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Algae

Sea Moss (Irish Moss)

Sea Moss (Irish Moss) is an algae-based supplement. It is mainly associated with use related to iodine deficiency, although the available evidence is not sufficient to establish that it reliably addresses this indication.

Curious about Sea Moss (Irish Moss) beyond its wellness reputation? See which areas of interest are discussed and how cautiously to read them.

Overview

Sea Moss (Irish Moss) is an algae-based supplement. It is mainly associated with use related to iodine deficiency, although the available evidence is not sufficient to establish that it reliably addresses this indication.

Barely researched: 9 studies. Last checked Oct 8, 2026.

0
human evidence
0
eligible
4
unclassified
2
animal / null result

Best-evidenced uses

EvidenceInsufficient
9
Studies

Evidence checked Oct 8, 2026 · newest study 2023

The text on this page was written before the latest evidence check. The tables and numbers are up to date.

Study designs:Case report1Animal study8
Study grades:
D
9

310 community reports across 3 platforms

Coverage

Effects
6
Side effects
5
Interactions
20
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.

These are research findings, not promises. A supplement does not replace medical treatment, and taking more does not work better.

What does research say?

None of these claims has good evidence yet. Best evidence first.

6 claims:3 not enough evidence3 not tested in people

  • Thyroid Health SupportNot enough evidence

    Too few or too small studies to know if it works.

    The one study found a benefit. Strongest study: a single case report. Amount studied: 1-2 g/day.

    Sea moss provides iodine needed for thyroid hormone synthesis when iodine intake is inadequate. Its iodine content is highly variable, so it is not a reliable standardized iodine therapy, and excess intake can impair thyroid function.

    Open the Thyroid Health Support page
  • Nutrient Deficiency ReplenishmentNot enough evidence

    Too few or too small studies to know if it works.

    The one study found a benefit. Amount studied: 1-4 g/day, for chronic.

    Nutrient deficiency replenishment was mentioned in 5 of 299 community reports, including 3 Reddit reports and 2 YouTube reports.

    Open the Nutrient Deficiency Replenishment page
  • Gut-Brain Axis SupportNot enough evidence

    Too few or too small studies to know if it works.

    The one study found a benefit. Amount studied: typical intake, for chronic.

    Open the Gut-Brain Axis Support page
  • Antioxidant Protection EnhancementNot tested in people

    Only tested in animals, cells or theory. Results like these often do not carry over to people.

    All 2 studies with a clear result found a benefit. Strongest study: an animal study. Amount studied: typical dietary intake, for 48 days.

    Open the Antioxidant Protection Enhancement page
  • Male Fertility ImprovementNot tested in people

    Only tested in animals, cells or theory. Results like these often do not carry over to people.

    The one study found a benefit. Strongest study: an animal study. Studied for 48 days.

    Open the Male Fertility Improvement page
  • Testosterone Level IncreaseNot tested in people

    Only tested in animals, cells or theory. Results like these often do not carry over to people.

    The one study found a benefit. Strongest study: an animal study. Studied for 48 days.

    Testosterone increased by 22.6% in a study in animals; this finding does not establish the same effect in people.

    Open the Testosterone Level Increase page

Only reported by users, not studied: Physical Energy Increase, Immune System Support, Mood Improvement, Chronic Pain Reduction, Sleep Quality Improvement, Constipation Relief, and 1 more.

Before you try it

What studies and reports say about side effects and who it may not suit.

Side effects

With weak evidence: Heavy Metal Accumulation, Thyroid Function Decrease, Thyroid Function Increase, Acne Worsening, and Intestinal Permeability Increase (Leaky Gut).

May not suit you if you have
Chronic Kidney Disease
Pregnancy, breastfeeding, children
Avoid in pregnancy and breastfeeding. Not enough data for children.
Reported by users
Bloating (10 posts), Headache (8 posts), and Nausea (5 posts)

General wellness information, not medical advice. Ask a doctor before you start, especially if you take medicines or have a health condition.

How people take it

Amounts from studies and from official limits.

