IngredientsLocust bean gum (LBG, carob gum, carob bean gum, carobin, E410) is a galactomannan vegetable gum extracted from the seeds of the carob tree (Ceratonia siliqua) and used as a thickening agent (gelling agent) in food technology. Additional synonyms include carubin and St. John's Bread gum. Its CAS Registry Number is 9000-40-2 and the EINECS number is 232-541-5. The plant belongs to the family Leguminosae.
LBG is a high molecular weight non-ionic galactomannan polysaccharide, extracted from the seeds of Ceratonia siliqua (carob tree, or locust bean tree, mainly found in the Mediterranean region). Its origins lie in the Middle East where it grows in dry areas with poor soils. The ancient Greeks brought the carob tree from its native lands to the Mediterranean basin, whereas Arabs moved the tree along the north African coast and into Spain and Portugal. Spain, Italy, Portugal, and Greece provide 70–75% of the world's total production.
Carob powder is produced from the fruit pod after removal of seeds, while the gum is produced from the seeds themselves. Carob trees have pods that contain both seeds and pulp. The seed's endosperm—the nutrient-rich tissue that surrounds the embryo within plant seeds—is milled to produce locust bean gum powder. The carob has a very uniform seed size, about 200 mg, and was used as a standard weight in medieval times by jewellers. It has been perpetuated until this day as the unit of gold measurement, the carat.
Locust bean gum occurs as a white to yellow-white powder. The seeds are generally prepared either by thermal, mechanical, or chemical treatment, and then the germ is eliminated. The next steps are milling and screening of the endosperm. Further steps are applied to obtain clarified LBG. The powder is purified by alcoholic precipitation using ethanol or isopropanol: dissolution in hot water, straining, adding alcohol, filtering the mixture when precipitation is formed, drying at room temperature, and powder grinding. As indicated by JECFA specifications, locust bean gum (E 410) is also produced in a purified form as clarified locust bean gum.
The locust bean gum is a polysaccharide extracted from the endosperm of the locust bean seed through different thermomechanical or chemical processes. It is an approved food additive with the European number E410 and a number of different food uses.
The carob tree has been recognised as a valuable resource for many centuries. The carob tree is important in the Mediterranean basin as a crop that can be grown on marginal lands where few other crops can be grown economically. Traditionally, carob trees are interplanted with olives, grapes, and nuts. The carob pods with their high sugar content have been used as cattle fodder. The bean, when made into powder, is sweet — with a flavor similar to chocolate — and has been used to sweeten foods and as a chocolate substitute.
The carob plant's common name "St. John's Bread" (referenced as "St. John's Bread") reflects an ancient association with the food consumed by John the Baptist in biblical tradition, rooted in the Middle Eastern and Mediterranean cultures that depended on the carob as a food staple.
More recently, the major interest in the carob tree has been the extraction of the gum from the seeds. Historically, carob pods were cultivated across the Mediterranean for their nutritional value; the seeds' remarkable uniformity made them a tool of commerce, while the pod pulp served as both human food and animal fodder. The locust bean is an ancient Mediterranean fruit used to make locust bean gum from seeds. Locust bean fruit and gum are rich in bioactive compounds that can be helpful in the treatment of conditions involving the digestive system, as well as cancer, hyperlipidemia, and diabetes.
LBG is considered as the first galactomannan used as an additive in industries such as the paper industry, textile industry, pharmaceutical industry, cosmetic industry, and food industries. Its industrialised use in food manufacturing expanded significantly through the twentieth century.
According to documentation provided to EFSA, locust bean gum consists of 87–88% (on dry basis) high molecular weight polysaccharides composed of mannose and galactose units (galactomannans) in an approximate ratio of 4:1. The remaining 12–13% consists mainly of protein and fibrous matter such as residues from the germ, seed coat, and cell wall material. LBG galactomannans are composed of linear chains of (1→4)-linked β-d-mannopyranosyl units with varying amounts of single (1→6)-linked α-d-galactopyranosyl residues as side chains.
Locust bean gum is composed of a straight backbone chain of D-mannopyranose units with a side-branching unit of D-galactopyranose, having an average of one D-galactopyranose unit branch on every fourth D-mannopyranose unit. Galactomannans are distinguished from each other based on the mannose-to-galactose ratio (M/G); the ratio ranges approximately between 1:1, 2:1, 3:1, or 4:1 for fenugreek, guar, tara, or locust bean gum, respectively.
