development measures, and any adverse effects is uncertain.”
Key Findings:
- This is equivalent to an increase of 38.32 µg/L (95% CI 24.03 to 52.61 µg/L).
- This effect was not observed in the meta-analysis of non-RCTs (SMD 0.25, 95% CI -0.16 to 0.66; 3 non-RCTs, 262 participants; very low-quality evidence).
- The evidence on the effect of iodine fortification of foods, beverages, condiments, or seasonings other than salt on reducing goitre, improving physical development measures, and any adverse effects is uncertain.
- However, our findings suggest that the intervention likely increases urinary iodine concentration.
He Q et al. • Australian critical care : official journal of the Confederation of Australian Critical Care Nurses (2025)
“Antimicrobial mouthwashes, especially chlorhexidine, pose potential risks in ICU patients; oxidising solutions demonstrate relative safety.”
Key Findings:
- Oxidising agents showed a trend towards reducing the incidence of VAP compared to the control group (risk ratio: 0.24, 95% confidence interval: 0.05-1.10).
- Administration of saline was associated with a notable reduction in ICU mortality (risk ratio: 0.18, 95% confidence interval: 0.04-0.88) versus no mouthwash.
- Antimicrobial mouthwashes, especially chlorhexidine, pose potential risks in ICU patients; oxidising solutions demonstrate relative safety.
- Saline solution emerges as a promising alternative, associated with a significant reduction in mortality rates.
Machinski E et al. • The Journal of arthroplasty (2025)
“In this meta-analysis, chlorhexidine and povidone-iodine had a significantly reduced risk of PJI as compared with saline irrigation in total joint arthroplasty.”
Key Findings:
- The random-effect model analysis revealed a PJI rate of 1.02% (95% confidence interval (CI): 0.77 to 1.35; I2 = 90%) for the total cohort.
- Among 24,025 patients who received irrigation with either povidone-iodine or chlorhexidine, the PJI rate was 0.86% (95% CI: 0.63 to 1.17; I2 = 75%).
- Povidone-iodine significantly reduced the risk of PJI compared to saline (risk ratio (RR) 0.60, 95% CI: 0.37 to 0.95; P = 0.029; I2 = 61%).
- However, no significant difference was observed in the subgroups for total hip arthroplasty (RR 0.92, 95% CI: 0.52 to 1.61; P = 0.57; I2 = 0%) and total knee arthroplasty (RR 0.92, 95% CI: 0.47 to 1.77; P = 0.21; I2 = 35%).
Widmer AF et al. • JAMA (2024)
“Povidone iodine in alcohol as preoperative skin antisepsis was noninferior to chlorhexidine gluconate in alcohol in preventing SSIs after cardiac or abdominal surgery.”
Key Findings:
- Patients were 32.7% and 33.9% female in the povidone iodine and chlorhexidine gluconate groups, respectively.
- The unadjusted relative risk for povidone iodine vs chlorhexidine gluconate was 0.92 (95% CI, 0.69-1.23).
- Povidone iodine in alcohol as preoperative skin antisepsis was noninferior to chlorhexidine gluconate in alcohol in preventing SSIs after cardiac or abdominal surgery.
Study Type Distribution
Goals This Supplement Supports
This information is for educational purposes only and is not intended as medical advice. Always consult a qualified healthcare provider before starting any supplement.