Plant Profiler

Carob (Ceratonia siliqua)

Carob (Ceratonia siliqua) Image
Synonyms / Common Names / Related Terms
Alanine, algaroba, arobon, Caesalpinioideae (subfamily), carob bean gum, carob flour, carob gum, carobel, caruba, cellulose, ceratonia gum, Ceratonia siliqua, cheshire gum, China-Eisenwein, cinnamic acid, Fabaceae (family), flavonoids, free gallic acid, fructose, galactomannan, gallic acid, gallotannins, glucose, glycine, goma de garrofín, gomme de caroube, gumilk, hemicellulose, Leguminosae (family), leucine, locust bean, locust bean gum, maltose, methyl gallate, Pomana A, phenolic antioxidants, phenylalanine, praline, St. John's bread, sucrose, tannins, Thiacyl au Caroube, tyrosine, valine.

Mechanism of Action


  • Constituents: The two main carob pod parts are (by weight): pulp (90%) and seed (10%).20 Chemical composition of the pulp depends on cultivar, origin, and harvesting time. Carob pulp is high in total sugar content (48-56%), mainly sucrose (32-38%), glucose (5-6%), fructose (5-7%) and maltose. In addition it contains about 18% cellulose and hemicellulose. The mineral composition (in mg per 100g of pulp) is: K=1100, Ca=307, Mg=42, Na=13, Cu=0.23, Fe=104, Mn=0.4, Zn=0.59. The lipids consist of approximately equal proportions of saturated and unsaturated acids. Five amino acids were found in pod extracts (alanine, glycine, leucine, praline, and valine), also tyrosine and phenylalanine. Ripe carob pods contain a large amount of condensed tannins (16-20% of dry weight). Constituents of the seed, or bean, are (by weight): coat (30-33%), endosperm (42-46%) and embryo or germ (23-25%). The seed coat contains antioxidants. The endosperm is the galactomannan carob bean gum. It consists of a polysaccharide composed of mannose and galactose sugar units (ratio 4:1) which is highly viscous in water, over a wide range of temperature and pH. Carob seed oil has a very high essential fatty acid content.21
  • Carob fiber contains 24 polyphenol compounds with a yield of 3.94g/kg (dry weight), including: free gallic acid (42% of polyphenols by weight), gallotannins (29%), and methyl gallate (1%), while simple phenols, mainly cinnamic acid, make up about 2% of the total.22 Flavonoids represented 26% of the polyphenols, and the glycosides myricetin- and quercetin-3-O-alpha-L-rhamnoside represented around 9% and 10%, respectively.
  • Carob pods contain 448mg/kg extractable polyphenols comprising gallic acid, hydrolyzable and condensed tannins, flavonol-glycosides, and traces of isoflavonoids.23 Carob fiber (total polyphenol content = 4142mg/kg) shows the highest concentrations in flavonol-glycosides and hydrolyzable tannins, whereas roasted carob products contain the highest levels of gallic acid.
  • Anticancer effects: In an in vitro study using a mouse hepatocellular carcinoma cell line (T1), two carob extracts showed a marked alteration of T1 cell proliferation in a dose-related fashion reaching the maximum effect at 1mg/mL.24 Moreover, leaf and pod extracts were able to induce apoptosis in T1 cell lines after 24 hours of treatment, mediating a direct activation of the caspase 3 pathway. These effects may be due to gallic acid, (-) epigallocatechin-3-gallate and (-) epicatechin-3-gallate in pod and leaf extracts (concentration 6.28mg/g in carob leaf extract and 1.36mg/g in carob pod extract).
  • In an in vitro study, carob modulated the growth of both human colon carcinoma and colon adenoma cells in a manner dependent on growth kinetics of the cell line.25 Highly proliferating cells were more susceptible to the growth inhibitory properties than cells with a lower cell turn over, which may be due to scavenging mechanisms or the induction of stress response enzymes. Evidence points to an induction of the cellular defense systems.
  • Carob pods and leaves, especially the young leaves, have substances that can act on peripheral benzodiazepine receptors in an in vitro study, suggesting the possible utilization of leaf extracts as chemopreventive agents.19
  • Antidiabetes effects: In a rat study, addition of 2.5% carob bean gum to an oral glucose tolerance test solution significantly reduced rebound hypoglycemia, dose dependently.10 In a clinical trial, locust bean gum significantly (p<0.05) decreased the glucose response and glycemic index of subjects with type 2 diabetes when eating a high glycemic index food.9 Locust bean gum decreased the subjects' insulinemic response and insulinemic index, but not significantly. Carob bean gum had no significant effect on glycemic response in subjects with type 2 diabetes and a BMI >30kg/m2, whereas insulinemic response decreased.