Typical dose
500 mg a day, as Sea Moss Extract (Standardized)
Forms
Sea Moss Extract (Standardized), Sea Moss (Irish Moss), Raw Sea Moss (Chondrus crispus), and Sea Moss Topical Gel

The expert view shows every study, dose protocol and source.

How it works

The clearest proposed mechanism for Sea Moss (Irish Moss) centers on iodine and thyroid hormone production. Iodine from sea moss provides the substrate for thyroid hormone synthesis, while Zinc supports thyroid peroxidase, an enzyme required in that process. Iron also supports iodine utilization because iron deficiency can impair thyroid peroxidase activity.

Effects

6 listed

Start here

The best we have, but the evidence is still weak

  1. Thyroid Health SupportCertaintyLowSourceReference knowledgenot used for recommendations2 other sources

    Sea moss provides iodine needed for thyroid hormone synthesis when iodine intake is inadequate. Its iodine content is highly variable, so it is not a reliable standardized iodine therapy, and excess intake can impair thyroid function.

    What the sources found

    2 positive · 0 neutral · 0 negativeconfidence 53/100

    How big is the effect

    No study gave a number we could compare, so the size is not known.

    Why this rating

    Rests on: reports and reference sources, no studies

    • No studies: low at most
    • Not eligible as a recommendation: low at most

    Where the evidence comes from

    • Community reports1
    • Reference knowledge1

    Dose & course

    1-2 g/day

    Who it applies to

    • Adults
    • Unspecified

    Why it isn't used for recommendations

    No oral-route evidence in adults

    Show studies (2)
    Reference knowledgepositive75% confidence

    Sea moss is a natural source of iodine, a critical substrate for thyroid hormone synthesis. Adequate iodine intake is essential for maintaining euthyroid status, particularly in iodine-deficient individuals.

    1-2 g/dayweeks to monthsEstablished pharmacology
    Community reportsmoderate effectpositive30% confidence

    This effect was mentioned in 4 of 299 community reports discussing it (Reddit 2, YouTube 2).

    4 mentionsReddit 2 · Youtube 2
    Open Thyroid Health Support
    →
  2. Nutrient Deficiency ReplenishmentCertaintyLowSourceReference knowledgelong-termnot used for recommendations2 other sources

    Nutrient deficiency replenishment was mentioned in 5 of 299 community reports, including 3 Reddit reports and 2 YouTube reports.

    What the sources found

    2 positive · 0 neutral · 0 negativeconfidence 53/100

    How big is the effect

    No study gave a number we could compare, so the size is not known.

    Why this rating

    Rests on: reports and reference sources, no studies

    • No studies: low at most
    • Not eligible as a recommendation: low at most

    Where the evidence comes from

    • Community reports1
    • Reference knowledge1

    Dose & course

    1-4 g/day · chronic

    Timing

    felt within days · sustained

    Who it applies to

    • Adults

    Why it isn't used for recommendations

    No oral-route evidence in adults

    Show studies (2)
    Reference knowledgepositive70% confidence

    Sea moss provides bioavailable forms of iodine, potassium, magnesium, calcium, and trace minerals, supporting electrolyte and micronutrient balance, especially in deficient states.

    1-4 g/dayChronicEstablished pharmacology
    Community reportsmoderate effectpositive36% confidence

    This effect was mentioned in 5 of 299 community reports discussing it (Reddit 3, YouTube 2).

    5 mentionsReddit 3 · Youtube 2felt within dayssustained
    Open Nutrient Deficiency Replenishment
    →
Very low probability(4)
  1. Gut-Brain Axis SupportCertaintyVery lowSourceReference knowledgenot used for recommendations1 other source

    What the sources found

    1 positive · 0 neutral · 0 negativeconfidence 60/100

    How big is the effect

    No study gave a number we could compare, so the size is not known.

