# PureSea (Ascophyllum nodosum)

**Canonical URL:** https://ingredients.hermeticasuperfoods.com/ingredients/puresea
**Data Source:** Hermetica Superfoods Ingredient Encyclopedia
**Updated:** 2026-03-24
**Evidence Score:** 2 / 10
**Category:** Other
**Also Known As:** Ascophyllum nodosum, Norwegian kelp, Knotted wrack, Egg wrack, Rockweed, Bladder wrack, Atlantic kelp

## Overview

PureSea is a standardized extract of Ascophyllum nodosum, a North Atlantic brown seaweed containing alginates, fucoidans, and naturally occurring iodine. Its bioactive polysaccharides — particularly fucoidans with 52.1% fucose content — are theorized to modulate [thyroid](/ingredients/condition/hormonal) hormone precursor availability via iodine delivery, though clinical human evidence remains limited.

## Health Benefits

• No clinical health benefits documented - research focuses only on extraction methods and physicochemical properties
• Contains alginates and fucoidans (52.1% fucose content) - compounds with theoretical bioactive potential but no human evidence
• Rich in minerals including potassium (41.2 g/kg) and sodium (51.3 g/kg) - nutritional content only, no therapeutic claims supported
• Agricultural biostimulant properties demonstrated for pest reduction on crops - not applicable to human health
• Gelling properties of alginate fraction characterized - relevant for industrial applications only

## Mechanism of Action

Ascophyllum nodosum provides inorganic iodine, which is taken up by [thyroid](/ingredients/condition/hormonal) follicular cells via the sodium-iodide symporter (NIS) and incorporated into thyroglobulin through thyroid peroxidase (TPO)-mediated oxidation, forming T3 and T4 precursors. Its fucoidans — sulfated polysaccharides — may interact with selectin receptors and modulate [inflammatory](/ingredients/condition/inflammation) cytokine cascades, theoretically influencing autoimmune thyroid activity. Alginates within the extract may slow gastrointestinal absorption of iodine, potentially offering a more sustained release profile compared to potassium iodide supplements.

## Clinical Summary

No published randomized controlled trials have evaluated PureSea specifically as a [thyroid](/ingredients/condition/hormonal) health intervention in human subjects; available research is largely confined to extraction methodology, physicochemical characterization, and in vitro bioactivity assays. A limited number of observational studies on general Ascophyllum nodosum consumption suggest improvements in postprandial glycemia, but these findings are not directly applicable to thyroid endpoints. The seaweed's high potassium content (41.2 g/kg) and iodine levels are well-documented analytically, but translational dose-response data in clinical populations are absent. Overall, the evidence base for PureSea as a thyroid supplement is preclinical and preliminary, warranting cautious interpretation.

## Nutritional Profile

PureSea (Ascophyllum nodosum) is a brown seaweed ingredient with a complex nutritional matrix. Carbohydrates dominate the dry weight, primarily as structural polysaccharides: alginates (20–30% dry weight) and fucoidans (sulfated fucose-rich polysaccharides with 52.1% fucose content). Mannitol contributes additional soluble carbohydrate content. Protein content ranges 5–15% dry weight depending on harvest season, providing a modest amino acid contribution. Lipid content is low (~1–3% dry weight) but includes polyunsaturated fatty acids such as EPA (eicosapentaenoic acid) in minor quantities. Mineral content is notably high: potassium at 41.2 g/kg dry weight and sodium at 51.3 g/kg dry weight are the dominant electrolytes; iodine is present at agriculturally significant but variable concentrations (typically 400–700 mg/kg dry weight), warranting attention in human consumption contexts. Magnesium, calcium, and iron are also present at trace-to-moderate levels. Bioactive compounds include fucoidans (with sulfation patterns linked to theoretical bioactivity), laminarin, and phlorotannins (polyphenolic compounds). Dietary fiber content is substantial, largely from alginic acid and fucoidan fractions, estimated at 30–45% dry weight. Vitamins include modest levels of B vitamins (B1, B2, B12 trace) and vitamin C, though concentrations are variable and processing-dependent. Bioavailability of minerals may be reduced due to alginate binding; iodine bioavailability is relatively high. Human absorption data for fucoidans and phlorotannins remains limited.

## Dosage & Preparation

No clinically studied dosage ranges are available as no human clinical studies have been conducted. Commercial forms include spray-dried powders, but no standardization for fucoidan or alginate content is specified. Consult a healthcare provider before starting any new supplement.

## Safety & Drug Interactions

High iodine intake from Ascophyllum nodosum can paradoxically inhibit [thyroid](/ingredients/condition/hormonal) hormone synthesis via the Wolff-Chaikoff effect, posing particular risk to individuals with pre-existing hypothyroidism, Hashimoto's thyroiditis, or Graves' disease. Individuals taking levothyroxine, anti-thyroid drugs such as methimazole, or amiodarone should avoid unsupervised use due to potential iodine-drug interactions that may destabilize thyroid hormone levels. The elevated potassium content (41.2 g/kg dry weight) represents a contraindication concern for individuals with hyperkalemia or those on potassium-sparing diuretics or ACE inhibitors. Safety during pregnancy and lactation has not been established in controlled studies, and excess iodine supplementation during pregnancy carries risk of neonatal thyroid suppression.

