Fucoxanthin is a marine carotenoid xanthophyll pigment primarily found in brown seaweeds such as Undaria pinnatifida and Laminaria japonica. It features a unique structure with an allenic bond, epoxide group, and conjugated polyene chain that confers strong antioxidant properties. Research indicates potential roles in anti-obesity effects via UCP1 upregulation in fat tissue, anti-inflammatory activity, and metabolic regulation. As a lipophilic compound, it is absorbed better with dietary fats. It is used in nutraceuticals but degrades under heat, light, and oxygen exposure. Naturally occurring in edible algae consumed in Asian diets for centuries.