    Why this rating

    Rests on: reports and reference sources, no studies

    • No studies: low at most
    • Not eligible as a recommendation: low at most

    Where the evidence comes from

    • Reference knowledge1

    Dose & course

    typical intake · chronic

    Who it applies to

    • Adults

    Why it isn't used for recommendations

    Very little evidence on file

    Show studies (1)
    Reference knowledgepositive60% confidence

    Carrageenan in sea moss may modulate gut microbiota composition and intestinal barrier function, indirectly influencing neuroinflammation and mood regulation via the gut-brain axis.

    typical intakeChronicEstablished pharmacology
    Open Gut-Brain Axis Support
    →
  2. Antioxidant Protection EnhancementCertaintyVery lowSourceAnimal researchnot used for recommendations1 cited study · 1 other source

    What the sources found

    2 positive · 0 neutral · 0 negativeconfidence 41/100

    How big is the effect

    No study gave a number we could compare, so the size is not known.

    Why this rating

    Rests on: animal or lab studies only

    • Animal or lab studies only: low at most
    • Not eligible as a recommendation: low at most

    Where the evidence comes from

    • Article1
    • Reference knowledge1

    Dose & course

    typical dietary intake · 48 days

    Who it applies to

    • Adults
    • Animal
    • Parenteral
    • Unspecified

    Why it isn't used for recommendations

    Very little evidence on file

    Show studies (2)
    Animal studyDAnimalpositive12% confidence2021

    The effect of Red Seaweed (Chondrus crispus) on the fertility of male albino rats.

    Decreased by 18.2% vs pre-treated group; significant

    -18.2%Moderate effectHigh risk of bias
    1 mg per injection48 daysPMID 34220241
    Reference knowledgepositive70% confidence

    Sea moss contains polyphenols and sulfated polysaccharides (e.g., carrageenan) with demonstrated in vitro antioxidant activity, contributing to systemic free radical scavenging.

    typical dietary intakeacute and chronicEstablished pharmacology
    Open Antioxidant Protection Enhancement
    →
  3. Male Fertility ImprovementCertaintyVery lowSourceAnimal researchanimal / in-vitro onlynot adult-relevantnot used for recommendations1 cited study

    What the sources found

    1 positive · 0 neutral · 0 negativeconfidence 12/100

    How big is the effect

    No study gave a number we could compare, so the size is not known.

    Why this rating

    Rests on: animal or lab studies only

    • Animal or lab studies only: low at most
    • Not eligible as a recommendation: low at most

    Where the evidence comes from

    • Article1

    Dose & course

    48 days

    Who it applies to

    • Animal
    • Parenteral

    Why it isn't used for recommendations

    Very little evidence on file

    Show studies (1)
    Animal studyDAnimalpositive12% confidence2021

    The effect of Red Seaweed (Chondrus crispus) on the fertility of male albino rats.

    Increased by 35% vs pre-treated (control) group; significant

    35%Large effectHigh risk of bias
    1 mg per injection48 daysPMID 34220241
    Open Male Fertility Improvement
    →
  4. Testosterone Level IncreaseCertaintyVery lowSourceAnimal researchanimal / in-vitro onlynot adult-relevantnot used for recommendations1 cited study

    Testosterone increased by 22.6% (p<0.05) in a study in animals; this finding does not establish the same effect in people.

    What the sources found

    1 positive · 0 neutral · 0 negativeconfidence 10/100

    How big is the effect

    No study gave a number we could compare, so the size is not known.

    Why this rating

    Rests on: animal or lab studies only

    • Animal or lab studies only: low at most
    • Not eligible as a recommendation: low at most

    Where the evidence comes from

    • Article1

    Dose & course

    48 days

    Who it applies to

    • Animal
    • Parenteral

    Why it isn't used for recommendations

    Very little evidence on file

    Show studies (1)
    Animal studyDAnimalpositive10% confidence2021

    The effect of Red Seaweed (Chondrus crispus) on the fertility of male albino rats.

    Increased by 22.6% vs pre-treated group; reported as significant in text, though the abstract calls it insignificant

    22.6%Moderate effectHigh risk of biasStudies disagree
    1 mg per injection48 daysPMID 34220241
    Open Testosterone Level Increase
    →

22 more mentioned only by users

Side effects

5 listed

Highest probability

  1. Heavy Metal AccumulationCertaintyLowSourceReference knowledge1 other source

    Seaweeds including sea moss can accumulate heavy metals such as arsenic, lead, and mercury from contaminated waters, and product quality varies significantly.

