(Locust Bean Gum)


         This substance was evaluated for acceptable daily intake for man
    by the Joint FAO/WHO Expert Committee on Food Additives in 1969, 1973
    and 1975 (see Annex I, Refs. 19, 32 and 37). Toxicological monographs
    were issued in 1969, 1973 and 1975 (see Annex I, Refs. 20, 33 and 38).

         Since the previous evaluation, additional data have become
    available and are summarized and discussed in the following monograph.
    The previously issued monographs have been expanded and are reproduced
    in their entirety below.



         In a bioavailable calorie assay, groups of 10 male weanling rats
    (Sprague-Dawley) were given 5 g basal diet or basal diet plus 0.5, 1,
    2 g sucrose or 0.5, 1, 2 g gum for 10 days. Comparison of the carcass
    weight gain showed that carob bean gum was not a source of
    bioavailable calories (Robaislek, 1974).

         Fifteen controls and 18 male test rats, after three days on
    normal diet followed by a 12 hour fast, received two-and-one-half days
    in their diet either 67% cocoa butter with wheat flour or 67% cocoa
    butter with 33% carob bean gum. Glycogen accumulated in the liver but
    far less efficiently than with wheat flour (Krantz et al., 1948).

         A digestibility study in groups of five male and five female rats
    (Purdue strain) on a mannose-free diet showed that 85-100% of mannose
    fed as 1% carob bean gum in the diet for 18 hours was excreted in the
    faeces over a total of 30 hours. 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 (Tsai & Whistler, 1975).


    *    Carob bean gum (also called locust bean gum) is the material
         separated and variously refined from the endosperm of the seed of
         the carob tree, Ceratonia siliqua, a large leguminous evergreen
         that is widely cultivated in the Mediterranean area. The
         carbohydrate component of carob bean gum is considered to be a
         neutral galactomannan polymer consisting of a main chain of 1,4-
         linked D-mannose units with a side chain of D-galactose on every
         fourth or fifth unit, attached through 1,6-glycosidic linkages to
         the polymannose chain. (FASEB/LSRO/SCOGS-3)

         Incubation of solutions or suspensions with human gastric juice,
    duodenal juice + bile, pancreatic juice and succus entericus with or
    without added rabbit small gut membrane enzymes produced no evidence
    of hydrolysis (Semenza, 1975). Rat large gut microflora partially
    hydrolysed carob bean gum in vitro (Towle & Schranz, 1975) after
    conditioning to 1% carob bean gum in the diet for three weeks.

         Groups each of eight male Holtzman rats were maintained on a
    purified synthetic diet, or the diet plus 1% cholesterol, or the diet
    + 1% cholesterol + 10% carob bean gum for 28 days. The increased liver
    cholesterol and liver total lipid induced by cholesterol feeding was
    largely counteracted by concurrent feeding of carob bean gum (Ershoff
    & Wells, 1962).

         Groups each of 12 chicks, one day old were fed a casein sucrose
    basel diet supplement with 3% cholesterol and either 10%, 6%, 3%, 2%,
    1.5% or 1.0% locust bean gum for 27 days. At the end of the test
    period, plasma cholesterol was determined. At the 10% level, there was
    a 35% reduction of plasma cholesterol, no significant effect in body
    weight or food consumption. At the 6% level, there was a moderate
    reduction in cholesterol level. There was a wide variation in the
    hypocholesterolemic activity of the carob bean gums tested with some
    preparation being totally inactive (Fahrenbach et al., 1966).

         The effect of carob or locust bean gum on nitrogen (N) balance
    and dry matter digestibility was studied in rats. Seventy-two weanling
    male Sprague-Dawley rats were divided into a control and five
    experimental groups of 12 animals each. Various gums including locust
    bean gum were fed at the 10% level in a casein-saccharose-corn starch
    diet. Following a three-day adaptation period, feed remnants, urine
    and faeces were collected during an eight-day balance period. Trypsin
    inhibitory activity was measured in each diet. Carob bean gum caused a
    significant rise in faecal N loss, resulting in a marked reduction of
    apparent protein digestibility from 87.8% in the controls to 75%.
    Urinary N was significantly lower than controls. Faecal dry matter was
    also significantly increased by carob bean gum. There was only slight
    trypsin inhibition caused by carob bean gum (Harmuth-Hoene &
    Schwerdtfeger, 1979).

