Other Name(s):

Agar-Agar, Agarose, Agarose Gel, Agaropectin, Agarweed, Algue de Java, Chinese Gelatin, Colle du Japon, Garacilaria confervoides, Gélatine de Chine, Gelidiella acerosa, Gelidium amanasii, Gelidium cartilagineum, Gelidium crinale, Gelidium divaricatum, Gelidium pacificum, Gelidium vagum, Gelosa, Gelosae, Gélose, Japanese Isinglas, Kanten Diet, Kanten Jelly, Kanten Plan, Layor Carang, Mousse de Ceylan, Mousse de Jaffna, Qion Zhi, Seaweed Gelatin, Vegetable Gelatin, Vegetarian Gelatin.


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 does it work?

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.


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Uses & Effectiveness

Possibly Effective for...

  • Obesity. 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.

Insufficient Evidence to Rate Effectiveness for...

  • Diabetes. Taking a product containing agar gel (Slim Kanten) by mouth daily while following a traditional Japanese diet for 12 weeks does not improve pre-meal blood sugar levels or insulin resistance in obese people with type 2 diabetes and impaired glucose tolerance more effectively than following a traditional Japanese diet alone. However, agar seems to help lower body weight and body mass index in these individuals.
  • High levels of a chemical called bilirubin in the blood of newborns (infant jaundice). Most early research suggests that giving agar by mouth for 5 days does not reduce bilirubin levels in infants with newborn jaundice. However, when given by mouth along with light therapy, agar seems to increase the bilirubin-lowering effects of light therapy and reduce the length of time that light therapy is needed.
  • Constipation.
  • Other conditions.
More evidence is needed to rate the effectiveness of agar for these uses.

Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, and Insufficient Evidence to Rate (detailed description of each of the ratings).

Side Effects

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.


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Special Precautions & Warnings

Children: Agar is POSSIBLY SAFE when 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.


Medications taken by mouth (Oral drugs)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

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 appropriate dose of agar depends on several factors such as the user's age, health, and several other conditions. At this time there is not enough scientific information to determine an appropriate range of doses for agar. Keep in mind that natural products are not always necessarily safe and dosages can be important. Be sure to follow relevant directions on product labels and consult your pharmacist or physician or other healthcare professional before using.

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Blum, D. and Etienne, J. Agar in control of hyperbilirubinemia. J Pediatr 1973;83(2):345. View abstract.

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Caglayan, S., Candemir, H., Aksit, S., Kansoy, S., Asik, S., and Yaprak, I. Superiority of oral agar and phototherapy combination in the treatment of neonatal hyperbilirubinemia. Pediatrics 1993;92(1):86-89. View abstract.

Calle-Pascual, A. L., Marenco, G., Asis, M. J., Bordiu, E., Romeo, S., Romero, C., Martin, P. J., Maranes, J. P., and Charro, A. L. Effects of different proportions of carbohydrates, polysaccharides/monosaccharides, and different fibers on the metabolic control in diabetic rats. Metabolism 1986;35(10):919-923. View abstract.

Calvert, R., Schneeman, B. O., Satchithanandam, S., Cassidy, M. M., and Vahouny, G. V. Dietary fiber and intestinal adaptation: effects on intestinal and pancreatic digestive enzyme activities. Am J Clin Nutr 1985;41(6):1249-1256. View abstract.

Chen, H., Yan, X., Zhu, P., and Lin, J. Antioxidant activity and hepatoprotective potential of agaro-oligosaccharides in vitro and in vivo. Nutr J 2006;5:31. View abstract.

Colomer, J., Moya, M., Marco, V., De, Paredes C., Escriva, F., and Vila, R. [Variations in hyperbilirrubinemia in low birth weight newborns under phototherapy and continous or discontinous agar oral administration (author's transl)]. An.Esp.Pediatr. 1975;8 Suppl 1:27-32. View abstract.

Dennery, P. A. Pharmacological interventions for the treatment of neonatal jaundice. Semin.Neonatol. 2002;7(2):111-119. View abstract.

Ebbesen, F. and Moller, J. Agar ingestion combined with phototherapy in jaundiced newborn infants. Biol.Neonate 1977;31(1-2):7-9. View abstract.

French, S. J. and Read, N. W. Effect of guar gum on hunger and satiety after meals of differing fat content: relationship with gastric emptying. Am J Clin Nutr 1994;59(1):87-91. View abstract.

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Hoie, L. H., Morgenstern, E. C., Gruenwald, J., Graubaum, H. J., Busch, R., Luder, W., and Zunft, H. J. A double-blind placebo-controlled clinical trial compares the cholesterol-lowering effects of two different soy protein preparations in hypercholesterolemic subjects. Eur.J.Nutr. 2005;44(2):65-71. View abstract.

