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Kelp

Swanson
4.7
★ ★ ★ ★ ★
(4234 ratings)
Iodine 225 mcg
Ascophyllum nodosum 56 mg
Product Image
Score87
A focused iodine option with a focused formula with useful regional source disclosure. Its value is mainly for inadequate intake, while natural kelp can vary more than purified iodide salts.
How scoring works
Quantity:250 Tablet(s) • (250 servings)
Goals:
Metabolism Boost
Energy

Score 87

A focused iodine option with a focused formula with useful regional source disclosure. Its value is mainly for inadequate intake, while natural kelp can vary more than purified iodide salts.
How scoring works
$11.09($0.04 per serving)
iHerb
$ 11.09
iHerb
$ 11.09
Amazon
$ 11.09
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Analysis

The formula delivers 225 mcg from Atlantic kelp in a tablet. A focused formula with useful regional source disclosure.

Iodine supports thyroid-hormone production and may help energy or metabolic function when dietary intake is inadequate. It is not a stimulant, and extra iodine is unlikely to improve these goals when thyroid status is already adequate.

The main limitation is that natural kelp can vary more than purified iodide salts. The product is most sensible for adults who want moderate iodine from Atlantic kelp, with total iodine intake considered before regular use.

Who is it for
  • adults who want moderate iodine from Atlantic kelp
  • people whose diet provides too little iodine
Best for
  • targeted iodine support
  • supporting normal thyroid-hormone production when iodine intake is low

Pros

  • Clearly states an iodine amount of 225 mcg
  • A focused formula with useful regional source disclosure
  • Tablet keeps use straightforward

Cons

  • Natural kelp can vary more than purified iodide salts
  • Benefits are conditional on inadequate iodine intake
  • Whole-seaweed iodine can be less consistent than purified iodide

Warnings

  • Seaweed iodine can vary, so avoid adding another iodine supplement without reviewing total intake.
  • Unstated contaminant controls matter for long-term use of a marine-sourced ingredient.
  • People with autoimmune thyroid disease, thyroid nodules, or thyroid-medicine use should obtain condition-specific guidance.

Nutrient quality

89 Highest impact

The regional kelp source and iodine amount support good routine suitability. Natural iodine variability remains a limitation compared with an isolated iodide salt.

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Ingredient transparency

87 Highest impact

The iodine amount, kelp weight, and Atlantic origin are clearly shown. Complete tablet ingredients and intake directions are not included in the supplied data.

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Customer satisfaction

73 High impact

The supplied average rating is strong and backed by a very large review pool. No review text is available to assess recurring complaints or firsthand tolerance and ease of use.

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Value for money

98 Highest impact

The suitable dose and clear source strongly justify the low relative cost. The appropriate dose and very low serving cost create excellent practical value.

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Report analysis

Goals

Metabolism Boost
Impact
High effect
B- Goal FitA Strength of SupportC- CoverageA+ Formula Quality

Kelp-derived iodine supports thyroid hormone production and therefore has a direct link to metabolic regulation. The benefit is most meaningful for people whose iodine intake is insufficient.

The 225 mcg amount fits routine daily support and the Atlantic kelp source is clearly identified. Natural kelp can vary more than purified iodide, but the focused formula provides useful depth without an excessive dose.

Study evidence
Iodine Mixed 17 studies
Energy
Impact
High effect
B Goal FitA- Strength of SupportC- CoverageA Formula Quality
Iodine · 225 mcg

Kelp provides a clearly stated 225 mcg iodine amount that supports normal thyroid-hormone production when iodine intake is inadequate. The Atlantic kelp source gives useful origin disclosure and the one-tablet formula is simple.

Iodine supports energy only indirectly through thyroid function and will not act like a stimulant when status is already adequate. Natural kelp can vary more than purified iodide, so people with thyroid disease should discuss supplemental iodine with their thyroid clinician.

Study evidence
Iodine Adverse 3 studies

Ingredients

IngredientAmount per serving
Iodine (Kelp)
225 mcg
Atlantic Kelp (Iodine)
56 mg
Adults 18–50
Report overview
Iodine (Kelp) · 225 mcg OverallScore96
A- Active Ingredient Quality & BioavailabilityA+ Dose, Safety & Label TransparencyA+ Value

Kelp supplies iodine in a useful whole-food form, and the amount suits routine daily support. Atlantic sourcing adds useful origin transparency. Low serving cost makes it a practical daily option.

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Sources

Published studies used for the product analysis and the top-ranked studies for each ingredient and goal.