         Carob bean gum has been noted to contain tannins, which depress
    appetite and growth and trypsin inhibitors, which are also growth
    inhibitory (LSRO/FASEB/SCOGS-3, 1972).


    Special studies on teratogenicity

         Teratogenical experiments with four species of animals (rats,
    mice, hamsters and rabbits) did not indicate that the test material
    was a teratogen to mice at 280 mg/kg bw and 1300 mg/kg, although 5/21
    dams died at the latter dose. Up to 1300 mg/kg in rats, up to

    1000 mg/kg in hamsters and at 196 mg/kg in rabbits no teratological
    effects were seen. At 910 mg/kg in rabbits, most of the pregnant dams
    died (Morgareidge, 1972).

         In one study, carob bean gum was injected via the air cell and
    yolk or albumen routes into fertile eggs prior to and after 96 hours
    of incubation. Eggs were candied at 48-hour intervals and dead embryos
    were examined for stage of development and defects. At hatching, all
    chicks were examined for gross defects and samples were taken for
    gross skeletal staining and histopathological examination. Although
    the authors do not state levels of carob bean gum injected, they note
    anophthalmia, phocomelia, micromelia and torticollis occurring with
    carob bean gum (Naber & Smothers, 1975).

    Special studies on mutagenicity

         Mutagenic tests on rats and mice using three different methods
    gave negative results. There was no measurable mutagenic response in
    recombination frequency for Sacc. cerev. in host-mediated assay at
    5 g/kg or in vitro. No adverse effects were seen on chromosomes in rat
    bone marrow or human lung cell cultures. The dominant lethal test in
    rats was negative (Maxwell & Newell, 1972).

         Carob (locust) bean gum was evaluated for genetic activity in
    microbial assays with and without the addition of mammalian metabolic
    activation preparations. Indicator organisms used were Saccharomyces
    cerevisiae and Salmonella typhimurium, strains TA-1535, TA-1537
    and TA-1538. Mammalian metabolic activation preparations were from
    mouse (ICR adult), rat (Sprague-Dawley adult) and monkey (Macaca
    mulatta adult). Carob (locust) bean gum did not exhibit genetic
    activity in any of the assays employed (Brusick, 1975).

    Acute toxicity


    Species      Route       mg/kg bw               Reference

    Rat          Oral         >5000           Maxwell & Newell, 1972

    Short-term studies


         Groups of 10 males and 10 females were fed in their diet carob
    bean gum at levels of 0%, 1%, 2% or 5% for 90 days. General condition,
    behaviour, survival, growth, food intake, haematology, blood
    biochemistry and urinalysis showed no treatment-related differences
    between test and control groups at any dietary level except that the

    last glucose level was slightly increased in the 5% group. Gross and
    microscopic examination did not reveal any pathological changes
    attributable to ingestion of the gum. The increase in the relative
    weight of the caecum at the 2% level is not considered to be of
    toxicological importance (Til et al., 1974).

         Groups each of newly weaned Sprague-Dawley rats (10/group) were
    fed a soybean-corn meal diet containing 2% locust (carob) bean gum for
    36 days. Locust bean gum had no effect in the digestibility of the
    diet, nor was there any significant effect on growth (Vohra et al.,


         Four groups of five male and five female Beagles were fed 0%, 1%
    5% or 10% of a precooked mixture of carob bean and guar gum
    (proportions unknown) for 30 weeks. Only at the 10% level were
    hypermotility and soft, bulky stools observed, probably of not
    toxicological significance. Also at the 10% level digestibility was
    reduced. No adverse haematological, urinary, gross and
    histopathological and ophthalmological findings were noted (Cox et
    al., 1974).