    What the sources found

    0 not observed · 0 unclear · 1 reportedconfidence 70/100

    How big is the effect

    No study gave a number we could compare, so the size is not known.

    Where the evidence comes from

    • Reference knowledge1
    Show studies (1)
    Reference knowledgenegative70% confidence

    Sea moss can bioaccumulate arsenic, lead, cadmium, and mercury from seawater; chronic consumption may lead to toxic metal accumulation, especially in contaminated harvest regions.

    Open Heavy Metal Accumulation
    →
  2. Thyroid Function DecreaseCertaintyLowSourceReference knowledge1 other source

    Excess iodine can produce a sustained Wolff-Chaikoff effect and cause or worsen hypothyroidism, especially in people with preexisting thyroid disease.

    What the sources found

    0 not observed · 0 unclear · 1 reportedconfidence 60/100

    How big is the effect

    No study gave a number we could compare, so the size is not known.

    Where the evidence comes from

    • Reference knowledge1
    Show studies (1)
    Reference knowledgenegative60% confidence

    High iodine intake can paradoxically suppress thyroid function (Wolff-Chaikoff effect), particularly in individuals with autoimmune thyroiditis or prior thyroid damage.

    Open Thyroid Function Decrease
    →
  3. Thyroid Function IncreaseCertaintyLowSourceReference knowledge1 other source

    Thyrotoxicosis (Jod-Basedow phenomenon) has been reported.

    What the sources found

    0 not observed · 0 unclear · 1 reportedconfidence 60/100

    How big is the effect

    No study gave a number we could compare, so the size is not known.

    Where the evidence comes from

    • Reference knowledge1
    Show studies (1)
    Reference knowledgenegative60% confidence

    Excessive iodine can induce hyperthyroidism, especially in those with pre-existing thyroid conditions.

    Open Thyroid Function Increase
    →
  4. Acne WorseningCertaintyLowSourceReference knowledge1 other source

    High iodide exposure can rarely provoke or worsen acneiform eruptions.

    What the sources found

    0 not observed · 0 unclear · 1 reportedconfidence 55/100

    How big is the effect

    No study gave a number we could compare, so the size is not known.

    Where the evidence comes from

    • Reference knowledge1
    Show studies (1)
    Reference knowledgenegative55% confidence

    High iodine intake can exacerbate acne in susceptible individuals.

    Open Acne Worsening
    →
  5. Intestinal Permeability Increase (Leaky Gut)CertaintyLowSourceReference knowledge1 other source

    What the sources found

    0 not observed · 0 unclear · 1 reportedconfidence 50/100

    How big is the effect

    No study gave a number we could compare, so the size is not known.

    Where the evidence comes from

    • Reference knowledge1
    Show studies (1)
    Reference knowledgenegative50% confidence

    Carrageenan, a component of sea moss, has been shown in some studies to increase intestinal permeability and promote gut inflammation, though human relevance is debated.

    Open Intestinal Permeability Increase (Leaky Gut)
    →

9 more mentioned only by users

Don't take it if

Conditions and states that rule it out7 listed

Highest probability

  1. Chronic Kidney DiseaseCertaintyMediumSourceReference knowledgeTheoretical

    Where the evidence comes from

    • Reference knowledge

    Confidence

    confidence 70/100

    Rationale

    Impaired renal excretion of potassium combined with sea moss's high potassium content increases the risk of life-threatening hyperkalemia.

    Open Chronic Kidney Disease
    →
Low probability(6)
  1. HyperthyroidismCertaintyLowSourceReference knowledgeTheoretical

    Excess iodine from sea moss can provide additional substrate for thyroid hormone overproduction, potentially worsening hyperthyroidism.

    Where the evidence comes from

    • Reference knowledge

    Confidence

    confidence 80/100

    Rationale

    High iodine content can exacerbate hyperthyroidism or trigger thyrotoxicosis in susceptible individuals.

