{"ok":true,"entry":{"slug":"kelp","kind":"supplement","name":"kelp","aliases":["Laminaria","bladderwrack","seaweed iodine"],"brands_sg":["Life Extension","NOW Foods","Nature's Way","Oregon's Wild Harvest","NaturesPlus"],"class":"seaweed","tags":["general"],"use_for":"an iodine source; iodine is part of thyroid hormones","use_after":"no timing data — iodine limits are set per day","use_duration":null,"take_with":null,"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"],"dose_note":"the adult RDA for iodine is 150 mcg a day and the UL 1,100 mcg; Singapore caps supplement iodine at 0.15 mg a day, and measured kelp products vary widely against those figures","dosage":{"ul":1100,"unit":"mcg","fda_dv":150,"rda_ai":150,"ul_status":"established","population":"general adult — all four values are for iodine, kelp's active constituent, not for kelp mass","hsa_max_daily":150},"ul_status":"established","sg_class":null,"cautions":["any thyroid condition — even small amounts of kelp can have antithyroid actions; ask your doctor first","product labelling may be insufficient — measured iodine per dose ranged 5 to 5,600 mcg","high intakes can cause goiter, elevated TSH and hypothyroidism"],"clashes":[{"src":["ods_iodine_supp"],"note":"high doses of iodine can have an additive effect","with":"anti-thyroid medications (e.g. methimazole)"}],"sources":[{"id":"ods_iodine","url":"https://web.archive.org/web/20230529002645/https://ods.od.nih.gov/factsheets/Iodine-HealthProfessional/","label":"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","quote":"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","accessed":"2026-08-27"},{"id":"ods_iodine_supp","url":"https://web.archive.org/web/20230529002645/https://ods.od.nih.gov/factsheets/Iodine-HealthProfessional/","label":"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","quote":"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","accessed":"2026-08-27"},{"id":"kelp_iodine2021","url":"https://europepmc.org/article/PMC/PMC8035890","label":"Food & Nutrition Research 2021 — Commercially available kelp and seaweed products: valuable iodine source or risk of excess intake? (96 products analysed by ICP-MS)","quote":"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.","accessed":"2026-08-27"},{"id":"thyroid_rev2021","url":"https://europepmc.org/article/PMC/PMC8077470","label":"European Thyroid Journal 2021 — Iodine, Seaweed, and the Thyroid (review, key messages)","quote":"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.","accessed":"2026-08-27"},{"id":"hsa_iodine","url":"https://file.go.gov.sg/hsa-chp-prohibited-restricted-ing-guidelines.pdf","label":"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","quote":"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","accessed":"2026-08-27"},{"id":"hsa_hs_limits","url":"https://file.go.gov.sg/hsa-hs-guidelines.pdf","label":"HSA Singapore — Health Supplements Guidelines (Jan 2026), clause 4.8 + Table 5: Minerals Limits","quote":"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","accessed":"2026-08-27"},{"id":"iherb_sg","url":"https://sg.iherb.com/c/kelp","label":"iHerb Singapore — Kelp category, default (best-selling) order","quote":"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","accessed":"2026-08-27"}],"brand_certs":null,"updated_at":"2026-08-29T16:16:23.779398+08:00"},"disclaimer":"kozen-x is not a medical device and does not give medical advice. it lists what published sources have written down. absence of a record is not the same as safe."}