The Ultimate Guide To Brown Seaweed: Benefits, Studies, Side Effects, & More

Published on April 26, 2023

By Kristen Boye BS, Natural Health

Kristen Boye

Kristen Boye is a natural health expert, writer, copywriter, and editor. Kristen was raised on an organic farm in British Columbia which inspired her life’s work. She holds a Bachelor’s Degree in Natural Health, is a Certified Natural Foods Chef, co-owner of a medicinal herb farm, and is a natural foods and children’s health advocate. Kristen lives with her husband and two children on their medicinal herb farm in Western North Carolina.

Seaweed has been a dietary staple in traditional Asian and coastal cultures for thousands of years.

Various species of seaweed have been used in culinary dishes for flavor and texture, as traditional herbal preparations, fertilizers, and food additives.REF#1445 

Seaweed has also been traditionally consumed to help prevent nutrient deficiencies, primarily iodine deficiency.REF#1446 

Although seaweed consumption is most popular within Asian and Pacific-dwelling cultures, Westerners are starting to catch on to the health benefits of these flavorful sea vegetables.

In this article, you’ll learn about a special type of seaweed known as Padina pavonica or Brown Seaweed and how it can help support bone health, digestion, neurological health, and more.*

What is Brown Seaweed (Padina pavonica)

Most Westerners are familiar with three to five types of seaweed, like:

  • Nori: The type of seaweed used to make sushi or seaweed snacks
  • Agar agar: A vegan alternative to gelatin
  • Carrageenan: A somewhat controversial food additive used as a thickener and emulsifier
  • Kelp: The big seaweed you see floating around the Pacific Ocean
  • And Wakame: The type of seaweed used in Japanese seaweed salads

However, did you know there are thousands of seaweed species growing along our ocean shores?

Many of these edible seaweeds are sought-after in the supplement industry for their naturally occurring bioavailable compounds, such as minerals and polysaccharides and polyphenols (types of antioxidant groups).REF#1445 REF#1446

Brown seaweed, also known as Padina pavonica, Padina, PPE, or Peacock’s Tail, is a unique type of seaweed found in the Mediterranean sea.

It is used as a food, traditional botanical, biofertilizer, animal feed, and plant growth promoter. It also plays an important role in the environmental monitoring and managing coastal marine ecosystems.REF#1447

It’s also been traditionally used as an:REF#1447

  • Natural insecticide 
  • Antioxidant
  • Liver-health
  • And for metabolic health.

The glowing white film that rests on its brown leaves comes from the presence of calcium carbonate deposits on the outside of the algae. 

These crystals are not known to develop spontaneously in the Mediterranean and are normally only formed in controlled conditions. 

The plant's ability to fix calcium to its outer structure has led researchers to study its mechanisms and if it could be transformed into a biological agent to support calcium formation and absorption in humans.

The Health Benefits Of Brown Seaweed (Padina pavonica)

All edible seaweeds, including Brown Seaweed, offer a wealth of health-promoting nutrients, including:

  • Iodine: An essential nutrient lacking in many unfortified foods
  • Essential fatty acids: Such as omega 3s, which support cardiovascular health and inflammatory response REF#1448
  • Antioxidants: Such as polyphenols and polysaccharides (alginates) which play a vital role in protecting cellsREF#1449
  • Fiber: Which promotes regularity and heart health while nourishing the gut microbiomeREF#1450
  • Unique proteins not found in land-based foods: Such as specific lectins, phycobiliproteins, peptides, and amino acidsREF#1451
  • And other essential vitamins and minerals: Such as vitamin A, C, B-vitamins, copper, and magnesiumREF#1452

However, Brown Seaweed has demonstrated some potentially unique health benefits due to its specific plant compounds.

#1: Brown Seaweed May Support Bone Health

Earlier, we mentioned the unique ability of Brown Seaweed to produce and fix calcium to its outer structure, a process thought impossible outside of a controlled environment until this discovery.

This has led researchers to study brown seaweed as a possible natural substance to support human calcium formation and absorption.

But does it work? Initial studies appear promising.

