Ascophyllum nodosum: Overview, Uses, Side Effects, Precautions, Interactions, Dosing and Reviews

Overview

Ascophyllum nodosum is a type of brown seaweed. It is found along the shorelines in cold areas of the world, such as Northern Canada and Iceland.

Ascophyllum nodosum is now protected in many countries because of over-harvesting for a chemical called alginate. It also contains nutrients such as carbohydrates, iodine, and fatty acids such as oleic acid.

People use Ascophyllum nodosum for tooth plaque, gum disease, iodine deficiency, weight loss, and many other conditions, but there is no good scientific evidence to support these uses.

Don't confuse Ascophyllum nodosum with other types of seaweed, such as blue-green algae, dulse, Ecklonia cava, Fucus vesiculosus, laminaria, or sea moss. These are not the same.

Uses & Effectiveness

We currently have no information for Ascophyllum nodosum overview.

Side Effects

When taken by mouth: Ascophyllum nodosum is possibly safe when used for up to 6 months. It's usually well-tolerated. But seaweeds such as Ascophyllum nodosum can accumulate high levels of heavy metals such as arsenic. Purchasing a product that is certified as being free of heavy metals can reduce the risk of heavy metal exposure.

Special Precautions and Warnings

Pregnancy and breast-feeding: There isn't enough reliable information to know if Ascophyllum nodosum is safe to use when pregnant or breast-feeding. Stay on the safe side and avoid use.

Thyroid disorders: Ascophyllum nodosum contains iodine. Long-term use or high doses of iodine might make certain thyroid disorders worse. Also, people with autoimmune thyroid disease might be especially sensitive to the harmful effects of iodine.

Interactions

Moderate Interaction

Be cautious with this combination

Amiodarone (Cordarone) interacts with Ascophyllum nodosum
Ascophyllum nodosum and amiodarone both contain iodine. Taking Ascophyllum nodosum with amiodarone might increase the levels of iodine in the blood. Too much iodine in the blood can cause side effects that affect the thyroid.
Medications for an overactive thyroid (antithyroid drugs) interacts with Ascophyllum nodosum
Ascophyllum nodosum contains iodine. Iodine can increase or decrease thyroid function. Taking Ascophyllum nodosum along with medications for an overactive thyroid might change the effects of these medications.
Thyroid hormone interacts with Ascophyllum nodosum
Ascophyllum nodosum contains iodine. Iodine can increase or decrease thyroid function. Taking Ascophyllum nodosum along with thyroid hormone medications might increase the effects of these medications.

Dosing

Ascophyllum nodosum has most often been used by adults as a dried powder at doses of 500 mg by mouth daily for up to 6 months. Speak with a healthcare provider to find out what dose might be best for a specific condition.

View References

REFERENCES:

Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: National Academy Press, 2002. Available at: www.nap.edu/books/0309072794/html/.

Sterling JB, Heymann WR. Potassium iodide in dermatology: a 19th century drug for the 21st century-uses, pharmacology, adverse effects, and contraindications. J Am Acad Dermatol 2000;43:691-7.

Paradis, M. E., Couture, P., and Lamarche, B. A randomised crossover placebo-controlled trial investigating the effect of brown seaweed (Ascophyllum nodosum and Fucus vesiculosus) on postchallenge plasma glucose and insulin levels in men and women. Appl.Physiol Nutr.Metab 2011;36(6):913-919.

Hall, A. C., Fairclough, A. C., Mahadevan, K., and Paxman, J. R. Ascophyllum nodosum enriched bread reduces subsequent energy intake with no effect on post-prandial glucose and cholesterol in healthy, overweight males. A pilot study. Appetite 2012;58(1):379-386.

Le Tutour B, Benslimane F, Gouleau MP, and et al. Antioxidant and pro-oxidant activities of the brown algae, Laminaria digitata, Himanthalia elongata, Fucus vesiculosus, Fucus serratus and Ascophyllum nodosum. J Applied Phycology 1998;10(2):121-129.

Hoang TD, Mai VQ, Clyde PW, Shakir MK. Over-the-counter-drug-induced thyroid disorders. Endocr Pract. 2013 Mar-Apr;19(2):268-74.

van Dijken JW, Koistinen S, Ramberg P. A randomized controlled clinical study of the effect of daily intake of Ascophyllum nodosum alga on calculus, plaque, and gingivitis. Clin Oral Investig 2015;19:1507-18.

Combet E, Ma ZF, Cousins F, et al. Low-level seaweed supplementation improves iodine status in iodine-insufficient women. Br J Nutr 2014;112:753-61.

Seeley RH, Schlesinger WH. Sustainable seaweed cutting? The rockweed (Ascophyllum nodosum) industry of Maine and the Maritime Provinces. Ann N Y Acad Sci 2012;1249:84-103.

O'Neill A, Gupta BS, Phillips DH. Distribution of arsenic and risk assessment of activities on a golf course fertilised with arsenic-containing Ascophyllum nodosum seaweed. Sci Total Environ 2014;482-483:252-9.

