Seaweed Polysaccharides: A Rational Approach for Food Safety Studies

Marine macroalgae (seaweed) are a rich source of bioactive polysaccharides such as agar, carrageenan, and alginate. These three compounds are classified as food additive ingredients, widely used as gelling, thickening, stabilizing, and emulsifying agents in the food, nutraceutical, pharmaceutical, and cosmetic industries. However, the growing concern for a safer world has sparked renewed interest in their safety evaluation. Unlike synthetic compounds with specified structures, seaweed polysaccharides exhibit substantial structural heterogeneity due to variations in species, habitat, and processing, affecting bioactivity, digestibility, and interactions within the gastrointestinal tract. Although the safety of these compounds is generally accepted, there are still significant gaps in our understanding of their physicochemical behaviour. This highlights the need to develop a standardized digestion model to ensure their safety and evaluate their potential long-term health effects. Most of these compounds are only partially absorbed in the upper gastrointestinal tract, where they are fermented into metabolites with varying health effects. The safety of carrageenan, in particular, remains a subject of debate due to ambiguous results reported by various researchers' groups. This review highlights the importance of adopting standardized digestion assays, integrated analytical tools, and multidisciplinary approaches. These are crucial for thoroughly evaluating the molecular integrity, metabolism, and biological impact of seaweed polysaccharides, which will ultimately support evidence-based regulatory frameworks and ensure their safe use in human nutrition. This critical analysis focuses on food safety and security, with a methodology that can be applied to other foods or compounds.