  • However, in an in vitro study, a mixture of xanthan and carob bean gum (X/LBG = 1:1) had the greatest viscosity at equivalent concentrations and shear rates and was more effective than guar gum, xanthan, or carob bean gum at inhibiting glucose movement.11 However, it was not more efficient in lowering postprandial blood glucose and plasma insulin in human subjects when incorporated in a drink containing 50g glucose.
  • Antidiarrheal effects: In a laboratory study, 20 of 36 bacterial strains isolated from the duodenum of infants with diarrhea showed adherence by all methods.7 The cell-free carbohydrate fraction of carrot soup and a 2% solution of carob blocked hemagglutination and adherence of Escherichia coli on isolated intestinal epithelial cells, and the active blocking agent was found in the oligosaccharide fraction of the carob solution.
  • Antioxidant (free radical scavenging) effects: In an in vitro antioxidant study, the crude polyphenol fraction from carob showed a stronger inhibitory effect against the discoloration of beta-carotene than other polyphenol compounds, such as catechins and procyanidins.26 he crude polyphenol fraction had weaker antioxidant activity in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging, erythrocyte ghost, and microsomal systems than authentic polyphenol compounds at the same concentrations. In an in vitro study using ultraviolet irradiation-induced lipid peroxidation, locust bean gum showed antioxidative effects.27
  • Antiviral effects: In an in vitro study in Vero cells, carob bean gum polysaccharides seemed to block a step in rubella virus replication subsequent to virus attachment, such as internalization and/or uncoating.18 The polysaccharides had no effect on infection initiated by transfection of cells with RVRNA.
  • Digestive effects: In a clinical Lundh test, a carob bean flour-supplemented diet significantly (α<0.01) reduced the duodenal content aspirated for 90 minutes, compared to a control.28 Based on an animal study, carob protein plus essential amino acids does not significantly influence peripheral glutamine status.29
  • Gastroesophageal reflux effects (in infants): Literature on gastroesophageal reflux in infants can be divided into studies addressing clinically apparent reflux (vomiting or regurgitation) and reflux as measured by pH probe or other methods. Carob bean gum used as a formula thickener decreases reflux as measured by intraluminal impedance but not as measured by pH probe.30 There is very limited evidence or expert opinion regarding breastfed infants, particularly with regard to preservation of breastfeeding during therapy.31,32,33 Although thickened formulas do not appear to reduce measurable reflux, they may reduce vomiting.34
  • Gastrointestinal effects: Carob bean gum has been shown to alter food structure, texture, and viscosity, and hence the rate of starch degradation during digestion.35 The effect of carob bean gum on bowel transit time is uncertain. In one clinical trial, bowel transit time was not significantly affected by the carob bean gum; however, total dry fecal weight was significantly increased after the refined fibers compared with that after the basal diet.36 This finding was supported by another clinical study in infants.17 However, in another a clinical trial, addition of locust bean gum to a nutrient semisolid meal strongly delayed the emptying rate in healthy subjects.16 This result is supported by a rat study, in which the addition of carob bean gum to test diets reduced the rate of gastric emptying and thus slowed down the passage of food from the stomach into the upper small intestine.10 Although carob bean gum's effect on gastric emptying is uncertain, it does affect mineral absorption of, fecal weight, and urinary nitrogen. In a rat study, a 10% carob bean gum diet significantly decreased urinary nitrogen, and significantly increased fecal dry matter and fecal nitrogen loss, resulting in a marked reduction of apparent protein digestibility.5 In another rat study, a 3% (weight/weight) yeast RNA and a 5% (weight/weight) viscous carob bean gum diet significantly decreased serum uric acid concentration, which may be accomplished by the inhibition of digestion for dietary RNA and/or absorption of the hydrolyzed compounds.6 Carob bean gum interfered with the absorption of zinc, chromium, copper and cobalt1,2,3,4, and may reduce absorption of iron2,3,4. Insoluble high polyphenol content natural carob fiber increased intake and fecal weight, but did not significantly affect fat digestibility.8