  1. U-Shaped Associations Between Urinary Iodine Concentration and the Prevalence of Metabolic Disorders: A Cross-Sectional Study.
    Jin M; Zhang Z; Li Y; Teng D; Shi X; Ba J; Chen B; Du J; He L; Lai X; Teng X; Li Y; Chi H; Liao E; Liu C; Liu L; Qin G; Qin Y; Quan H; Shi B; Sun H; Tang X; Tong N; Wang G; Zhang JA; Wang Y; Xue Y; Yan L; Yang J; Yang L; Yao Y; Ye Z; Zhang Q; Zhang L; Zhu J; Zhu M; Ning G; Mu Y; Zhao J; Teng W; Shan Z · Thyroid : official journal of the American Thyroid Association · 2021
    Cross-sectional study51,795 participantsMetabolism Boost forIodine
  2. Energy level and fatigue after surgery for thyroid cancer: A population-based study of patient-reported outcomes.
    Hughes DT; Reyes-Gastelum D; Kovatch KJ; Hamilton AS; Ward KC; Haymart MR · Surgery · 2020
    Cohort study2,584 participantsEnergy forIodine
  3. Iodine deficiency and real-life supplementation ineffectiveness in Polish pregnant women and its impact on thyroid metabolism.
    Filipowicz D; Szczepanek-Parulska E; Mikulska-Sauermann AA; Karaźniewicz-Łada M; Główka FK; Szymanowski K; Ołtarzewski M; Schomburg L; Ruchała M · Frontiers in endocrinology · 2023
    Cross-sectional study91 participantsMetabolism Boost forIodine
  4. Association of radioactive iodine treatment with survivorship symptoms and primary care utilisation in women of reproductive age with thyroid cancer: a retrospective cohort study.
    Devanarayan P; Hartman M; Partin M · Family medicine and community health · 2026
    Cohort study10,882 participantsEnergy forIodine
  5. Iodine Supplementation Decreases Hypercholesterolemia in Iodine-Deficient, Overweight Women: A Randomized Controlled Trial.
    Herter-Aeberli I; Cherkaoui M; El Ansari N; Rohner R; Stinca S; Chabaa L; von Eckardstein A; Aboussad A; Zimmermann MB · The Journal of nutrition · 2015
    Randomized trial163 participantsMetabolism Boost forIodine
  6. Health-Related Quality of Life in Differentiated Thyroid Cancer Survivors: A Cross-Sectional Study From Turkey.
    Gültekin A; Kahraman MY; Şengöz T; Şimşek FS · Head & neck · 2026
    Cross-sectional study202 participantsEnergy forIodine
  7. The relationship between excessive iodine during pregnancy and adverse pregnancy complications.
    Li S; Zha H; Cui Y; Sun L; Yu L; Yuan Q · Endocrine · 2025
    Cohort study595 participantsMetabolism Boost forIodine
  8. Effect of oral iodized oil on thyroid size and thyroid hormone metabolism in children with concurrent selenium and iodine deficiency.
    Zimmermann MB; Adou P; Torresani T; Zeder C; Hurrell RF · European journal of clinical nutrition · 2000
    Single-arm trial51 participantsMetabolism Boost forIodine
  9. Serum Iodine Concentration as a Biomarker for Individual Iodine Nutrition and Thyroid Function in Pregnant Women: A Cross-Sectional Study in Hubei Province.
    Xu M; Dai X; Wang Z; Guo C; Zhang B; Guo H · Public health nutrition · 2026
    Cross-sectional study1,197 participantsMetabolism Boost forIodine
  10. Urinary Iodine Concentration and Thyroid Hormone Metabolism in Pregnant Women and Neurodevelopment in Their Children: A Longitudinal Canadian Birth Cohort.
    Berghuis SA; Hall M; Krzeczkowski JE; Goodman CV; Chevrier J; Ayotte P; Lanphear B; Till C · Nutrients · 2025
    Cohort study1,501 participantsMetabolism Boost forIodine
  11. A study on the differences in urinary iodine and serum iodine in relation to children's iodine nutrition and lipids.
    Zhang Y; Xu L; Wang L; Gao H; Hao J; Dong L; Qiu L; Wang J; Yan S; Liu L · Lipids in health and disease · 2026
    Cross-sectional studyMetabolism Boost forIodine
  12. Serum Manganese, Cobalt, Copper, Zinc, Selenium, and Iodine Levels, and the Incidence of Type 2 Diabetes: A Nested Case-control Study.
    Ito A; Yamamoto S; Iwai-Shimada M; Kobayashi Y; Isobe T; Iwai K; Nakayama SF; Konishi M; Watanabe Y; Yamamoto S; Nakagawa T; Yamazaki S; Mizoue T · Biological trace element research · 2026
    Case-control study936 participantsMetabolism Boost forIodine
  13. Iron status influences the efficacy of iodine prophylaxis in goitrous children in Côte d'Ivoire.
    Zimmermann MB · International journal for vitamin and nutrition research. Internationale Zeitschrift fur Vitamin- und Ernahrungsforschung. Journal international de vitaminologie et de nutrition · 2002
    OtherMetabolism Boost forIodine
  14. Persistence of goiter despite oral iodine supplementation in goitrous children with iron deficiency anemia in Côte d'Ivoire.
    Zimmermann M; Adou P; Torresani T; Zeder C; Hurrell R · The American journal of clinical nutrition · 2000
    Non-randomized trial109 participantsMetabolism Boost forIodine