Mechanism of Action
Ingested iodine is absorbed in the small intestine as iodide, then actively captured by the thyroid gland through a dedicated transporter (the sodium-iodide symporter, a membrane protein that pumps iodide into thyroid cells). The thyroid concentrates iodine at levels 20 to 50 times higher than blood levels.
Inside the gland, iodide is incorporated into a storage protein called thyroglobulin. This process, known as organification, produces the hormones T4 and T3. T4 circulates in the blood and serves as a reservoir. T3, the biologically active form, is produced locally in target tissues by selenium-dependent enzymes (the deiodinases).
T3 then enters the nucleus of target cells. There, it activates the transcription of genes involved in energy production, protein synthesis and tissue maintenance. This gene-regulatory mechanism explains the thyroid's systemic influence across all organs.
Key Benefits
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A thyroid that runs at its proper pace: iodine contributes to the normal production of thyroid hormones and normal thyroid function. Decades of research on thyroid physiology underpin this foundational role.
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A mind that keeps its edge: iodine contributes to normal cognitive function. Thyroid hormones, of which iodine is the constituent atom, govern the reading of many genes in brain cells.
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Energy available at the right pace: iodine contributes to normal energy-yielding metabolism. Thyroid hormones set resting energy expenditure, what the body consumes while doing nothing at all.
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Nerves that transmit quickly and cleanly: iodine contributes to normal functioning of the nervous system. Thyroid hormones take part in myelination, the formation of the sheath that protects nerves and speeds signal transmission.
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Skin that renews properly: iodine contributes to the maintenance of normal skin. Thyroid hormones support the renewal of epidermal cells and the regulation of skin hydration.
Dosage & Forms
Several forms of iodine are available in oral supplementation. Potassium iodide (KI) is the pharmaceutical reference, used in most clinical studies and public health programmes. Sodium iodide offers comparable properties but is less common in formulations. Seaweed extracts (kelp, bladderwrack) provide iodine in organic form, with variable content from batch to batch, making dosing less reproducible.
Recommended daily intake is approximately 150 µg for adults. The upper safety limit is set at 600 µg/day in Europe. The dosage in the Singular formula is expressed in µg of elemental iodine, the form in which reference intakes and the safety limit are established. Potassium iodide was selected for the fixed, known ratio between the salt and the iodine it provides, and for its compatibility with the other bioactives in the formula.
In the Singular Formula
Inclusion rationale
Iodine contributes to the normal production of thyroid hormones and normal thyroid function, to normal cognitive function and to normal energy-yielding metabolism. An essential constituent of the thyroid hormones T3 (triiodothyronine) and T4 (thyroxine), iodine holds a central position in regulating the basal metabolism of virtually every cell in the body. The thyroid concentrates circulating iodine to synthesize T4, which is then converted to T3 (the active form) by enzymes called deiodinases, whose activity depends on selenium (also present in the formula). This iodine-selenium synergy governs the conversion of T4 into T3. Despite table salt iodization in many countries, nutritional surveys reveal that certain populations remain at suboptimal intake, particularly people limiting their consumption of salt, dairy or fish. Thyroid function directly influences thermogenesis, heart rate, cell renewal and cognitive functions. Its useful window is narrow in both directions, with insufficient intake and excessive intake alike disturbing the gland, which makes reading iodine status relevant from a longevity perspective. Potassium iodide form, stable and well absorbed.
Selected form
Potassium iodide (KI) spray-dried onto a maltodextrin carrier, which accounts for most of its mass. Potassium iodide provides a fixed, known ratio between the salt and the iodine it contains, where seaweed extracts vary from batch to batch. This dilution carrier allows a microgram-scale dose to be distributed evenly throughout the formula. Iodine contributes to the normal production of thyroid hormones and normal thyroid function, and to normal cognitive function.
Formula dosage
0 to 150 µg.
Dose expressed as active substance, excluding excipients and carriers of the raw material.
