- Type
- Seaweed
- How serious
- Moderate severity
- Evidence
- Strong evidence
Why it is flagged
Too much iodine disturbs the thyroid as surely as too little, and a gram of dried kelp can carry several times the adult upper level of 1,100 µg a day. Health Canada's Kelp Products monograph caps a licensed product at 1 g of kelp and 800 µg of iodine a day and tells pregnant and breastfeeding users to ask a practitioner first; its warning on a kelp product names pregnancy, breastfeeding and thyroid disease as the groups at risk, since unborn babies are very sensitive to high iodine and may be born with an enlarged thyroid.
Health topics it bears on
Sources
- Kelp Products Health Canada (Natural Health Products Ingredients Database), 2026
- Dietary reference intakes tables: Reference values for elements Health Canada, 2025
- Health Canada Warns Consumers Not to use Trophic Kelp & Glutamic Acid HCl Due to Health Risk Health Canada, 2008
- Binding maximum iodine levels in edible seaweeds may help reduce health-relevant intake levels (BfR Opinion No. 044/2026) German Federal Institute for Risk Assessment (Bundesinstitut für Risikobewertung), 2026
- Fucus – herbal medicinal product (European Union herbal monograph on Fucus vesiculosus L., thallus) European Medicines Agency, 2014
- ATA Statement on the Potential Risks of Excess Iodine Ingestion and Exposure American Thyroid Association, 2013
Also listed as
kelp powder, kelp extract, sea kelp, norwegian kelp, atlantic kelp, kelp meal, kombu, konbu, makombu, japanese kelp, sea tangle, laminaria, laminaria digitata, laminaria japonica, laminaria hyperborea, saccharina japonica, ascophyllum nodosum, knotted wrack, macrocystis pyrifera, giant kelp, bladderwrack, bladder wrack, fucus vesiculosus, fucus, black tang, kelpware, varech, algue kombu, laminaire, laminaires, fucus vésiculeux, goémon, alga kombu, kombu-alge, blasentang