Using gel-permeation chromatography, the average molecular weight of locust bean gum ranged from 0.3–2.0 million, depending on seed source, plant growing conditions, and manufacturing conditions. It has an extended ribbon-like structure at the solid state and a semi-flexible coil-like conformation in solution.
Solutions of 1% w/w are highly viscous (2,000–6,000 mPa·s); 2–5% w/w swollen dispersions show gel-like behaviour. Soluble in water with the addition of heat, LBG solutions do not form gels by themselves but enhance those produced by other types of hydrocolloids such as xanthan and carrageenan.
The degree of galactose substitution on the mannose chain affects water solubility of the galactomannan. This is why guar gum is cold-water soluble, whereas LBG shows low solubility at ambient temperature and requires heat treatment for maximum solubility to achieve the best water-binding capacity. The molecular size, mannose-to-galactose ratio, and galactose distribution in the mannose backbone chain together influence solubility and control the rheological properties of LBG. Specifically, LBG swells partially in cold water but requires heating to approximately 82°C for complete solubility.
LBG is a vegetable galactomannan extensively used in the food industry as a thickening agent (E410). Its molecular conformation in aqueous solutions determines its solubility and rheological performance. LBG is an interesting polysaccharide also because of its synergistic behaviour with other biopolymers (xanthan gum, carrageenan, etc.). In locust bean gum, the ratio of mannose to galactose is higher than in guar gum, giving it slightly different properties and allowing the two gums to interact synergistically so that together they make a thicker gel than either one alone.
Locust bean gum (E 410) is an authorised food additive in the EU. An acceptable daily intake (ADI) of 'not specified' was allocated by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) in 1981. Although not evaluated by the Scientific Committee for Food (SCF), it was accepted by the SCF in 1991 for use in weaning food, and in 1994, in infant formulae for special medical purposes. The FDA lists locust bean gum as Generally Recognized As Safe (GRAS) for food uses.
The U.S. Food and Drug Administration (FDA) has identified locust bean gum as one of the isolated or synthetic non-digestible carbohydrates that meets the definition of dietary fiber.
The central bioactive constituent of LBG is the galactomannan polysaccharide itself. Locust bean gum is practically undigested, not absorbed intact, but significantly fermented by enteric bacteria in humans. Locust bean gum functions like other soluble dietary fibers and is not absorbed intact in the gut; instead, it passes into the colon where it undergoes fermentation by gut microbiota.
As a viscous soluble fiber, LBG slows down the degradation of carbohydrates during digestion to regulate postprandial blood glucose and insulin levels — important events in the prevention and treatment of obesity and diabetes. In vitro and in vivo data have shown that LBG remains intact in the stomach, resists digestion, and is not absorbed in the human gut.
All of the carbs in LBG come from fiber in the form of galactomannan polysaccharides. These long chains of soluble fiber allow the gum to gel and thicken in liquid. Because this fiber is not absorbed in the body and turns into gel in the digestive tract, it helps soften stool and can reduce constipation.
Soluble fiber is thought to be heart-healthy, as it can bind to dietary cholesterol, preventing it from being absorbed into the bloodstream. The high-viscosity gel formed by LBG in the intestinal lumen is understood to trap bile acids and cholesterol, impeding enterohepatic recirculation — a mechanism shared by other viscous soluble fibers such as psyllium and beta-glucan.
Locust bean gum, as a dietary fiber, has a variety of physiological effects. Several studies have demonstrated that LBG enzyme hydrolysate can increase the content of beneficial bacteria, inhibit the proliferation of harmful bacteria, and maintain the balance of microecology. Results from preclinical research indicate that locust bean gum hydrolysate (LBGH) promoted the levels of short-chain fatty acids (SCFAs), which was beneficial for alleviating intestinal inflammation.
The hypocholesterolaemic effects of locust bean gum were reported by Zavoral et al. (1987) in familial hypercholesterolaemic adults and children and were shown to be a safe and effective approach to controlling hyperlipidaemia. Research published in the American Journal of Clinical Nutrition examined the effects of locust bean gum on adults and children with either high cholesterol or normal cholesterol; all subjects consumed food products that either contained no LBG or contained LBG in an amount ranging from 8 to 30 grams per day. The LBG group showed greater decreases in overall cholesterol as well as LDL cholesterol levels, with no negative side effects recorded; the study concluded that including LBG in food appeared to be a non-risky way to successfully decrease high cholesterol levels.
Locust beans are rich in dietary fibers shown to lower triglycerides and LDL cholesterol levels, assisting with weight loss and having a positive impact on treating hypercholesterolaemia and reducing the risk of cardiovascular diseases. Locust bean fiber has been shown to be effective in decreasing the levels of LDL cholesterol and total cholesterol levels in the bloodstream.
