Iodine for Hashimoto
Verdict: Insufficient Evidence
Across 5 PubMed studies, the evidence for Iodine in Hashimoto grades Tier D — counter-evidence. Research is still too limited to draw a firm conclusion.
D 🔴 D Counter-Evidence Insufficient Evidence
Why this grade7-layer evidence engine
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Scoring transparency
All scores computed by a 7-layer evidence engine — fully auditableRaw score 0.33
D
C
B
A
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← counter-evidence / ineffectiveeffective / strong evidence →
Final grade
D · Insufficient Evidence
Confidence
86%
Highly consistent evidence
Evidence level
E2
Multiple high-quality MAs (≥2 independent, consistent)
▸View the full decision path (audit trail)
- compute_raw_score — 加權公式: L2×0.30 + L3×0.25 + L5×0.25 + L11×0.10 + L1×0.10 = 0.331
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 高品質 SR/MA 顯示 negative 主導 (2 negative > 0 positive)，下層 RCT 不能推翻
- tier_strict_requirement_check — Tier 條件達標，未降階
- detect_disputes — 偵測到 0 個 hard + 0 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status
PubMed studies (5)L2 · primary research & systematic reviews
U-shaped relationship between iodine status and thyroid autoimmunity risk in adults
Finding: Dose-response meta-analysis of 22 studies (69,987 participants) confirmed a U-shaped relationship in which iodine excess raised thyroid-autoimmunity risk (cross-sectional OR 1.68, 95% CI 1.11-2.53, p=0.014) as did iodine deficiency (OR 1.50, 95% CI 1.03-2.17, p=0.032) versus adequate intake.
View on PubMed Iodine Intake from Universal Salt Iodization Programs and Hashimoto's Thyroiditis: A Systematic Review
Finding: Of 74 studies (31 reporting antibodies across 14 countries), antibody positivity rose or stayed high in 8 countries after USI and fell in only 4, leading authors to conclude unmonitored excess iodine 'could explain (at least in part) the prevalence and distribution' of Hashimoto's; no benefit of iodine for HT was reported.
View on PubMed The effect of iodine restriction on thyroid function in patients with hypothyroidism due to Hashimoto's thyroiditis
Finding: In iodine-replete Korea, restricting iodine to <100 ug/day for 3 months restored euthyroidism in 78.3% (18/23) of patients vs 45.5% of unrestricted controls, with significant within-group fT4/TSH changes (p<0.05); recovery was likelier with lower baseline TSH (p=0.005).
View on PubMed The Influence of Nutritional Intervention in the Treatment of Hashimoto's Thyroiditis-A Systematic Review
Finding: Across 9 studies, the single iodine-restriction trial (Yoon 2003) showed 'No improvement... on the iodine-restricted diet' with no significant between-group difference, whereas energy restriction, gluten/lactose elimination, and Nigella sativa did improve antibody/thyroid markers.
View on PubMed Relationship Between Thyroid Hormonal Status in Patients with a Hypothyroid Form of Hashimoto's Thyroiditis and Iodine Concentrations in Drinking Water
Finding: Among 168 Hashimoto's patients, higher drinking-water iodine correlated directly with TgAb and TPOAb titres and inversely with TSH (statistically significant regressions), suggesting higher iodine exposure tracks with greater autoimmune activity, especially in women.
View on PubMed Regulatory & authoritative positionsL4/L5 · FDA / EMA / NIH ODS / Cochrane / Mayo …
L4a US FDA
Supportive
Iodized salt or iodized table salt is the article of commerce, salt for human food use, to which has been added cuprous iodide or potassium iodide. The label shall bear the statement 'This salt supplies iodide, a necessary nutrient'. Cuprous iodide and potassium iodide may be added to table salt as a source of dietary iodine in an amount not greater than 0.01 percent. source↗
L4b EU EFSA
Supportive
Iodine contributes to normal cognitive function, normal functioning of the nervous system, the maintenance of normal skin, normal production of thyroid hormones and normal thyroid function, and contributes to normal growth of children source↗
L4c UK NHS
Cautious
Adults need 140 micrograms (μg) of iodine a day. Most people should be able to get all the iodine they need by eating a varied and balanced diet. Taking high doses of iodine for long periods of time could change the way your thyroid gland works. This can lead to a wide range of different symptoms, such as weight gain. Taking 0.5mg or less a day of iodine supplements is unlikely to cause any harm. source↗
L4d TW TFDA / 衛福部
Supportive
孕婦碘的每日建議攝取量為225微克，較一般成人140微克高出許多；衛生福利部建議孕婦及哺乳婦使用加碘鹽，並可適量攝取含碘量豐富的食物，如海帶、海藻類等。 source↗
L4e WHO
Supportive
All food-grade salt, used in household and food processing should be fortified with iodine as a safe and effective strategy for the prevention and control of iodine deficiency disorders in populations living in stable and emergency settings. source↗
L5a NIH Office of Dietary Supplements
Supportive
Iodine is a mineral found in some foods. The body needs iodine to make thyroid hormones. These hormones control the body's metabolism and many other important functions. The body also needs thyroid hormones for proper bone and brain development during pregnancy and infancy. source↗
L5b Mayo Clinic
Cautious
Too much iodine in the diet may function as a trigger among people already at risk for Hashimoto's disease. source↗
L5c Cleveland Clinic
Neutral
Hashimoto's disease is the most common cause of hypothyroidism in countries with widely available iodized salt and other iodine-enriched foods. Iodine deficiency is the most common cause in other countries. source↗
L5d Harvard Health
Cautious
In people with a genetic susceptibility, the onset of Hashimoto's thyroiditis can be triggered by factors such as high iodine intake, pregnancy, or cigarette smoking. source↗
L5e Specialty Society (condition-mapped)
Cautious
The American Thyroid Association (ATA) recommends adding to the diet a daily oral supplement that contains 150 μg of iodine in planning for pregnancy, during pregnancy, and during the postpartum period to achieve this. ... These results suggest that routine iodine supplementation in the doses recommended by national guidelines may be safely given to pregnant women with preexisting Hashimoto's t… source↗