  • Hyperlipidemia effects: The lipid-lowering effect of an insoluble dietary fiber from carob pulp has been investigated in various clinical studies. Carob bean gum alone or with other dietary fibers appears to be an effective, safe approach to controlling hyperlipidemia and a useful adjunct to the dietary management of elevated plasma cholesterol in adults12 and LDL cholesterol levels in children and adolescents with elevated plasma LDL cholesterol levels13. These findings are also supported in animal studies. In rats, the increased liver cholesterol and liver total lipid induced by cholesterol feeding was largely counteracted by concurrent feeding of carob bean gum.14 In one day-old chicks, there was a dose-dependent cholesterol on 6 and 10% locust bean gum diets.15
  • Weight loss effects: In a clinical trial, consumption of a carob pulp preparation decreased postprandial responses of acylated ghrelin, triglycerides, and nonesterified fatty acids and altered respiratory quotient, suggesting a change toward increased fatty acid oxidation.37 Ingestion of carob bean gum in rats on a cocoa butter diet reduced glycogen accumulation in the liver.38


  • Absorption: In a bioavailable calorie assay in rats, comparison of the carcass weight gain showed that carob bean gum was not a source of bioavailable calories.39
  • Locust bean gum has a capacity to form very viscous stable solutions in high dilution (1% and lower) and its potential interaction with other polysaccharides, having a synergistic effect.20
  • Metabolism: Rat large gut microflora partially hydrolyzed carob bean gum in vitro.40 This finding was supported by a rat study, in which a considerable portion of carob bean gum ingested was metabolized, presumably due to the action of intestinal bacteria.1
  • Although the biological value and net protein utilization assays for the unsupplemented carob germ isolate were low in a rat study, (biological value 0.36 ± 0.016, net protein utilization 0.35 ± 0.015), supplementation with amino acids resulted in a positive increase with values of 0.66 ± 0.013 and 0.64 ± 0.013 for biological value and net protein utilization, respectively.41
  • Based on an animal study, carob protein plus essential amino acids is believed to be extensively metabolized by the splanchnic tissues and does not significantly influence peripheral glutamine status.29
  • In a clinical trial, glutamine bound to carob protein increases peak plasma glutamine concentration by between 18% and 23% from basal values.42
  • Excretion: A digestibility study in rats 85-100% of mannose fed as 1% carob bean gum was excreted in the feces over a total of 30 hours.43 Some decrease in chain length of galactomannan may have occurred, probably through the action of the microflora as mammals are not known to possess mannosidase. Liberation of galactose units was not determined.


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  2. Bosscher, D., Robberecht, H., Van Cauwenbergh, R., Caillie-Bertrand, M., and Deelstra, H. Binding of mineral elements to locust bean gum influences availability in vitro. Biol Trace Elem Res  2001;81(1):79-92. 11508334
  3. Bosscher, D., Caillie-Bertrand, M., and Deelstra, H. Effect of thickening agents, based on soluble dietary fiber, on the availability of calcium, iron, and zinc from infant formulas. Nutrition 2001;17(7-8):614-618. 11448582
  4. Bosscher, D., Caillie-Bertrand, M., and Deelstra, H. Do thickening properties of locust bean gum affect the amount of calcium, iron and zinc available for absorption from infant formula? In vitro studies. Int J Food Sci Nutr  2003;54(4):261-268. 12850887