Evidence assessment: The primary human clinical data on LBG's cholesterol effects derives largely from a small number of controlled trials, including the Zavoral et al. (1987) study, conducted in relatively small populations using LBG-enriched foods at doses of 8–30 g/day. This evidence is promising but limited in scale; it is consistent with the known mechanisms of viscous soluble fibers. Larger, independently replicated trials are lacking.
Locust bean gum is considered a dietary fiber suitable as a supplement for weight control and for the treatment of diabetes and hyperlipidaemia. As a viscous soluble fiber, it slows down the degradation of carbohydrates during digestion to regulate postprandial blood glucose and insulin levels — important events in the prevention and treatment of obesity and diabetes.
An animal study published in the journal Phytotherapy Research examined the effects of both guar gum and locust bean gum on blood glucose and insulin levels. The animal subjects were given a diet containing 15% of either locust bean gum or guar gum for two to six consecutive weeks. The researchers observed that the subjects experienced a decrease in both insulin levels and glucose levels. The animal subjects also had lower blood cholesterol levels by the end of the study.
LBG has a lower impact on the glucose response and has a much higher viscosity than thickeners based on starch compounds, allowing a smaller quantity of thickener to provide the same result.
Evidence assessment: The blood-glucose data in humans is primarily mechanistic or extrapolated from animal studies. There are no large, well-controlled human trials specifically testing LBG as an antidiabetic intervention at this time. Effects are biologically plausible but remain preliminary for direct human glucose management.
LBG is a galactomannan polysaccharide used as a thickener in infant formulas with the therapeutic aim to treat uncomplicated gastro-oesophageal reflux (GER). In the context of uncomplicated but persistent GER, one of the recommended approaches is the use of dietary interventions employing thickening agents or thickened infant formulas. Such interventions are most often based on slowly or non-digestible polysaccharide food components (cereals, starch, guar gum, soy fibre, locust bean gum). Among those thickening agents, LBG is extensively used in a large range of commercially thickened infant formulas prescribed to treat GER. To exert a beneficial effect on reflux, LBG-thickened formulas in general contain an average level situated at 0.5 g/100 mL of LBG.
A multi-center prospective randomised controlled trial (RCT) was conducted as a tolerance and safety study investigating the thickener locust bean gum in infants with regurgitation, to support the re-evaluation of the safety of LBG in infant formula. The primary objective was to demonstrate that after an 8-week intervention, stool consistency was not inferior in infants fed an anti-regurgitation formula containing LBG vs. the stool consistency of infants fed with an unthickened control formula. A total of 103 full-term infants with regurgitation were randomised to the test or control formula. The test formula contained LBG at 0.4 g/100 mL.
The new anti-regurgitation formula combining locust bean gum with pre- and postbiotics was found to be well-tolerated and safe; both AR formulae improved regurgitation and most gastrointestinal symptoms within one week of intervention. Locust bean gum-thickened formula decreased infant regurgitation, was well tolerated, and improved parental quality of life; stool composition and frequency of the infants remained within the physiological range.
AR formulae containing LBG have been demonstrated to be safe and effective in reducing the frequency and volume of regurgitation in numerous clinical studies of infants with regurgitation.
Evidence assessment: This is the most clinically well-supported area of LBG use in a health context. Multiple controlled trials and real-world studies consistently demonstrate efficacy in reducing regurgitation frequency and volume in formula-fed infants. The evidence base is stronger here than for any other proposed health application of LBG.
Locust bean gum, as a dietary fiber, has a variety of physiological effects. In one study, locust bean gum hydrolysate (LBGH) was obtained from the acid hydrolysis of locust bean gum and then characterised and tested. Results indicated that LBGH promoted the levels of SCFAs, which was beneficial for alleviating intestinal inflammation.
Several studies have demonstrated that LBG enzyme hydrolysate can increase the content of beneficial bacteria, inhibit the proliferation of harmful bacteria, and maintain the balance of microecology.
Evidence assessment: The prebiotic evidence for LBG comes predominantly from preclinical (animal and in vitro) studies. Human trials specifically testing LBG's prebiotic effects on microbiome composition or function are not yet well established. Mechanistically, LBG's fermentability by colonic bacteria is well documented, but clinical translation requires further study.
A 2022 study published in Frontiers in Microbiology (PMC9399726) investigated the properties of locust bean gum hydrolysate (LBGH) in a dextran sulfate sodium-induced colitis model. Results indicated that LBGH promoted the levels of SCFAs, which was beneficial for alleviating intestinal inflammation.