    Open Hyperthyroidism
    →
  2. PregnancyCertaintyLowSourceReference knowledgeTheoretical

    Excess iodine can cause fetal thyroid dysfunction, including both hypothyroidism and hyperthyroidism, because the fetal thyroid is highly sensitive to iodine fluctuations.

    Where the evidence comes from

    • Reference knowledge

    Confidence

    confidence 80/100

    Rationale

    Excessive iodine intake from sea moss may disrupt fetal thyroid development; risk of neonatal hypothyroidism or goiter due to transplacental passage of excess iodine.

    Open Pregnancy
    →
  3. BreastfeedingCertaintyLowSourceReference knowledgeTheoretical

    Iodine transfers into breast milk, and excess iodine can cause thyroid dysfunction in infants because their thyroid is sensitive to iodine levels.

    Where the evidence comes from

    • Reference knowledge

    Confidence

    confidence 75/100

    Rationale

    High iodine levels in sea moss can concentrate in breast milk, potentially causing infant thyroid dysfunction including transient hypothyroidism.

    Open Breastfeeding
    →
  4. Graves' DiseaseCertaintyLowSourceReference knowledgeTheoretical

    Iodine supplementation can exacerbate Graves' disease and interfere with its treatment. Sea moss should be avoided in this autoimmune thyroid condition.

    Where the evidence comes from

    • Reference knowledge

    Confidence

    confidence 75/100

    Rationale

    Sea moss provides high amounts of iodine, which can exacerbate hyperthyroidism in Graves' disease by providing substrate for uncontrolled thyroid hormone synthesis.

    Open Graves' Disease
    →
  5. Hashimoto's ThyroiditisCertaintyLowSourceReference knowledgeTheoretical

    Excess iodine may worsen autoimmune thyroiditis and accelerate thyroid damage in people with Hashimoto's Thyroiditis.

    Where the evidence comes from

    • Reference knowledge

    Confidence

    confidence 75/100

    Rationale

    Excess iodine can worsen autoimmune thyroiditis and accelerate thyroid damage.

    Open Hashimoto's Thyroiditis
    →
  6. Thyroid NodulesCertaintyLowSourceReference knowledgeTheoretical

    High iodine intake may stimulate autonomous thyroid nodule function, potentially leading to hyperthyroidism.

    Where the evidence comes from

    • Reference knowledge

    Confidence

    confidence 70/100

    Rationale

    Iodine may stimulate growth or activity of autonomous thyroid nodules, potentially causing hyperthyroidism.

    Open Thyroid Nodules
    →

Pregnancy, breastfeeding and children

What is known for each group. Ask a doctor before using it in any of them.

  • PregnancyAvoid

    Studies or guidelines say to avoid it in this group.

    Excessive iodine intake from sea moss may disrupt fetal thyroid development; risk of neonatal hypothyroidism or goiter due to transplacental passage of excess iodine.

  • BreastfeedingAvoid

    Studies or guidelines say to avoid it in this group.

    High iodine levels in sea moss can concentrate in breast milk, potentially causing infant thyroid dysfunction including transient hypothyroidism.

  • ChildrenNot enough data

    Too little research to say anything. This is not a clearance.

Interactions

Combine with caution

Highest severity first

  1. AmiodaroneTheoreticalCaution

    Amiodarone already supplies a large iodine burden, so additional variable iodine from sea moss may increase the risk of iodine-induced hypothyroidism or hyperthyroidism.

    Where the evidence comes from

    • Reference knowledge

    Confidence

    confidence 75/100

    Open Amiodarone
    →
  2. Iodinated Contrast MediaTheoreticalCaution

    Iodinated Contrast Media contains massive iodine loads, and combining it with sea moss supplementation could trigger thyroid dysfunction through Jod-Basedow or Wolff-Chaikoff effects.

    Where the evidence comes from

    • Reference knowledge

    Confidence

    confidence 75/100

    Open Iodinated Contrast Media
    →
  3. Levothyroxine (T4)TheoreticalCaution

    Sea moss’s high iodine content can interfere with thyroid hormone synthesis and destabilize levothyroxine dosing, potentially causing hypothyroidism or hyperthyroidism.