In vitro (test tube) research has shown Brown Seaweed extract supports the speedy formation of bone and bone homeostasis.REF#1453

Researchers noted their excitement at Brown Seaweed’s potential to support bone health and normal bone aging, especially in older people. However, more research is necessary before it can be recommended.

#2: Brown Seaweed May Support Neurological Health 

Brain health is a concern for people young and old.

These concerns area driving force behind the study of natural substances, such as Brown Seaweed, Ginkgo, Lemon Balm, and other nootropic herbs, which may support cognitive health.

New research has found a correlation between inflammatory response and key aspects of brain health and aging.REF#1454 REF#1455 REF#1456 

This is potentially good news for people already committed to supporting a healthy inflammatory response through diet and lifestyle.

Certain herbs and functional foods, such as Brown Seaweed, have also been shown to promote normal inflammatory processes within the brain.*

A 2021 study published in the Swedish journal Molecules found extracts of Brown Seaweed/ Padina pavonica supported the integrity of mitochondrial membranes (the energy cells within the brain).

The researchers believe the bioactive compounds in Brown Seaweed, such as alginates, are likely responsible for its potentially healthy effect.

More research is needed to confirm these effects, but the results of this preliminary lab study are exciting.

Furthermore, as previously mentioned, Brown Seaweed is also a good source of iodine and essential fatty acids, which are critical for normal cognitive function.

Per the World Health Organization, iodine deficiency is “the single most important preventable cause of brain damage” worldwide.REF#1457 

This is due to the effects of suboptimal thyroid function in mothers on babies in-utero and the impact of iodine deficiency throughout a lifetime.REF#1458 

#3: Brown Seaweed May Support Healthy Thyroid Function

As noted in The Ethnobotany of Seaweeds, Traditional coastal cultures relied on seaweed as a flavoring agent and functional food to help prevent thyroid problems.*

Thanks to the addition of iodine to most table salt, full-blown iodine deficiency isn’t as prevalent as it was many years ago.

Plus, most of the world’s population lives in iodine-deficient locations.REF#1459 

Although these numbers may look daunting, many health experts believe eating more iodine-rich foods is a simple solution.

Research has shown iodine promotes healthy thyroid function, including normal levels of the thyroid hormones T4, T3, and TSH.*

However, some thyroid conditions do not respond well to additional dietary iodine. Always check with your doctor before increasing your iodine consumption.

Gaia Herbs combines Brown Seaweed with Ashwagandha and Schisandra into the best-selling Thyroid Support formula.

#4: Brown Seaweed Promotes Healthy Digestive Functions

In Japan, Kanten Gellies (a gelatin-like dessert made with agar agar) are eaten to soothe the stomach and promote overall digestive health.

Research has shown extracts of Brown Seaweed and other types of seaweed contain beneficial antioxidant polysaccharides known as alginates.

These polysaccharides are rich in a plant compound known as mannuronic acid, which may have a protective effect on the gastrointestinal system.REF#1460 

As previously mentioned, Brown Seaweed also contains fiber and other digestion-friendly nutrients, making it an excellent traditional food for digestion and gut health.*

Learn more about the gut microbiome and digestive health from a naturopath and medical herbalist in: Understanding The Microbiome & Tips To Maintain A Healthy Gut.

Brown Seaweed Side Effects & Contraindications

Various types of Brown Seaweed have been consumed for thousands of years, and there are no serious indications of side effects from normal consumption.

However, due to its natural iodine content, over-consumption of Brown Seaweed (or any seaweed) can cause the same symptoms as iodine deficiency. Including:REF#1461

  • Goiter
  • Elevated TSH levels
  • Hypothyroidism

Studies have also shown that excessive iodine intake can cause thyroiditis and thyroid papillary cancer.

Iodine poisoning is rare and is may be caused by very large doses of iodine.

Symptoms include burning of the mouth, throat, and stomach; fever; abdominal pain; nausea, vomiting, diarrhea, weak pulse, and coma.