  5. Harmuth-Hoene, A. E. and Schwerdtfeger, E. Effect of indigestible polysaccharides on protein digestibility and nitrogen retention in growing rats. Nutr Metab 1979;23(5):399-407. 481831
  6. Koguchi, T., Nakajima, H., Koguchi, H., Wada, M., Yamamoto, Y., Innami, S., Maekawa, A., and Tadokoro, T. Suppressive effect of viscous dietary fiber on elevations of uric acid in serum and urine induced by dietary RNA in rats is associated with strength of viscosity. Int J Vitam Nutr Res 2003;73(5):369-376. 14639801
  7. Guggenbichler, J. P. Adherence of enterobacteria in infantile diarrhea and its prevention. Infection 1983;11(4):239-242. 6352511
  8. Ruiz-Roso, B., Perez-Olleros, L., and Garcia-Cuevas, M. [Effect of natural carob fibers and other dietary fibers on the digestibility of fats and nitrogen in rats]. Nutr Hosp 1999;14(4):159-163. 10502955
  9. Feldman, N., Norenberg, C., Voet, H., Manor, E., Berner, Y., and Madar, Z. Enrichment of an Israeli ethnic food with fibres and their effects on the glycaemic and insulinaemic responses in subjects with non-insulin-dependent diabetes mellitus. Br J Nutr 1995;74(5):681-688. 8541274
  10. Tsai, A. C. and Peng, B. Effects of locust bean gum on glucose tolerance, sugar digestion, and gastric motility in rats. J Nutr 1981;111(12):2152-2156. 7031203
  11. Edwards, C. A., Blackburn, N. A., Craigen, L., Davison, P., Tomlin, J., Sugden, K., Johnson, I. T., and Read, N. W. Viscosity of food gums determined in vitro related to their hypoglycemic actions. Am J Clin Nutr 1987;46(1):72-77. 3604971
  12. Haskell, W. L., Spiller, G. A., Jensen, C. D., Ellis, B. K., and Gates, J. E. Role of water-soluble dietary fiber in the management of elevated plasma cholesterol in healthy subjects. Am J Cardiol 2-15-1992;69(5):433-439. 1310566
  13. Kwiterovich, P. O., Jr. The role of fiber in the treatment of hypercholesterolemia in children and adolescents. Pediatrics 1995;96(5 Pt 2):1005-1009. 7494671
  14. Ershoff, B. H. and Wells, A. F. Effects of gum guar, locust bean gum and carrageenan on liver cholesterol of cholesterolfed rats. Proc Soc Exp Biol Med 1962;110:580-582. 13890693
  15. Fahrenbach, M. J., Riccardi, B. A., and Grant, W. C. Hypocholesterolemic activity of mucilaginous polysaccharides in White Leghorn cockerels. Proc Soc Exp Biol Med 1966;123(2):321-326. 5924467
  16. Darwiche, G., Bjorgell, O., and Almer, L. O. The addition of locust bean gum but not water delayed the gastric emptying rate of a nutrient semisolid meal in healthy subjects. BMC Gastroenterol  6-6-2003;3(1):12. 12793910
  17. Rivier, C. [The effectiveness of nestargel.]. Schweiz Med Wochenschr  3-8-1952;82(10):256-258. 14930738
  18. Mastromarino, P., Petruzziello, R., Macchia, S., Rieti, S., Nicoletti, R., and Orsi, N. Antiviral activity of natural and semisynthetic polysaccharides on the early steps of rubella virus infection. J Antimicrob Chemother  1997;39(3):339-345. 9096183
  19. Avallone, R., Cosenza, F., Farina, F., Baraldi, C., and Baraldi, M. Extraction and purification from Ceratonia siliqua of compounds acting on central and peripheral benzodiazepine receptors. Fitoterapia 2002;73(5):390-396. 12165334
  20. Batlle, I. and Tous, J. Carob tree. Ceratonia siliqua L. Promoting the conservation and use of underutilized and neglected crops. Institute of Plant Genetics and Crop Plant Research 1997;17
  21. Orhan, I. and Sener, B. Fatty acid content of selected seed oils. J Herb Pharmacother  2002;2(3):29-33. 15277087
  22. Owen, R. W., Haubner, R., Hull, W. E., Erben, G., Spiegelhalder, B., Bartsch, H., and Haber, B. Isolation and structure elucidation of the major individual polyphenols in carob fibre. Food Chem Toxicol 2003;41(12):1727-1738. 14563398
  23. Papagiannopoulos, M., Wollseifen, H. R., Mellenthin, A., Haber, B., and Galensa, R. Identification and quantification of polyphenols in carob fruits (Ceratonia siliqua L.) and derived products by HPLC-UV-ESI/MSn. J Agric Food Chem 6-16-2004;52(12):3784-3791. 15186098