    Where the evidence comes from

    • Reference knowledge

    Confidence

    confidence 75/100

    Open Levothyroxine (T4)
    →
  4. Methimazole (Antithyroid)TheoreticalCaution

    Excess iodine from sea moss can override the antithyroid effect of Methimazole, potentially causing loss of thyroid control and thyrotoxicosis.

    Where the evidence comes from

    • Reference knowledge

    Confidence

    confidence 70/100

    Open Methimazole (Antithyroid)
    →
  5. Propylthiouracil (Antithyroid)TheoreticalCaution

    High iodine intake from sea moss can antagonize the therapeutic action of Propylthiouracil, risking exacerbation of hyperthyroidism.

    Where the evidence comes from

    • Reference knowledge

    Confidence

    confidence 70/100

    Open Propylthiouracil (Antithyroid)
    →
  6. WarfarinTheoreticalCaution

    Sea moss is not established to contain clinically significant amounts of vitamin K; any effect on warfarin is theoretical and product-dependent.

    Where the evidence comes from

    • Reference knowledge

    Confidence

    confidence 70/100

    Open Warfarin
    →
Unrated(6)
  1. ACE InhibitorsTheoreticalCaution

    ACE Inhibitors can increase potassium levels, and the potassium in sea moss may add to the risk of hyperkalemia.

    Where the evidence comes from

    • Reference knowledge

    Confidence

    confidence 60/100

    Open ACE Inhibitors
    →
  2. Antiplatelet AgentsTheoreticalCaution

    Clinically relevant antiplatelet activity from oral sea moss is not established; any additive effect with antiplatelet drugs is theoretical.

    Where the evidence comes from

    • Reference knowledge

    Confidence

    confidence 60/100

    Open Antiplatelet Agents
    →
  3. Angiotensin II Receptor Blockers (ARBs)TheoreticalCaution

    Angiotensin II Receptor Blockers (ARBs) can increase potassium levels, while sea moss is high in potassium; combined use may increase hyperkalemia risk, especially in patients with reduced kidney function.

    Where the evidence comes from

    • Reference knowledge

    Confidence

    confidence 60/100

    Open Angiotensin II Receptor Blockers (ARBs)
    →
  4. LithiumTheoreticalCaution

    Lithium and excess iodine can both suppress thyroid function, increasing the risk of hypothyroidism and goiter.

    Where the evidence comes from

    • Reference knowledge

    Confidence

    confidence 60/100

    Open Lithium
    →
  5. Potassium-Sparing DiureticsTheoreticalCaution

    Sea moss contains significant potassium, so combining it with Potassium-Sparing Diuretics may increase the risk of hyperkalemia, especially in patients with reduced kidney function.

    Where the evidence comes from

    • Reference knowledge

    Confidence

    confidence 60/100

    Open Potassium-Sparing Diuretics
    →
  6. Digoxin (Cardiac Glycoside)TheoreticalCaution

    Sea moss may affect serum potassium, and potassium abnormalities can influence digoxin toxicity; however, sea moss is not established to alter potassium enough to change digoxin effect.

    Where the evidence comes from

    • Reference knowledge

    Confidence

    confidence 55/100

    Open Digoxin (Cardiac Glycoside)
    →

Okay to combine with

Highest probability of useful synergy

  1. SupplementsSeleniumCertaintyMediumSourceReference knowledgeComplementary

    Selenium is an essential cofactor for iodothyronine deiodinases, which convert T4 to active T3; with iodine from Sea Moss (Irish Moss), it supports thyroid hormone metabolism.

    Where the evidence comes from

    • Reference knowledge

    Confidence

    confidence 65/100

    Open Selenium
    →
  2. SupplementsKelpCertaintyMediumSourceReference knowledgeComplementary

    Bladderwrack is also rich in iodine and often combined with sea moss for synergistic thyroid support.

    Where the evidence comes from

    • Reference knowledge

    Confidence

    confidence 60/100

    Open Kelp
    →
  3. SupplementsZincCertaintyMediumSourceReference knowledgeComplementary

    Zinc is required for thyroid peroxidase enzyme function and works complementarily with iodine from Sea Moss (Irish Moss) for thyroid hormone synthesis.

