Comparative review reveals key differences in seaweed bioactive compounds and health effects across red, green and brown species
A comprehensive comparative review published in Food Research International has systematically analysed the chemical composition, bioactive profiles, safety concerns and machine learning applications across the three major edible seaweed categories – Chlorophyta, Phaeophyceae and Rhodophyta – providing food scientists and manufacturers with a detailed framework for developing seaweed-derived functional food ingredients.
For food scientists working with seaweed-derived ingredients, the review offers critical guidance on species selection, ingredient functionality and safety compliance. The authors identify substantial compositional differences that directly affect techno-functional performance – including gelation, emulsification, and antioxidant capacity – across the three seaweed categories. Critically, the findings highlight that heavy metal contamination in Phaeophyceae, and excessive iodine content in species such as Saccharina latissima, represent significant regulatory hurdles for manufacturers, particularly in European and Australasian markets.
The review also signals an emerging role for machine learning (ML) in quality control, processing optimisation and composition prediction – capabilities with direct relevance to industrial-scale seaweed processing.
Distinct chemical profiles across seaweed categories
The review, authored by Sunan Wang, Yi Qiu and Fan Zhu from the University of Auckland and affiliated institutions, draws on literature published between 2023 and 2025 to establish clear compositional distinctions between the three seaweed types.
Rhodophyta (red seaweed) stand out for their protein content – up to 48% dry weight in Palmaria palmata – as well as their richness in dietary fibre, agar, carrageenan, vitamins C and B6, and phycobiliproteins. Phaeophyceae (brown seaweed) are characterised by high concentrations of alginate, fucoidan, laminarin, phlorotannins, fucoxanthin and iodine. Chlorophyta (green seaweed) are distinguished by their ulvan polysaccharide content, high magnesium levels and favourable sodium-to-potassium ratios.
The authors note that “Chlorophyta, Phaeophyceae and Rhodophyta can be distinguished by distinct phenotypic traits, chemical components, physicochemical characteristics, sensory properties, and bioactive potencies.”
Bioactivity and health effects: what the evidence shows
All three seaweed categories demonstrated antioxidative, antimicrobial, anti-inflammatory, neuroprotective, anticancer and antidiabetic properties in in vitro and in vivo studies, though the underlying bioactive compounds and mechanisms differ substantially between types.
Phaeophyceae showed the strongest performance in metal chelation, free radical scavenging and neuroprotection, attributed largely to their phlorotannin content. As the authors note: “Phaeophyceae excels in metal chelation, free radical scavenging and neuroprotection.” Phlorotannins – polymeric derivatives of phloroglucinol found exclusively in brown seaweed – exhibit structural complexity that enables greater antioxidative activity than the phenolic acids and flavonoids predominant in red and green species.
Clinical evidence, however, remains limited. The authors caution that the biological activities documented largely in laboratory settings are “hardly supported by clinical trials,” underscoring a significant evidence gap for manufacturers seeking to substantiate health claims.
Safety and regulatory considerations
Heavy metal contamination presents the most pressing food safety concern. The review reports that Phaeophyceae show the highest mean levels of arsenic, with dried kombu (Saccharina japonica) recording total arsenic levels of 54.8 mg/kg – well above regulatory thresholds in multiple jurisdictions. Iodine content in brown seaweed species such as Saccharina japonica was recorded at up to 3,529 mg/kg in dried product, far exceeding maximum residue limits set by Food Standards Australia New Zealand (1 mg/g dry weight) and the European Food Safety Authority (2 mg/g dry weight).
IgE-mediated allergenic responses associated with carrageenan-containing red seaweed genera including Eucheuma, Chondrus and Gigartina also warrant attention for product labelling and formulation decisions.
Machine learning applications in seaweed research
The review documents a growing body of ML-driven research applied to seaweed morphological identification, chemical composition prediction, quality control and processing optimisation. ML models have achieved accuracy rates exceeding 98% in impurity detection and morphological classification. One stacked ensemble model successfully predicted hydrothermal treatment conditions for Phyllospora comosa (Phaeophyceae) that reduced arsenic concentrations to below FSANZ regulatory limits.
The authors identify key constraints: “Small sample sizes and poor model interpretability limited current ML applications,” alongside “a lack of standardisation for error measures.”
Research gaps and future priorities
The authors identify 13 priority areas for future investigation, including large-scale clinical trials, standardised analytical methods, maximum contaminant levels for novel seaweed food products, and the development of ML-based quantitative structure-activity relationship models. The review calls for combining bioactive compounds across seaweed types to explore synergistic functional and health effects – an approach with considerable potential for novel ingredient development.
As the authors conclude: “The findings of this review provide fundamental knowledge for developing functional foods with seaweed-derived ingredients.”
Journal reference
Wang, S., Qiu, Y., & Zhu, F. (2026). A comparative review of red, green, and brown seaweed: Bioactive components, health effects, and machine learning approaches. Food Research International, 234, Article 118420. https://doi.org/10.1016/j.foodres.2026.118420