  24. Corsi, L., Avallone, R., Cosenza, F., Farina, F., Baraldi, C., and Baraldi, M. Antiproliferative effects of Ceratonia siliqua L. on mouse hepatocellular carcinoma cell line. Fitoterapia 2002;73(7-8):674-684. 12490228
  25. Klenow, S., Glei, M., Beyer-Sehlmeyer, G., Haber, B., and Pool-Zobel, B. L. Carob Fiber - Functional effects on human colon cell line HT29. Poster, Functional Food: Safety Aspects  2004;
  26. Kumazawa, S., Taniguchi, M., Suzuki, Y., Shimura, M., Kwon, M. S., and Nakayama, T. Antioxidant activity of polyphenols in carob pods. J Agric Food Chem 1-16-2002;50(2):373-377. 11782210
  27. Trommer, H. and Neubert, R. H. The examination of polysaccharides as potential antioxidative compounds for topical administration using a lipid model system. Int J Pharm 7-14-2005;298(1):153-163. 15955644
  28. Sommer, H. and Kasper, H. The effect of dietary fiber on the pancreatic excretory function. Hepatogastroenterology 1980;27(6):477-483. 6162770
  29. Boza, J. J., Turini, M., Moennoz, D., Montigon, F., Vuichoud, J., Gueissaz, N., Gremaud, G., Pouteau, E., Piguet-Welsch, C., Finot, P. A., and Ballevre, O. Effect of glutamine supplementation of the diet on tissue protein synthesis rate of glucocorticoid-treated rats. Nutrition 2001;17(1):35-40. 11165886
  30. Wenzl, T. G., Schneider, S., Scheele, F., Silny, J., Heimann, G., and Skopnik, H. Effects of thickened feeding on gastroesophageal reflux in infants: a placebo-controlled crossover study using intraluminal impedance. Pediatrics 2003;111(4 Pt 1):e355-e359. 12671151
  31. Aggett, P. J., Agostoni, C., Goulet, O., Hernell, O., Koletzko, B., Lafeber, H. L., Michaelsen, K. F., Milla, P., Rigo, J., and Weaver, L. T. Antireflux or antiregurgitation milk products for infants and young children: a commentary by the ESPGHAN Committee on Nutrition. J Pediatr Gastroenterol Nutr 2002;34(5):496-498. 12050572
  32. McPherson, V., Wright, S. T., and Bell, A. D. Clinical inquiries. What is the best treatment for gastroesophageal reflux and vomiting in infants? J Fam Pract  2005;54(4):372-375. 15833233
  33. Puntis, J. W. Re: Effect of locust bean gum in anti-regurgitant milk on the regurgitation in uncomplicated gastroesophageal reflux. J Pediatr Gastroenterol Nutr 2005;40(1):101-102. 15625439
  34. Carroll, A. E., Garrison, M. M., and Christakis, D. A. A systematic review of nonpharmacological and nonsurgical therapies for gastroesophageal reflux in infants. Arch Pediatr Adolesc Med 2002;156(2):109-113. 11814369
  35. Brennan, C. S. Dietary fibre, glycaemic response, and diabetes. Mol Nutr Food Res 2005;49(6):560-570. 15926145
  36. Scholfield, D. J., Behall, K. M., Bhathena, S. J., Kelsay, J., Reiser, S., and Revett, K. R. A study on Asian Indian and American vegetarians: indications of a racial predisposition to glucose intolerance. Am J Clin Nutr 1987;46(6):955-961. 3318380
  37. Gruendel, S., Garcia, A. L., Otto, B., Mueller, C., Steiniger, J., Weickert, M. O., Speth, M., Katz, N., and Koebnick, C. Carob pulp preparation rich in insoluble dietary fiber and polyphenols enhances lipid oxidation and lowers postprandial acylated ghrelin in humans. J Nutr 2006;136(6):1533-1538. 16702317
  38. Krantz, J. C., Jr., Carr, C. J., and de Farson, C. B. Guar polysaccharide as a precursor of glycogen. J Amer Diet Assoc 1948;24:212.
  39. Robaislek, E. Bioavailable calorie assay of Guar gum. Unpublished report from WARF Institute, Inc. 1974;
  40. Towle, G. A. and Schranz, R. E. The action of rat microflora on carob bean gum solutions in vitro. Unpublished report from Hercules Research Center 1975;
  41. Drouliscos, N. J. and Malefaki, V. Nutritional evaluation of the germ meal and its protein isolate obtained from the carob seed (Ceratonia siliqua) in the rat. Br J Nutr 1980;43(1):115-123. 7189405
  42. Boza, J. J., Maire, J., Bovetto, L., and Ballevre, O. Plasma glutamine response to enteral administration of glutamine in human volunteers (free glutamine versus protein-bound glutamine). Nutrition 2000;16(11-12):1037-1042. 11118821
  43. Tsai, L. B. and Whistler, R. L. Digestibility of galactomannans. Unpublished report to the World Health Organization 1975;

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