Fucoxanthin isis a marine carotenoid mainly found in brown algae, giving them a brown or olive-green color. Fucoxanthin is investigated for its anti-inflammatory, antinociceptive and anti-cancer effects. In vivo studies have demonstrated that oral administration of fucoxanthin inhibited carcinogenesis in an animal model of duodenal, skin, colon and liver cancer. Fucoxanthin causes antitumor and anticarcinogenic effects by inducing G1 cell-cycle arrest and apoptosis by modulating expression of various cellular molecules and cellular signal transduction pathways, but the exact mechanism of anti-cancer action of fucoxanthin is not fully elucidated. Fucoxanthin regulates lipids metabolism, the effect most likely mediated by AMK-activated protein kinase. A clinical trial of fucoxanthin against non-alcoholic fatty liver disease is ongoing.