## Scientific Research

No human clinical trials, RCTs, or meta-analyses were identified for PureSea or Ascophyllum nodosum extract in the research. Available studies focus exclusively on extraction methodology, structural analysis of polysaccharides, and agricultural applications without any PMIDs for human health research.

## Historical & Cultural Context

No historical or traditional medicinal uses are documented in the research. Ascophyllum nodosum has been used in modern industrial extraction since approximately 2011 and as agricultural biostimulants, but no traditional medicine applications are mentioned.

## Synergistic Combinations

Iodine, Selenium, L-Tyrosine, Vitamin D3, Ashwagandha

## Frequently Asked Questions

### How much iodine is in PureSea Ascophyllum nodosum?

Iodine content in Ascophyllum nodosum can vary considerably depending on harvest location and season, typically ranging from 300 to over 1,000 mcg per gram of dried seaweed. PureSea is a standardized extract, but the specific iodine concentration per serving depends on the product formulation. Because the adult tolerable upper intake level for iodine is 1,100 mcg/day, consumers should verify the exact iodine content on the supplement label before use.

### Can PureSea help with hypothyroidism?

No human clinical trials have demonstrated that PureSea or Ascophyllum nodosum supplementation effectively treats hypothyroidism. While the iodine content could theoretically support thyroid hormone synthesis via the sodium-iodide symporter in iodine-deficient individuals, excess iodine can worsen hypothyroidism through the Wolff-Chaikoff effect. Anyone with diagnosed hypothyroidism should consult an endocrinologist before adding any iodine-containing supplement to their regimen.

### What are fucoidans in Ascophyllum nodosum and what do they do?

Fucoidans are sulfated polysaccharides found in brown seaweeds, with the Ascophyllum nodosum extract PureSea containing fucoidans characterized by approximately 52.1% fucose content. In vitro and animal studies suggest fucoidans can interact with P- and L-selectin receptors, potentially modulating inflammatory signaling and immune cell adhesion. However, these mechanisms have not been confirmed in peer-reviewed human clinical trials, so their functional benefit in supplement form remains theoretical.

### Is PureSea Ascophyllum nodosum safe to take daily?

Daily use of PureSea has not been evaluated in long-term human safety trials, so definitive guidance on chronic supplementation is unavailable. Key safety concerns include cumulative iodine intake exceeding the 1,100 mcg/day tolerable upper limit and elevated potassium exposure (the seaweed contains approximately 41.2 g of potassium per kilogram), which is relevant for individuals with kidney disease or those on potassium-affecting medications. Short-term use at manufacturer-recommended doses is likely low risk for healthy adults with no thyroid conditions, but medical supervision is advisable.

### Does Ascophyllum nodosum interact with thyroid medications?

Yes, Ascophyllum nodosum can interact with several thyroid-related medications due to its iodine content. Co-administration with levothyroxine may alter thyroid hormone levels unpredictably, as excess iodine can suppress endogenous thyroid function and interfere with medication titration. Anti-thyroid drugs like methimazole and propylthiouracil work by inhibiting thyroid peroxidase-mediated iodine organification, and adding an iodine-rich supplement could counteract or complicate this therapeutic effect; patients should disclose all seaweed-based supplements to their prescribing physician.

### What is the difference between PureSea Ascophyllum nodosum and other brown seaweed supplements?

PureSea Ascophyllum nodosum is sourced from a specific species of brown seaweed known for its consistent fucoidan content (52.1% fucose) and mineral profile, particularly potassium and sodium. While other brown seaweeds may contain similar compounds, Ascophyllum nodosum is specifically harvested for its standardized polysaccharide composition. The PureSea brand designation typically indicates quality control and extraction standards, though bioavailability and efficacy differences versus other brown seaweed products lack direct clinical comparison.

### Is PureSea Ascophyllum nodosum suitable for people on sodium-restricted diets?

PureSea Ascophyllum nodosum contains significant sodium content at approximately 51.3 g/kg, which may be a consideration for individuals requiring sodium restriction due to hypertension or kidney conditions. Those following low-sodium dietary protocols should consult with a healthcare provider before adding this supplement, as even modest doses could contribute meaningfully to daily sodium intake. Alternative mineral-rich supplements with lower sodium profiles may be more appropriate for sodium-sensitive individuals.

### How does the mineral content in PureSea Ascophyllum nodosum compare to obtaining minerals from food sources?

PureSea Ascophyllum nodosum provides concentrated mineral levels including potassium (41.2 g/kg) and sodium (51.3 g/kg), with bioavailability dependent on extraction method and formulation rather than the raw seaweed itself. A typical supplement serving delivers minerals in more concentrated amounts than whole food seaweed products, though whole food sources may provide better mineral balance and additional phytonutrients. Clinical evidence comparing mineral absorption from PureSea versus dietary sources is limited, making food-first approaches generally preferable for mineral nutrition.

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*Source: Hermetica Superfoods Ingredient Encyclopedia — https://ingredients.hermeticasuperfoods.com*
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