Introduction
The rise of seaweed superfoods
Nutrient and bioactive profile
How seaweed compounds combat inflammation and aging
How seaweed waste fuels the circular economy
Safety and risks
References
Further reading
Seaweeds are no longer just salad; they’re the blueprint for a sustainable, brain-boosting future powered by marine innovation.
Image Credit: Lesterman / Shutterstock.com
Introduction
Seaweed is increasingly recognized as a sustainable and functional food source that supports human health, including cognitive function and cardiovascular balance, through the gut-brain axis.4,5 This article examines its neuroprotective potential and addresses current safety challenges related to heavy metal and iodine accumulation.2,11
The rise of seaweed superfoods
Seaweed is an umbrella term for thousands of macroscopic marine algae species, including Rhodophyta, Phaeophyta, and Chlorophyta. Historically, it has been a dietary staple in many Asian countries, commonly consumed in soups, salads, and pickles.1,2
Seaweed cultivation offers a uniquely sustainable food source, requiring no arable land, fresh water, or synthetic fertilizers, while also providing ecosystem services such as carbon sequestration and nitrogen removal.3 According to recent EU sustainability reports, the seaweed sector is expected to reach a market value of EUR 9 billion by 2030, highlighting its role in global food transition efforts.11
Seaweed’s dense nutritional and bioactive profile underpins its reputation as a superfood. Phlorotannins, fucoidan, and other polyphenols exhibit antioxidant and neuroprotective properties, which are linked to reduced neuroinflammation and cognitive decline.4,6
Nutrient and bioactive profile
Nutriomics research reveals that consumable seaweeds have biochemical compositions distinct from terrestrial plants.1-3 Protein content varies widely, from 5–24% of dry weight in brown algae to as high as 47% in red species. These proteins are rich in essential amino acids and show higher digestibility when enzymatically processed or fermented using marine fungi such as Paradendryphiella salina.1
Dietary fiber accounts for up to 75% of seaweed’s dry mass, dominated by soluble polysaccharides like fucoidan, alginate, and carrageenan, which act as prebiotics that modulate gut microbiota. Studies confirm that these fibers stimulate beneficial bacterial genera and increase short-chain fatty acid (SCFA) production, which in turn influences brain and immune health.5
Although the total lipid content is low (1–5% dry weight), seaweeds are a unique plant source of omega-3 long-chain fatty acids, notably EPA and DHA, which support cognitive function and promote anti-inflammatory balance.4,5
Seaweed also provides calcium, potassium, and iron, alongside vitamins A, C, E, and B12.5 Recent compositional analyses highlight seaweed as one of the few vegetarian sources of bioavailable vitamin B12 and vitamin K.11
Compounds such as fucoxanthin and phlorotannins contribute to antioxidant and anti-aging properties relevant to the prevention of neurodegeneration.4,5,6
How seaweed compounds combat inflammation and aging
Phlorotannins and fucoidan are potent antioxidants that neutralize free radicals and suppress inflammatory pathways such as NF-κB. These compounds also inhibit amyloid-beta aggregation and tau phosphorylation, key pathological steps in Alzheimer’s disease.4,5,6
Prebiotic polysaccharides from seaweed ferment in the colon to yield SCFAs like butyrate, which improve gut barrier integrity and reduce systemic inflammation.5
A 2025 meta-analysis of 29 randomized controlled trials found that consuming edible algae lowered systolic and diastolic blood pressure by 2.05 and 1.87 mmHg, respectively. Doses above 3 g/day produced reductions exceeding 3 mmHg, underscoring a dose-response relationship.7
Additional meta-analyses confirm that brown algae reduce LDL cholesterol and total cholesterol,8 and improve glucose homeostasis by lowering fasting plasma glucose by 4.6 mg/dL and postprandial glucose by 7.1 mg/dL.9
Collectively, these findings position seaweed as a multifunctional food capable of modulating metabolic, vascular, and neural pathways that contribute to healthy aging.4,7-9
How seaweed waste fuels the circular economy
Adopting a circular economic model transforms seaweed byproducts into valuable resources. Research demonstrates that industrial residues and beach-cast seaweed can be repurposed for use in renewable energy and as fertilizers.10
Some seaweed as a renewable and sustainable resource. (A) Kelp (Saccharina) Phaeophyceae; (B) dulse (Palmaria palmata) Rhodophyta; (C) nori (Porphyra/Pyropia) Rhodophyta; (D) wakame (Undaria pinnatifida) Phaeophyceae.3
Composting seaweed biomass yields premium biofertilizers that enhance soil quality and water retention, with market values two to three times higher than conventional compost.10
In Denmark, integrating 90% of coastal seaweed waste into energy and fertilizer production resulted in a 32,800-ton reduction in annual CO₂ emissions.10
