Hashimoto's Thyroiditis
Hashimoto's Thyroiditis is a metabolic condition involving the thyroid. This page distinguishes the condition itself from the interventions studied in relation to it, such as Selenium.
See Hashimoto's Thyroiditis in context as a metabolic condition.
This list shows research findings, not treatments. Nothing here replaces medical care. If you have this condition, talk to a doctor.
What may help
What studies found for each option, best evidence first.
1 option:1 some evidence
Red Light Therapy (Photobiomodulation)practiceSome evidence it helpsSize of effect: Not known
Some human studies found a benefit. More research could change this.
All 2 studies with a clear result found a benefit.
In a randomized trial of 60 people with Hashimoto's thyroiditis who were taking levothyroxine, photobiomodulation improved fatigue, sleep, behavioural status, and pain compared with sham. A review of six clinical studies also described outcomes involving autoantibodies, levothyroxine dose, and thyroid structure, but characterized the evidence as limited and heterogeneous.
Open the Red Light Therapy (Photobiomodulation) page
May not suit people with this condition
Supplements and practices linked to problems for people with this condition.
Sea Moss (Irish Moss)supplementUnclear
Excess iodine may worsen autoimmune thyroiditis and accelerate thyroid damage in people with Hashimoto's Thyroiditis.
Open the Sea Moss (Irish Moss) page
The expert view shows every study, dose protocol and source.
What may help
Interventions recorded as helping with this condition1 listedMost likely to help, from the evidence we have
- →PracticesRed Light Therapy (Photobiomodulation)CertaintyMediumSourceClinical
In a randomized trial of 60 people with Hashimoto's thyroiditis who were taking levothyroxine, photobiomodulation improved fatigue, sleep, behavioural status, and pain compared with sham. A review of six clinical studies also described outcomes involving autoantibodies, levothyroxine dose, and thyroid structure, but characterized the evidence as limited and heterogeneous.
Who was studied
- People with a condition
- Hashimotos Thyroiditis
Open Red Light Therapy (Photobiomodulation)Study result
Six included clinical studies evaluated PBM/LLLT in CAT, reporting autoantibody, LT4 dose and structural outcomes; evidence is limited and heterogeneous.
What to avoid
Interventions recorded as making it worse1 listedHighest probability
- →SupplementsSea Moss (Irish Moss)CertaintyLowSourceReference knowledge
Excess iodine may worsen autoimmune thyroiditis and accelerate thyroid damage in people with Hashimoto's Thyroiditis.
Open Sea Moss (Irish Moss)Rationale
Excess iodine can worsen autoimmune thyroiditis and accelerate thyroid damage.
How to read the evidence
Evidence tier — overall strength of the evidence for the whole compound
- StrongWell established — backed by strong, consistent human research.
- ModerateSome genuine support, but mostly from small or lower-quality studies. Promising, not proven.
- PreliminaryEarly-stage evidence — a promising hypothesis, not an established effect yet.
- LimitedVery limited evidence — treat this as a hypothesis, not proof.
- InsufficientNot enough good evidence to draw conclusions yet.
Certainty — how sure we can be that the effect is real
- Very highVery sure — strong, consistent evidence
- HighFairly sure — consistent evidence from good studies
- MediumModerately sure — new studies could change this
- LowNot sure — little or mixed evidence
- Very lowVery unsure — almost no usable evidence
Source — where the data comes from
- Meta-analysisPooled analysis of many trials — the strongest evidence
- RCTRandomized controlled trial — a strong human study design
- ClinicalA human clinical study
- Reference knowledgeFrom general health-science or pharmacology references, not a study of this exact claim
- Animal researchStudied in animals, not humans
- Community reportsAggregated user reports — anecdotal signal, not evidence
- TheoreticalMechanism-based reasoning, not yet tested
Study grade — quality of each underlying study (A best, D weakest)
- AHigh-quality — strong, consistent human trials
- BGood — solid evidence with some limitations
- CModerate — limited, small, or mixed-quality studies
- DWeak — preliminary, indirect, or animal-only
Confidence — how strongly the sources back a finding
A 0–100 score from study quality and agreement
Most supplement evidence is graded C–D. Read it as preliminary signal, not proof.
Full write-up
What is it
Hashimoto's Thyroiditis is a metabolic condition involving the thyroid. This page distinguishes the condition itself from the interventions studied in relation to it, such as Selenium. Information about diagnosis, monitoring, or treatment is best discussed with a qualified clinician.
Evidence-backed options
Selenium is the option associated with Hashimoto's Thyroiditis in the available evidence. Findings concern possible reductions in TPOAb and TSH levels, along with improvements in well-being or mood. The evidence also distinguishes between selenium forms, with selenomethionine described as more effective than sodium selenide and selenium yeast in this context.
The available information does not specify how much Selenium was taken, how long it was used, or how quickly changes appeared. It therefore cannot establish a typical dose, treatment duration, or expected time to response. These findings relate to selected laboratory and well-being outcomes and should not be interpreted as evidence that Selenium treats every aspect of Hashimoto's Thyroiditis. Discussing the relevance of this option with a clinician is appropriate.
What to avoid
Iodine and Sea Moss (Irish Moss) are flagged for the same reason: excess iodine may worsen the autoimmune thyroid inflammation associated with Hashimoto's Thyroiditis and accelerate thyroid damage or destruction. The concern therefore relates to their potential to increase iodine exposure, rather than to two separate mechanisms.
Because Hashimoto's Thyroiditis involves autoimmune thyroid inflammation, iodine-containing supplements warrant particular care when considering products in this category. The appropriateness of any supplement can depend on an individual’s thyroid condition and overall care plan, so these options are best discussed with a clinician.