         Groups of 20-day-old chickens were fed diets containing 0.25%,
    0.52%, 12% and 22% carob bean gum for three weeks. Growth depression
    was dose related and marked at the 2% level of intake (Kratzer et al.,
    1967; Vohra & Kratzer, 1964).

         Groups of day-old broiler chickens (seven per group, breed not
    specified) were fed a soybean protein-corn based diet containing 2%
    carob (locust) bean gum for 24 days. The dietary intake of the
    chickens was measured daily for the last week of the experimental
    period; digestibility of the test diet was calculated from the dry
    weights of the feed and excreta. The average body weight of chickens
    and the digestibility of the diet was reduced significantly by the
    inclusion of locust (carob) bean gum in the diet (Vohra et al., 1979).

    Japanese quail

         Groups of day-old Japanese quail (10 per group) were fed a
    soybean-meal-corn based diet containing 2% locust (carob) bean gum for
    either 35 or 37 days. The dietary intake of the quail was measured
    daily for the last week of their experimental period; the
    digestibility of the diet was calculated from the day weights of the
    feed and excreta. Average body weight and digestibility of the diet
    was significantly reduced by inclusion of locust (carob) bean gum in
    the diet (Vohra et al., 1979).

    Long-term studies

         None available.


         A clinical study of a commercial preparation of carob bean grain
    as a laxative in doses of "two heaping teaspoonfuls" in 56 patients,
    some of whom took the preparation regularly for two years, resulted in
    no untoward effects related to the gastrointestinal tract, and no
    allergenic reaction (Holbrook, 1951).

         Eight infants between the ages of 2.5-5 months were fed meals of
    sugared milk or sugared milk plus a 1% powder extract from carob bean.
    Addition of the carob supplement did not alter the duration of the
    gastrointestinal transit time of the meal. Physiological aerophagy was
    markedly suppressed by the supplement (Rivier, 1952).

         In patients with renal failure, ingestion of 25 g of locust bean
    gum/day had a laxative effect, decreased high blood pressure, and
    caused a fall in serum urea, creatinine, and phosphorus by the second
    week of treatment (Yatzidis et al., 1979).


         In vitro tests with human enzyme preparations show little
    utilization by the gut. Carob bean gut was not teratogenic in several
    mammalian species although it did produce terata in the chick embryo
    assay. The available short-term studies in the rat and dog showed no
    evidence of adverse effects at the 5% level. The effects noted in
    feeding trials are those expected of a non-metabolized polymeric
    substance acting as a bulking agent. Carob bean gum is used in
    pharmaceutical preparations.

         The previously requested long-term feeding and reproduction
    studies are not yet available.


    Estimate of acceptable daily intake for man

    Acceptable daily intake not specified.*,**


    Required by 1984

    (1) An adequate long-term study in a rodent species.

    (2) Reproduction studies.


    *    The statement "ADI not specified" means that, on the basis of the
         available data (toxicological, biochemical, and other), the total
         daily intake of the substance, arising from its use or uses at
         the levels necessary to achieve the desired effect and from its
         acceptable background in food, does not, in the opinion of the
         Committee, represent a hazard to health.  For this reason, and
         for the reasons stated in individual evaluations, the
         establishment of an acceptable daily intake (ADI) in mg/kg bw is
         not deemed necessary.

    **   Temporary.


    Brusick, D. Mutagenic evaluation of compound FDA 71-14 PM9000-40-2.
         Locust bean gum. Unpublished report from Litton Bionetics, Inc.
         Submitted to the World Health Organization by the US Food and
         Drug Administration, 1975

    Cox, G. E., Baily, D. E. & Morgareidge, K. Subacute feeding in dogs
         with a precooked gum blend. Unpublished report from the Food and
         Drugs Labs, Inc., submitted to the World Health Organization by
         Hercules B. V., 1974

    Ershoff, B. H. & Wells, A. G. Effects of gum guar, locust bean gum and
         carrageenan on liver cholesterol of cholesterol-fed rats. Proc.
         Soc. exp. Biol. Med., 110, (3), 580-582, 1962

