**Background:** Alginate is a hydrophilic, anionic polysaccharide extracted from brown algae (e.g., *Ascophyllum nodosum*, *Laminaria hyperborea*) and bacteria (*Azotobacter*, *Pseudomonas*). Its structure consists of (1,4)-linked α-L-guluronate (G) and β-D-mannuronate (M) blocks; the G-block content and M/G ratio determine gelation properties. Alginate is valued for biocompatibility, ease of gelation, bioadhesion, and biodegradability, leading to applications in cosmetics, food, medicine, dentistry, and environmental protection. This review aims to provide an extensive survey of alginate's structure, chemical properties, and applications, and to suggest future perspectives.
**Methods:** This is a narrative review that synthesizes existing literature on alginate-based materials. The authors searched the Google Scholar database for publications combining the terms "alginate" with "environment," "medicine," "cosmetics," and "food" from 2000 to 2023. They also reviewed specific studies on alginate extraction, modification techniques (e.g., cryogelation, non-solvent phase separation, carbon-dioxide-induced gelation), and recent advances (2013–2023) in alginate composites for various applications.
**Key Results:** The review reports that alginate's gelation is induced by divalent cations (Ca²⁺, Ba²⁺, Mg²⁺), and its pH responsivity allows shrinking at low pH and swelling at higher pH. In cosmetics, alginate from *Sargassum vulgare* showed higher antimicrobial effect than a commercial preservative (glyceryl caprylate/undecylenate) against *Staphylococcus aureus*, *Pseudomonas aeruginosa*, *Candida albicans*, *Aspergillus brasiliensis*, and *Escherichia coli* (ISO 11930 standard). In food, alginate coatings on fresh-cut Fuji apples prolonged shelf life from 4 days (control) to 2 weeks. In medicine, alginate scaffolds seeded with cardiomyocytes prevented cardiac function deterioration after myocardial infarction in rats. For environmental protection, alginate–carboxymethyl cellulose gel beads removed Pb²⁺ with 99% adsorption rate; iron nanoparticles–calcium alginate hydrogel membrane removed Cr(VI) with 99.5% efficiency; and sodium alginate/β-cyclodextrin/graphene oxide nanocomposite removed methylene blue dye with 84.98% removal rate. The number of publications on alginate-based materials from 2000 to 2023 was highest in environmental protection (367,047 total results), followed by medicine (291,449), food (277,054), and cosmetics (68,648). For alginate-based products specifically, environmental field had 30,767 publications, medicine 24,279, food 24,334, and cosmetics 5,692.
**Clinical Implications:** Alginate's biocompatibility, non-toxicity, and biodegradability make it suitable for wound dressings (e.g., alginate hydrogel hemp nonwoven composite, carboxymethyl chitosan/sodium alginate hydrogel with simvastatin), tissue engineering (e.g., injectable alginate/hydroxyapatite scaffold for bone, fullerenol/alginate hydrogel for cardiovascular tissue), and drug delivery (e.g., doxorubicin-loaded alginate-g-poly(N-isopropylacrylamide) micelles). In dentistry, alginate is used as impression material and for enamel regeneration (oxidized alginate–carboxymethyl chitosan hydrogels). The review emphasizes that alginate-based materials can reduce infection risk, promote healing, and provide sustained drug release. However, limitations include poor stability in high pH and large pore size, which can be addressed by crosslinking and composite formation. Future directions include enzymatically engineered alginates with improved stability and non-conventional gelation methods (cryogelation, CO₂-induced gelation) to create materials mimicking natural tissues.