Agar is a plant. People use it to make medicine.

People take agar to lose weight, especially in Japan. In Japan agar is called “kanten,” and it is the main ingredient in “the kanten plan” or “the kanten diet.”

Agar is also used to treat diabetes and constipation.

In dentistry, agar is used to make dental impressions.

In manufacturing processes, agar is used as an ingredient in emulsions, suspensions, gels, and certain suppositories.

How it works

Agar contains a gel-like substance that bulks up in the gut. This stimulates the intestines and creates a bowel movement. That's why agar is commonly used as a laxative.

Agar's bulking effect also explains its use for weight loss. Agar tends to make people feel full, so they might stop eating earlier than they otherwise would. Some people think this reaction will lead to weight loss. But so far, there is no reliable scientific evidence that supports this weight loss theory.


Possibly Effective

Taking a product containing agar gel (Slim Kanten) by mouth daily while following a traditional Japanese diet for 12 weeks appears to reduce body weight and body mass index in obese people with type 2 diabetes and impaired glucose tolerance more effectively than following a traditional Japanese diet alone.


Possibly safe

Agar is POSSIBLY SAFE for most adults when taken by mouth with at least one 8-ounce glass of water. If it is not taken with enough water, agar can swell and block the esophagus or bowel. Immediate medical attention is necessary if chest pain, vomiting, or difficulty swallowing or breathing occurs after taking agar. In some people, agar may also raise cholesterol.



Children: Agar isPOSSIBLY SAFEwhen given by mouth to infants for a short period of time.

Pregnancy and breast-feeding: There is not enough reliable information about the safety of taking agar if you are pregnant or breast-feeding. Stay on the safe side and avoid use.

Bowel blockage (obstruction): Agar might make bowel obstruction worse, especially if it isn't taken with enough water or other liquid. Get medical advice before taking agar if you have a bowel obstruction.

Trouble swallowing: Agar might swell up and block the eating tube (esophagus) if it isn't taken with enough water or other liquid. This can be especially dangerous for someone who has trouble swallowing. Get medical advice before taking agar if you have a swallowing problem.

Colon cancer: There is some concern that eating a certain type of dietary fiber, such agar, might increase the risk of developing colon tumors. Get medical advice before taking agar if you have a history of or are at risk for colon cancer.


Always consult with your doctor.
Medications taken by mouth (Oral drugs)

Agar is a thick gel. Agar might stick to some medications in the stomach and intestines. Taking agar at the same time as medications that you take by mouth might decrease how much medication your body absorbs, and possibly decrease the effectiveness of your medication. To prevent this interaction, take agar at least one hour after medications you take by mouth.

The information provided on this page is for reference purposes and is not meant to be used as a medical advice, diagnosis or treatment. Always consult with a medical professional.