    Fahrenbach, M. J., Riccardi, B. A. & Grant, W. E. Hypocholesterolemic
         activity of mucilaginous polysaccharides in White Leghorn
         cockerels. Proc. Soc. exp. Biol. Med., 13(2), 321-6, 1966

    Harmuth-Hoene, A. & Schwerdtfeger, E. Effect of indigestible
         polysaccharrides on protein digestibility and nitrogen retention
         in growing rats. Nut. Metab., 23, 399-407, 1979

    Holbrook, A. A. The behaviour of carob bean in the gastrointestinal
         tract of man. A. J. Dig. Dis., 18, 24-28, 1951

    Krantz, J. C., Jr., Carr, C. J. & de Farson, C. B. Guar polysaccharide
         as a precursor of glycogen. J. Amer. diet. Ass., 24, 212,

    Kratzer, F. H., Rajaguru, R. W. A. S. B. & Vohra, P. The effect of
         polysaccharides on energy utilization, nitrogen retention and fat
         absorption in chickens. Poultry Sci., 48, 1489-1493, 1967

    LRSO/FASEB. Evaluation of the health aspects of carob bean gum as a
         food - SCOGS-3, 1972

    Maxwell, W. A. & Newell, G. W. Study of the mutagenic effects of FDA
         71-14 (Locust bean gum). Unpublished report from the Stanford
         Research Institute submitted to the World Health Organization by
         Hercules B. V., 1972

    Morgareidge, K. Teratological evaluation of FDA-71-14 (Locust bean
         gum). Unpublished report from the Food and Drug Research Labs,
         Inc. submitted to the World Health Organization by Hercules B.
         V., 1972

    Naber, E. C. & Smothers, S. E. Patterns of toxicity and teratogenicity
         in the chick embryo resulting from the administration of certain
         nutrients and food additives. Poultry Sci., 54(5), 1806, 1975

    Rivier, C. Recherches sur le mode d'action du Nestargel. Schweiz.
         Mediz., 82, 256, 1952

    Robaislek, E. Bioavailable calorie assay of Guar gum. Unpublished
         report from WARF Institute, Inc. submitted to the World Health
         Organization by Institut Europeen des Industries de la Gomme de
         Caroube, 1974

    Semenza, G. Report on the possible digestion of locust bean gum in the
         stomach and/or in the small intestine in an in vitro study.
         Unpublished report from the Eidgenossische Technische Hochschule
         Zurich submitted to the World Health Organization by the Institut
         Europeen des Industries de la Gomme de Caroube, 1975

    Til, H. P., Spanjers, M. Th. & de Groot, A. P. Subchronic toxicity
         study with locust bean gum in rats. Unpublished report from
         Centraal Instituut voor Voedingsonderzoek TNO submitted to the
         World Health Organization by Hercules B.V. and Institut Europeen
         des Industries de la Gomme de Caroube, 1974

    Towle, G. A. & Schranz, R. E. The action of rat microflora on carob
         bean gum solutions in vitro. Unpublished report from Hercules
         Research Center submitted to the World Health Organization by
         Hercules Incorporated, 1975

    Tsai, L. B. & Whistler, R. L. Digestibility of galactomannans.
         Unpublished report submitted to the World Health Organization by
         Professor H. Neukom, Chairman of the Technical Committee of
         Institut Europeen des Industries de la Gomme de Caroube, 1975

    Vohra, P. & Kratzer, F. H. Growth inhibitory effects of certain
         polysaccharides for chickens. Poultry Sci., 43, 1164-1170,

    Vohra, P., Shariff, G. & Kratzer, F. H. Growth inhibitory effect of
         some gums and pectin for Tribolium castaneum larvae, chickens
         and Japanese quail. Nutr. Rep. Internatl., 19(4), 463-469,

    Yatzidis, H., Koutsicos, D. & Digenis, P. Newer oral sorbents in
         uremia. Clin. Nephrol., 11(2), 105-106, 1979

    See Also:
       Toxicological Abbreviations
       Carob bean gum  (FAO Nutrition Meetings Report Series 46a)
       Carob bean gum (WHO Food Additives Series 5)
       CAROB BEAN GUM (JECFA Evaluation)