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Kelp

Supplement seaweed general nutrition
Aka: Laminaria, bladderwrack, seaweed iodine
Brands seen in Singapore: Life Extension, NOW Foods, Nature's Way, Oregon's Wild Harvest, NaturesPlus
Not medical advice. Check with your doctor or pharmacist before you start, stop or change the timing of anything you take.
How to use
What it’s for
An iodine source; iodine is part of thyroid hormones
When to take
No timing data — iodine limits are set per day
Pros & cons
Pros
  • A food-based iodine source; the DV is 150 mcg
  • Iodine is an essential component of T4 and T3
  • SG caps supplement iodine at 0.15 mg a day
Cons
  • Iodine ranged 5-5,600 mcg per daily dose in products
  • Even small amounts can have antithyroid actions
  • Excess iodine can disturb thyroid function
Sources
  1. NIH ODS — Iodine, Fact Sheet for Health Professionals (“Updated: April 28, 2022”), Introduction + Table 1 RDAs + Table 3 ULs; read via the web.archive.org capture 20230529002645 because ods.od.nih.gov 403s direct fetches · read 2026-08-27
    what it says
    “Iodine is an essential component of the thyroid hormones thyroxine (T4) and triiodothyronine (T3) … Table 1 lists the current RDAs for iodine … 19+ years 150 mcg … Tolerable Upper Intake Levels (ULs) for Iodine … 1,100 mcg”
  2. NIH ODS — Iodine, Fact Sheet for Health Professionals (“Updated: April 28, 2022”), Iodine and Dietary Supplements / Daily Value footnote / Interactions with Medications; read via the web.archive.org capture 20230529002645 · read 2026-08-27
    what it says
    “Supplements containing kelp, a seaweed that contains iodine, are also available … The DV for iodine is 150 mcg for adults … Taking high doses of iodine with anti-thyroid medications can have an additive effect”
  3. Food & Nutrition Research 2021 — Commercially available kelp and seaweed products: valuable iodine source or risk of excess intake? (96 products analysed by ICP-MS) · read 2026-08-27
    what it says
    “The iodine content in one portion of wholefood macroalgae products ranged from 128 to 62,400 μg … and in supplements it ranged from 5 to 5,600 μg per daily dose.”
  4. European Thyroid Journal 2021 — Iodine, Seaweed, and the Thyroid (review, key messages) · read 2026-08-27
    what it says
    “excess iodine intake can also result in thyroid function disorders … Caution against consumption of brown seaweeds (kelps) is required as even small amounts can have antithyroid actions while product labelling may be insufficient.”
  5. HSA Singapore — Guidelines on Prohibited and Restricted Ingredients in HS and TM (Oct 2025), Annex A row 55 (Iodine); no row for Chondrus crispus, Laminaria, kelp or seaweed · read 2026-08-27
    what it says
    “Iodine … Restricted use in HS and TM … When for oral use by general adult population, the maximum recommended daily dose should not provide more than 0.15mg”
  6. HSA Singapore — Health Supplements Guidelines (Jan 2026), clause 4.8 + Table 5: Minerals Limits · read 2026-08-27
    what it says
    “HS for use by the general adult population should not contain vitamins and minerals exceeding the stipulated limits stated in Tables 4 and 5 … Table 5: Minerals Limits … Iodine 0.15 mg”
  7. iHerb Singapore — Kelp category, default (best-selling) order · read 2026-08-27
    what it says
    “1 - 32 of 32 results … Life Extension, Sea-Iodine™, 1,000 mcg … NOW Foods, Kelp, 150 mcg … Nature's Way, Whole Thallus Kelp … Oregon's Wild Harvest, Organic Kelp … NaturesPlus, Icelandic Kelp”
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Updated 2026-08-29. Every line above traces to a numbered source. Kozen-X is not a medical device and does not give medical advice. It lists what published sources have written down — nothing more. A pair not listed is unrecorded, not cleared. Before you start, stop or re-time anything, talk to your doctor or pharmacist.