    Where the evidence comes from

    • Reference knowledge

    Confidence

    confidence 60/100

    Open Zinc
    →
  4. SupplementsProbioticsCertaintyMediumSourceReference knowledgeComplementary

    Sea moss acts as a prebiotic due to its carrageenan and fiber content, providing a substrate for beneficial gut bacteria; co-administration with probiotics may enhance gut health synergistically.

    Where the evidence comes from

    • Reference knowledge

    Confidence

    confidence 55/100

    Open Probiotics
    →
  5. SupplementsVitamin C (Ascorbic Acid)CertaintyMediumSourceReference knowledgePotentiating

    Vitamin C enhances the absorption of non-heme iron present in sea moss, potentially improving its nutrient replenishment effects for iron status.

    Where the evidence comes from

    • Reference knowledge

    Confidence

    confidence 55/100

    Open Vitamin C (Ascorbic Acid)
    →

Weakens or is weakened by

Highest probability

  1. SupplementsCalciumCertaintyMediumSourceReference knowledgeCompetitive

    Taking Calcium and Sea Moss simultaneously can cause Calcium to bind with minerals in Sea Moss, reducing absorption of iodine, potassium, and other trace minerals from both sources.

    Where the evidence comes from

    • Reference knowledge

    Confidence

    confidence 60/100

    Open Calcium
    →
  2. LithiumCertaintyMediumSourceReference knowledgeDepleting

    Iodine in sea moss may reduce the efficacy of lithium in bipolar disorder by altering thyroid function, which can indirectly destabilize mood regulation and increase risk of lithium-induced goiter or hypothyroidism.

    Where the evidence comes from

    • Reference knowledge

    Confidence

    confidence 60/100

    Also listed as dangerous interaction — do not combine. This antagonist entry explains the pharmacological mechanism.

    Open Lithium
    →
  3. SupplementsIronCertaintyMediumSourceReference knowledgeCompetitive

    Iron and iodine share transport mechanisms; high-dose iron may reduce iodine absorption from sea moss, impairing thyroid support.

    Where the evidence comes from

    • Reference knowledge

    Confidence

    confidence 55/100

    Open Iron
    →

Forms & dosage

Raw Sea Moss (Chondrus crispus)

Oral4/10

Iodine and heavy-metal levels may vary depending on where the raw dried sea moss was harvested. Thorough washing and sourcing from a reputable supplier are recommended.

Bioavailability
Low
Availability
Health & supplement stores
Rating
4/10 · Minimal

The most traditional and widely available form, but nutrient content is highly variable and bioavailability is uncharacterized. Lacks standardization.

May cause digestive upset in sensitive individuals due to high fiber and carrageenan content.

4 g · Daily

Pharmacology
Daily total
4 g
Time of day
Any time
With meals
Any time

Sea Moss (Irish Moss)

Oral5/10

This form is perishable, so it must be refrigerated and consumed within a few weeks. It is often combined with lime or other preservatives.

Bioavailability
Low
Availability
Health & supplement stores
Rating
5/10 · Minimal

The most popular consumer form, but essentially identical to raw powder in nutrient profile. Gel formation may slightly improve digestibility.

Perishable and requires refrigeration. Tolerability is generally good, but the carrageenan content can be a gut irritant for some.

10 g · Daily

Pharmacology
Daily total
10 g
Time of day
Any time
With meals
Any time

Sea Moss Extract (Standardized)

Oral6/10
Bioavailability
Moderate
Availability
Health & supplement stores
Rating
6/10 · Minimal

Offers a more concentrated and potentially more consistent dose than raw or gel forms, but still lacks robust clinical data on specific bioactive compounds.

May be better tolerated than raw sea moss as it contains less indigestible fiber.

500 mg · Daily

Pharmacology
Daily total
500 mg
Time of day
Any time
With meals
Any time

Sea Moss Topical Gel

Topical3/10
Availability
Health & supplement stores
Rating
3/10 · Minimal

Purely a cosmetic form with no evidence of systemic absorption. Used for its mucilaginous and mineral content on the skin.

