From Cathy Wong,
Your Guide to Alternative Medicine.
FREE Newsletter. Sign Up Now!

About.com Health's Disease and Condition content is reviewed by our Medical Review Board

What is Fucoxanthin?

Fucoxanthin is a type of carotenoid found naturally in edible brown seaweed such as wakame (Undaria pinnatifida) and hijiki (Hijikia fusiformis), which are used widely in Asian cuisine. Wakame is the seaweed used in miso soup.

Fucoxanthin is also found in much smaller amounts in red seaweed (the kind typically used in Japanese sushi rolls) and green seaweed.

Both wakame and hijiki are available at Japanese specialty food stores, some health food stores and online. Although brown seaweed is the richest source of fucoxanthin, you would have to eat an unrealistic amount of it daily to get fucoxanthin levels close to those used in research studies.

Fucoxanthin is also available as a nutritional supplement in capsule form and can be found in some health food stores and online.

Why Do People Use Fucoxanthin

• Weight Loss
  

  Fucoxanthin is being explored for weight loss. So far, only animal studies have been done. Japanese researchers have found that fucoxanthin (isolated from wakame) promotes the loss of abdominal fat in obese mice and rats. Animals lost five to 10% of their body weight.

  Although it's not fully understood how fucoxanthin works, it appears to target a protein called UCP1 that increases the rate at which abdominal fat is burned. Abdominal fat, also called white adipose tissue, is the kind of fat that surrounds our organs and is linked to heart disease and diabetes. Fucoxanthin also appears to stimulate the production of DHA, one of the omega-3 fatty acids found in fatty fish such as salmon.

  Although it's promising and already a popular nutritional supplement, more research is needed to determine if fucoxanthin will work in the same way in humans. If it does prove to be effective, fucoxanthin could be developed into a diet pill for obesity.

• Diabetes
  

  Fucoxanthin has also been found in animal studies to decrease insulin and blood glucose levels. Researchers hypothesize that fucoxanthin anti-diabetes effect may be because fucoxanthin appears to promote the formation of DHA (the omega-3 fatty acid found in fish oil). DHA is thought to increase insulin sensitivity, improve triglycerides and reduce LDL ("bad") cholesterol.

• Cancer
  

  Preliminary research in test tubes suggests that fucoxanthin may have anti-tumor effects. No studies have looked at whether this holds true in humans or if taken orally. It's far too early for fucoxanthin to be used as a complementary treatment for cancer.

Side Effects

Because there hasn't been research on fucoxanthin in humans, the possible side effects aren't known.

People shouldn't consume large amounts of wakame or other types of seaweed as a source of fucoxanthin. Seaweed is rich in iodine and excessive consumption may result in iodine poisoning. High levels of iodine can interfere with the function of the thyroid gland. Also, consuming excess amounts of iodine-rich foods isn't recommended if there is a known allergy or hypersensitivity to iodine.

Sources:

Maeda H, Hosokawa M, Sashima T, Funayama K, Miyashita K. Effect of medium-chain triacylglycerols on anti-obesity effect of fucoxanthin. J Oleo Sci. (2007) 56.12: 615-621.

Maeda H, Hosokawa M, Sashima T, Funayama K, Miyashita K. Fucoxanthin from edible seaweed, Undaria pinnatifida, shows antiobesity effect through UCP1 expression in white adipose tissues. Biochem Biophys Res Commun. (2005) 332.2:392-397.

Maeda H, Hosokawa M, Sashima T, Miyashita K. Dietary combination of fucoxanthin and fish oil attenuates the weight gain of white adipose tissue and decreases blood glucose in obese/diabetic KK-Ay mice. J Agric Food Chem. (2007) 55.19: 7701-7706.