Holt, S., Heading, R. C., Carter, D. C., Prescott, L. F., and Tothill, P. Effect of gel fibre on gastric emptying and absorption of glucose and paracetamol. Lancet 3-24-1979;1(8117):636-639. View abstract.

Jacobs, L. R. Relationship between dietary fiber and cancer: metabolic, physiologic, and cellular mechanisms. Proc Soc Exp.Biol.Med 1986;183(3):299-310. View abstract.

Kemper, K., Horwitz, R. I., and McCarthy, P. Decreased neonatal serum bilirubin with plain agar: a meta-analysis. Pediatrics 1988;82(4):631-638. View abstract.

Kim, S. W., Doh, J. H., and Choe, J. W. Oral Agar and Conventional Phototherapy Combination in the Treament of Neonatal Hyperbilirubinemia. J Korean Pediatr Soc 1997;40(7):931-938.

Lavin, J. H. and Read, N. W. The effect on hunger and satiety of slowing the absorption of glucose: relationship with gastric emptying and postprandial blood glucose and insulin responses. Appetite 1995;25(1):89-96. View abstract.

Maeda, H., Yamamoto, R., Hirao, K., and Tochikubo, O. Effects of agar (kanten) diet on obese patients with impaired glucose tolerance and type 2 diabetes. Diabetes Obes.Metab 2005;7(1):40-46. View abstract.

Maurer, H. M., Shumway, C. N., Draper, D. A., and Hossaini, A. A. Controlled trial comparing agar, intermittent phototherapy, and continuous phototherapy for reducing neonatal hyperbilirubinemia. J Pediatr. 1973;82(1):73-76. View abstract.

Meloni, T., Costa, S., Corti, R., and Cutillo, S. Agar in control of hyperbilirubinemia of full-term newborn infants with erythrocyte G-6-PD deficiency. Biol.Neonate 1978;34(5-6):295-298. View abstract.

Minekus, M., Jelier, M., Xiao, J. Z., Kondo, S., Iwatsuki, K., Kokubo, S., Bos, M., Dunnewind, B., and Havenaar, R. Effect of partially hydrolyzed guar gum (PHGG) on the bioaccessibility of fat and cholesterol. Biosci.Biotechnol.Biochem. 2005;69(5):932-938. View abstract.

Moller, J. Agar ingestion and serum bilirubin values in newborn infants. Acta Obstet.Gynecol.Scand.Suppl 1974;29:61-63. View abstract.

Odell, G. B., Gutcher, G. R., Whitington, P. F., and Yang, G. Enteral administration of agar as an effective adjunct to phototherapy of neonatal hyperbilirubinemia. Pediatr Res 1983;17(10):810-814. View abstract.

Osada, T., Shibuya, T., Kodani, T., Beppu, K., Sakamoto, N., Nagahara, A., Ohkusa, T., Ogihara, T., and Watanabe, S. Obstructing small bowel bezoars due to an agar diet: diagnosis using double balloon enteroscopy. Intern.Med 2008;47(7):617-620. View abstract.

Romagnoli, C., Polidori, G., Foschini, M., Cataldi, L., De, Turris P., Tortorolo, G., and Mastrangelo, R. Agar in the management of hyperbilirubinaemia in the premature baby. Arch.Dis.Child 1975;50(3):202-204. View abstract.

Ross, K. A., Pyrak-Nolte, L. J., and Campanella, O. H. The effect of mixing conditions on the material properties of an agar gel-microstructural and macrostructural considerations. Food Hydrocolloids 2006;20(1):79-87.

Sanaka, M., Yamamoto, T., Anjiki, H., Nagasawa, K., and Kuyama, Y. Effects of agar and pectin on gastric emptying and post-prandial glycaemic profiles in healthy human volunteers. Clin Exp.Pharmacol.Physiol 2007;34(11):1151-1155. View abstract.

Schellong, G., Quakernack, K., and Fuhrmans, B. [The influence of agar feeding on serum bilirubin in the physiologic jaundice of the newbron infant (author's transl)]. Z.Geburtshilfe Perinatol. 1974;178(1):34-39. View abstract.

Schneeman, B. O. Fiber, inulin and oligofructose: similarities and differences. J Nutr 1999;129(7 Suppl):1424S-1427S. View abstract.

Wilmshurst, P. and Crawley, J. C. The measurement of gastric transit time in obese subjects using 24Na and the effects of energy content and guar gum on gastric emptying and satiety. Br.J Nutr 1980;44(1):1-6. View abstract.

Windorfer, A., Jr., Kunzer, W., Bolze, H., Ascher, K., Wilcken, F., and Hoehne, K. Studies on the effect of orally administered agar on the serum bilirubin level of premature infants and mature newborns. Acta Paediatr.Scand. 1975;64(5):699-702. View abstract.

American Academy of Pediatrics Subcommittee on Hyperbilirubinemia. Management of hyperbilirubinemia in the newborn infant 35 or more weeks of gestation. Pediatrics 2004;114(1):297-316.

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