Generally well-tolerated topically, but can cause irritation in sensitive individuals.

Research & prescription forms (1)

Forms used in research or medicine — not everyday consumer products.

Chondrus crispus Extract (Research Grade)

OralDelivery research

Research suppliers only · research only

A purified, non-commercial extract used in in-vitro and animal studies to investigate specific bioactives like carrageenans and peptides, not sold as a consumer supplement.

Used to isolate mechanisms of action, such as immunomodulatory or antiviral effects, distinct from whole-plant consumer products.

Community experience

Based on 310 public posts from Reddit, YouTube, and Bluesky.

Signal found10 signals3 platforms
Reddit 250YouTube 49Bluesky 11

What users report (not studied)

No study backs these. They come only from public posts and videos.

10 outcomes mentioned across 310 public reports. A report often mentions several, so these counts do not add up to the total.

Reported benefits7

Reported side effects3

What people report taking

dose read from 11 of 310 reports

Too few reports gave a readable dose, so no typical dose is shown.

Forms taken

Gel40Capsule26Gummy10Pill6

How often

Daily119As needed4Regularly3Cycling2

Self-reported from public posts and videos. Not evidence of effect, and not a recommendation.

More

Write-up

For Sea Moss (Irish Moss), the listed marker is Immunoglobulin A, a lab-based biomarker rather than a number you can measure at home. The expected direction is an increase, reported in mg/dL. A result that does not increase is information about the observed change, but it should not be treated by itself as proof that Sea Moss (Irish Moss) is working or not working.

A practical way to check this marker is the Immune Standard panel, which includes Immunoglobulin A and does not require fasting. Recheck after 3.5 weeks rather than measuring again too early, since timing affects how the result is interpreted. This is self-tracking information, not a diagnosis; results that appear abnormal or raise concern belong with a clinician.

References

10 screened · 8 analysed · 10 listed below

Studies and sources cited on this page. Evidence quality varies — check the grade on each.

  1. Maine organic dairy producers' receptiveness to seaweed supplementation and effect of Chondrus crispus on enteric methane emissions in lactating cows.Front Vet Sci2023Animal studyD
  2. “Fueling the Fire” - Irish Sea-Moss Resulting in Jod-Basedow Phenomenon in a Patient With Grave’s DiseaseJ Endocr Soc2021Case StudyDn=1
  3. The effect of Red Seaweed (Chondrus crispus) on the fertility of male albino rats.Saudi J Biol Sci2021Animal studyD
  4. Effects of Dietary Inclusion of Seaweed, Heat Stress and Genetic Strain on Performance, Plasma Biochemical and Hematological Parameters in Laying Hens.Animals (Basel)2020Animal studyD
  5. Feed Supplementation with Red Seaweeds, Chondrus crispus and Sarcodiotheca gaudichaudii, Reduce Salmonella Enteritidis in Laying Hens.Front Microbiol2017Animal studyD
  6. Red Seaweeds Sarcodiotheca gaudichaudii and Chondrus crispus down Regulate Virulence Factors of Salmonella Enteritidis and Induce Immune Responses in Caenorhabditis elegans.Front Microbiol2016Animal studyD
  7. A Cultivated Form of a Red Seaweed (Chondrus crispus), Suppresses β-Amyloid-Induced Paralysis in Caenorhabditis elegans.Mar Drugs2015Animal studyD
  8. Prebiotic effects of diet supplemented with the cultivated red seaweed Chondrus crispus or with fructo-oligo-saccharide on host immunity, colonic microbiota and gut microbial metabolites.BMC Complement Altern Med2015Animal studyD
  9. Feed supplementation with red seaweeds, Chondrus crispus and Sarcodiotheca gaudichaudii, affects performance, egg quality, and gut microbiota of layer hens.Poult Sci2014Animal studyD
  10. Established pharmacology

Diatelos provides general wellness information based on published research. It is not medical advice. Talk to a clinician before starting any new supplement or practice, especially if you have a health condition, are pregnant, or take medication.