Roll Call

Kelp — answers to seaweed (often a source of iodine)

Plant

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A dried, ground preparation of brown seaweed, most often varieties of kelp. On a supplement label it typically functions as a natural source of iodine rather than a distinct nutrient in its own right.

Why it’s used

Taken as a plant-based way to get iodine, a mineral the thyroid needs to make its hormones.

What the evidence is for

providing dietary iodine for thyroid hormone synthesis.

What the evidence says

NIH's Office of Dietary Supplements identifies iodine as essential for thyroid hormone production, with a well-established Recommended Dietary Allowance. Kelp itself is not separately studied as a supplement so much as it is a delivery vehicle for iodine, and its iodine content varies widely and unpredictably by species and batch, which the same fact sheet flags as a practical concern for dosing accuracy.

Dose studied

150–1100 mcg — adult RDA (150 mcg) up to the tolerable upper intake level for iodine (1,100 mcg), per NIH ODS.

Context

Because iodine content in kelp products is inconsistent, published iodine-intake research does not translate into a reliable per-gram dose of kelp itself.

Educational information, not medical or safety advice. Consult a professional for allergies or medical concerns.