“Ascophyllum nodosum?”Here!knotted wrack, a type of brown seaweed

Plant

Hasn’t appeared in a scanned product yet.

As a supplement

Talk to your doctor or pharmacist.

Roll Call does not check drug interactions or assess personal safety.

A species of brown kelp harvested from cold-water coastlines, used as a food ingredient and dietary supplement, and naturally rich in iodine and polysaccharides such as fucoidan.

Why it’s used

Taken by some for general mineral intake, digestive support, or weight management, and as a natural iodine source.

What the evidence says

NIH's Office of Dietary Supplements notes seaweed generally as a variable and sometimes very high source of dietary iodine, but there is no dedicated body of clinical evidence establishing a specific health benefit for Ascophyllum nodosum supplementation itself. Human trials on claimed effects such as weight or metabolic support are sparse and inconsistent.

Context

Iodine content in seaweed products can vary enormously by batch and preparation, which complicates interpreting any dose used in the limited studies available.

Rumors

1
Ascophyllum nodosum supplements can be contaminated with heavy metals such as arsenic.
Not gradedhealth and safety evidence
Sources cited — no verdict reached.
What was measured is not yet noted.
- Case Report: Potential Arsenic Toxicosis Secondary to Herbal Kelp Supplement (Peer-reviewed) · Funding not checked
Who’s saying this
- Darwin Nutrition — a publisher: nutrition and supplement comparison media funded by affiliation and sponsored articles
  How we know who this is
  “Fondé en 2019, Darwin Nutrition est un média indépendant d’information et de comparaison sur la nutrition et les compléments alimentaires.” (their page)
  “Notre site est gratuit, financé par l’affiliation et, ponctuellement, par des articles sponsorisés clairement identifiés.” (their page)
2
Ascophyllum nodosum extract blocks fat and sugar absorption and helps control weight.
Does not support — suggestivehealth and safety evidence
Measured as an outcome.
- Marginal Impact of Brown Seaweed Ascophyllum nodosum and Fucus vesiculosus Extract on Metabolic and Inflammatory Response in Overweight and Obese Prediabetic Subjects (Peer-reviewed) · Funding not checked
- Effects of an Extract of the Brown Seaweed Ascophylum nodosum on Postprandial Glycaemic Control in Healthy Subjects: A Randomized Controlled Study (Peer-reviewed) · Funded by European Union's Horizon 2020 research and innovation programme (Marie Skłodowska-Curie grant 713654); product and some salaries from Marigot Ltd. (government) · Authors declare a conflict of interest
- Clinical Efficacy of Brown Seaweeds Ascophyllum nodosum and Fucus vesiculosus in the Prevention or Delay Progression of the Metabolic Syndrome: A Review of Clinical Trials (Peer-reviewed) · Funding not checked
Who’s saying this
- Nexira — a brand: supplies natural and organic plant-based ingredients
  How we know who this is
  “Founded in 1895, Nexira has been a key innovator in the food, health and nutrition industries.” (their page)
  “Nexira is dedicated to providing only the best natural and organic plant-based ingredients .” (their page)
3
Ascophyllum nodosum given as a daily supplement reduces plaque, tartar and bad breath in dogs.
Supports — suggestivehealth and safety evidence
Studied in: small/toy breed dogs with mild-to-moderate periodontal disease post dental cleaning.
Measured as a biomarker.
- Effects of Edible Treats Containing Ascophyllum nodosum on the Oral Health of Dogs: A Double-Blind, Randomized, Placebo-Controlled Single-Center Study (Peer-reviewed) · Funded by Sweden Care AB (industry) · Authors declare a conflict of interest
Who’s saying this
- Swedencare — a brand: sells pet health products such as ProDen PlaqueOff®
  How we know who this is
  “Today, Swedencare has established itself in all major markets as an innovative and reliable pet health company.” (their page)
  “For many years, we built the business around our product family in dental health, ProDen PlaqueOff® .” (their page)
4
The high iodine content of Ascophyllum nodosum supplements is a threat to health.
Supports — suggestivehealth and safety evidence
Studied in: adult consuming kelp-containing weight-loss supplement (case report).
Measured as an outcome.
- Commercially available kelp and seaweed products – valuable iodine source or risk of excess intake? (Peer-reviewed) · Funded by Institute of Marine Research (government) · No conflicts declared
- Thyroid dysfunction following a kelp-containing marketed diet (Peer-reviewed) · Funded by FARB funds of the University of Salerno · No conflicts declared
Who’s saying this
- Medium — a platform — posts are by its users: publishing platform funded by paid memberships rather than ads
  How we know who this is
  “Medium is a home for human stories and ideas.” (their page)
  “Instead of selling ads or selling your data, we’re supported by a growing community of over a million Medium members who believe in our mission.” (their page)
5
Ascophyllum nodosum (kelp) boosts the immune system.
Does not supporthealth and safety evidence
Measured as a biomarker.
- Ascophyllan Supplementation Is Safe and Associated with Exploratory Modulation of Innate Immune Phenotypes, Biochemical Parameters, and the Gut Microbiome in a Randomized Pilot Trial (Peer-reviewed) · Funding not checked
Who’s saying this
- Medium — a platform — posts are by its users: publishing platform funded by paid memberships rather than ads
  How we know who this is
  “Medium is a home for human stories and ideas.” (their page)
  “Instead of selling ads or selling your data, we’re supported by a growing community of over a million Medium members who believe in our mission.” (their page)