Simmons-Boyce JL, Purcell SL, Nelson CM, MacKinnon SL. Dietary Ascophyllum nodosum increases urinary excretion of tricarboxylic acid cycle intermediates in male Sprague-dawley rats. J Nutr 2009;139:1487-94.

Sorge US, Henriksen M, Bastan A, et al. Short communication: Iodine concentrations in serum, milk, and tears after feeding Ascophyllum nodosum to dairy cows-A pilot study. J Dairy Sci 2016;99:8472-6.

Mayer MA, Finlayson G, Fischman D, et al. Evaluation of the satiating properties of a nutraceutical product containing Garcinia cambogia and Ascophyllum nodosum extracts in healthy volunteers. Food Funct 2014;5:773-9.

Gabbia D, Dall'Acqua S, Di Gangi IM, et al. The phytocomplex from Fucus vesiculosus and Ascophyllum nodosum controls postprandial plasma glucose levels: An in vitro and in vivo study in a mouse model of NASH. Mar Drugs 2017;15(2). pii: E41.

Marinval N, Saboural P, Haddad O, et al. Identification of a pro-angiogenic potential and cellular uptake mechanism of a LMW highly sulfated fraction of fucoidan from Ascophyllum nodosum. Mar Drugs 2016;14(10). pii: E185.

Steevensz AJ, Mackinnon SL, Hankinson R, et al. Profiling phlorotannins in brown macroalgae by liquid chromatography-high resolution mass spectrometry. Phytochem Anal 2012;23(5):547-53.

van Ginneken VJ, Helsper JP, de Visser W, et al. Polyunsaturated fatty acids in various macroalgal species from North Atlantic and tropical seas. Lipids Health Dis 2011;10:104.

Zhang W, Du JY, Jiang Z, et al. Ascophyllan purified from Ascophyllum nodosum induces Th1 and Tc1 immune responses by promoting dendritic cell maturation. Mar Drugs 2014;12(7):4148-64.

Jiang Z, Abu R, Isaka S, et al. Inhibitory effect of orally-administered sulfated polysaccharide ascophyllan isolated from ascophyllum nodosum on the growth of sarcoma-180 solid tumor in mice. Anticancer Res 2014;34(4):1663-71.

Bahar B, O'Doherty JV, Hayes M, Sweeney T. Extracts of brown seaweeds can attenuate the bacterial lipopolysaccharide-induced pro-inflammatory response in the porcine colon ex vivo. J Anim Sci 2012;90 Suppl 4:46-8.

Terpend K, Bisson JF, Le Gall C, Linares E. Effects of ID-alG on weight management and body fat mass in high-fat-fed rats. Phytother Res 2012;26(5):727-33.

Corona G, Ji Y, Anegboonlap P, et al. Gastrointestinal modifications and bioavailability of brown seaweed phlorotannins and effects on inflammatory markers. Br J Nutr 2016;115(7):1240-53.

Baldrick FR, McFadden K, Ibars M, et al. Impact of a (poly)phenol-rich extract from the brown algae Ascophyllum nodosum on DNA damage and antioxidant activity in an overweight or obese population: a randomized controlled trial. Am J Clin Nutr. 2018;108(4):688-700.

Nicolucci A, Rossi MC, Petrelli M. Effectiveness of Ascophyllum nodosum and Fucus vesiculosus on metabolic syndrome components: a real-world, observational study. J Diabetes Res 2021;2021:3389316.

Vodouhè M, Marois J, Guay V, et al. Marginal impact of brown seaweed Ascophyllum nodosum and Fucus vesiculosus extract on metabolic and inflammatory response in overweight and obese prediabetic subjects. Mar Drugs 2022;20(3):174.

Tung YT, Wu CH, Chen WC, et al. Ascophyllum nodosum and Fucus vesiculosus extracts improved lipid metabolism and inflammation in high-energy diet-induced hyperlipidemia rats. Nutrients 2022;14(21):4665.

Mega DF, Sharma P, Kipar A, et al. Phlorotannin-Rich Ascophyllum nodosum Seaweed Extract Inhibits Influenza Infection. Viruses 2024;16(12):1919.

CONDITIONS OF USE AND IMPORTANT INFORMATION: This information is meant to supplement, not replace advice from your doctor or healthcare provider and is not meant to cover all possible uses, precautions, interactions or adverse effects. This information may not fit your specific health circumstances. Never delay or disregard seeking professional medical advice from your doctor or other qualified health care provider because of something you have read on WebMD. You should always speak with your doctor or health care professional before you start, stop, or change any prescribed part of your health care plan or treatment and to determine what course of therapy is right for you.

This copyrighted material is licensed from Therapeutic Research Center, LLC. Information from this source is evidence-based and objective, and without commercial influence. For professional medical information on natural medicines, see Natural Medicines Comprehensive Database Professional Version.
Licensed from Therapeutic Research Center, LLC
Copyright © 1995-2025 by Therapeutic Research Center, LLC. All Rights Reserved.

Ascophyllum nodosum - Uses, Side Effects, and More