What Works Skin — Independent · Evidence-First · Ad-FreeIssue 014 · 20 April 2026 · Next: 04 Maywhatworksskin.com
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Supplement · Trend Watch · Sea moss

P. 23 · BRIEF

Sea moss.

TikTok cure-all. No skin-specific human data.

The 2023–24 wellness trend that washed up on Indian shelves a year later. A red algae with genuine micronutrient content (iodine, magnesium, potassium) — and nothing in the published literature that justifies the 'cure-all' positioning. We say no.

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— § 02

What the literature shows.

Skin endpoints (any)
—

No defensible human RCTs on sea moss for skin endpoints. The category is built entirely on social-media testimonial.

10%
Iodine repletion (when deficient)
Established

Sea moss contains highly variable iodine content — sometimes much more than recommended daily intake. Not a controlled iodine source.

70%
Mineral content (Mg, K, Ca)
Established

Real micronutrient profile. The same micronutrients are available from a multivitamin at one-tenth the price and with predictable dosing.

60%
Heavy metal contamination
Surveillance studies

Wild-harvested sea moss frequently shows arsenic, cadmium, and lead above advisable thresholds. Source matters; testing is essential.

Caution
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— § 03

Forms and bioavailability.

Raw sea moss gel

Absorption · Variable

Home-soaked dried algae. Iodine and contaminant content unpredictable. Hard to dose responsibly.

Sea moss capsules 1000 mg

Absorption · Variable

Standardised packaging; ingredient consistency depends on the brand and harvest source.

'Sea moss + bladderwrack + burdock'

Absorption · Variable

The 'Dr. Sebi-inspired' combination popular on social. No skin-specific evidence; iodine content can be very high.

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Bottom line

A trend with no skin-specific evidence and a real safety conversation around iodine and heavy metals. Skip.

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— § 04

Frequently asked.

Why is iodine a concern?

Sea moss is iodine-rich and iodine content varies widely between batches. Excess iodine can trigger thyroid dysfunction (both hyper- and hypothyroid presentations, depending on baseline status), and a daily sea moss habit can substantially exceed recommended iodine intake without the consumer realising. People with pre-existing thyroid disease should not take sea moss.

What about the heavy metal stories?

Wild-harvested sea moss accumulates ocean-water heavy metals (particularly arsenic and cadmium). Lab testing of commercial samples has repeatedly shown contamination above advisory thresholds. Buy only from vendors who provide third-party heavy-metal testing per batch — and most do not.

Is there any defensible use case?

Sea moss is a perfectly fine occasional addition to a varied diet, like other seaweeds. The case against is not for the food; it is for the daily-supplement form sold with skin and 'wellness' marketing claims that the evidence does not support.

What should I take instead?

If your concern is mineral micronutrient sufficiency, a tested multivitamin with appropriate iodine (~150 mcg/d) does the same job at one-tenth the cost and one-hundredth the contamination risk. If your concern is skin, see the rest of this section.