A number of edible brown seaweeds, including kombu, hijiki, wakame and limu moui, contain high levels of fucoidan. Some edible marine invertebrates, like sea cucumbers and sea anemones, also contain high levels of fucoidan.
Fucoidan is a complex carbohydrate that is mainly found in Asian diets, particularly in Japanese cuisine. Researchers have found that fucoidan has anti-inflammatory and anti-cancer properties. In a 2011 study, scientists discovered that fucoidan could kill cells that caused lung cancer. In 2015, a scientist found that fucoidan could help alleviate symptoms of bowel disorders in animals. Scientists have not extensively tested the effects of fucoidan in humans.