Synergies in the formula
Linked Biomarkers
Safety & Precautions
Iodine in oral supplementation is well tolerated at nutritional doses (up to 150-200 µg/day). The upper safety limit established by European authorities is 600 µg/day for adults. Chronic iodine excess can disrupt thyroid function, particularly in individuals with a pre-existing thyroid vulnerability.
Iodine supplementation is not recommended in cases of uncontrolled hyperthyroidism, active autoimmune thyroiditis or use of thyroid medications (levothyroxine, antithyroid drugs) without prior medical advice. Individuals taking amiodarone or lithium should consult a healthcare professional before supplementing. Iodine is cleared by the kidneys, and reduced clearance exposes to accumulation. Where impaired kidney function is declared, the Singular formula sets iodine aside.
During pregnancy and breastfeeding, iodine requirements increase (200-250 µg/day per European recommendations). Any supplementation during these periods should be validated by a healthcare professional. In children and adolescents, intake should be adapted to the age group.
The safety profile of potassium iodide has been documented for over a century. Adverse effects at nutritional doses remain exceptional.
Scientific Studies
| Authors | Year | Type | Journal | |
|---|---|---|---|---|
| Zimmermann MB, Boelaert K | 2015 | Review | Lancet Diabetes & Endocrinology | View on PubMed |
Iodine deficiency and thyroid disorders Comprehensive review of thyroid disorders linked to insufficient iodine intake, covering global epidemiology, pathophysiological mechanisms and prevention strategies through salt iodisation. | ||||
| Soriguer F et al. | 2011 | Randomised Controlled Trial | British Journal of Nutrition | View on PubMed |
Iodine intakes of 100-300 μg/d do not modify thyroid function and have modest anti-inflammatory effects Randomised trial in 30 adults with normal thyroid function and already sufficient iodine intake, allocated to 100, 200 or 300 µg of potassium iodide daily for six months. The authors report no modification of thyroid function across this dose window, which brackets the one used in the formula. | ||||
| Bath SC et al. | 2013 | Cohort Study | The Lancet | View on PubMed |
Effect of inadequate iodine status in UK pregnant women on cognitive outcomes in their children: results from the Avon Longitudinal Study of Parents and Children (ALSPAC) British observational study of 1,040 mother-child pairs: lower maternal iodine status in the first trimester is associated with lower verbal IQ and reading comprehension scores in children at age 8-9. The design observes an association and tests no supplementation. | ||||
| Gowachirapant S et al. | 2017 | Randomised Controlled Trial | Lancet Diabetes & Endocrinology | View on PubMed |
Effect of iodine supplementation in pregnant women on child neurodevelopment: a randomised, double-blind, placebo-controlled trial Randomised double-blind trial in 832 pregnant women with mildly insufficient iodine intake, in India and Thailand: 200 µg of iodine daily until delivery, with children assessed at ages 5-6. No difference in verbal IQ (89.5 vs 90.2) or performance IQ (97.5 vs 99.1) between the two groups. | ||||
| Harding KB et al. | 2017 | Meta-analysis | Cochrane Database of Systematic Reviews | View on PubMed |
Iodine supplementation for women during the preconception, pregnancy and postpartum period Cochrane meta-analysis of iodine supplementation in women before, during and after pregnancy. The authors conclude that available data are insufficient to determine either benefits or harms, and note more frequent digestive intolerance under supplementation. | ||||
| Taylor PN et al. | 2018 | Review | Nature Reviews Endocrinology | View on PubMed |
Global epidemiology of hyperthyroidism and hypothyroidism Review of the global epidemiology of thyroid disorders, documenting the relationship between population iodine status and the frequency of gland dysfunction in both directions. | ||||
| Farebrother J et al. | 2019 | Review | Annals of the New York Academy of Sciences | View on PubMed |
Excess iodine intake: sources, assessment, and effects on thyroid function Review of the sources of excess iodine intake, the assessment methods and their effects on thyroid function. It informs the upper side of the curve and the European safety limit. | ||||
| Zimmermann MB | 2009 | Review | Endocrine Reviews | View on PubMed |
Iodine deficiency Landmark review covering iodine biochemistry, the consequences of insufficient intake on the thyroid and brain development, and global salt iodisation programmes. | ||||