Evidence assessment: This evidence is purely preclinical (animal model). No human clinical trials have examined LBG or its hydrolysate as a treatment for inflammatory bowel disease at the time of the available published literature.
Locust bean gum is considered a dietary fiber suitable as a supplement for weight control. The mechanism proposed is viscosity-mediated satiety: LBG gels in the digestive tract, slowing gastric emptying and nutrient absorption, which may reduce caloric intake. However, locust bean gum is used in very small quantities in most foods, so consumers may not reap the benefits of soluble fiber by consuming products that merely contain it as an additive.
Evidence assessment: No dedicated human clinical trials specifically addressing LBG supplementation for weight management have been identified in the peer-reviewed literature. The proposed effect is an extrapolation of the general evidence on viscous soluble fiber and satiety.
LBG is available commercially as a fine white powder, used both as a food ingredient and as a standalone supplement. Typical usage level in food is 0.1–1.0%.
In the context of cholesterol management, one study looked at the effects of locust bean gum in 17 adults and 11 children, some of whom had familial, or inherited, high cholesterol. The group that ate foods containing 8–30 grams of locust bean gum per day for 2 weeks experienced greater improvements in cholesterol than a control group.
In infant anti-regurgitation formula, LBG-thickened formulas in general contain an average level of 0.5 g/100 mL of LBG. The multi-centre RCT referenced above used a test formula containing LBG at 0.4 g/100 mL.
In the animal blood glucose study, the animal subjects were given a diet containing 15% of either locust bean gum or guar gum for two to six consecutive weeks. This dose would not be applicable to human use without direct clinical study.
LBG has a lower caloric value and has been reported to have a higher viscosity in vitro compared to starches, allowing a smaller quantity to provide the same thickening result.
EFSA's re-evaluation concluded that no numerical Acceptable Daily Intake (ADI) was necessary, as it does not pose a safety concern for the general population at reported use levels. The FDA lists locust bean gum as Generally Recognized As Safe (GRAS) for food uses. Overall, toxicological studies show no evidence of carcinogenicity, genotoxicity, or reproductive toxicity.
The main side effects reported relate to excessive fiber intake, such as bloating or loose stools at high doses. For normal dietary exposure, it is safe. As EFSA pointed out, hypersensitivity and undesirable gastrointestinal effects, such as diarrhoea, frequent loose stools, and flatulence, occurred when locust bean gum was used to treat gastro-oesophageal reflux in infants and young children.
In human adults, there are few case reports of allergy to locust bean gum after oral ingestion. However, most of the reports described rhinitis and asthma that were essentially caused by occupational contact with locust bean gum. The EFSA Panel recognised the possible potential allergenicity of locust bean gum but noted that the specification and origin of the gum are lacking in these studies.
The EFSA Panel noted some case reports of hypersensitivity reactions, including the case of a 5-month-old infant associated with locust bean gum. The prevalence of LBG-hypersensitivity after ingestion is expected to be very low in the overall population.
Post-marketing data from industry did not show serious adverse events among over 50 million units sold, except for one single case of allergic reaction.
Mainly in vitro studies have suggested that LBG could negatively modify the absorption efficiency of some minerals. This has not been confirmed as clinically significant in controlled human studies, but it is a noted data gap in EFSA's risk assessment framework.
Locust bean gum was re-evaluated by EFSA in 2017. As a follow-up to that assessment, the Panel on Food Additives and Flavourings (FAF) was requested to assess the safety of locust bean gum (E 410) for its uses as a food additive in food for infants below 16 weeks of age. The Panel identified a reference point of 1,400 mg/kg body weight per day based on reduced blood zinc levels in a piglet study. It applied the margin of exposure (MoE) for the safety assessment; a MoE above 1 would not raise a safety concern. A MoE above 1 was obtained for some of the scenarios and exposure levels for infants.
The additional safety and tolerance evidence from paediatric data has been integrated as part of the total weight of evidence to confirm the safety and tolerability of LBG in healthy term infants treated by dietary interventions for uncomplicated gastro-oesophageal reflux.
Some batches were recalled in 2021 in the EU because of ethylene oxide contamination — a manufacturing impurity issue rather than an intrinsic hazard of the gum itself. According to the recent JECFA evaluation (summary of JECFA, 2016), a limit of 0.5 mg/kg for lead was introduced for locust bean gum and locust bean gum (clarified) for use in infant formula.
Health conditions that Locust bean gum may help support.
Body systems that Locust bean gum may help support.
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