Emerging green-extraction technologies now recover bioactives, such as alginates and phlorotannins, from seaweed waste at costs under $0.70/kg, creating nutraceutical and cosmetic ingredients from material that was once discarded.3,10
Safety and risks
Seaweeds efficiently sequester both nutrients and contaminants. This dual capacity means they can accumulate heavy metals, including arsenic, cadmium, lead, and mercury, posing potential health risks if unregulated.1,2
A Malaysian risk assessment reported a hazard index (HI) of 4.38 for metal exposure, exceeding WHO limits.2 However, separate iodine risk analyses indicate that toxicity concerns depend strongly on species and intake levels.11
A 2025 Korean nationwide study found average iodine levels of 2,432 mg/kg dry weight in sea tangle (Saccharina japonica), compared to less than 200 mg/kg in most red and green algae. Iodine-related hazard indices remained below 1.0 under Korean MFDS guidelines but exceeded 1.0 under EFSA and JECFA standards, particularly for sea tangle and hijiki.11
Cooking significantly reduces iodine exposure - boiling or blanching can remove up to 90%, and the bioavailability of iodine from seaweed is approximately 75% compared to iodide supplements.11
In some species, a one-gram serving may deliver over 4,000 µg of iodine, about seven times the EFSA upper intake level of 600 µg/day.11
International regulations vary widely: Germany limits iodine to 20 mg/kg, France to 2,000–6,000 mg/kg (depending on the species), and Australia restricts imports above 1,000 mg/kg.11 Harmonized global labeling and intake guidance are increasingly necessary as seaweed consumption expands.2,11
Overall, evidence from recent meta-analyses and risk assessments supports the safety of seaweed consumption when moderate and sourcing is monitored for heavy metals and iodine.2,11
References
- Salgado, C. L., Muñoz, R., Blanco, A., & Lienqueo, M. E. (2021). Valorization and upgrading of the nutritional value of seaweed and seaweed waste using the marine fungi Paradendryphiella salina to produce mycoprotein. Algal Research 53. DOI:10.1016/j.algal.2020.102135, https://linkinghub.elsevier.com/retrieve/pii/S2211926420310031.
- Elekwachi, L. O., Hirschkop, D., & Tlusty, M. F. (2023). REVIEW OF THE LITERATURE ON THE SEAWEED INDUSTRY AND FOOD SAFETY ISSUES. University of Massachusetts Boston. DOI:10.13140/RG.2.2.27576.32004, https://www.researchgate.net/publication/376683232_REVIEW_OF_THE_LITERATURE_ON_THE_SEAWEED_INDUSTRY_AND_FOOD_SAFETY_ISSUES.
- Pereira, L., & Cotas, J. (2024). Seaweed: a sustainable solution for greening drug manufacturing in the pursuit of sustainable healthcare. Exploration of Drug Science 2(1); 50–84. DOI:10.37349/eds.2024.00036, https://www.explorationpub.com/Journals/eds/Article/100836.
- Cokdinleyen, M., dos Santos, L. C., de Andrade, C. J., et al. (2024). A Narrative Review on the Neuroprotective Potential of Brown Macroalgae in Alzheimer's Disease. Nutrients 16(24); 4394. DOI:10.3390/nu16244394, https://www.mdpi.com/2072-6643/16/24/4394.
- Hagan, M., & Fungwe, T. (2025). Investigating the Effect of Seaweed Bioactive Compounds on Gut Microbiota Composition and Dysbiosis: A Systematic Review. Current Developments in Nutrition 9. DOI:10.1016/j.cdnut.2025.106433, https://ffhdj.com/index.php/AgricultureFBC/article/view/1596.
- Cadar, E., Popescu, A., Dragan, A., et al. (2025). Bioactive Compounds of Marine Algae and Their Potential Health and Nutraceutical Applications: A Review. Marine Drugs 23(4), 152. DOI:10.3390/md23040152, https://www.mdpi.com/1660-3397/23/4/152.
- Casas‐Agustench, P., Mínguez, S., Brookes, Z., & Bescos, R. (2025). Edible Algae Reduce Blood Pressure in Humans: A Systematic Review and Meta‐Analysis of Randomised Controlled Trials. Journal of Human Nutrition and Dietetics 38(4). DOI:10.1111/jhn.70095, https://onlinelibrary.wiley.com/doi/10.1111/jhn.70095.
- Shin, D., Shim, S. R., Wu, Y., et al. (2023). How Do Brown Seaweeds Work on Biomarkers of Dyslipidemia? A Systematic Review with Meta-Analysis and Meta-Regression. Marine Drugs 21(4); 220. DOI:10.3390/md21040220, https://www.mdpi.com/1660-3397/21/4/220.
- Vaughan, K., Ranawana, V., Cooper, D., & Aceves-Martins, M. (2021). Effect of brown seaweed on plasma glucose in healthy, at-risk, and type 2 diabetic individuals: systematic review and meta-analysis. Nutrition Reviews 80(5); 1194-1205. DOI:10.1093/nutrit/nuab069, https://academic.oup.com/nutritionreviews/article/80/5/1194/6359344.
- Eriksen, M. L., Salvador, R., Kjærsgaard, N. C., et al. (2025). Circular business models for composting waste seaweed: Potential, barriers, and enablers. European Journal of Sustainable Development 14(4); 39-50. DOI:10.14207/ejsd.2025.v14n4p39, https://ecsdev.org/ojs/index.php/ejsd/article/view/1777.
- Lee, Y., Park, H. J., Jo, M., et al. (2025). Analysis and Risk Assessment of Total Iodine Content in Edible Seaweeds in South Korea. Foods 14(16); 2865. DOI:10.3390/foods14162865, https://www.mdpi.com/2304-8158/14/16/2865.
Further Reading
Last Updated: Nov 6, 2025