But don't don your scuba gear just yet. The compound, called fucoxanthin, isn't ready for prime time.
Fucoxanthin is an antioxidant found in wakame, a type of brown kelp used in Asian cuisine.
Fucoxanthin burned fat in lab tests on rats and obese mice, prompting the rodents to lose weight, report Kazuo Miyashita, PhD, and colleagues.
Their findings were presented today at the American Chemical Society's 232nd national meeting, in San Francisco.
Miyashita is a chemistry professor in the Graduate School of Fisheries Sciences at Hokkaido University in Hokkaido, Japan.
He and his colleagues didn't try to feed seaweed to rodents. Instead, the researchers isolated fucoxanthin and added it to the animals' chow.
The fucoxanthin appeared to boost the rodents' production of a protein involved in fat metabolism, according to the researchers.
Also, levels of the omega-3 fatty acid DHA (docosahexaenoic acid) rose in the rodent livers when the animals were fed fucoxanthin with soybean oil.
DHA is one of the omega-3 fatty acids found in fatty fish such as salmon and has been linked to protective benefits against conditions like heart disease and depression.
It would be impractical for people to eat enough seaweed to see such a benefit, Miyashita notes in an American Chemical Society news release.
He says he hopes to develop a pill containing fucoxanthin, adding that studies in humans may be three to five years away.
SOURCES: American Chemical Society's 232nd National Meeting & Exposition, San Francisco, Sept. 10-14, 2006. News release, American Chemical Society.
By Miranda Hitti
Reviewed by Louise Chang