Fucoidan

Fucoidan is a sulfated polysaccharide extracted from the cell walls of brown seaweeds — kelp, wakame, mozuku, bladderwrack. The same molecule that gives seaweed its slippery feel is doing the heavy lifting in J-beauty marine-ingredient lines (Albion, SK-II's marine collections, Decorté) and increasingly in K-beauty. The clinical data is genuinely strong: published trials show measurable hydration improvements at 8 weeks, anti-inflammatory effects at the molecular level (suppresses NF-κB), and wound-healing acceleration in surgical recovery studies. Fucoidan also has independent research as an antiviral and immune-modulator, which is why it crosses over into supplement and pharma research. In skincare, it sits in the same humectant + soothing tier as hyaluronic acid + centella, but with a marine-ingredient story that resonates particularly well in J-beauty editorial. Worth checking the INCI for if you have sensitive or dehydrated skin.