So, what is considered normal versus excessive intake of iodine and iodine-rich foods?REF#1461

  • The recommended daily allowance (RDA) of iodine for adult men and women 19+ years is 220 mcg and 290 mcg daily for pregnant and lactating women
  • The Tolerable Upper-Intake Level (UL) of iodine for adults 19+ years and pregnant and lactating women is 1,100 mcg daily

Per the National Institutes of Health, iodine intakes from foods and supplements are unlikely to exceed the UL in most people.

Some people, such as those with autoimmune thyroid disease and iodine deficiency, may experience adverse effects with iodine intakes considered safe for the general population.

Allergic reactions to seaweeds are rare but could occur.

Consuming Brown Seaweed, or any type of iodine-rich food, may not be helpful for all thyroid conditions, so check with your healthcare practitioner.

Talk to your healthcare professional for individual recommendations.

Certain types of iodine supplements have the potential to interact with some types of medications, including certain thyroid, heart, and potassium-sparing diuretic drugs.

Since Brown Seaweed is a whole food, it may not have this effect. Always check with your doctor or healthcare practitioner before starting any new supplement while taking medication.

How To Start Taking Brown Seaweed To Support Your Health

It’s easy to find various seaweeds, like nori, dulse, and wakame, in your local natural foods store, Asian market, restaurants, or online.

However, if you’re interested in Brown Seaweed/Padina pavonica extract, you can find Brown Seaweed/Padina Pavonica Extract in Gaia Herbs Thyroid Support formula.

For more helpful information on the health benefits of seaweeds and iodine, check out the following resources in our Herb Library & Seeds of Knowledge blog:


  • 1. The Editors of Encyclopaedia Britannica, "Seaweed", Mar 22, 2023.
  • 2. Isabella A. Abbott, "Ethnobotany of seaweeds: clues to uses of seaweeds", Part of the Developments in Hydrobiology book series (DIHY,volume 116).
  • 3. Abid Ali Ansari et al.,, "Brown Alga Padina: A review", International Journal of Botany Studies, ISSN: 2455-541X, Impact Factor: RJIF 5.12, Volume 4; Issue 1; January 2019; Page No. 01-03.
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  • 8. U.S. DEPARTMENT OF AGRICULTURE, "Seaweed, spirulina, dried", Data Type:SR Legacy Food Category:Vegetables and Vegetable Products FDC ID: 170495 NDB Number:11667 FDC Published:4/1/2019.
  • 9. Minetti M, Bernardini G, Biazzo M, Gutierrez G, Geminiani M, Petrucci T, Santucci A, "Padina pavonica Extract Promotes In Vitro Differentiation and Functionality of Human Primary Osteoblasts", Mar Drugs. 2019 Aug 15;17(8):473. doi: 10.3390/md17080473. PMID: 31443264; PMCID: PMC6724011..
  • 10. , "Direct link shown between brain inflammation, neuron death, and cognitive changes in mice", March 24, 2022.
  • 11. University of Washington School of Medicine/UW Medicine, "Chronic sinus inflammation appears to alter brain activity", April 8, 2021.
  • 12. Sartori AC, Vance DE, Slater LZ, Crowe M, "The impact of inflammation on cognitive function in older adults: implications for healthcare practice and research", J Neurosci Nurs. 2012 Aug;44(4):206-17. doi: 10.1097/JNN.0b013e3182527690. PMID: 22743812; PMCID: PMC3390758..
  • 13. World Health Organization, "Assessment of iodine deficiency disorders and monitoring their elimination: a guide for programme managers, 3rd ed", 1 September 2007 | Publication.
  • 14. , "Thyroid Disorders and Pregnancy", .
  • 15. Taylor P et al.,, "Global epidemiology of hyperthyroidism and hypothyroidism", .
  • 16. Ammar HH, Lajili S, Sakly N, Cherif D, Rihouey C, Le Cerf D, Bouraoui A, Majdoub H, "Influence of the uronic acid composition on the gastroprotective activity of alginates from three different genus of Tunisian brown algae", Food Chem. 2018 Jan 15;239:165-171. doi: 10.1016/j.foodchem.2017.06.108. Epub 2017 Jun 21. PMID: 28873554.
  • 17. National Institute of Health, "Iodine", .