Nutricost Irish Sea Moss Extract (with Bladderwrack & Burdock Root) Review

The listing states it plainly: "Delivers 400mg of 10:1 Irish Sea Moss extract per serving" — that's 400mg of a concentrated extract, which at a 10:1 ratio is equivalent to roughly 4,000mg of raw sea moss. Two capsules make a serving, 60 servings a bottle. That is a real, checkable disclosure, and it's the number to compare against a raw-powder capsule like Double Wood's 1,200mg (you can't compare 400 to 1,200 directly — compare the 4,000mg raw-equivalent). The Supplement Facts panel also gives milligrams for the other two botanicals: 200mg of a 20:1 Bladderwrack Extract and 200mg of a 10:1 Burdock Root Extract — every ingredient in the trio carries a printed number. What the label still doesn't give you is a direct iodine figure in micrograms, which is the gap that actually matters, because bladderwrack is the higher-iodine ingredient of the three.

The listing doesn't say, and we won't guess. Nutricost describes it as Irish sea moss extract but doesn't state whether the raw material is wildcrafted (harvested from the ocean) or pool-grown (farmed in tanks). If explicit wildcrafted sourcing matters to you, Double Wood (#1) and Peak Performance (#7) both state it outright. Nutricost's strength is its manufacturing claim — a GMP-compliant, NSF-certified facility — rather than a detailed sourcing story.

It's the caveat that matters most here, and it's the one the label won't help you with. Measured side by side in the same analysis, bladderwrack ran about 120 µg of iodine per gram against Irish moss's 16 µg/g — roughly seven times more (Aakre 2021, PMID 33889064). So in a sea moss + bladderwrack trio, the bladderwrack is usually the dominant iodine source, not the sea moss. For scale: the adult RDA is 150 µg/day (NIH Office of Dietary Supplements) and the US tolerable upper limit is 1,100 µg/day (Institute of Medicine / NASEM, adults 19+) — note that Europe's EFSA sets its adult ceiling lower, at 600 µg/day, which is why any upper limit is worth naming its source. Nutricost discloses 400mg of 10:1 sea moss extract and 200mg of 20:1 bladderwrack extract, but no iodine figure — so even though the bladderwrack dose is now known, the actual iodine content it delivers is still unknown. Iodine's relationship with thyroid function is U-shaped — too much disrupts it just as too little does. If you have a thyroid condition, take thyroid medication, or are pregnant or breastfeeding, talk to a clinician before starting any bladderwrack trio, including this one. If you'd rather keep it simpler, choose a single-herb pick like Double Wood (#1).

It's a manufacturing-quality signal, and a real one — Nutricost states the product is made in a GMP-compliant, NSF-certified facility and is vegan and GMO-free. That speaks to how the product is produced. It is not the same as a per-batch NSF Certified for Sport seal on this specific SKU, and it doesn't publish a heavy-metal or iodine certificate of analysis. So it's a genuine, above-average quality claim for this hype-driven category — just don't over-read it as independent batch verification of iodine content.

The first-time buyer who wants the popular trio, a recognizable value brand, and the lowest reasonable cost per serving without overthinking it. At roughly $0.28 a serving from an NSF-certified facility, it's the easiest low-risk entry point. Choose differently if you specifically want pure single-herb sea moss with a stated testing claim (Double Wood, #1 — which also works out cheaper per serving), the traditional raw-gel form (EverSmith, #3), or a trio dosed higher across all three botanicals (American Standard, #5).

1. [1] Smyth 2021 PMID 33981614 — Iodine, Seaweed, and the Thyroid. A review of seaweed's rising dietary profile and its thyroid implications: seaweeds can be both a useful iodine source and a source of excessive, highly variable iodine, and people with underlying thyroid disease are most susceptible. The core safety reason a bladderwrack trio like this warrants caution.
2. [2] Katagiri 2017 PMID 28282437 — Effect of excess iodine intake on thyroid diseases in different populations: A systematic review and meta-analyses including observational studies. Across a 50-study review, the adult hypothyroidism signal comes from three cross-sectional studies, where excess iodine intake was associated with higher odds of overt and subclinical hypothyroidism versus adequate intake (odds ratios ~2.78 and ~2.03). Worth reading precisely: the excess-iodine exposure in those populations was mainly iodised salt or drinking water, not seaweed. It establishes that too much iodine is a real thyroid risk rather than a theoretical one — it does not measure sea moss.
3. [3] Aakre 2021 PMID 33889064 — Commercially available kelp and seaweed products - valuable iodine source or risk of excess intake?. Measured iodine by ICP-MS in 96 commercial macroalgae products. Bladderwrack averaged 120 µg/g against Irish moss (Chondrus crispus) at 16 µg/g — roughly seven times more, which is why a bladderwrack trio's iodine load is driven by the bladderwrack rather than the sea moss. Irish moss was among the few species whose portion did NOT exceed the upper limit. Labelling was poor across the board: only 24 of the 96 products declared an iodine content at all, and for 18 of those 24 the measured value deviated from the declared one by more than 50%.
4. [4] LactMed 2026 PMID 41730053 — Sea Moss. The sea-moss-specific lactation monograph, and the strongest safety statement on this page. It notes sea moss carries iodine plus heavy metals — arsenic, lead, cadmium and mercury — taken up from the water it grew in, and that maternal excess iodine from seaweed has caused thyroid suppression in breastfed infants. Its conclusion is direct: sea moss should be avoided during breastfeeding unless iodine and heavy-metal levels have been shown to be low enough to be safe. This is the citation behind our breastfeeding caution, which previously carried none.
5. [5] Park 2024 PMID 38248672 — An Update on the Chemical Constituents and Biological Properties of Selected Species of an Underpinned Genus of Red Algae: Chondrus. A review cataloguing Chondrus (Irish sea moss) constituents and a range of biological activities reported largely in vitro and in animal models. Establishes that sea moss contains genuinely bioactive compounds — while being explicit that this is bench and compositional science, not human efficacy proof.